[top]
000
FXUS65 KGGW 051643
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
1043 AM MDT SUN JUL 5 2009
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH TUESDAY...
SHOWERS AND THUNDERSTORMS ARE STEADILY DISSIPATING AND EXITING THE
REGION THIS MORNING AS A WEAK SHORTWAVE TROUGH DEPARTS EASTWARD
OVER NORTH DAKOTA. A SURFACE TROUGH IS ANCHORED OVER CENTRAL
MONTANA ASSOCIATED WITH A 1000-500MB THICKNESS RIDGE. THIS WILL
PROVIDE ENHANCED LOW LEVEL CONVERGENCE OVER YESTERDAY INCREASING
THE LIKELIHOOD OF AFTERNOON THUNDERSTORMS...ESPECIALLY AS ANOTHER
UPPER SHORTWAVE...CURRENTLY OVER WESTERN MONTANA...STEADILY PLODS
EAST THROUGH THE LONGWAVE STEERING FLOW. SURFACE DEWPOINTS ARE
REMAINING IN THE MID TO UPPER 50S AS OF 16Z. IF THESE VALUES
REMAIN STEADY OR ONLY SLOWLY FALL THROUGH THE AFTERNOON LOW LEVEL
MOISTURE COULD BE DEEPER THAN INITIALLY EXPECTED...WHICH WOULD
SUGGEST GREATER INSTABILITY. IN THIS CASE A FEW STRONGER STORMS
COULD DEVELOP...AND THERE COULD BE AN ISOLATED SEVERE STORM AS A
BOUNDARY IS PRESENT ACROSS THE NORTHEAST CORNER OF THE CWA. THE
WIND HAS DIMINISHED TO LESS THAN 20 MPH ACROSS FORT PECK LAKE. AT
THIS POINT IT IS NOT EXPECTED TO INCREASE...SO THE LAKE WIND
ADVISORY WILL BE CANCELLED. AJZ
PREVIOUS SHORT TERM DISCUSSION...
THE UPPER RIDGE AXIS SHIFTS INTO WESTERN MONTANA TODAY MAINTAINING
NW FLOW ALOFT OVER THE FORECAST AREA. THE MORNING WILL SEE A WEAK
DISTURBANCE IN THE UPPER FLOW EXIT THE NORTHERN ZONES TO THE EAST
BY NOON. A CLOSED UPPER LOW OFF THE PACNW COAST WILL PUSH FARTHER
EAST AMPLIFYING THE RIDGE. AS A RESULT THE LOCAL AREA WILL
EXPERIENCE SLIGHTLY ABOVE SEASONAL TEMPERATURES TODAY AS HEIGHTS
INCREASE. ONCE AGAIN THE CENTRAL REGION WITH SLIGHT DISTURBANCES
IN THE UPPER FLOW WILL EXPERIENCE AFTERNOON AND EVENING
THUNDERSTORMS WHICH COULD DRIFT INTO OUR AREA. THE SURFACE
HIGH...THAT PREVENTED THUNDERSTORMS FROM MOVING TOO FAR INTO OUR
AREA SUNDAY...WILL ALSO DRIFT A LITTLE MORE EAST PROVIDING A BIT
MORE INSTABILITY. SO WILL MAINTAIN A SLIGHT CHANCE FOR THUNDER AND
ASSOCIATED SHOWERS.
THE RIDGE AXIS PASSES OVER THE LOCAL AREA MONDAY AS THE PACIFIC
LOW MOVES INTO BRITISH COLUMBIA...SENDING SW UPPER FLOW INTO THE
CENTRAL REGION. WITH A REPEAT IN MAXIMUM TEMPERATURES FROM THE
PREVIOUS DAY AND A THERMAL RIDGE NUDGING INTO OUR SW
ZONES...ANOTHER ROUND OF THUNDERSTORMS CAN BE EXPECTED. THE LEE
SURFACE TROUGH CLOSES OFF OVER CENTRAL MT FOCUSING INSTABILITY AND
MOISTURE WITH THE UPPER JET LATE AFTERNOON AND EVENING. WITH THE
DYNAMIC FORCING...THUNDERSTORMS...SOME POSSIBLY SEVERE...ARE ONCE
AGAIN ON THE MENU. BUT EXACTLY WHERE IS STILL IN QUESTION BASED ON
MODEL DIFFERENCES. MODELS ALSO DIFFER A BIT ON MOISTURE...BUT
AROUND AN INCH OF PRECIPITABLE WATER IS REASONABLE. THE NORTHERN
ZONES AND SOUTHERN SASKATCHEWAN COULD SEE SOME HEAVY RAIN MONDAY
NIGHT.
TUESDAY CAN EXPECT SEASONAL TEMPERATURES AS THE THERMAL RIDGE
MOVES INTO N DAKOTA. HOWEVER SW FLOW ALOFT WILL CONTINUE TO
SUPPORT THE DEVELOPMENT OF A FEW THUNDERSTORMS. SCT
.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
UPPER LOW THAT IS FORECASTED TO BE OVER BRITISH COLUMBIA ON
TUESDAY AND WEDNESDAY MOVES EAST ACROSS SASKATCHEWAN ON THURSDAY.
THE ECMWF REMAINS CONSISTENT IN TURNING THIS LOW INTO AN OPEN
TROUGH BY THE TIME IT REACHES SASKATCHEWAN AND EASTERN MONTANA
THURSDAY MORNING. THE 00Z GFS MAINTAINS A CLOSED LOW INTO SASKATCHEWAN
WHILE EARLIER RUNS HAVE VARIED FROM AN OPEN TROUGH SIMILAR TO THE
ECMWF TO HAVING JUST SOUTHWEST FLOW ALOFT OVER THE AREA. WILL KEEP
THE FORECAST CLOSER TO THE ECMWF SOLUTION FOR NOW. SOUTHWEST FLOW
ALOFT AHEAD OF THIS TROUGH TUESDAY NIGHT AND WEDNESDAY WILL BRING
MOISTURE INTO THE FORECAST AREA. THIS SHOULD YIELD A GOOD CHANCE
OF THUNDERSTORMS WEDNESDAY AND WEDNESDAY NIGHT WHEN A FRONTAL
SYSTEM PASSES THROUGH THE AREA.
DRIER AIR WILL MOVE INTO EASTERN MONTANA AS THE SYSTEM EXITS THE
AREA DURING THE DAY ON THURSDAY. WILL LEAVE A SLIGHT CHANCE OF
STORMS IN THE FORECAST FOR NOW AS LINGERING INSTABILITY IS
POSSIBLE.
MODELS DIFFERENCES SHOW UP NEXT WEEKEND. THE 00Z NOW HAS THE
UPPER RIDGE FOR FRIDAY THROUGH SUNDAY THAT THE LAST SEVERAL ECMWF
RUNS SHOWED. HOWEVER...THE ECMWF NOW HAS NW FLOW ALOFT WITH A
SHORTWAVE FRIDAY NIGHT WHILE KEEPING THE RIDGE TO THE WEST UNTIL SUNDAY.
WILL KEEP NEXT WEEKEND DRY FOR THE MOST PART FOR NOW.
&&
.AVIATION...
VFR CONDITIONS EXPECTED MOST OF THE TIME WITH SCATTERED TO BROKEN
MID AND HIGH CLOUDS. A FEW THUNDERSTORMS NEAR THE NORTH DAKOTA
BORDER WILL MOVE EAST OF THE REGION LATE THIS MORNING. ADDITIONAL
THUNDERSTORMS MAY DEVELOP AGAIN LATE THIS AFTERNOON AND OVERNIGHT.
WINDS WILL BE FROM THE EAST AT 10 KNOTS OR LESS. RAE
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
[top]
000
FXUS65 KMSO 051640
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
1040 AM MDT SUN JUL 5 2009
.UPDATE...
FORECAST HIGH TEMPERATURES HAVE BEEN COOLED A FEW DEGREES
TODAY...CITING CLOUD COVER ACROSS THE AREA.
&&
.PREV DISCUSSION... /ISSUED 912 AM MDT SUN JUL 5 2009/
UPDATE...
AREAL COVERAGE OF THUNDERSTORMS HAS BEEN INCREASED FOR THE
REMAINDER OF THIS MORNING BASED ON RECENT OBSERVATIONAL TRENDS.
PREV DISCUSSION... /ISSUED 432 AM MDT SUN JUL 5 2009/
.POTENTIAL FOR SEVERE THUNDERSTORMS ACROSS NORTHWEST MONTANA
MONDAY AFTERNOON...
DISCUSSION...A WEAK MID-LEVEL SHORT WAVE WEATHER DISTURBANCE...
ROTATING WITHIN THE FLOW OVER OREGON...IS APPROACHING THE IDAHO
BORDER THIS MORNING. THUNDERSTORMS HAVE CONTINUED THROUGHOUT THE
NIGHT ALONG THIS DISTURBANCE AND SHOULD CONTINUE DURING THE
MORNING HOURS AS THE SHORT WAVE MOVES OVER CENTRAL IDAHO.
THIS AFTERNOON THE ATMOSPHERE OVER WESTERN MONTANA AND CENTRAL
IDAHO WILL ONCE AGAIN DESTABILIZE...EVEN MORE SO THAN PREVIOUS DAYS
WITH INSTABILITY EXISTING IN NUMERICAL MODEL DATA TO THE CANADIAN
BORDER BY THIS AFTERNOON. DESPITE SOMEWHAT INCREASED CLOUD COVER
LATER THIS AFTERNOON...SUFFICIENT DAYTIME HEATING WILL LEAD TO
EXCEPTIONALLY WARM CONDITIONS WITH HIGH BEING AT LEAST AS WARM...IF
NOT WARMER THAN YESTERDAYS OBSERVED VALUES. THESE FACTORS COMBINED
WITH A FULLY MOISTENED ATMOSPHERE FROM DAYS OF MID-LEVEL SUB-
TROPICAL MOISTURE INFILTRATION WILL LEAD TO WIDESPREAD
THUNDERSTORM DEVELOPMENT TODAY ACROSS IDAHO AND WESTERN MONTANA.
HOWEVER ONLY MODERATE POTENTIAL FOR SEVERE THUNDERSTORMS EXISTS
TODAY SINCE THE WIND PROFILE FROM THE SURFACE TO 10,000 FEET ALOFT
IS WEAKLY SHEARED. AS A RESULT...SOME THUNDERSTORMS THAT DO FORM
WILL BE CAPABLE OF SMALL HAIL UP TO AROUND ONE-HALF OF AN INCH
DIAMETER AND GUSTY WINDS TO 50 MPH. AN OCCASIONAL STORM MAY SPIKE
STRONGER FOR A BRIEF PERIOD OF TIME...ESPECIALLY LATE IN THE
AFTERNOON OR EARLY EVENING HOURS. HOWEVER THESE STORMS SHOULD BE
LIMITED IN NATURE GIVEN THE PREVIOUS REASONING.
CONDITIONS WILL RAPIDLY BECOME MORE FAVORABLE FOR SEVERE
THUNDERSTORMS ON MONDAY AFTERNOON...ESPECIALLY ACROSS NORTHWEST
MONTANA. A PACIFIC TROUGH OF LOW PRESSURE WILL APPROACHES THE
REGION TONIGHT...CAUSING THE UPPER LEVEL RIDGE OF HIGH PRESSURE TO
MOVE EAST. THE ENSUING SOUTHWESTERLY FLOW ALOFT WILL PRODUCE A
HIGHLY DIRECTIONALLY WIND SHEARED ENVIRONMENT OVER NORTHWEST
MONTANA. TO ADD ADDITIONAL WIND SHEAR TO THE PROFILE...FORECAST
MODELS ARE SHOWING AN ACCELERATION IN THE UPPER LEVEL JET STREAM
MOVING INTO THE NORTHERN ROCKIES AT THE SAME TIME. ADD TO THE
EQUATION ABUNDANT INSTABILITY AIDED BY AN APPROACHING
COOLER...DRIER AIRMASS AND STRONG...ORGANIZED THUNDERSTORMS APPEAR
QUITE LIKELY FROM GENERALLY I-90 NORTH AND EAST TO THE CONTINENTAL
DIVIDE. DAMAGING WIND GUSTS IN EXCESS OF 60 MPH AND LARGE HAIL
GREATER THAN ONE INCH IN DIAMETER APPEAR LIKELY WITH THUNDERSTORM
ACROSS THIS REGION. THUS A HAZARDOUS WEATHER OUTLOOK WILL BE
ISSUED TO FURTHER DISCUSS THE POTENTIAL FOR SEVERE THUNDERSTORMS
TODAY AND TOMORROW. THE MAJORITY OF THESE THUNDERSTORMS WILL
QUICKLY MOVE NORTHEAST MONDAY EVENING AS DRIER MORE STABLE AIR
ENTERS THE REGION.
TUESDAY THROUGH SATURDAY...MUCH COOLER AND UNSETTLED WEATHER WILL
BE OVER THE NORTHERN ROCKIES TUESDAY AND WEDNESDAY AS THE UPPER
TROUGH REMAINS OVER THE NORTHWEST U.S. A STRONG SHORTWAVE WILL
EJECT OUT OF THE LONGWAVE TROUGH AND PUSH OVER THE AREA WEDNESDAY.
THUS THIS CONTINUES TO LOOK LIKE THE COOLEST AND WETTEST DAY.
LOWER ATMOSPHERIC LAPSE RATES COULD STILL SUPPORT SOME
THUNDERSTORMS IF FORCING IS SUFFICIENT...BUT INSTABILITY INTO
MIDWEEK WILL BE MUCH LESS SIGNIFICANT THAN TODAY AND MONDAY. THE
AIR MASS WILL BEGIN TO DRY AND WARM LATER IN THE WEEK AS THE
LONGWAVE TROUGH RETROGRADES OFF THE WEST COAST LEAVING A
PERSISTENT SOUTHWEST FLOW OVER THE NORTHERN ROCKIES.
AVIATION...SHOWERS AND THUNDERSTORMS WILL BECOME MORE WIDESPREAD
TODAY...LARGELY IMPACTING ALL AIRFIELDS AND TERMINALS TODAY.
THE STRONGER STORMS WILL PRODUCE SMALL HAIL AND GUSTY WINDS TO 40
KT WITH THE THREAT FOR A FEW ISOLATED SEVERE THUNDERSTORMS POSSIBLE
WITH BRIEF WIND GUSTS TO AROUND 50 KT.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&
$$
SHORT TERM...99
LONG TERM....99
AVIATION...99
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000
FXUS65 KTFX 051527
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
920 AM MDT SUN JUL 5 2009
UPDATE...UPPER LEVEL DISTURBANCE RIDING ACROSS THE TOP OF THE BROAD
UPPER RIDGE OVER NRN ROCKIES ALREADY PRODUCING AREA OF SHOWERS AND
THUNDERSTORMS OVER CENTRAL ID/WESTERN MT. PRECIP SHOULD MOVE INTO
SW MT LATER THIS MORNING AND THEN INTO CENTRAL/NORTH CENTRAL MT THIS
AFTN. LIKE PAST FEW DAYS...INSTABILITY AND WIND SHEAR ALOFT IS
SUFFICIENT FOR SOME STORMS TO BE STRONG TO SEVERE WITH HAIL AND
GUSTY WINDS. 12Z MODELS SHOW BEST SEVERE PARAMETERS ALONG THE
HILINE THIS EVE. STORMS WILL DISSIPATE AROUND SUNSET.
FIRST LOOK AT INCOMING MORNING DATA STILL INDICATING POSSIBLE
WIDESPREAD SEVERE WEATHER EVENT TOMORROW. MORE DETAILS TO COME IN
THIS AFTERNOON`S FORECAST DISCUSSION. WARANAUSKAS
.DISCUSSION...
TODAY THROUGH TUESDAY...FOR TODAY EXPECT ANOTHER DAY OF SCATTERED
MAINLY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS. IT LOOKS
LIKE THERE MIGHT BE A LITTLE LESS INSTABILITY OVER THE PLAINS
RELATIVE TO YESTERDAY. OVER SOUTHWEST MONTANA AM SEEING ABOUT THE
SAME INSTABILITY AS YESTERDAY. A WEATHER DISTURBANCE ALOFT OVER
SOUTHWEST OREGON IS EXPECTED TO MOVE THROUGH SOUTHWEST MONTANA
DURING THE DAY AND SHOULD HELP TRIGGER THE SHOWERS AND
THUNDERSTORMS IN THAT REGION. EXPECT SHOWERS AND THUNDERSTORMS TO
DIMINISH NEAR AND AFTER DARK. THE MAIN WEATHER CONCERN DURING THE
PERIOD WILL BE THE POSSIBILITY OF SEVERE THUNDERSTORMS MONDAY
AFTERNOON AND EVENING. SHOULD SEE SLIGHTLY GREATER INSTABILITY
THAN TODAY. THERE WILL BE IMPRESSIVE LIFT AHEAD OF A COLD FRONT
WHICH WILL MOVE THROUGH MOST OF THE FORECAST AREA MONDAY AFTERNOON
AND EVENING. WIND PROFILES FROM THE SURFACE AND ON UP ALSO FAVOR
SEVERE STORMS. FOR TUESDAY THE COLD FRONT MENTIONED ABOVE WILL GET
HUNG UP FROM CENTRAL MONTANA TO SOUTHWEST MONTANA. EXPECT SHOWERS
AND THUNDERSTORMS TO DEVELOP NEAR THIS FRONT DURING THE AFTERNOON
THEN SPREAD NORTHEAST DURING THE EVENING. BLANK
TUESDAY NIGHT THROUGH FRIDAY NIGHT...MODELS SEEM TO BE IN BETTER
AGREEMENT WITH HANDLING THE ARRIVAL OF AN UPPER-LEVEL TROUGH INTO
THE PACIFIC NORTHWEST AT THE START OF THE PERIOD. WITH PREDOMINANT
SOUTHWEST FLOW...A FAIR AMOUNT OF PACIFIC MOISTURE WILL SPREAD
INTO THE REGION ON TUESDAY NIGHT WHILE LIFT ALOFT ASSOCIATED WITH
A SERIES OF SHORTWAVES PROMOTES LIFT AND SUPPORT FOR NOCTURNAL
CONVECTION. THUS...INCREASED POPS FOR TUESDAY NIGHT. THE MAIN
DIFFERENCE BETWEEN THE ECMWF AND GFS MODELS IS THE PLACEMENT OF THE
HEAVIEST PRECIPITATION SINCE IT WILL DEPEND ON WHERE THE BEST LIFT
SETS UP SO WILL CONTINUE TO MONITOR THIS TREND. THE UNSETTLED
PATTERN WILL CONTINUE INTO WEDNESDAY AND WEDNESDAY NIGHT SO HAVE
KEPT CHANCE POPS IN THE FORECAST FOR THIS TIME FRAME. CLOUDS AND
PRECIPITATION WILL KEEP TEMPERATURES ABOUT 10 TO 15 DEGREES BELOW
AVERAGE. ON THURSDAY...A WEAK RIDGE MOVES INTO MONTANA WHICH WILL
YIELD QUIETER CONDITIONS ACROSS THE FORECAST AREA...BUT TEMPERATURES
WILL STILL BE SLIGHTLY BELOW AVERAGE WITH NORTHWEST FLOW PRESENT.
STILL KEPT SLIGHT CHANCE OF POPS MAINLY IN THE MOUNTAINS WHERE
TERRAIN-BASED INSTABILITY WILL BE PRESENT. MODELS DIVERGE BY FRIDAY
WITH GFS A BIT SLOWER THAN THE ECMWF AS NEXT SHORTWAVE ENERGY
ARRIVES. NEAR AVERAGE TEMPS ARE EXPECTED BY FRIDAY AND HAVE KEPT
POPS CLOSER TO CLIMATOLOGICAL VALUES. MLS
SATURDAY THROUGH SUNDAY...MODELS ARE IN BASIC AGREEMENT DURING THIS
PERIOD...WITH SOME DIFFERENCES IN TIMING OF FEATURES. A WEAK UPPER
LEVEL RIDGE DRIFTS EASTWARD ACROSS THE REGION BY SUNDAY AFTERNOON.
PARTLY CLOUDY SKIES ARE EXPECTED FOR MOST LOCATIONS. LIMITED
MOISTURE AND INSTABILITY WILL RESULT IN MOSTLY CLOUDY SKIES OVER THE
MOUNTAINS...WITH ISOLATED SHOWERS AND A FEW MAINLY AFTERNOON AND
EVENING THUNDERSTORMS. SHOWERS AND THUNDERSTORMS WILL BE A LITTLE
MORE WIDESPREAD OVER THE WESTERN MOUNTAINS. TEMPERATURES ARE
EXPECTED TO TO BE NEAR SEASONAL AVERAGES. EK
&&
.AVIATION...
UPDATED 1200Z.
ISOLATED SHOWERS AND THUNDERSTORMS WILL AFFECT FAR NORTHEASTERN
MONTANA THIS MORNING INCLUDING KHVR SO HAVE KEPT VCTS...HOWEVER AM
EXPECTING THE ACTIVITY TO NOT DIRECTLY AFFECT THE KHVR TERMINAL.
OTHERWISE...VFR CONDITIONS WILL CONTINUE TO PREVAIL ACROSS THE
FORECAST AREA THROUGH EARLY MONDAY MORNING. ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS WILL DEVELOP ONCE AGAIN AFTER 18Z SUNDAY
AND SOME STORMS MAY PRODUCE OCCL MVFR CONDITIONS IN ADDITION TO
GUSTY WINDS...BRIEF HEAVY RAINFALL AND HAIL. CONVECTION WILL
DECREASE TOWARDS SUNSET ON SUNDAY EVENING BUT A FEW SHOWERS MAY
LINGER ACROSS NORTH-CENTRAL MONTANA NEAR KCTB AND KHVR. MLS
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 85 57 83 52 / 30 20 30 30
CTB 80 53 75 46 / 20 30 50 30
HLN 88 59 89 53 / 30 20 30 30
BZN 87 54 90 50 / 30 10 20 30
WEY 72 43 76 39 / 30 30 20 30
DLN 79 53 81 48 / 30 10 20 20
HVR 89 56 87 52 / 20 30 30 50
LWT 82 53 80 49 / 30 20 30 40
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BLANK
LONG TERM...MLS/KURDY
AVIATION...MLS
WEATHER.GOV/GREATFALLS
000
FXUS65 KMSO 051512
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
912 AM MDT SUN JUL 5 2009
.UPDATE...
AREAL COVERAGE OF THUNDERSTORMS HAS BEEN INCREASED FOR THE
REMAINDER OF THIS MORNING BASED ON RECENT OBSERVATIONAL TRENDS.
&&
.PREV DISCUSSION... /ISSUED 432 AM MDT SUN JUL 5 2009/
..POTENTIAL FOR SEVERE THUNDERSTORMS ACROSS NORTHWEST MONTANA
MONDAY AFTERNOON...
DISCUSSION...A WEAK MID-LEVEL SHORT WAVE WEATHER DISTURBANCE...
ROTATING WITHIN THE FLOW OVER OREGON...IS APPROACHING THE IDAHO
BORDER THIS MORNING. THUNDERSTORMS HAVE CONTINUED THROUGHOUT THE
NIGHT ALONG THIS DISTURBANCE AND SHOULD CONTINUE DURING THE
MORNING HOURS AS THE SHORT WAVE MOVES OVER CENTRAL IDAHO.
THIS AFTERNOON THE ATMOSPHERE OVER WESTERN MONTANA AND CENTRAL
IDAHO WILL ONCE AGAIN DESTABILIZE...EVEN MORE SO THAN PREVIOUS DAYS
WITH INSTABILITY EXISTING IN NUMERICAL MODEL DATA TO THE CANADIAN
BORDER BY THIS AFTERNOON. DESPITE SOMEWHAT INCREASED CLOUD COVER
LATER THIS AFTERNOON...SUFFICIENT DAYTIME HEATING WILL LEAD TO
EXCEPTIONALLY WARM CONDITIONS WITH HIGH BEING AT LEAST AS WARM...IF
NOT WARMER THAN YESTERDAYS OBSERVED VALUES. THESE FACTORS COMBINED
WITH A FULLY MOISTENED ATMOSPHERE FROM DAYS OF MID-LEVEL SUB-
TROPICAL MOISTURE INFILTRATION WILL LEAD TO WIDESPREAD
THUNDERSTORM DEVELOPMENT TODAY ACROSS IDAHO AND WESTERN MONTANA.
HOWEVER ONLY MODERATE POTENTIAL FOR SEVERE THUNDERSTORMS EXISTS
TODAY SINCE THE WIND PROFILE FROM THE SURFACE TO 10,000 FEET ALOFT
IS WEAKLY SHEARED. AS A RESULT...SOME THUNDERSTORMS THAT DO FORM
WILL BE CAPABLE OF SMALL HAIL UP TO AROUND ONE-HALF OF AN INCH
DIAMETER AND GUSTY WINDS TO 50 MPH. AN OCCASIONAL STORM MAY SPIKE
STRONGER FOR A BRIEF PERIOD OF TIME...ESPECIALLY LATE IN THE
AFTERNOON OR EARLY EVENING HOURS. HOWEVER THESE STORMS SHOULD BE
LIMITED IN NATURE GIVEN THE PREVIOUS REASONING.
CONDITIONS WILL RAPIDLY BECOME MORE FAVORABLE FOR SEVERE
THUNDERSTORMS ON MONDAY AFTERNOON...ESPECIALLY ACROSS NORTHWEST
MONTANA. A PACIFIC TROUGH OF LOW PRESSURE WILL APPROACHES THE
REGION TONIGHT...CAUSING THE UPPER LEVEL RIDGE OF HIGH PRESSURE TO
MOVE EAST. THE ENSUING SOUTHWESTERLY FLOW ALOFT WILL PRODUCE A
HIGHLY DIRECTIONALLY WIND SHEARED ENVIRONMENT OVER NORTHWEST
MONTANA. TO ADD ADDITIONAL WIND SHEAR TO THE PROFILE...FORECAST
MODELS ARE SHOWING AN ACCELERATION IN THE UPPER LEVEL JET STREAM
MOVING INTO THE NORTHERN ROCKIES AT THE SAME TIME. ADD TO THE
EQUATION ABUNDANT INSTABILITY AIDED BY AN APPROACHING
COOLER...DRIER AIRMASS AND STRONG...ORGANIZED THUNDERSTORMS APPEAR
QUITE LIKELY FROM GENERALLY I-90 NORTH AND EAST TO THE CONTINENTAL
DIVIDE. DAMAGING WIND GUSTS IN EXCESS OF 60 MPH AND LARGE HAIL
GREATER THAN ONE INCH IN DIAMETER APPEAR LIKELY WITH THUNDERSTORM
ACROSS THIS REGION. THUS A HAZARDOUS WEATHER OUTLOOK WILL BE
ISSUED TO FURTHER DISCUSS THE POTENTIAL FOR SEVERE THUNDERSTORMS
TODAY AND TOMORROW. THE MAJORITY OF THESE THUNDERSTORMS WILL
QUICKLY MOVE NORTHEAST MONDAY EVENING AS DRIER MORE STABLE AIR
ENTERS THE REGION.
TUESDAY THROUGH SATURDAY...MUCH COOLER AND UNSETTLED WEATHER WILL
BE OVER THE NORTHERN ROCKIES TUESDAY AND WEDNESDAY AS THE UPPER
TROUGH REMAINS OVER THE NORTHWEST U.S. A STRONG SHORTWAVE WILL
EJECT OUT OF THE LONGWAVE TROUGH AND PUSH OVER THE AREA WEDNESDAY.
THUS THIS CONTINUES TO LOOK LIKE THE COOLEST AND WETTEST DAY.
LOWER ATMOSPHERIC LAPSE RATES COULD STILL SUPPORT SOME
THUNDERSTORMS IF FORCING IS SUFFICIENT...BUT INSTABILITY INTO
MIDWEEK WILL BE MUCH LESS SIGNIFICANT THAN TODAY AND MONDAY. THE
AIR MASS WILL BEGIN TO DRY AND WARM LATER IN THE WEEK AS THE
LONGWAVE TROUGH RETROGRADES OFF THE WEST COAST LEAVING A
PERSISTENT SOUTHWEST FLOW OVER THE NORTHERN ROCKIES.
AVIATION...SHOWERS AND THUNDERSTORMS WILL BECOME MORE WIDESPREAD
TODAY...LARGELY IMPACTING ALL AIRFIELDS AND TERMINALS TODAY.
THE STRONGER STORMS WILL PRODUCE SMALL HAIL AND GUSTY WINDS TO 40
KT WITH THE THREAT FOR A FEW ISOLATED SEVERE THUNDERSTORMS POSSIBLE
WITH BRIEF WIND GUSTS TO AROUND 50 KT.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&
$$
UPDATE...ZUMPFE
SHORT TERM...DICKERSON
LONG TERM....WHITMORE
AVIATION...DICKERSON
[top]
000
FXUS65 KBYZ 051459
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
859 AM MDT SUN JUL 5 2009
.SHORT TERM...VALID FOR TDY AND MON...
MOSTLY CLEAR SKIES THIS MORNING WILL SUPPORT A STRONG WARMUP AND
CONVECTIVE PARAMETERS ARE SLIGHTLY DECREASED FROM PREVIOUS DAYS.
WITH WEAK UPPER LEVEL RIDGING EXPECTED THIS AFTERNOON AHEAD OF A
TROF IMPACTING THE PACIFIC NORTHWEST THINK THAT AIRMASS WILL
REMAIN CAPPED UNTIL LATER IN THE DAY. HOWEVER...SHORTWAVE OVER
IDAHO THIS MORNING GENERATED LIGHTNING IN THAT PART OF THE WORLD
OVERNIGHT AND DESPITE LOOKING WEAK ON THE MODELS THIS COULD BE AN
INDICATOR THAT THE WAVE IS A BIT MORE POTENT THAN DEPICTED. EXPECT
TEMPS TO WARM TO NEAR 90 TODAY BUT THEN EXPECT CONVECTION TO
DEVELOP AS THE IDAHO WAVE APPROACHES. ANOTHER WEAK SHEAR DAY WITH
MODEST CAPES BUT SUSPECT CLOUD BASES WILL BE HIGHER WHICH WOULD
SUPPORT MORE OUTFLOW DEVELOPMENT. CONVECTION SHOULD SETTLE DOWN
TONIGHT WITH DIURNAL COOLING. NO UPDATES. BORSUM
.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...
MODELS CONTINUE IN GOOD AGREEMENT THROUGH THE EXTENDED...APPEARS
AS THOUGH GFS HAS TRENDED TOWARD THE EC LATER IN THE PERIOD TO
SUPPORT MORE AMPLIFIED RIDGING BY FRIDAY NIGHT. BEGIN THE EXTENDED
PERIOD IN RELATIVELY STRONG SOUTHWEST FLOW ALOFT...WHICH REMAINS
IN PLACE THROUGH THURSDAY MORNING. MONSOONAL FLOW LOOKS LIKE IT
WILL BE DEFLECTED EASTWARD INTO THE DAKOTAS...WHICH ALSO SEE BEST
CONVECTIVE SUPPORT. WE WILL HAVE MULTIPLE WAVES THROUGH THE
REGION IN THIS PERIOD...BUT DRY AIR ALOFT WILL LIMIT SOME
CONVECTION...HOWEVER...SOME VERY HEAVY PRECIP IN SOME AREAS OVER
THE PAST WEEK OR SO SHOULD KEEP THE BOUNDARY LAYER PRETTY MOIST
AND GIVE A CHANCE FOR AT LEAST SCATTERED THUNDER ACROSS THE
REGION. ATTEMPTED TO IDENTIFY MORE SIGNIFICANT WAVES AND BOOSTED
POPS SLIGHTLY FOR THOSE PERIODS...AS WITH WAVE MOVING THROUGH WED
THROUGH THURSDAY MORNING. ALSO CONTINUED COOLING TREND FOR TUESDAY THROUGH
THURSDAY AS SCATTERED SHOWERS/THUNDER DURING THE DAY WILL LIMIT
SOME HEATING AND RELATIVELY DRY CONDITIONS WILL ALLOW MORE COOLING
OVERNIGHT. RIDGING BEGINS TO BUILD INTO THE REGION AGAIN ON
FRIDAY...BECOMING MORE AMPLIFIED BY SATURDAY...POINTING TO A WARM
UP AGAIN...AND RELATIVELY DRY CONDITIONS...BUT AGAIN CANNOT RULE
OUT LOCALIZED DEVELOPMENT DUE TO BOUNDARY LAYER MOISTURE. WENT
WITH SUB CLIMO POPS AS LOOKS PRETTY DRY AT THIS POINT AND BOUNDARY
LAYER MOISTURE COULD BE GETTING PLAYED OUT. HOWEVER...QUESTION
REMAINS AS TO WHAT SFC THERMAL LOW WILL DO AT THIS POINT...APPEARS
TO STRENGTHEN...AND IF IT MANAGES TO TAP THE MONSOONAL
MOISTURE...IT COULD MAKE FOR AN INTERESTING WEEKEND. GILSTAD
&&
.AVIATION...
VFR WILL PREVAIL THROUGH EARLY AFTERNOON. ISOLATED TO SCATTERED
THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS AFTERNOON AND
EVENING...ESPECIALLY IN WESTERN PARTS AS THEY INITIATE OVER THE
MOUNTAINS. LOCAL MVFR IS POSSIBLE IN THE STRONGER CELLS. WINDS
WILL BE RELATIVELY LIGHT TODAY...BUT COULD BECOME GUSTY NEAR ANY
STORMS THAT DEVELOP. JKL
&&
.PRELIMINARY POINT TEMP/POPS...
TDY MON TUE WED THU FRI SAT
-------------------------------------------------------
BIL 088 062/090 060/085 058/081 054/079 057/083 057/085
2/T 21/B 22/T 23/T 32/T 22/T 22/T
LVM 084 052/086 050/082 050/077 047/075 047/081 049/082
3/T 23/T 32/T 22/T 22/T 32/T 22/T
HDN 091 058/093 060/089 057/086 051/084 055/088 056/088
2/T 21/B 22/T 23/T 32/T 22/T 22/T
MLS 090 062/091 064/088 063/086 056/088 060/086 060/086
2/T 21/B 22/T 23/T 42/T 22/T 22/T
4BQ 087 060/090 062/087 063/087 056/081 057/086 058/087
2/T 21/B 11/B 22/T 32/T 22/T 22/T
BHK 086 061/088 061/084 061/083 058/082 058/087 058/084
2/T 21/B 12/T 22/T 32/T 22/T 22/T
SHR 085 054/090 056/086 057/085 049/082 052/083 052/085
3/T 32/T 22/T 22/T 31/B 22/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KTFX 051144
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
544 AM MDT SUN JUL 5 2009
UPDATED AVIATION
.DISCUSSION...
TODAY THROUGH TUESDAY...FOR TODAY EXPECT ANOTHER DAY OF SCATTERED
MAINLY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS. IT LOOKS
LIKE THERE MIGHT BE A LITTLE LESS INSTABILITY OVER THE PLAINS
RELATIVE TO YESTERDAY. OVER SOUTHWEST MONTANA AM SEEING ABOUT THE
SAME INSTABILITY AS YESTERDAY. A WEATHER DISTURBANCE ALOFT OVER
SOUTHWEST OREGON IS EXPECTED TO MOVE THROUGH SOUTHWEST MONTANA
DURING THE DAY AND SHOULD HELP TRIGGER THE SHOWERS AND
THUNDERSTORMS IN THAT REGION. EXPECT SHOWERS AND THUNDERSTORMS TO
DIMINISH NEAR AND AFTER DARK. THE MAIN WEATHER CONCERN DURING THE
PERIOD WILL BE THE POSSIBILITY OF SEVERE THUNDERSTORMS MONDAY
AFTERNOON AND EVENING. SHOULD SEE SLIGHTLY GREATER INSTABILITY
THAN TODAY. THERE WILL BE IMPRESSIVE LIFT AHEAD OF A COLD FRONT
WHICH WILL MOVE THROUGH MOST OF THE FORECAST AREA MONDAY AFTERNOON
AND EVENING. WIND PROFILES FROM THE SURFACE AND ON UP ALSO FAVOR
SEVERE STORMS. FOR TUESDAY THE COLD FRONT MENTIONED ABOVE WILL GET
HUNG UP FROM CENTRAL MONTANA TO SOUTHWEST MONTANA. EXPECT SHOWERS
AND THUNDERSTORMS TO DEVELOP NEAR THIS FRONT DURING THE AFTERNOON
THEN SPREAD NORTHEAST DURING THE EVENING. BLANK
TUESDAY NIGHT THROUGH FRIDAY NIGHT...MODELS SEEM TO BE IN BETTER
AGREEMENT WITH HANDLING THE ARRIVAL OF AN UPPER-LEVEL TROUGH INTO
THE PACIFIC NORTHWEST AT THE START OF THE PERIOD. WITH PREDOMINANT
SOUTHWEST FLOW...A FAIR AMOUNT OF PACIFIC MOISTURE WILL SPREAD
INTO THE REGION ON TUESDAY NIGHT WHILE LIFT ALOFT ASSOCIATED WITH
A SERIES OF SHORTWAVES PROMOTES LIFT AND SUPPORT FOR NOCTURNAL
CONVECTION. THUS...INCREASED POPS FOR TUESDAY NIGHT. THE MAIN
DIFFERENCE BETWEEN THE ECMWF AND GFS MODELS IS THE PLACEMENT OF THE
HEAVIEST PRECIPITATION SINCE IT WILL DEPEND ON WHERE THE BEST LIFT
SETS UP SO WILL CONTINUE TO MONITOR THIS TREND. THE UNSETTLED
PATTERN WILL CONTINUE INTO WEDNESDAY AND WEDNESDAY NIGHT SO HAVE
KEPT CHANCE POPS IN THE FORECAST FOR THIS TIME FRAME. CLOUDS AND
PRECIPITATION WILL KEEP TEMPERATURES ABOUT 10 TO 15 DEGREES BELOW
AVERAGE. ON THURSDAY...A WEAK RIDGE MOVES INTO MONTANA WHICH WILL
YIELD QUIETER CONDITIONS ACROSS THE FORECAST AREA...BUT TEMPERATURES
WILL STILL BE SLIGHTLY BELOW AVERAGE WITH NORTHWEST FLOW PRESENT.
STILL KEPT SLIGHT CHANCE OF POPS MAINLY IN THE MOUNTAINS WHERE
TERRAIN-BASED INSTABILITY WILL BE PRESENT. MODELS DIVERGE BY FRIDAY
WITH GFS A BIT SLOWER THAN THE ECMWF AS NEXT SHORTWAVE ENERGY
ARRIVES. NEAR AVERAGE TEMPS ARE EXPECTED BY FRIDAY AND HAVE KEPT
POPS CLOSER TO CLIMATOLOGICAL VALUES. MLS
SATURDAY THROUGH SUNDAY...MODELS ARE IN BASIC AGREEMENT DURING THIS
PERIOD...WITH SOME DIFFERENCES IN TIMING OF FEATURES. A WEAK UPPER
LEVEL RIDGE DRIFTS EASTWARD ACROSS THE REGION BY SUNDAY AFTERNOON.
PARTLY CLOUDY SKIES ARE EXPECTED FOR MOST LOCATIONS. LIMITED
MOISTURE AND INSTABILITY WILL RESULT IN MOSTLY CLOUDY SKIES OVER THE
MOUNTAINS...WITH ISOLATED SHOWERS AND A FEW MAINLY AFTERNOON AND
EVENING THUNDERSTORMS. SHOWERS AND THUNDERSTORMS WILL BE A LITTLE
MORE WIDESPREAD OVER THE WESTERN MOUNTAINS. TEMPERATURES ARE
EXPECTED TO TO BE NEAR SEASONAL AVERAGES. EK
&&
.AVIATION...
UPDATED 1200Z.
ISOLATED SHOWERS AND THUNDERSTORMS WILL AFFECT FAR NORTHEASTERN
MONTANA THIS MORNING INCLUDING KHVR SO HAVE KEPT VCTS...HOWEVER AM
EXPECTING THE ACTIVITY TO NOT DIRECTLY AFFECT THE KHVR TERMINAL.
OTHERWISE...VFR CONDITIONS WILL CONTINUE TO PREVAIL ACROSS THE
FORECAST AREA THROUGH EARLY MONDAY MORNING. ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS WILL DEVELOP ONCE AGAIN AFTER 18Z SUNDAY
AND SOME STORMS MAY PRODUCE OCCL MVFR CONDITIONS IN ADDITION TO
GUSTY WINDS...BRIEF HEAVY RAINFALL AND HAIL. CONVECTION WILL
DECREASE TOWARDS SUNSET ON SUNDAY EVENING BUT A FEW SHOWERS MAY
LINGER ACROSS NORTH-CENTRAL MONTANA NEAR KCTB AND KHVR. MLS
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 85 57 83 52 / 30 20 30 30
CTB 80 53 75 46 / 20 30 50 30
HLN 88 59 89 53 / 30 20 30 30
BZN 87 54 90 50 / 30 10 20 30
WEY 72 43 76 39 / 30 30 20 30
DLN 79 53 81 48 / 30 10 20 20
HVR 89 56 87 52 / 20 30 30 50
LWT 82 53 80 49 / 30 20 30 40
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BLANK
LONG TERM...MLS/KURDY
AVIATION...MLS
WEATHER.GOV/GREATFALLS
000
FXUS65 KTFX 051033
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
433 AM MDT SUN JUL 5 2009
.DISCUSSION...
TODAY THROUGH TUESDAY...FOR TODAY EXPECT ANOTHER DAY OF SCATTERED
MAINLY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS. IT LOOKS
LIKE THERE MIGHT BE A LITTLE LESS INSTABILITY OVER THE PLAINS
RELATIVE TO YESTERDAY. OVER SOUTHWEST MONTANA AM SEEING ABOUT THE
SAME INSTABILITY AS YESTERDAY. A WEATHER DISTURBANCE ALOFT OVER
SOUTHWEST OREGON IS EXPECTED TO MOVE THROUGH SOUTHWEST MONTANA
DURING THE DAY AND SHOULD HELP TRIGGER THE SHOWERS AND
THUNDERSTORMS IN THAT REGION. EXPECT SHOWERS AND THUNDERSTORMS TO
DIMINISH NEAR AND AFTER DARK. THE MAIN WEATHER CONCERN DURING THE
PERIOD WILL BE THE POSSIBILITY OF SEVERE THUNDERSTORMS MONDAY
AFTERNOON AND EVENING. SHOULD SEE SLIGHTLY GREATER INSTABILITY
THAN TODAY. THERE WILL BE IMPRESSIVE LIFT AHEAD OF A COLD FRONT
WHICH WILL MOVE THROUGH MOST OF THE FORECAST AREA MONDAY AFTERNOON
AND EVENING. WIND PROFILES FROM THE SURFACE AND ON UP ALSO FAVOR
SEVERE STORMS. FOR TUESDAY THE COLD FRONT MENTIONED ABOVE WILL GET
HUNG UP FROM CENTRAL MONTANA TO SOUTHWEST MONTANA. EXPECT SHOWERS
AND THUNDERSTORMS TO DEVELOP NEAR THIS FRONT DURING THE AFTERNOON
THEN SPREAD NORTHEAST DURING THE EVENING. BLANK
TUESDAY NIGHT THROUGH FRIDAY NIGHT...MODELS SEEM TO BE IN BETTER
AGREEMENT WITH HANDLING THE ARRIVAL OF AN UPPER-LEVEL TROUGH INTO
THE PACIFIC NORTHWEST AT THE START OF THE PERIOD. WITH PREDOMINANT
SOUTHWEST FLOW...A FAIR AMOUNT OF PACIFIC MOISTURE WILL SPREAD
INTO THE REGION ON TUESDAY NIGHT WHILE LIFT ALOFT ASSOCIATED WITH
A SERIES OF SHORTWAVES PROMOTES LIFT AND SUPPORT FOR NOCTURNAL
CONVECTION. THUS...INCREASED POPS FOR TUESDAY NIGHT. THE MAIN
DIFFERENCE BETWEEN THE ECMWF AND GFS MODELS IS THE PLACEMENT OF
THE HEAVIEST PRECIPITATION SINCE IT WILL DEPEND ON WHERE THE BEST LIFT
SETS UP SO WILL CONTINUE TO MONITOR THIS TREND. THE UNSETTLED
PATTERN WILL CONTINUE INTO WEDNESDAY AND WEDNESDAY NIGHT SO HAVE
KEPT CHANCE POPS IN THE FORECAST FOR THIS TIME FRAME. CLOUDS AND
PRECIPITATION WILL KEEP TEMPERATURES ABOUT 10 TO 15 DEGREES BELOW
AVERAGE. ON THURSDAY...A WEAK RIDGE MOVES INTO MONTANA WHICH WILL
YIELD QUIETER CONDITIONS ACROSS THE FORECAST AREA...BUT
TEMPERATURES WILL STILL BE SLIGHTLY BELOW AVERAGE WITH NORTHWEST
FLOW PRESENT. STILL KEPT SLIGHT CHANCE OF POPS MAINLY IN THE
MOUNTAINS WHERE TERRAIN-BASED INSTABILITY WILL BE PRESENT. MODELS
DIVERGE BY FRIDAY WITH GFS A BIT SLOWER THAN THE ECMWF AS NEXT
SHORTWAVE ENERGY ARRIVES. NEAR AVERAGE TEMPS ARE EXPECTED BY
FRIDAY AND HAVE KEPT POPS CLOSER TO CLIMATOLOGICAL VALUES. MLS
SATURDAY THROUGH SUNDAY...MODELS ARE IN BASIC AGREEMENT DURING THIS
PERIOD...WITH SOME DIFFERENCES IN TIMING OF FEATURES. A WEAK UPPER
LEVEL RIDGE DRIFTS EASTWARD ACROSS THE REGION BY SUNDAY AFTERNOON.
PARTLY CLOUDY SKIES ARE EXPECTED FOR MOST LOCATIONS. LIMITED
MOISTURE AND INSTABILITY WILL RESULT IN MOSTLY CLOUDY SKIES OVER THE
MOUNTAINS...WITH ISOLATED SHOWERS AND A FEW MAINLY AFTERNOON AND
EVENING THUNDERSTORMS. SHOWERS AND THUNDERSTORMS WILL BE A LITTLE
MORE WIDESPREAD OVER THE WESTERN MOUNTAINS. TEMPERATURES ARE
EXPECTED TO TO BE NEAR SEASONAL AVERAGES. EK
&&
.AVIATION...
UPDATED 0440Z.
VFR CONDITIONS WILL CONTINUE TO PREVAIL ACROSS THE FORECAST AREA
THROUGH SUNDAY EVENING. ISOLATED THUNDERSTORMS WILL CONTINUE TO
AFFECT FAR NORTHEASTERN PORTIONS OF CENTRAL MONTANA OVERNIGHT.
STORMS WILL BRING BRIEF HEAVY RAINFALL AND HAIL FOR OCCASIONAL MVFR
CONDITIONS AT TIMES. ISOLATED TO SCATTERED THUNDERSTORMS WILL
DEVELOP ONCE AGAIN AFTER 18Z SUNDAY...MAINLY IN SOUTHERN PORTIONS OF
THE FORECAST AREA...AND ARE EXPECTED TO CONTINUE THROUGH LATE SUNDAY
EVENING. MPJ
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 85 57 83 52 / 30 20 30 30
CTB 80 53 75 46 / 20 30 50 30
HLN 88 59 89 53 / 30 20 30 30
BZN 87 54 90 50 / 30 10 20 30
WEY 72 43 76 39 / 30 30 20 30
DLN 79 53 81 48 / 30 10 20 20
HVR 89 56 87 52 / 20 30 30 50
LWT 82 53 80 49 / 30 20 30 40
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BLANK
LONG TERM...MLS/KURDY
AVIATION...MLS
WEATHER.GOV/GREATFALLS
000
FXUS65 KMSO 051032
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
432 AM MDT SUN JUL 5 2009
...POTENTIAL FOR SEVERE THUNDERSTORMS ACROSS NORTHWEST MONTANA
MONDAY AFTERNOON...
.DISCUSSION...A WEAK MID-LEVEL SHORT WAVE WEATHER DISTURBANCE...
ROTATING WITHIN THE FLOW OVER OREGON...IS APPROACHING THE IDAHO
BORDER THIS MORNING. THUNDERSTORMS HAVE CONTINUED THROUGHOUT THE
NIGHT ALONG THIS DISTURBANCE AND SHOULD CONTINUE DURING THE
MORNING HOURS AS THE SHORT WAVE MOVES OVER CENTRAL IDAHO.
THIS AFTERNOON THE ATMOSPHERE OVER WESTERN MONTANA AND CENTRAL
IDAHO WILL ONCE AGAIN DESTABILIZE...EVEN MORE SO THAN PREVIOUS DAYS
WITH INSTABILITY EXISTING IN NUMERICAL MODEL DATA TO THE CANADIAN
BORDER BY THIS AFTERNOON. DESPITE SOMEWHAT INCREASED CLOUD COVER
LATER THIS AFTERNOON...SUFFICIENT DAYTIME HEATING WILL LEAD TO
EXCEPTIONALLY WARM CONDITIONS WITH HIGH BEING AT LEAST AS WARM...IF
NOT WARMER THAN YESTERDAYS OBSERVED VALUES. THESE FACTORS COMBINED
WITH A FULLY MOISTENED ATMOSPHERE FROM DAYS OF MID-LEVEL SUB-
TROPICAL MOISTURE INFILTRATION WILL LEAD TO WIDESPREAD
THUNDERSTORM DEVELOPMENT TODAY ACROSS IDAHO AND WESTERN MONTANA.
HOWEVER ONLY MODERATE POTENTIAL FOR SEVERE THUNDERSTORMS EXISTS
TODAY SINCE THE WIND PROFILE FROM THE SURFACE TO 10,000 FEET ALOFT
IS WEAKLY SHEARED. AS A RESULT...SOME THUNDERSTORMS THAT DO FORM
WILL BE CAPABLE OF SMALL HAIL UP TO AROUND ONE-HALF OF AN INCH
DIAMETER AND GUSTY WINDS TO 50 MPH. AN OCCASIONAL STORM MAY SPIKE
STRONGER FOR A BRIEF PERIOD OF TIME...ESPECIALLY LATE IN THE
AFTERNOON OR EARLY EVENING HOURS. HOWEVER THESE STORMS SHOULD BE
LIMITED IN NATURE GIVEN THE PREVIOUS REASONING.
CONDITIONS WILL RAPIDLY BECOME MORE FAVORABLE FOR SEVERE
THUNDERSTORMS ON MONDAY AFTERNOON...ESPECIALLY ACROSS NORTHWEST
MONTANA. A PACIFIC TROUGH OF LOW PRESSURE WILL APPROACHES THE
REGION TONIGHT...CAUSING THE UPPER LEVEL RIDGE OF HIGH PRESSURE TO
MOVE EAST. THE ENSUING SOUTHWESTERLY FLOW ALOFT WILL PRODUCE A
HIGHLY DIRECTIONALLY WIND SHEARED ENVIRONMENT OVER NORTHWEST
MONTANA. TO ADD ADDITIONAL WIND SHEAR TO THE PROFILE...FORECAST
MODELS ARE SHOWING AN ACCELERATION IN THE UPPER LEVEL JET STREAM
MOVING INTO THE NORTHERN ROCKIES AT THE SAME TIME. ADD TO THE
EQUATION ABUNDANT INSTABILITY AIDED BY AN APPROACHING
COOLER...DRIER AIRMASS AND STRONG...ORGANIZED THUNDERSTORMS APPEAR
QUITE LIKELY FROM GENERALLY I-90 NORTH AND EAST TO THE CONTINENTAL
DIVIDE. DAMAGING WIND GUSTS IN EXCESS OF 60 MPH AND LARGE HAIL
GREATER THAN ONE INCH IN DIAMETER APPEAR LIKELY WITH THUNDERSTORM
ACROSS THIS REGION. THUS A HAZARDOUS WEATHER OUTLOOK WILL BE
ISSUED TO FURTHER DISCUSS THE POTENTIAL FOR SEVERE THUNDERSTORMS
TODAY AND TOMORROW. THE MAJORITY OF THESE THUNDERSTORMS WILL
QUICKLY MOVE NORTHEAST MONDAY EVENING AS DRIER MORE STABLE AIR
ENTERS THE REGION.
TUESDAY THROUGH SATURDAY...MUCH COOLER AND UNSETTLED WEATHER WILL
BE OVER THE NORTHERN ROCKIES TUESDAY AND WEDNESDAY AS THE UPPER
TROUGH REMAINS OVER THE NORTHWEST U.S. A STRONG SHORTWAVE WILL
EJECT OUT OF THE LONGWAVE TROUGH AND PUSH OVER THE AREA WEDNESDAY.
THUS THIS CONTINUES TO LOOK LIKE THE COOLEST AND WETTEST DAY.
LOWER ATMOSPHERIC LAPSE RATES COULD STILL SUPPORT SOME
THUNDERSTORMS IF FORCING IS SUFFICIENT...BUT INSTABILITY INTO
MIDWEEK WILL BE MUCH LESS SIGNIFICANT THAN TODAY AND MONDAY. THE
AIR MASS WILL BEGIN TO DRY AND WARM LATER IN THE WEEK AS THE
LONGWAVE TROUGH RETROGRADES OFF THE WEST COAST LEAVING A
PERSISTENT SOUTHWEST FLOW OVER THE NORTHERN ROCKIES.
&&
.AVIATION...SHOWERS AND THUNDERSTORMS WILL BECOME MORE WIDESPREAD
TODAY...LARGELY IMPACTING ALL AIRFIELDS AND TERMINALS TODAY.
THE STRONGER STORMS WILL PRODUCE SMALL HAIL AND GUSTY WINDS TO 40
KT WITH THE THREAT FOR A FEW ISOLATED SEVERE THUNDERSTORMS POSSIBLE
WITH BRIEF WIND GUSTS TO AROUND 50 KT.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&
$$
SHORT TERM...DICKERSON
LONG TERM....WHITMORE
AVIATION...DICKERSON
000
FXUS65 KGGW 050924
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
324 AM MDT SUN JUL 5 2009
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH TUESDAY...
THE UPPER RIDGE AXIS SHIFTS INTO WESTERN MONTANA TODAY
MAINTAINING NW FLOW ALOFT OVER THE FORECAST AREA. THE MORNING WILL
SEE A WEAK DISTURBANCE IN THE UPPER FLOW EXIT THE NORTHERN ZONES
TO THE EAST BY NOON. A CLOSED UPPER LOW OFF THE PACNW COAST WILL
PUSH FARTHER EAST AMPLIFYING THE RIDGE. AS A RESULT THE LOCAL AREA
WILL EXPERIENCE SLIGHTLY ABOVE SEASONAL TEMPERATURES TODAY AS
HEIGHTS INCREASE. ONCE AGAIN THE CENTRAL REGION WITH SLIGHT
DISTURBANCES IN THE UPPER FLOW WILL EXPERIENCE AFTERNOON AND
EVENING THUNDERSTORMS WHICH COULD DRIFT INTO OUR AREA. THE SURFACE
HIGH...THAT PREVENTED THUNDERSTORMS FROM MOVING TOO FAR INTO OUR
AREA SUNDAY...WILL ALSO DRIFT A LITTLE MORE EAST PROVIDING A BIT
MORE INSTABILITY. SO WILL MAINTAIN A SLIGHT CHANCE FOR THUNDER AND
ASSOCIATED SHOWERS.
THE RIDGE AXIS PASSES OVER THE LOCAL AREA MONDAY AS THE PACIFIC
LOW MOVES INTO BRITISH COLUMBIA...SENDING SW UPPER FLOW INTO THE
CENTRAL REGION. WITH A REPEAT IN MAXIMUM TEMPERATURES FROM THE
PREVIOUS DAY AND A THERMAL RIDGE NUDGING INTO OUR SW
ZONES...ANOTHER ROUND OF THUNDERSTORMS CAN BE EXPECTED. THE LEE
SURFACE TROUGH CLOSES OFF OVER CENTRAL MT FOCUSING INSTABILITY AND
MOISTURE WITH THE UPPER JET LATE AFTERNOON AND EVENING. WITH THE
DYNAMIC FORCING...THUNDERSTORMS...SOME POSSIBLY SEVERE...ARE ONCE
AGAIN ON THE MENU. BUT EXACTLY WHERE IS STILL IN QUESTION BASED ON
MODEL DIFFERENCES. MODELS ALSO DIFFER A BIT ON MOISTURE...BUT
AROUND AN INCH OF PRECIPITABLE WATER IS REASONABLE. THE NORTHERN
ZONES AND SOUTHERN SASKATCHEWAN COULD SEE SOME HEAVY RAIN MONDAY
NIGHT.
TUESDAY CAN EXPECT SEASONAL TEMPERATURES AS THE THERMAL RIDGE
MOVES INTO N DAKOTA. HOWEVER SW FLOW ALOFT WILL CONTINUE TO
SUPPORT THE DEVELOPMENT OF A FEW THUNDERSTORMS. SCT
.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
UPPER LOW THAT IS FORECASTED TO BE OVER BRITISH COLUMBIA ON
TUESDAY AND WEDNESDAY MOVES EAST ACROSS SASKATCHEWAN ON THURSDAY.
THE ECMWF REMAINS CONSISTENT IN TURNING THIS LOW INTO AN OPEN
TROUGH BY THE TIME IT REACHES SASKATCHEWAN AND EASTERN MONTANA
THURSDAY MORNING. THE 00Z GFS MAINTAINS A CLOSED LOW INTO
SASKATCHEWAN WHILE EARLIER RUNS HAVE VARIED FROM AN OPEN TROUGH
SIMILAR TO THE ECMWF TO HAVING JUST SOUTHWEST FLOW ALOFT OVER THE
AREA. WILL KEEP THE FORECAST CLOSER TO THE ECMWF SOLUTION FOR NOW.
SOUTHWEST FLOW ALOFT AHEAD OF THIS TROUGH TUESDAY NIGHT AND
WEDNESDAY WILL BRING MOISTURE INTO THE FORECAST AREA. THIS SHOULD
YIELD A GOOD CHANCE OF THUNDERSTORMS WEDNESDAY AND WEDNESDAY NIGHT
WHEN A FRONTAL SYSTEM PASSES THROUGH THE AREA.
DRIER AIR WILL MOVE INTO EASTERN MONTANA AS THE SYSTEM EXITS THE
AREA DURING THE DAY ON THURSDAY. WILL LEAVE A SLIGHT CHANCE OF
STORMS IN THE FORECAST FOR NOW AS LINGERING INSTABILITY IS
POSSIBLE.
MODELS DIFFERENCES SHOW UP NEXT WEEKEND. THE 00Z NOW HAS THE
UPPER RIDGE FOR FRIDAY THROUGH SUNDAY THAT THE LAST SEVERAL ECMWF
RUNS SHOWED. HOWEVER...THE ECMWF NOW HAS NW FLOW ALOFT WITH A
SHORTWAVE FRIDAY NIGHT WHILE KEEPING THE RIDGE TO THE WEST UNTIL
SUNDAY. WILL KEEP NEXT WEEKEND DRY FOR THE MOST PART FOR NOW.
&&
.AVIATION...
VFR CONDITIONS EXPECTED MOST OF THE TIME WITH SCATTERED TO BROKEN
MID AND HIGH CLOUDS. AN AREA OF THUNDERSTORMS WITH HEAVY RAIN
BETWEEN KOLF AND KSDY AT 09Z MAY AFFECT KSDY AND KGDV EARLY THIS
MORNING WITH A BRIEF PERIOD OF MVFR CONDITIONS. ANOTHER AREA OF
SHOWERS WITH ISOLATED THUNDERSTORMS OVER AND NORTH OF KHVR COULD
AFFECT THE TAF SITES THIS MORNING ESPECIALLY KGGW AND KOLF.
THERE IS A CHANCE OF MORE THUNDERSTORMS THIS AFTERNOON AND
TONIGHT. WINDS WILL BE FROM THE EAST AT 10 KNOTS OR LESS.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KBYZ 050858
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
258 AM MDT SUN JUL 5 2009
.SHORT TERM...VALID FOR TDY AND MON...
LATEST SHORT WAVE ENERGY PROGRESSING EAST ACROSS FAR EASTERN
MONTANA EARLY THIS MORNING. SHOWERS AND THUNDERSTORMS HAVE
MAINTAINED THEMSELVES AHEAD OF THIS SYSTEM WITH CLEARING COMING IN
BEHIND. THIS ACTIVITY SHOULD CLEAR PAST THE EASTERN MONTANA
BORDER AROUND DAYBREAK. BEHIND THIS SYSTEM...UPPER HEIGHTS BUILD
ACROSS THE ROCKIES IN RESPONSE TO A STRONG UPPER LOW ADVANCING
TOWARD THE WEST COAST. THIS SHOULD RESULT IN LESS THUNDERSTORM
COVERAGE FOR THE REGION TODAY. STILL SOME WEAK ENERGY WILL TOP THE
RIDGE THIS AFTERNOON. INSTABILITY REMAINS WEAK...BUT ENOUGH TO
MAINTAIN MENTION OF AN ISOLATED STORM INTO THIS EVENING. MOST OF
THE ACTIVITY WILL DEVELOP OVER THE MOUNTAINS WITH A FEW
PROGRESSING ACROSS THE PLAINS BY LATE THIS AFTERNOON AND EVENING.
STILL MAINTAINING SOME PWATS CLOSE TO AN INCH...SO THE ISOLATED
ACTIVITY THAT DOES FORM SHOULD STILL BE WET. LOOKS DRY FOR LATE
TONIGHT INTO MONDAY MORNING. UPPER RIDGE BEGINS A SHIFT EAST OF
THE AREA LATE MONDAY AS SOME STRONGER ENERGY LIFTS NORTHEAST IN
SOUTHWEST FLOW ACROSS WESTERN AND CENTRAL MONTANA. STRONG DYNAMICS
WITH THIS SYSTEM WILL BE ENOUGH TO DEVELOP SOME STRONG TO SEVERE
THUNDERSTORMS LATE MONDAY INTO MONDAY EVENING AS 1000-2000 CAPES
COMBINE WITH STRONG SHEAR. RIGHT NOW...THE STRONGEST DYNAMICS ARE
FORECAST JUST NORTHWEST OF OUR FORECAST AREA...BUT WILL HAVE TO BE
MONITORED. LATEST NAM INDICATING STORMS FORMING AS FAR SOUTHEAST
AS BILLINGS. FOR NOW...HAVE INCREASED STORM CHANCES FOR AREAS IN
AN LVM-ROUNDUP LINE....WITH LESSER CHANCES AS YOU GO SOUTHEAST. AS
FOR TEMPERATURES...READINGS ARE ON THE RISE. DRIER AND WARMER
AIRMASS TODAY SHOULD PUSH TEMPS CLOSE TO 90. MONDAY SHOULD BE A BIT
WARMER...ALTHOUGH MOST AREAS WILL MAINTAIN A SOUTHEAST FLOW AHEAD
OF APPROACHING TROUGH. THIS SHOULD KEEP TEMPS FROM PUSHING TOO FAR
INTO THE 90S. FRIEDERS
.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...
MODELS CONTINUE IN GOOD AGREEMENT THROUGH THE EXTENDED...APPEARS
AS THOUGH GFS HAS TRENDED TOWARD THE EC LATER IN THE PERIOD TO
SUPPORT MORE AMPLIFIED RIDGING BY FRIDAY NIGHT. BEGIN THE EXTENDED
PERIOD IN RELATIVELY STRONG SOUTHWEST FLOW ALOFT...WHICH REMAINS
IN PLACE THROUGH THURSDAY MORNING. MONSOONAL FLOW LOOKS LIKE IT
WILL BE DEFLECTED EASTWARD INTO THE DAKOTAS...WHICH ALSO SEE BEST
CONVECTIVE SUPPORT. WE WILL HAVE MULTIPLE WAVES THROUGH THE
REGION IN THIS PERIOD...BUT DRY AIR ALOFT WILL LIMIT SOME
CONVECTION...HOWEVER...SOME VERY HEAVY PRECIP IN SOME AREAS OVER
THE PAST WEEK OR SO SHOULD KEEP THE BOUNDARY LAYER PRETTY MOIST
AND GIVE A CHANCE FOR AT LEAST SCATTERED THUNDER ACROSS THE
REGION. ATTEMPTED TO IDENTIFY MORE SIGNIFICANT WAVES AND BOOSTED
POPS SLIGHTLY FOR THOSE PERIODS...AS WITH WAVE MOVING THROUGH WED
THROUGH THURSDAY MORNING. ALSO CONTINUED COOLING TREND FOR TUESDAY THROUGH
THURSDAY AS SCATTERED SHOWERS/THUNDER DURING THE DAY WILL LIMIT
SOME HEATING AND RELATIVELY DRY CONDITIONS WILL ALLOW MORE COOLING
OVERNIGHT. RIDGING BEGINS TO BUILD INTO THE REGION AGAIN ON
FRIDAY...BECOMING MORE AMPLIFIED BY SATURDAY...POINTING TO A WARM
UP AGAIN...AND RELATIVELY DRY CONDITIONS...BUT AGAIN CANNOT RULE
OUT LOCALIZED DEVELOPMENT DUE TO BOUNDARY LAYER MOISTURE. WENT
WITH SUB CLIMO POPS AS LOOKS PRETTY DRY AT THIS POINT AND BOUNDARY
LAYER MOISTURE COULD BE GETTING PLAYED OUT. HOWEVER...QUESTION
REMAINS AS TO WHAT SFC THERMAL LOW WILL DO AT THIS POINT...APPEARS
TO STRENGTHEN...AND IF IT MANAGES TO TAP THE MONSOONAL
MOISTURE...IT COULD MAKE FOR AN INTERESTING WEEKEND. GILSTAD
&&
.AVIATION...
A LINE OF SHOWERS AND THUNDERSTORMS CURRENTLY IMPACTING
KMLS...CONTINUE TO PUSH EASTWARD THROUGH EASTERN MONTANA...BUT HAS
BEEN WEAKENING. FLIGHT CONDITIONS IN AND NEAR THESE STORMS WILL BE
REDUCED TO MVFR TO IFR RANGE IN HEAVY RAIN.
THERE IS A SLIGHT CHANCE OF FOG DEVELOPMENT BY EARLY MORNING
ACROSS THE AREA...PARTICULARLY ALONG AREA RIVERS AND STREAMS. IFR
OR LOWER CONDITIONS CAN BE EXPECTED IN ANY FOG THAT DOES
DEVELOP. OTHERWISE SKIES WILL BE MOSTLY CLEAR...RESULTING IN
PREVAILING VFR CONDITIONS THROUGH EARLY AFTERNOON TODAY. GILSTAD
&&
.PRELIMINARY POINT TEMP/POPS...
TDY MON TUE WED THU FRI SAT
-------------------------------------------------------
BIL 088 062/090 060/085 058/081 054/079 057/083 057/085
2/T 21/B 22/T 23/T 32/T 22/T 22/T
LVM 084 052/086 050/082 050/077 047/075 047/081 049/082
3/T 23/T 32/T 22/T 22/T 32/T 22/T
HDN 091 058/093 060/089 057/086 051/084 055/088 056/088
2/T 21/B 22/T 23/T 32/T 22/T 22/T
MLS 090 062/091 064/088 063/086 056/088 060/086 060/086
2/T 21/B 22/T 23/T 42/T 22/T 22/T
4BQ 087 060/090 062/087 063/087 056/081 057/086 058/087
2/T 21/B 11/B 22/T 32/T 22/T 22/T
BHK 086 061/088 061/084 061/083 058/082 058/087 058/084
2/T 21/B 12/T 22/T 32/T 22/T 22/T
SHR 085 054/090 056/086 057/085 049/082 052/083 052/085
3/T 32/T 22/T 22/T 31/B 22/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KTFX 050440
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1040 PM MDT SAT JUL 4 2009
.UPDATE...NO MAJOR GRID CHANGES TONIGHT. TWEAKED WINDS AND TEMPS
TO OBSERVATIONS. A FEW LINGERING SHOWERS AND A COUPLE CELLS REMAIN
ACROSS CENTRAL MONTANA. THEY ARE DRIFTING GENERALLY EAST AND MAY
CONTINUE TO DROP SOME HAIL AND HEAVY RAIN OVER THE NEXT COUPLE
HOURS. OVERALL FORECAST IS ON TRACK THOUGH. TOMORROW LOOKS TO BE
YET ANOTHER DAY WITH CONVECTIVE ACTIVITY BEING THE MAIN FOCUS.
&&
.AVIATION...
UPDATED 0440Z.
VFR CONDITIONS WILL CONTINUE TO PREVAIL ACROSS THE FORECAST AREA
THROUGH SUNDAY EVENING. ISOLATED THUNDERSTORMS WILL CONTINUE TO
AFFECT FAR NORTHEASTERN PORTIONS OF CENTRAL MONTANA OVERNIGHT.
STORMS WILL BRING BRIEF HEAVY RAINFALL AND HAIL FOR OCCASIONAL MVFR
CONDITIONS AT TIMES. ISOLATED TO SCATTERED THUNDERSTORMS WILL
DEVELOP ONCE AGAIN AFTER 18Z SUNDAY...MAINLY IN SOUTHERN PORTIONS OF
THE FORECAST AREA...AND ARE EXPECTED TO CONTINUE THROUGH LATE SUNDAY
EVENING. MPJ
&&
.PREV DISCUSSION...
/ISSUED 550 PM MDT SAT JUL 4 2009/
TODAY THROUGH MONDAY EVENING...LOCAL ENVIRONMENT
BEGINNING TO DESTABILIZE OVER A WIDE AREA AS EVIDENCED BY NEW
DEVELOPMENT OF SEVERAL MODERATE TO STRONG THUNDERSTORMS ACROSS THE
CENTRAL PORTION OF THE FORECAST AREA. ALTHOUGH HILINE AREA HAS
BEEN MOSTLY CLEAR AND DRY THIS AFTN...SHOULD BEGIN TO SEE STORMS
DEVELOP THERE SHORTLY AS LEADING EDGE OF PACIFIC MOISTURE HAS
CROSSED OVER THE DIVIDE IN GLACIER COUNTY AND IS HEADED EAST ALONG
US/CAN BORDER. HALF- TO ONE-INCH DIAMETER HAIL AND 50-60 MPH WIND
GUSTS WILL BE POSSIBLE WITH ANY OF THESE STORMS.
MODELS MAINTAINED CONSISTENCY ON BRIEF STRENGTHENING THE UPPER RIDGE
OVER THE NRN ROCKIES TOMORROW. THIS WILL TURN UPPER LEVEL FLOW A BIT
MORE WESTERLY RESULTING IN TEMPS REACHING 8 TO 10 DEG ABOVE NORMAL
TOMORROW AFTN. MODELS ALSO BRING ONE MORE PLUME OF PAC MOISTURE
ACROSS THE TOP OF THE RIDGE...SO HAVE CONTINUED MENTION OF
THUNDERSTORMS FOR SUN AFTN/EVE. RIDGE THEN WEAKENS AND MOVES INTO
ERN MT ON MON IN RESPONSE TO UPPER LEVEL TROF COMING ASHORE IN
BC/WA. TROF WILL PUSH NEW PLUME OF PAC MOISTURE OVER WESTERN HALF
OF MT SO ANOTHER ROUND OF THUNDERSTORMS...SOME OF WHICH COULD BE
STRONG...LOOKS LIKELY FOR MON AFTN/EVE. TEMPERATURES WILL REMAIN
ABOVE NORMAL ON MON. WARANAUSKAS
MONDAY NIGHT THROUGH THURSDAY NIGHT...THE ECMWF AND GFS MODELS ARE
NOT IN AS GOOD AGREEMENT TONIGHT AS THEY WERE LAST NIGHT. THE MAIN
DIFFERENCE DURING THIS FORECAST PERIOD IS HOW THEY HANDLE AN UPPER
TROUGH OFF THE PACIFIC NORTHWEST COAST LATE MONDAY NIGHT. THE ECMWF
IS MUCH FASTER THAN THE GFS IN MOVING THIS FEATURE THROUGH THE
FORECAST AREA. THE ECMWF HAS IT MOVING THROUGH ON WEDNESDAY WHILE
THE GFS MOVES IT THROUGH THURSDAY NIGHT. DESPITE THIS DIFFERENCE THE
ECMWF AND GFS AGREE ON THE TREND OF INCREASING THE CHANCES OF
PRECIPITATION FROM TUESDAY TO WEDNESDAY. OF COURSE WITH THE ECMWF
THIS TREND IS DUE TO THE UPPER TROUGH MOVING INTO THE AREA. WITH THE
GFS THERE IS A WEAK DISTURBANCE ALOFT THAT TRIGGERS SOME
THUNDERSTORMS ON WEDNESDAY. THIS IDEA REVERSES ON THURSDAY AS THE
GFS HAS THE UPPER TROUGH APPROACHING THE AREA WHICH RESULTS IN SOME
THUNDERSTORMS. THE ECMWF ON THE OTHER HAND HAS A WEAK WEATHER
DISTURBANCE ALOFT THAT TRIGGERS SOME THUNDERSTORMS. THE INHERITED
CHANCE OF PRECIPITATION FORECASTS HANDLE THESE TRENDS WELL SO MADE
ONLY A FEW MINOR CHANGES. ALSO THE INHERITED IDEA OF HAVING COOLER
TEMPERATURES ON WEDNESDAY AND THURSDAY RELATIVE TO TUESDAY LOOKS
GOOD BUT DID LOWER HIGHS FOR THURSDAY OVER THE PLAINS SOME. BLANK
FRIDAY THROUGH SATURDAY....MODELS ARE NOT IN REAL GOOD AGREEMENT
DURING THIS PERIOD. GFS BRINGS A WEAKENING TROUGH OVER A RIDGE
CENTERED OVER THE SOUTHWEST U.S. WHILE THE ECMWF HAS THIS RIDGE
BUILDING OVER WESTERN MONTANA. CONTINUITY FAVORS THE ECMWF WHICH WAS
USED AS THE BASIS OF THIS FORECAST. PARTLY CLOUDY SKIES ARE EXPECTED
FOR MOST LOCATIONS. OVER AND NEAR THE MOUNTAINS SUFFICIENT MOISTURE
AND INSTABILITY RESULT IN MOSTLY CLOUDY SKIES WITH ISOLATED SHOWERS
AND A FEW MAINLY AFTERNOON AND EVENING THUNDERSTORMS. SHOWERS AND
THUNDERSTORMS WILL BE MORE NUMEROUS OVER THE WESTERN MOUNTAINS.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 56 86 59 84 / 40 20 20 20
CTB 49 80 53 79 / 20 20 20 30
HLN 56 89 59 89 / 20 20 20 20
BZN 55 89 54 90 / 30 20 20 20
WEY 42 74 43 77 / 50 30 30 30
DLN 53 82 54 81 / 30 30 30 20
HVR 52 87 55 87 / 20 20 20 20
LWT 52 82 54 82 / 30 20 20 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GUSTAFSON
LONG TERM...COULSTON
AVIATION...MPJ
WEATHER.GOV/GREATFALLS
000
FXUS65 KBYZ 050315
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
915 PM MDT SAT JUL 4 2009
.SHORT TERM...VALID FOR SUN AND MON...
UPDATE TO ZONES AND AFP THIS EVENING. UPPER WAVE MOVING ACROSS
THE AREA THIS EVENING ALONG WITH DEEP LAYER OF INSTABILITY WHICH
COMBINED TO INITIATED CONVECTION OVER THE WESTERN AND CENTRAL
ZONES. UPPER WAVE DID BRING BETTER SHEAR INTO THE AREA AND
ALLOWED A FOR A FEW STRONG THUNDERSTORMS TO DEVELOP. HEAVY RAIN
FELL OVER SOUTHERN GOLDEN VALLEY COUNTY WITH 1 TO 2 INCHES OF
RAIN FALLING THEIR. UPPER WAVE WILL CONTINUE TO PUSH EASTWARD
OVERNIGHT BUT THUNDERSTORMS WILL BE DIMINISHING IN STRENGTH WITH
LOSS OF DAYTIME HEATING. ANOTHER WAVE IS MOVING INTO THE AREA
FROM THE WEST AND A FEW ISOLATED STORMS WILL BE POSSIBLE OVER THE
WEST AND CENTRAL ZONES. DID REMOVE HEAVY RAIN WORDING FROM THESE
AREAS AS DRIER AIR IS MOVING IN. THERE IS STILL A CHANCE OF HEAVY
RAIN WITH THUNDERSTORMS OVER SOUTHEAST MONTANA TONIGHT AS UPPER
WAVE MOVES EAST AND DEEPER MOISTURE STILL EXIST. TRENDED POPS
DOWN TONIGHT MOST LOCATIONS ALONG WITH LOWER TEMPERATURES DOWN A
FEW DEGREES. RICHMOND
.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...
REGION UNDER STRONGER SOUTHWEST FLOW ALOFT ON TUESDAY AS AN
POSITIVE TILT UPPER LEVEL TROF OVER ALBERTA PUSHES THE RIDGE AXIS
INTO THE DAKOTAS. THIS PATTERN ALSO DEFLECTS MONSOONAL MOISTURE
AWAY FROM THE AREA AND PUSHES THE SURFACE TROUGH INTO THE DAKOTAS.
MOST OF THE MECHANISMS FOR CONVECTION WILL BE REDUCED BUT CAN NOT
RULE OUT AFTERNOON EVENING THUNDER WITH BOUNDARY LAYER RETAINING
MOISTURE FROM A WEEK OF PRECIPITATION OFF AND ON THROUGH THE AREA.
TEMPERATURES SHOULD BE MARKEDLY COOLER THAN MONDAY AND RETURN TO
THE 80S. HEIGHTS REBOUND ON WEDNESDAY AND SURFACE THERMAL TROUGH
BEGINS TO DEVELOP OVER SOUTHEAST MONTANA AND DESPITE UPPER LEVEL
FLOW LOOKING TO BE KEEPING DRY AIR ALOFT THINK THAT DEWPOINT
RETURN COULD SUPPORT ADDITIONAL THUNDER THREAT. SHOULD ALLOW FOR
TEMPERATURES TO REMAIN IN THE 80S BUT COULD SEE THE WESTERN ZONES
REMAIN COOLER ESPECIALLY IF THE DRIER AIR SUPPORTS LOWER OVERNIGHT
MINIMUMS. THURSDAY MODELS ARE IN AGREEMENT THAT BROAD RIDGING WILL
BEGIN TO INFLUENCE THE AREA. THIS SHOULD FURTHER CAP CONVECTIVE
CHANCES AND REALLY PLACE AN EMPHASIS ON THE DIURNAL COMPONENT WITH
TEMPERATURES PUSHING BACK INTO THE UPPER 80S. FRIDAY STARTS TO
LOOK INTERESTING AS THE SURFACE THERMAL LOW GAINS SOME STRENGTH
AND MODELS INDICATE AN INCREASE IN UPPER LEVEL WINDS. IF MOISTURE
DOES ROTATE BACK UP THE PLAINS IT COULD SET UP A FAVORABLE
THUNDERSTORM PATTERN...ESPECIALLY FOR NOCTURNAL STORMS WITH
OVERNIGHT CAP EROSION. TOO FAR INTO THE EXTENDED TO BE PRECISE
WITH THIS SORT OF DETAIL BUT DOES LOOK TO BE THE FIRST DAY THAT
THIS PATTERN BEGINS TO SET UP. MODELS IN LIMITED AGREEMENT FOR
FRIDAY AND NEXT WEEKEND AS THE ECMWF ANCHORS A RIDGE OVER THE AREA
AND THE GFS PUSHES THE RIDGE INTO THE DAKOTAS. NOT A DOMINANT
ENOUGH RIDGE TO ELIMINATE CONVECTION FROM THE FORECAST AND COULD
SEE TEMPS BEGIN INCHING TOWARDS 90. BORSUM
&&
.AVIATION...
A LINE OF SHOWERS AND THUNDERSTORMS WILL PUSH ACROSS CENTRAL
PORTIONS OF THE FORECAST AREA THROUGH MIDNIGHT. THIS CONVECTION
SHOULD DISSIPATE LATE TONIGHT BEFORE MAKING IT MUCH PAST A MILES
CITY TO BROADUS LINE. MVFR CONDITIONS IN MODERATE TO HEAVY RAIN
WILL ACCOMPANY THESE STORMS...ALONG WITH WIND GUSTS TO AROUND 40
MPH. THERE IS A SLIGHT CHANCE OF FOG DEVELOPMENT BY EARLY SUNDAY
MORNING ACROSS THE AREA...PARTICULARLY ALONG AREA RIVERS AND
STREAMS. IFR OR LOWER CONDITIONS CAN BE EXPECTED WITH ANY FOG THAT
DOES DEVELOP. OTHERWISE VFR FLIGHT CONDITIONS CAN BE EXPECTED
THROUGH MID DAY SUNDAY. CHAMBERS
&&
.PRELIMINARY POINT TEMP/POPS...
SUN MON TUE WED THU FRI SAT
-----------------------------------------------------------
BIL 059/088 062/090 061/088 058/083 054/079 057/081 057/085
32/T 21/B 22/T 22/T 22/T 22/T 22/T
LVM 048/084 052/086 051/084 050/079 047/075 047/079 049/082
33/T 23/T 22/T 22/T 22/T 32/T 22/T
HDN 059/091 058/093 059/093 057/089 051/084 055/086 056/088
32/T 21/B 22/T 22/T 22/T 22/T 22/T
MLS 059/090 062/091 063/092 063/087 056/088 060/084 060/086
32/T 21/B 22/T 22/T 32/T 32/T 32/T
4BQ 057/087 060/090 061/092 063/087 056/081 057/084 058/087
32/T 21/B 11/B 22/T 22/T 22/T 22/T
BHK 056/086 061/088 060/088 061/083 058/082 058/084 058/084
22/T 21/B 22/T 22/T 32/T 22/T 22/T
SHR 052/085 054/090 055/089 057/085 049/082 052/081 052/085
43/T 32/T 22/T 22/T 22/T 22/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KGGW 050303 AAA
AFDGGW
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GLASGOW MT
903 PM MDT SAT JUL 4 2009
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH MONDAY...
THUNDERSTORMS ARE MOVING SOUTHEAST ACROSS THE CENTRAL AND
SOUTHEASTERN REGIONS. A FEW ARE DRIFTING INTO PHILLIPS AND
PETROLEUM COUNTIES THIS EVENING...WHICH COULD PRODUCE GUSTY WINDS
AND SMALL HAIL. INCREASED POPS TO CHANCE IN THE WEST. STORMS ARE
EXPECTED TO LOSE THEIR STRENGTH AS THEY DRIFT FURTHER INTO HIGHER
PRESSURE. OTHERWISE FORECAST IS IN GOOD SHAPE WITH ONLY MINOR GRID
EDITS BASED ON OBSERVATIONS. SCT
PREVIOUS DISCUSSION...
CURRENT GOES WATER VAPOR IMAGERY REVEALS WESTERLY FLOW ALOFT OVER
NORTHEAST MONTANA WITH A FEW IMPULSES EMBEDDED WITHIN THE LONGWAVE
FLOW...ONE OF WHICH IS TRIGGERING A FEW THUNDERSTORMS OVER CENTRAL
MONTANA THIS AFTERNOON. AT THE SURFACE...AN AREA OF HIGH PRESSURE
IS CENTERED OVER SOUTH CENTRAL SASKATCHEWAN WITH THE SURFACE RIDGE
BISECTING THE LOCAL FORECAST AREA. THIS HIGH PRESSURE SYSTEM HAS
BEEN STRONGER THAN EXPECTED...WITH AFTERNOON TEMPERATURES RUNNING
BELOW FORECAST VALUES AT THIS POINT. THE STRENGTH OF THE SURFACE
HIGH IS SUGGESTIVE OF MODEST SUBSIDENCE ALOFT...WHICH AT THIS
POINT HAS PREVENTED THE WAVE OVER CENTRAL MONTANA FROM ADVANCING
EASTWARD. ANOTHER SHORTWAVE IS TRIGGERING CONVECTION OVER
SOUTHWEST MONTANA WHERE THE ATMOSPHERE IS UNSTABLE. THIS AREA OF
INSTABILITY DOES REACH INTO THE FAR SOUTHWEST ZONES WHERE A FEW
THUNDERSTORMS COULD DRIFT IN FROM THE WEST LATE THIS AFTERNOON
INTO THIS EVENING. A FEW STORMS COULD CONTAIN MODEST WIND GUSTS
AND SMALL HAIL. THUNDERSTORM POTENTIAL APPEARS LIMITED ACROSS THE
REMAINDER OF THE AREA UNTIL THE HIGH PRESSURE RIDGE SLIDES EAST.
THE AREA OF PVA OVER SOUTHWEST MONTANA WILL MOVE ACROSS NORTHEAST
MONTANA OVERNIGHT. MEANWHILE...AN UPPER RIDGE WILL STRENGTHEN OVER
THE CONTINENTAL DIVIDE AS A VIGOROUS UPPER TROUGH DRIVES TOWARD
THE PACIFIC NORTHWEST. THIS WILL INDUCE A BAROCLINIC ZONE OVER THE
NORTHEAST CORNER OF THE CWA. THIS WILL BECOME THE FOCAL POINT FOR
A FEW SHOWERS OR THUNDERSTORMS IN THE NORTHEAST ZONES LATE TONIGHT
AND EARLY SUNDAY. TEMPERATURES WILL WARM WELL INTO THE 80S SUNDAY
FOR MOST OF THE AREA AS A THERMAL RIDGE BUILDS NORTH INTO CENTRAL
MONTANA. THE EXCEPTION WILL BE THE FAR NORTHEAST NEAR THE FRONTAL
ZONE WHERE TEMPERATURES WILL BE A FEW DEGREES COOLER.
THE UPPER RIDGE AXIS PASSES OVERHEAD SUNDAY NIGHT WITH SOUTHWEST
FLOW ALOFT DEVELOPING AHEAD OF THE APPROACHING PACIFIC TROUGH
MONDAY. THERE IS STILL SOME UNCERTAINTY IN THE POSITIONING OF THE
STRONGEST DYNAMICS. THE ECMWF...GEM...AND UKMET BRING THE
STRONGEST DYNAMICS INTO CENTRAL MONTANA MONDAY AFTERNOON...WHILE
THE GFS AND NAM SEND THE VIGOROUS SHORTWAVE INTO THE CANADIAN
PRAIRIES. NONETHELESS THE GFS AND NAM DO INDICATE MID-LEVEL
CONVERGENCE...WHICH PHASES WITH A SURFACE LOW OVER CENTRAL MONTANA
AND SOUTHEASTERLY LOW-LEVEL FLOW TO THE EAST DRAWING MOISTURE INTO
THE AREA. SO THE PATTERN DOES LOOK FAVORABLE FOR STRONG TO SEVERE
STORMS. MONDAY WILL BE ANOTHER WARM DAY AS THE THERMAL RIDGE
REMAINS OVER THE AREA. AJZ
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
GFS MOVING TOWARD THE SLIGHTLY MORE AMPLIFIED ECMWF SOLUTION FOR
THE EXTENDED PERIOD. FORECAST WAS ALREADY TRENDED TOWARD THE ECMWF
SO FEW CHANGES MADE. TROF MOVES THROUGH THE REGION MID TO LATE
WEEK WITH CHANCES OF THUNDERSTORMS...THE RIDGE REBOUNDS INTO THE
WEEKEND FOR A RETURN TO DRIER CONDITIONS. EBERT
PREVIOUS LONG TERM DISCUSSION...UPPER RIDGE MOVES TO THE EAST
MONDAY NIGHT AND TUESDAY. A SURFACE TROUGH OVER THE AREA COMBINED
WITH SHORTWAVES ON SOUTHWEST FLOW ALOFT WILL BRING A CHANCE OF
SHOWERS AND THUNDERSTORMS.
MODELS DIFFER ON HOW TO BRING UPPER TROUGH THAT IS FORECASTED TO
BE OFF THE WASHINGTON COAST ON TUESDAY INLAND. THE ECMWF BRINGS THE
TROUGH EAST INTACT PASSING THROUGH EASTERN MONTANA WEDNESDAY
NIGHT. THE GFS SIGNIFICANTLY WEAKENS THE TROUGH AND WAITS UNTIL
FRIDAY TO GET IT TO EASTERN MONTANA. THE ECMWF IS SHOWING BETTER
RUN TO RUN CONSISTENCY WITH THIS SYSTEM. IT LOOKS LIKE THERE COULD
BE A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS WHEN THE TROUGH
COMBINED WITH 100 KNOT JET MOVES THROUGH WEDNESDAY NIGHT. WEAK
SHORTWAVES BEHIND THE TROUGH COULD BRING ANOTHER CHANCE OF SHOWERS
AND THUNDERSTORMS THURSDAY.
THE MODELS DIFFER BETWEEN GFS HAVING ZONAL FLOW WITH WAVES AND
ECMWF HAVING UPPER RIDGE GOING INTO NEXT WEEKEND. WILL MENTION A
SLIGHT CHANCE OF THUNDERSTORMS ON SATURDAY FOR NOW.
&&
.AVIATION...
VFR CONDITIONS EXPECTED TO DOMINATE AT THE TAF SITES OVER THE NEXT
24 HOURS. HOWEVER THERE IS A CHANCE OF A SHOWER AND/OR
THUNDERSTORM OVERNIGHT THAT COULD BRING BRIEF PERIODS OF MVFR
CONDITIONS. RAE
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KTFX 050252
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
852 PM MDT SAT JUL 4 2009
.UPDATE...NO MAJOR GRID CHANGES TONIGHT. TWEAKED WINDS AND TEMPS
TO OBSERVATIONS. A FEW LINGERING SHOWERS AND A COUPLE CELLS REMAIN
ACROSS CENTRAL MONTANA. THEY ARE DRIFTING GENERALLY EAST AND MAY
CONTINUE TO DROP SOME HAIL AND HEAVY RAIN OVER THE NEXT COUPLE
HOURS. OVERALL FORECAST IS ON TRACK THOUGH. TOMORROW LOOKS TO BE
YET ANOTHER DAY WITH CONVECTIVE ACTIVITY BEING THE MAIN FOCUS.
&&
.AVIATION...
UPDATED 2350Z.
VFR CONDITIONS WILL GENERALLY PREVAIL ACROSS SOUTHWEST...CENTRAL...
AND NORTH CENTRAL MONTANA THROUGH THE FORECAST. ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO TRANSIT EAST
ACROSS THE REGION FOR A FEW HOURS. THE MAJORITY OF CURRENT STORMS
ARE ALONG A LINE JUST SOUTH OF HAVRE TO LEWISTOWN. THERE IS ONE
STRONG CELL ALSO CURRENTLY SOUTHWEST OF CUT BANK MOVING SOUTHEAST.
THERE IS A CHANCE FOR BRIEF HEAVY RAINFALL WITH OCCASIONAL MVFR
CONDITIONS AROUND ANY CELLS. STRONG GUSTY WINDS AND HAIL ARE ALSO
POSSIBLE AND LIKELY AROUND STRONGER THUNDERSTORMS. STORMS WILL
GRADUALLY DIMINISH FROM WEST TO EAST THROUGH 06Z...HOWEVER A CHANCE
OF SHOWERS WILL PERSIST BUT THE OVERNIGHT HOURS SHOULD BE MOSTLY
QUIET. TOMORROW AFTERNOON LOOKS TO AGAIN HAVE THE POTENTIAL FOR
ISOLATED THUNDERSTORM DEVELOPMENT...MOSTLY AT SOUTHERN
LOCATIONS...THUS THE PROB30 FOR -TSRA AT HELENA...BOZEMAN...AND
LEWISTOWN.
&&
.PREV DISCUSSION...
/ISSUED 550 PM MDT SAT JUL 4 2009/
TODAY THROUGH MONDAY EVENING...LOCAL ENVIRONMENT
BEGINNING TO DESTABILIZE OVER A WIDE AREA AS EVIDENCED BY NEW
DEVELOPMENT OF SEVERAL MODERATE TO STRONG THUNDERSTORMS ACROSS THE
CENTRAL PORTION OF THE FORECAST AREA. ALTHOUGH HILINE AREA HAS
BEEN MOSTLY CLEAR AND DRY THIS AFTN...SHOULD BEGIN TO SEE STORMS
DEVELOP THERE SHORTLY AS LEADING EDGE OF PACIFIC MOISTURE HAS
CROSSED OVER THE DIVIDE IN GLACIER COUNTY AND IS HEADED EAST ALONG
US/CAN BORDER. HALF- TO ONE-INCH DIAMETER HAIL AND 50-60 MPH WIND
GUSTS WILL BE POSSIBLE WITH ANY OF THESE STORMS.
MODELS MAINTAINED CONSISTENCY ON BRIEF STRENGTHENING THE UPPER RIDGE
OVER THE NRN ROCKIES TOMORROW. THIS WILL TURN UPPER LEVEL FLOW A BIT
MORE WESTERLY RESULTING IN TEMPS REACHING 8 TO 10 DEG ABOVE NORMAL
TOMORROW AFTN. MODELS ALSO BRING ONE MORE PLUME OF PAC MOISTURE
ACROSS THE TOP OF THE RIDGE...SO HAVE CONTINUED MENTION OF
THUNDERSTORMS FOR SUN AFTN/EVE. RIDGE THEN WEAKENS AND MOVES INTO
ERN MT ON MON IN RESPONSE TO UPPER LEVEL TROF COMING ASHORE IN
BC/WA. TROF WILL PUSH NEW PLUME OF PAC MOISTURE OVER WESTERN HALF
OF MT SO ANOTHER ROUND OF THUNDERSTORMS...SOME OF WHICH COULD BE
STRONG...LOOKS LIKELY FOR MON AFTN/EVE. TEMPERATURES WILL REMAIN
ABOVE NORMAL ON MON. WARANAUSKAS
MONDAY NIGHT THROUGH THURSDAY NIGHT...THE ECMWF AND GFS MODELS ARE
NOT IN AS GOOD AGREEMENT TONIGHT AS THEY WERE LAST NIGHT. THE MAIN
DIFFERENCE DURING THIS FORECAST PERIOD IS HOW THEY HANDLE AN UPPER
TROUGH OFF THE PACIFIC NORTHWEST COAST LATE MONDAY NIGHT. THE ECMWF
IS MUCH FASTER THAN THE GFS IN MOVING THIS FEATURE THROUGH THE
FORECAST AREA. THE ECMWF HAS IT MOVING THROUGH ON WEDNESDAY WHILE
THE GFS MOVES IT THROUGH THURSDAY NIGHT. DESPITE THIS DIFFERENCE THE
ECMWF AND GFS AGREE ON THE TREND OF INCREASING THE CHANCES OF
PRECIPITATION FROM TUESDAY TO WEDNESDAY. OF COURSE WITH THE ECMWF
THIS TREND IS DUE TO THE UPPER TROUGH MOVING INTO THE AREA. WITH THE
GFS THERE IS A WEAK DISTURBANCE ALOFT THAT TRIGGERS SOME
THUNDERSTORMS ON WEDNESDAY. THIS IDEA REVERSES ON THURSDAY AS THE
GFS HAS THE UPPER TROUGH APPROACHING THE AREA WHICH RESULTS IN SOME
THUNDERSTORMS. THE ECMWF ON THE OTHER HAND HAS A WEAK WEATHER
DISTURBANCE ALOFT THAT TRIGGERS SOME THUNDERSTORMS. THE INHERITED
CHANCE OF PRECIPITATION FORECASTS HANDLE THESE TRENDS WELL SO MADE
ONLY A FEW MINOR CHANGES. ALSO THE INHERITED IDEA OF HAVING COOLER
TEMPERATURES ON WEDNESDAY AND THURSDAY RELATIVE TO TUESDAY LOOKS
GOOD BUT DID LOWER HIGHS FOR THURSDAY OVER THE PLAINS SOME. BLANK
FRIDAY THROUGH SATURDAY....MODELS ARE NOT IN REAL GOOD AGREEMENT
DURING THIS PERIOD. GFS BRINGS A WEAKENING TROUGH OVER A RIDGE
CENTERED OVER THE SOUTHWEST U.S. WHILE THE ECMWF HAS THIS RIDGE
BUILDING OVER WESTERN MONTANA. CONTINUITY FAVORS THE ECMWF WHICH WAS
USED AS THE BASIS OF THIS FORECAST. PARTLY CLOUDY SKIES ARE EXPECTED
FOR MOST LOCATIONS. OVER AND NEAR THE MOUNTAINS SUFFICIENT MOISTURE
AND INSTABILITY RESULT IN MOSTLY CLOUDY SKIES WITH ISOLATED SHOWERS
AND A FEW MAINLY AFTERNOON AND EVENING THUNDERSTORMS. SHOWERS AND
THUNDERSTORMS WILL BE MORE NUMEROUS OVER THE WESTERN MOUNTAINS.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 56 86 59 84 / 40 20 20 20
CTB 49 80 53 79 / 20 20 20 30
HLN 56 89 59 89 / 20 20 20 20
BZN 55 89 54 90 / 30 20 20 20
WEY 42 74 43 77 / 50 30 30 30
DLN 53 82 54 81 / 30 30 30 20
HVR 52 87 55 87 / 20 20 20 20
LWT 52 82 54 82 / 30 20 20 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GUSTAFSON
LONG TERM...COULSTON
AVIATION...GUSTAFSON
WEATHER.GOV/GREATFALLS
000
FXUS65 KTFX 042352
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
550 PM MDT SAT JUL 4 2009
.DISCUSSION...
TODAY THROUGH MONDAY EVENING...LOCAL ENVIRONMENT
BEGINNING TO DESTABILIZE OVER A WIDE AREA AS EVIDENCED BY NEW
DEVELOPMENT OF SEVERAL MODERATE TO STRONG THUNDERSTORMS ACROSS THE
CENTRAL PORTION OF THE FORECAST AREA. ALTHOUGH HILINE AREA HAS
BEEN MOSTLY CLEAR AND DRY THIS AFTN...SHOULD BEGIN TO SEE STORMS
DEVELOP THERE SHORTLY AS LEADING EDGE OF PACIFIC MOISTURE HAS
CROSSED OVER THE DIVIDE IN GLACIER COUNTY AND IS HEADED EAST ALONG
US/CAN BORDER. HALF- TO ONE-INCH DIAMETER HAIL AND 50-60 MPH WIND
GUSTS WILL BE POSSIBLE WITH ANY OF THESE STORMS.
MODELS MAINTAINED CONSISTENCY ON BRIEF STRENGTHENING THE UPPER RIDGE
OVER THE NRN ROCKIES TOMORROW. THIS WILL TURN UPPER LEVEL FLOW A BIT
MORE WESTERLY RESULTING IN TEMPS REACHING 8 TO 10 DEG ABOVE NORMAL
TOMORROW AFTN. MODELS ALSO BRING ONE MORE PLUME OF PAC MOISTURE
ACROSS THE TOP OF THE RIDGE...SO HAVE CONTINUED MENTION OF
THUNDERSTORMS FOR SUN AFTN/EVE. RIDGE THEN WEAKENS AND MOVES INTO
ERN MT ON MON IN RESPONSE TO UPPER LEVEL TROF COMING ASHORE IN
BC/WA. TROF WILL PUSH NEW PLUME OF PAC MOISTURE OVER WESTERN HALF
OF MT SO ANOTHER ROUND OF THUNDERSTORMS...SOME OF WHICH COULD BE
STRONG...LOOKS LIKELY FOR MON AFTN/EVE. TEMPERATURES WILL REMAIN
ABOVE NORMAL ON MON. WARANAUSKAS
MONDAY NIGHT THROUGH THURSDAY NIGHT...THE ECMWF AND GFS MODELS ARE
NOT IN AS GOOD AGREEMENT TONIGHT AS THEY WERE LAST NIGHT. THE MAIN
DIFFERENCE DURING THIS FORECAST PERIOD IS HOW THEY HANDLE AN UPPER
TROUGH OFF THE PACIFIC NORTHWEST COAST LATE MONDAY NIGHT. THE ECMWF
IS MUCH FASTER THAN THE GFS IN MOVING THIS FEATURE THROUGH THE
FORECAST AREA. THE ECMWF HAS IT MOVING THROUGH ON WEDNESDAY WHILE
THE GFS MOVES IT THROUGH THURSDAY NIGHT. DESPITE THIS DIFFERENCE THE
ECMWF AND GFS AGREE ON THE TREND OF INCREASING THE CHANCES OF
PRECIPITATION FROM TUESDAY TO WEDNESDAY. OF COURSE WITH THE ECMWF
THIS TREND IS DUE TO THE UPPER TROUGH MOVING INTO THE AREA. WITH THE
GFS THERE IS A WEAK DISTURBANCE ALOFT THAT TRIGGERS SOME
THUNDERSTORMS ON WEDNESDAY. THIS IDEA REVERSES ON THURSDAY AS THE
GFS HAS THE UPPER TROUGH APPROACHING THE AREA WHICH RESULTS IN SOME
THUNDERSTORMS. THE ECMWF ON THE OTHER HAND HAS A WEAK WEATHER
DISTURBANCE ALOFT THAT TRIGGERS SOME THUNDERSTORMS. THE INHERITED
CHANCE OF PRECIPITATION FORECASTS HANDLE THESE TRENDS WELL SO MADE
ONLY A FEW MINOR CHANGES. ALSO THE INHERITED IDEA OF HAVING COOLER
TEMPERATURES ON WEDNESDAY AND THURSDAY RELATIVE TO TUESDAY LOOKS
GOOD BUT DID LOWER HIGHS FOR THURSDAY OVER THE PLAINS SOME. BLANK
FRIDAY THROUGH SATURDAY....MODELS ARE NOT IN REAL GOOD AGREEMENT
DURING THIS PERIOD. GFS BRINGS A WEAKENING TROUGH OVER A RIDGE
CENTERED OVER THE SOUTHWEST U.S. WHILE THE ECMWF HAS THIS RIDGE
BUILDING OVER WESTERN MONTANA. CONTINUITY FAVORS THE ECMWF WHICH WAS
USED AS THE BASIS OF THIS FORECAST. PARTLY CLOUDY SKIES ARE EXPECTED
FOR MOST LOCATIONS. OVER AND NEAR THE MOUNTAINS SUFFICIENT MOISTURE
AND INSTABILITY RESULT IN MOSTLY CLOUDY SKIES WITH ISOLATED SHOWERS
AND A FEW MAINLY AFTERNOON AND EVENING THUNDERSTORMS. SHOWERS AND
THUNDERSTORMS WILL BE MORE NUMEROUS OVER THE WESTERN MOUNTAINS.
TEMPERATURES ARE EXPECTED TO CLIMB TO NEAR SEASONAL AVERAGES. EK
&&
.AVIATION...
UPDATED 2350Z.
VFR CONDITIONS WILL GENERALLY PREVAIL ACROSS SOUTHWEST...CENTRAL...
AND NORTH CENTRAL MONTANA THROUGH THE FORECAST. ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO TRANSIT EAST
ACROSS THE REGION FOR A FEW HOURS. THE MAJORITY OF CURRENT STORMS
ARE ALONG A LINE JUST SOUTH OF HAVRE TO LEWISTOWN. THERE IS ONE
STRONG CELL ALSO CURRENTLY SOUTHWEST OF CUT BANK MOVING SOUTHEAST.
THERE IS A CHANCE FOR BRIEF HEAVY RAINFALL WITH OCCASIONAL MVFR
CONDITIONS AROUND ANY CELLS. STRONG GUSTY WINDS AND HAIL ARE ALSO
POSSIBLE AND LIKELY AROUND STRONGER THUNDERSTORMS. STORMS WILL
GRADUALLY DIMINISH FROM WEST TO EAST THROUGH 06Z...HOWEVER A CHANCE
OF SHOWERS WILL PERSIST BUT THE OVERNIGHT HOURS SHOULD BE MOSTLY
QUIET. TOMORROW AFTERNOON LOOKS TO AGAIN HAVE THE POTENTIAL FOR
ISOLATED THUNDERSTORM DEVELOPMENT...MOSTLY AT SOUTHERN
LOCATIONS...THUS THE PROB30 FOR -TSRA AT HELENA...BOZEMAN...AND
LEWISTOWN.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 56 86 59 84 / 20 20 20 20
CTB 51 80 53 79 / 20 20 20 30
HLN 57 89 59 89 / 20 20 20 20
BZN 52 89 54 90 / 30 20 20 20
WEY 40 74 43 77 / 50 30 30 30
DLN 51 82 54 81 / 30 30 30 20
HVR 53 87 55 87 / 20 20 20 20
LWT 51 82 54 82 / 30 20 20 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...WARANAUSKAS
LONG TERM...BLANK
AVIATION...GUSTAFSON
WEATHER.GOV/GREATFALLS
000
FXUS65 KTFX 042147
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
347 PM MDT SAT JUL 4 2009
.DISCUSSION...
TODAY THROUGH MONDAY EVENING...LOCAL ENVIRONMENT
BEGINNING TO DESTABILIZE OVER A WIDE AREA AS EVIDENCED BY NEW
DEVELOPMENT OF SEVERAL MODERATE TO STRONG THUNDERSTORMS ACROSS THE
CENTRAL PORTION OF THE FORECAST AREA. ALTHOUGH HILINE AREA HAS
BEEN MOSTLY CLEAR AND DRY THIS AFTN...SHOULD BEGIN TO SEE STORMS
DEVELOP THERE SHORTLY AS LEADING EDGE OF PACIFIC MOISTURE HAS
CROSSED OVER THE DIVIDE IN GLACIER COUNTY AND IS HEADED EAST ALONG
US/CAN BORDER. HALF- TO ONE-INCH DIAMETER HAIL AND 50-60 MPH WIND
GUSTS WILL BE POSSIBLE WITH ANY OF THESE STORMS.
MODELS MAINTAINED CONSISTENCY ON BRIEF STRENGTHENING THE UPPER RIDGE
OVER THE NRN ROCKIES TOMORROW. THIS WILL TURN UPPER LEVEL FLOW A BIT
MORE WESTERLY RESULTING IN TEMPS REACHING 8 TO 10 DEG ABOVE NORMAL
TOMORROW AFTN. MODELS ALSO BRING ONE MORE PLUME OF PAC MOISTURE
ACROSS THE TOP OF THE RIDGE...SO HAVE CONTINUED MENTION OF
THUNDERSTORMS FOR SUN AFTN/EVE. RIDGE THEN WEAKENS AND MOVES INTO
ERN MT ON MON IN RESPONSE TO UPPER LEVEL TROF COMING ASHORE IN
BC/WA. TROF WILL PUSH NEW PLUME OF PAC MOISTURE OVER WESTERN HALF OF
MT SO ANOTHER ROUND OF THUNDERSTORMS...SOME OF WHICH COULD BE
STRONG...LOOKS LIKELY FOR MON AFTN/EVE. TEMPERATURES WILL REMAIN
ABOVE NORMAL ON MON. WARANAUSKAS
MONDAY NIGHT THROUGH THURSDAY NIGHT...THE ECMWF AND GFS MODELS ARE
NOT IN AS GOOD AGREEMENT TONIGHT AS THEY WERE LAST NIGHT. THE MAIN
DIFFERENCE DURING THIS FORECAST PERIOD IS HOW THEY HANDLE AN UPPER
TROUGH OFF THE PACIFIC NORTHWEST COAST LATE MONDAY NIGHT. THE ECMWF
IS MUCH FASTER THAN THE GFS IN MOVING THIS FEATURE THROUGH THE
FORECAST AREA. THE ECMWF HAS IT MOVING THROUGH ON WEDNESDAY WHILE
THE GFS MOVES IT THROUGH THURSDAY NIGHT. DESPITE THIS DIFFERENCE THE
ECMWF AND GFS AGREE ON THE TREND OF INCREASING THE CHANCES OF
PRECIPITATION FROM TUESDAY TO WEDNESDAY. OF COURSE WITH THE ECMWF
THIS TREND IS DUE TO THE UPPER TROUGH MOVING INTO THE AREA. WITH THE
GFS THERE IS A WEAK DISTURBANCE ALOFT THAT TRIGGERS SOME
THUNDERSTORMS ON WEDNESDAY. THIS IDEA REVERSES ON THURSDAY AS THE
GFS HAS THE UPPER TROUGH APPROACHING THE AREA WHICH RESULTS IN SOME
THUNDERSTORMS. THE ECMWF ON THE OTHER HAND HAS A WEAK WEATHER
DISTURBANCE ALOFT THAT TRIGGERS SOME THUNDERSTORMS. THE INHERITED
CHANCE OF PRECIPITATION FORECASTS HANDLE THESE TRENDS WELL SO MADE
ONLY A FEW MINOR CHANGES. ALSO THE INHERITED IDEA OF HAVING COOLER
TEMPERATURES ON WEDNESDAY AND THURSDAY RELATIVE TO TUESDAY LOOKS
GOOD BUT DID LOWER HIGHS FOR THURSDAY OVER THE PLAINS SOME. BLANK
FRIDAY THROUGH SATURDAY....MODELS ARE NOT IN REAL GOOD AGREEMENT
DURING THIS PERIOD. GFS BRINGS A WEAKENING TROUGH OVER A RIDGE
CENTERED OVER THE SOUTHWEST U.S. WHILE THE ECMWF HAS THIS RIDGE
BUILDING OVER WESTERN MONTANA. CONTINUITY FAVORS THE ECMWF WHICH WAS
USED AS THE BASIS OF THIS FORECAST. PARTLY CLOUDY SKIES ARE EXPECTED
FOR MOST LOCATIONS. OVER AND NEAR THE MOUNTAINS SUFFICIENT MOISTURE
AND INSTABILITY RESULT IN MOSTLY CLOUDY SKIES WITH ISOLATED SHOWERS
AND A FEW MAINLY AFTERNOON AND EVENING THUNDERSTORMS. SHOWERS AND
THUNDERSTORMS WILL BE MORE NUMEROUS OVER THE WESTERN MOUNTAINS.
TEMPERATURES ARE EXPECTED TO CLIMB TO NEAR SEASONAL AVERAGES. EK
&&
.AVIATION...
UPDATED 1805Z.
VFR CONDITIONS WILL GENERALLY PREVAIL ACROSS SOUTHWEST...CENTRAL...
AND NORTH CENTRAL MONTANA THROUGH 18Z SUNDAY. ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DEVELOP THROUGH 21Z
ACROSS THE AREA. STORMS HAVE ALREADY DEVELOPED ALONG A
KDLN-TO-KLWT...WHICH WILL AFFECT THE KBZN KHLN KLWT TERMINALS. THE
BEST CHANCE FOR BRIEF HEAVY RAINFALL WITH OCCASIONAL MVFR CONDITIONS
WILL BE FROM KBZN NORTHEAST TO KLWT...WITH STRONG GUSTY WINDS AND
HAIL POSSIBLE WITH THESE THUNDERSTORMS. SIMILAR THUNDERSTORMS WILL
ALSO DEVELOP ALONG AND EAST OF A BOUNDARY FROM KCTB TO KLWT
(INCLUDING KHVR) AFTER 20Z...BUT THERE IS A BETTER CHANCE FOR
POTENTIALLY LARGE HAIL AND DAMAGING WIND GUSTS THERE. KGTF AND KHLN
WILL LIKELY HAVE WEAKER STORMS. STORMS WILL GRADUALLY DIMINISH FROM
WEST TO EAST THROUGH 06Z...BUT A CHANCE OF SHOWERS WILL PERSIST
OVERNIGHT NEAR KHVR. COULSTON
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 56 86 59 84 / 20 20 20 20
CTB 51 80 53 79 / 20 20 20 30
HLN 57 89 59 89 / 20 20 20 20
BZN 52 89 54 90 / 30 20 20 20
WEY 40 74 43 77 / 50 30 30 30
DLN 51 82 54 81 / 30 30 30 20
HVR 53 87 55 87 / 20 20 20 20
LWT 51 82 54 82 / 30 20 20 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...WARANAUSKAS
LONG TERM...BLANK
AVIATION...COULSTON
WEATHER.GOV/GREATFALLS
000
FXUS65 KBYZ 042103
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
303 PM MDT SAT JUL 4 2009
.SHORT TERM...VALID FOR SUN AND MON...
SCATTERED SHOWERS AND THUNDERSTORMS HAVE BEGUN TO FORM OVER THE
HIGHER TERRAIN ACROSS THE REGION. IT IS EXPECTED THAT THIS
ACTIVITY WILL CONTINUE INTO THE EVENING WITH A NUMBER OF CELLS
MOVING ONTO THE PLAINS. SURFACE DEW POINTS ARE GENERALLY IN THE
50S ACROSS THE CWA WITH TEMPERATURES EXPECTED TO WARM INTO THE
LOW 80S. LATEST LAPS ANALYSIS SHOWING AROUND 2000 J/KG OF SBCAPE
ACROSS WESTERN ZONES DOWN TO 1000 J/KG TO THE EAST. DEEP LAYER
SHEAR REMAINS RATHER MODEST WITH VALUES AROUND 25-30 KTS.
PRECIPITABLE WATERS ARE FORECAST TO REMAIN AROUND ONE INCH FOR
TODAY. MID-LVL LAPSE RATES ARE MODERATELY STEEP. SURFACE DEW
POINT DEPRESSIONS WILL CONTINUE TO INCREASE AS TEMPERATURES RISE
THIS AFTERNOON. THEREFORE...A FEW CELLS MAY BECOME STRONG WITH
HAIL AND GUSTY WINDS. HEAVY RAIN WILL BE POSSIBLE WITH ANY OF
THESE THUNDERSTORMS.
ACTIVITY IS EXPECTED TO QUIET DOWN AFTER SUNSET. UPPER RIDGE
BUILDS OVER THE REGION SUNDAY AS A TROUGH DIGS OVER THE PACIFIC
COAST. KEPT CHANCE POPS IN THE FORECAST AS UPPER-LEVEL ENERGY
CONTINUES TO MOVE THROUGH THE FLOW. LIMITED POPS TO MAINLY
WESTERN ZONES FOR MONDAY. UPPER TROUGH MOVES THROUGH THE PACIFIC
NORTHWEST DURING THIS TIME. HOWEVER...THE GREATER Q-G FORCING
APPEARS NW OF THE CWA. SCHUKNECHT
.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...
REGION UNDER STRONGER SOUTHWEST FLOW ALOFT ON TUESDAY AS AN
POSITIVE TILT UPPER LEVEL TROF OVER ALBERTA PUSHES THE RIDGE AXIS
INTO THE DAKOTAS. THIS PATTERN ALSO DEFLECTS MONSOONAL MOISTURE
AWAY FROM THE AREA AND PUSHES THE SURFACE TROUGH INTO THE DAKOTAS.
MOST OF THE MECHANISMS FOR CONVECTION WILL BE REDUCED BUT CAN NOT
RULE OUT AFTERNOON EVENING THUNDER WITH BOUNDARY LAYER RETAINING
MOISTURE FROM A WEEK OF PRECIPITATION OFF AND ON THROUGH THE AREA.
TEMPERATURES SHOULD BE MARKEDLY COOLER THAN MONDAY AND RETURN TO
THE 80S. HEIGHTS REBOUND ON WEDNESDAY AND SURFACE THERMAL TROUGH
BEGINS TO DEVELOP OVER SOUTHEAST MONTANA AND DESPITE UPPER LEVEL
FLOW LOOKING TO BE KEEPING DRY AIR ALOFT THINK THAT DEWPOINT
RETURN COULD SUPPORT ADDITIONAL THUNDER THREAT. SHOULD ALLOW FOR
TEMPERATURES TO REMAIN IN THE 80S BUT COULD SEE THE WESTERN ZONES
REMAIN COOLER ESPECIALLY IF THE DRIER AIR SUPPORTS LOWER OVERNIGHT
MINIMUMS. THURSDAY MODELS ARE IN AGREEMENT THAT BROAD RIDGING WILL
BEGIN TO INFLUENCE THE AREA. THIS SHOULD FURTHER CAP CONVECTIVE
CHANCES AND REALLY PLACE AN EMPHASIS ON THE DIURNAL COMPONENT WITH
TEMPERATURES PUSHING BACK INTO THE UPPER 80S. FRIDAY STARTS TO
LOOK INTERESTING AS THE SURFACE THERMAL LOW GAINS SOME STRENGTH
AND MODELS INDICATE AN INCREASE IN UPPER LEVEL WINDS. IF MOISTURE
DOES ROTATE BACK UP THE PLAINS IT COULD SET UP A FAVORABLE
THUNDERSTORM PATTERN...ESPECIALLY FOR NOCTURNAL STORMS WITH
OVERNIGHT CAP EROSION. TOO FAR INTO THE EXTENDED TO BE PRECISE
WITH THIS SORT OF DETAIL BUT DOES LOOK TO BE THE FIRST DAY THAT
THIS PATTERN BEGINS TO SET UP. MODELS IN LIMITED AGREEMENT FOR
FRIDAY AND NEXT WEEKEND AS THE ECMWF ANCHORS A RIDGE OVER THE AREA
AND THE GFS PUSHES THE RIDGE INTO THE DAKOTAS. NOT A DOMINANT
ENOUGH RIDGE TO ELIMINATE CONVECTION FROM THE FORECAST AND COULD
SEE TEMPS BEGIN INCHING TOWARDS 90. BORSUM
&&
.AVIATION...
THUNDERSTORM ACTIVITY WILL SPREAD ACROSS THE AREA THIS AFTERNOON
AND EVENING FROM WEST TO EAST. STORMS WILL BE SLOW MOVING
PRODUCING HEAVY RAIN WITH TEMPORARY RESTRICTIONS TO VISIBILITIES
AND POSSIBLY SMALL HAIL. STORMS WILL DISSIPATE BY MIDNIGHT.
REDEVELOPMENT OF THUNDERSTORMS IS EXPECTED ON SUNDAY. BORSUM
&&
.PRELIMINARY POINT TEMP/POPS...
SUN MON TUE WED THU FRI SAT
-----------------------------------------------------------
BIL 060/088 062/090 061/088 058/083 054/079 057/081 057/085
42/T 21/B 22/T 22/T 22/T 22/T 22/T
LVM 049/084 052/086 051/084 050/079 047/075 047/079 049/082
43/T 23/T 22/T 22/T 22/T 32/T 22/T
HDN 060/091 058/093 059/093 057/089 051/084 055/086 056/088
32/T 21/B 22/T 22/T 22/T 22/T 22/T
MLS 060/090 062/091 063/092 063/087 056/088 060/084 060/086
32/T 21/B 22/T 22/T 32/T 32/T 32/T
4BQ 058/087 060/090 061/092 063/087 056/081 057/084 058/087
32/T 21/B 11/B 22/T 22/T 22/T 22/T
BHK 057/086 061/088 060/088 061/083 058/082 058/084 058/084
22/T 21/B 22/T 22/T 32/T 22/T 22/T
SHR 053/085 054/090 055/089 057/085 049/082 052/081 052/085
43/T 32/T 22/T 22/T 22/T 22/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KGGW 042055
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
255 PM MDT SAT JUL 4 2009
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH MONDAY...
CURRENT GOES WATER VAPOR IMAGERY REVEALS WESTERLY FLOW ALOFT OVER
NORTHEAST MONTANA WITH A FEW IMPULSES EMBEDDED WITHIN THE LONGWAVE
FLOW...ONE OF WHICH IS TRIGGERING A FEW THUNDERSTORMS OVER CENTRAL
MONTANA THIS AFTERNOON. AT THE SURFACE...AN AREA OF HIGH PRESSURE
IS CENTERED OVER SOUTH CENTRAL SASKATCHEWAN WITH THE SURFACE RIDGE
BISECTING THE LOCAL FORECAST AREA. THIS HIGH PRESSURE SYSTEM HAS
BEEN STRONGER THAN EXPECTED...WITH AFTERNOON TEMPERATURES RUNNING
BELOW FORECAST VALUES AT THIS POINT. THE STRENGTH OF THE SURFACE
HIGH IS SUGGESTIVE OF MODEST SUBSIDENCE ALOFT...WHICH AT THIS
POINT HAS PREVENTED THE WAVE OVER CENTRAL MONTANA FROM ADVANCING
EASTWARD. ANOTHER SHORTWAVE IS TRIGGERING CONVECTION OVER
SOUTHWEST MONTANA WHERE THE ATMOSPHERE IS UNSTABLE. THIS AREA OF
INSTABILITY DOES REACH INTO THE FAR SOUTHWEST ZONES WHERE A FEW
THUNDERSTORMS COULD DRIFT IN FROM THE WEST LATE THIS AFTERNOON
INTO THIS EVENING. A FEW STORMS COULD CONTAIN MODEST WIND GUSTS
AND SMALL HAIL. THUNDERSTORM POTENTIAL APPEARS LIMITED ACROSS THE
REMAINDER OF THE AREA UNTIL THE HIGH PRESSURE RIDGE SLIDES EAST.
THE AREA OF PVA OVER SOUTHWEST MONTANA WILL MOVE ACROSS NORTHEAST
MONTANA OVERNIGHT. MEANWHILE...AN UPPER RIDGE WILL STRENGTHEN OVER
THE CONTINENTAL DIVIDE AS A VIGOROUS UPPER TROUGH DRIVES TOWARD
THE PACIFIC NORTHWEST. THIS WILL INDUCE A BAROCLINIC ZONE OVER THE
NORTHEAST CORNER OF THE CWA. THIS WILL BECOME THE FOCAL POINT FOR
A FEW SHOWERS OR THUNDERSTORMS IN THE NORTHEAST ZONES LATE TONIGHT
AND EARLY SUNDAY. TEMPERATURES WILL WARM WELL INTO THE 80S SUNDAY
FOR MOST OF THE AREA AS A THERMAL RIDGE BUILDS NORTH INTO CENTRAL
MONTANA. THE EXCEPTION WILL BE THE FAR NORTHEAST NEAR THE FRONTAL
ZONE WHERE TEMPERATURES WILL BE A FEW DEGREES COOLER.
THE UPPER RIDGE AXIS PASSES OVERHEAD SUNDAY NIGHT WITH SOUTHWEST
FLOW ALOFT DEVELOPING AHEAD OF THE APPROACHING PACIFIC TROUGH
MONDAY. THERE IS STILL SOME UNCERTAINTY IN THE POSITIONING OF THE
STRONGEST DYNAMICS. THE ECMWF...GEM...AND UKMET BRING THE
STRONGEST DYNAMICS INTO CENTRAL MONTANA MONDAY AFTERNOON...WHILE
THE GFS AND NAM SEND THE VIGOROUS SHORTWAVE INTO THE CANADIAN
PRAIRIES. NONETHELESS THE GFS AND NAM DO INDICATE MID-LEVEL
CONVERGENCE...WHICH PHASES WITH A SURFACE LOW OVER CENTRAL MONTANA
AND SOUTHEASTERLY LOW-LEVEL FLOW TO THE EAST DRAWING MOISTURE INTO
THE AREA. SO THE PATTERN DOES LOOK FAVORABLE FOR STRONG TO SEVERE
STORMS. MONDAY WILL BE ANOTHER WARM DAY AS THE THERMAL RIDGE
REMAINS OVER THE AREA. AJZ
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
GFS MOVING TOWARD THE SLIGHTLY MORE AMPLIFIED ECMWF SOLUTION FOR
THE EXTENDED PERIOD. FORECAST WAS ALREADY TRENDED TOWARD THE ECMWF
SO FEW CHANGES MADE. TROF MOVES THROUGH THE REGION MID TO LATE
WEEK WITH CHANCES OF THUNDERSTORMS...THE RIDGE REBOUNDS INTO THE
WEEKEND FOR A RETURN TO DRIER CONDITIONS. EBERT
PREVIOUS LONG TERM DISCUSSION...UPPER RIDGE MOVES TO THE EAST
MONDAY NIGHT AND TUESDAY. A SURFACE TROUGH OVER THE AREA COMBINED
WITH SHORTWAVES ON SOUTHWEST FLOW ALOFT WILL BRING A CHANCE OF
SHOWERS AND THUNDERSTORMS.
MODELS DIFFER ON HOW TO BRING UPPER TROUGH THAT IS FORECASTED TO
BE OFF THE WASHINGTON COAST ON TUESDAY INLAND. THE ECMWF BRINGS THE
TROUGH EAST INTACT PASSING THROUGH EASTERN MONTANA WEDNESDAY
NIGHT. THE GFS SIGNIFICANTLY WEAKENS THE TROUGH AND WAITS UNTIL
FRIDAY TO GET IT TO EASTERN MONTANA. THE ECMWF IS SHOWING BETTER
RUN TO RUN CONSISTENCY WITH THIS SYSTEM. IT LOOKS LIKE THERE COULD
BE A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS WHEN THE TROUGH
COMBINED WITH 100 KNOT JET MOVES THROUGH WEDNESDAY NIGHT. WEAK
SHORTWAVES BEHIND THE TROUGH COULD BRING ANOTHER CHANCE OF SHOWERS
AND THUNDERSTORMS THURSDAY.
THE MODELS DIFFER BETWEEN GFS HAVING ZONAL FLOW WITH WAVES AND
ECMWF HAVING UPPER RIDGE GOING INTO NEXT WEEKEND. WILL MENTION A
SLIGHT CHANCE OF THUNDERSTORMS ON SATURDAY FOR NOW.
&&
.AVIATION...
VFR CONDITIONS EXPECTED TO DOMINATE AT THE TAF SITES OVER THE NEXT
24 HOURS. HOWEVER THERE IS A CHANCE OF A SHOWER AND/OR
THUNDERSTORM OVERNIGHT THAT COULD BRING BRIEF PERIODS OF MVFR
CONDITIONS. RAE
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KMSO 042037
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
237 PM MDT SAT JUL 4 2009
.DISCUSSION...
TONIGHT THROUGH MONDAY...AN UPPER LEVEL RIDGE OF HIGH
PRESSURE...THAT HAS BROUGHT SEASONALLY WARM TEMPERATURES AND
AFTERNOON THUNDERSTORM ACTIVITY TO THE REGION DURING THE PAST
SEVERAL DAYS...WILL MOVE EAST OF THE CONTINENTAL DIVIDE DURING THE
NEXT 24 HOURS. THUNDERSTORM ACTIVITY FOR THE REMAINDER OF THIS
EVENING WILL EXIST MAINLY OVER SOUTHWEST MONTANA AND THE SALMON
RIVER CORRIDOR IN IDAHO...WHERE COOL AIR ALOFT IS ANTICIPATED TO BE
PRESENT THROUGH TONIGHT. THE INSTABILITY IN THIS AREA MAY ALLOW A
FEW STRONGER STORMS TO DEVELOP TOWARD SUNSET...WITH THE MAIN THREAT
BEING HAIL AND HEAVY RAIN. HOWEVER...THE CHANCE OF SEVERE WEATHER
APPEARS MARGINAL AT THE PRESENT TIME. BY SUNDAY...SOUTHWESTERLY FLOW
ALOFT IS EXPECTED TO DEVELOP OVER THE NORTHERN U.S. ROCKIES IN
ADVANCE OF A CLOSED LOW PRESSURE CIRCULATION. THIS CLOSED LOW WILL
INTRODUCE COLD AIR ALOFT AND THE PACIFIC JET STREAM TO THE AREA BY
MONDAY...WITH THUNDERSTORM ACTIVITY MOST PRONOUNCED ACROSS NORTHWEST
MONTANA. A SURFACE COLD FRONT IS ANTICIPATED DURING MONDAY...WITH
AFTERNOON TEMPERATURES COOLING 10 DEGREES OR GREATER AS COMPARED
TO SUNDAY AFTERNOON.
MONDAY NIGHT THROUGH FRIDAY...THIS PERIOD IS EXPECTED TO BE SIGNIFICANTLY
COOLER WITH A GOOD THREAT OF PRECIPITATION AS A TROUGH PATTERN
DEVELOPS OVER THE WESTERN U.S. THERE IS GOOD MODEL AGREEMENT ON THIS
THROUGH MIDWEEK. A GENERAL SOUTHWEST FLOW WILL PERSIST BEHIND THIS
FIRST WAVE MONDAY NIGHT THROUGH TUESDAY NIGHT MAINTAINING A SOMEWHAT
MOIST AND UNSTABLE AIR MASS. A MORE MOIST SHORTWAVE IS EXPECTED
WEDNESDAY. THIS WILL LIKELY BE THE COOLEST DAY WITH THE BEST SHOWER
COVERAGE THROUGHOUT THE REGION. MEDIUM RANGE MODELS BEGIN TO DIVERGE
THURSDAY AND FRIDAY WITH THE ECMWF SLOWLY TRANSITIONING TO A DRIER
LOW AMPLITUDE RIDGE AND THE GS HOLDING ONTO SOME TROUGHINESS ALONG
THE WEST COAST AND A WEST-SOUTHWEST FLOW OVER THE NORTHERN ROCKIES.
GIVEN THE STRENGTH AND AMPLITUDE OF THE LONG WAVE TROUGH...THINK THE
GFS MAY BE THE BETTER SOLUTION. THE CURRENT FORECAST OF TRENDING
LATE WEEK PRECIP CHANCES BACK TOWARD CLIMATOLOGY LOOKS GOOD.
&&
.AVIATION...
AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL CONTINUE TO EXIST OVER
THE REGION DURING THE NEXT 24 HOURS. THUNDERSTORM ACTIVITY WILL
EXIST NEAR KBTM AND KSMN THROUGH 05/0300Z. OCCASIONALLY GUSTY
WINDS WILL BE POSSIBLE IN THE VICINITY OF THUNDERSTORMS. A FEW OF
THESE STORMS MAY CONTAIN SMALL HAIL AS WELL. AFTER 05/0300Z...NO
SIGNIFICANT AVIATION WEATHER IMPACTS ARE ANTICIPATED.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&
$$
SHORT TERM...ZUMPFE
LONG TERM....KOLATA
AVIATION...ZUMPFE
000
FXUS65 KTFX 041807
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1205 PM MDT SAT JUL 4 2009
...UPDATE TO AVIATION...
UPDATE...BAND OF ISOLATED SHOWERS...WITH A WEAK THUNDERSTORM OR
TWO...CURRENTLY STRETCHES FROM NRN FERGUS COUNTY NORTHWESTWARD TO
EAST SIDE OF GLACIER NP AND IS MOVING STEADILY EASTWARD. UPDATED
THE 12-18Z POP/WEATHER GRIDS TO MATCH LOCATION OF THIS
ACTIVITY...BUT NO OTHER FORECAST CHANGES MADE AT THIS TIME.
INTENSITY OF AFTN/EVE THUNDERSTORMS STILL THE MAIN CONCERN TODAY.
12Z MODEL DATA SHOWS A BIT LESS WIND SHEAR AND MORE SPOTTY
PRECIPITATION COVERAGE THAN YESTERDAY. BUT WEAKER MORNING INVERSIONS
TODAY...ALONG WITH CURRENT MOSTLY CLEAR SKIES OVER WESTERN HALF OF
CWA...SHOULD PRODUCE MORE HEATING AND INSTABILITY FOR STORM
DEVELOPMENT. THUS WILL KEEP MENTION OF POSSIBLE STRONG STORMS WITH
HAIL AND GUSTY OUTFLOW WINDS IN THE FORECAST FOR AREAS FROM GREAT
FALLS SOUTHWARD. AS WITH PAST FEW DAYS...EXPECT MOST CONVECTIVE
ACTIVITY TO DISSIPATE AROUND SUNSET. WARANAUSKAS
.DISCUSSION...
TODAY THROUGH MONDAY...PACIFIC MOISTURE...MARGINAL INSTABILITY AND
LIGHT UPSLOPE WINDS HAVE ALLOWED FOR ISOLATED SHOWERS AND
THUNDERSTORMS TO DEVELOP ALONG THE CONTINENTAL DIVIDE AND ADJACENT
PLAINS THIS MORNING. CONVECTION WILL STAY MAINLY ISOLATED THIS
MORNING AND THEN BECOME MORE SCATTERED THIS AFTERNOON AS INSTABILITY
AND MOISTURE INCREASE. AT THIS TIME...BEST LIFT AND MOISTURE WILL BE
CONFINED TO SOUTHWEST MONTANA AS LAPSE RATES APPROACH DRY ADIABATIC
AND A WEAK UPPER-LEVEL SHORTWAVE PASSES THROUGH SO HAVE KEPT HIGHEST
POPS THERE. SOME STORMS MAY BECOME STRONG WITH HAIL AND GUSTY WINDS
POSSIBLE THIS AFTERNOON AND EVENING BUT ACTIVITY WILL LIKELY
DIMINISH BY SUNSET AS THE ATMOSPHERE BECOMES MORE STABLE. MODELS
SEEM TO BE IN FAIR AGREEMENT ON SUNDAY FOR AN UPPER-LEVEL RIDGE TO
BUILD OVER THE REGION. AS THE RIDGE AXIS MOVES OVER THE AREA...DRIER
AIR ALOFT WILL LIMIT SHOWER AND THUNDERSTORM ACTIVITY BUT CONTINUED
TO KEEP A SLIGHT CHANCE IN THE FORECAST DUE TO TYPICAL DIURNAL AND
TERRAIN ENHANCEMENT DURING THE AFTERNOON HOURS. TEMPERATURES WILL
REMAIN NEAR AVERAGE FOR TODAY AND THEN CLIMB ABOVE AVERAGE FOR
SUNDAY AND MONDAY WITH READINGS NEAR 90 DEGREES FOR SOME LOCATIONS.
PREDOMINANT SOUTHWEST FLOW WILL ALLOW FOR ABUNDANT PACIFIC MOISTURE
TO STREAM INTO THE REGION ON MONDAY AS A DEEPENING UPPER-LEVEL
TROUGH MOVES INTO THE PACIFIC NORTHWEST...HOWEVER MODELS BEGIN TO
DIVERGE DURING THIS PERIOD IN TERMS OF TIMING AND INTENSITY OF THE
TROUGH. NEVERTHELESS...MODEST INSTABILITY AND WIND SHEAR MAY LEAD TO
ADDITIONAL THUNDERSTORM DEVELOPMENT MONDAY AFTERNOON WITH THE
POTENTIAL FOR SOME STORMS TO BECOME STRONG WITH HAIL AND GUSTY WINDS
SO WILL CONTINUE TO CAREFULLY MONITOR THIS TREND. MLS
MONDAY NIGHT THROUGH THURSDAY NIGHT...THE ECMWF AND GFS MODELS ARE
NOT IN AS GOOD AGREEMENT TONIGHT AS THEY WERE LAST NIGHT. THE MAIN
DIFFERENCE DURING THIS FORECAST PERIOD IS HOW THEY HANDLE AN UPPER
TROUGH OFF THE PACIFIC NORTHWEST COAST LATE MONDAY NIGHT. THE ECMWF
IS MUCH FASTER THAN THE GFS IN MOVING THIS FEATURE THROUGH THE
FORECAST AREA. THE ECMWF HAS IT MOVING THROUGH ON WEDNESDAY WHILE
THE GFS MOVES IT THROUGH THURSDAY NIGHT. DESPITE THIS DIFFERENCE THE
ECMWF AND GFS AGREE ON THE TREND OF INCREASING THE CHANCES OF
PRECIPITATION FROM TUESDAY TO WEDNESDAY. OF COURSE WITH THE ECMWF
THIS TREND IS DUE TO THE UPPER TROUGH MOVING INTO THE AREA. WITH THE
GFS THERE IS A WEAK DISTURBANCE ALOFT THAT TRIGGERS SOME
THUNDERSTORMS ON WEDNESDAY. THIS IDEA REVERSES ON THURSDAY AS THE
GFS HAS THE UPPER TROUGH APPROACHING THE AREA WHICH RESULTS IN SOME
THUNDERSTORMS. THE ECMWF ON THE OTHER HAND HAS A WEAK WEATHER
DISTURBANCE ALOFT THAT TRIGGERS SOME THUNDERSTORMS. THE INHERITED
CHANCE OF PRECIPITATION FORECASTS HANDLE THESE TRENDS WELL SO MADE
ONLY A FEW MINOR CHANGES. ALSO THE INHERITED IDEA OF HAVING COOLER
TEMPERATURES ON WEDNESDAY AND THURSDAY RELATIVE TO TUESDAY LOOKS
GOOD BUT DID LOWER HIGHS FOR THURSDAY OVER THE PLAINS SOME. BLANK
FRIDAY THROUGH SATURDAY....MODELS ARE NOT IN REAL GOOD AGREEMENT
DURING THIS PERIOD. GFS BRINGS A WEAKENING TROUGH OVER A RIDGE
CENTERED OVER THE SOUTHWEST U.S. WHILE THE ECMWF HAS THIS RIDGE
BUILDING OVER WESTERN MONTANA. CONTINUITY FAVORS THE ECMWF WHICH WAS
USED AS THE BASIS OF THIS FORECAST. PARTLY CLOUDY SKIES ARE EXPECTED
FOR MOST LOCATIONS. OVER AND NEAR THE MOUNTAINS SUFFICIENT MOISTURE
AND INSTABILITY RESULT IN MOSTLY CLOUDY SKIES WITH ISOLATED SHOWERS
AND A FEW MAINLY AFTERNOON AND EVENING THUNDERSTORMS. SHOWERS AND
THUNDERSTORMS WILL BE MORE NUMEROUS OVER THE WESTERN MOUNTAINS.
TEMPERATURES ARE EXPECTED TO CLIMB TO NEAR SEASONAL AVERAGES. EK
&&
.AVIATION...
UPDATED 1805Z.
VFR CONDITIONS WILL GENERALLY PREVAIL ACROSS SOUTHWEST...CENTRAL...
AND NORTH CENTRAL MONTANA THROUGH 18Z SUNDAY. ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DEVELOP THROUGH 21Z
ACROSS THE AREA. STORMS HAVE ALREADY DEVELOPED ALONG A
KDLN-TO-KLWT...WHICH WILL AFFECT THE KBZN KHLN KLWT TERMINALS. THE
BEST CHANCE FOR BRIEF HEAVY RAINFALL WITH OCCASIONAL MVFR CONDITIONS
WILL BE FROM KBZN NORTHEAST TO KLWT...WITH STRONG GUSTY WINDS AND
HAIL POSSIBLE WITH THESE THUNDERSTORMS. SIMILAR THUNDERSTORMS WILL
ALSO DEVELOP ALONG AND EAST OF A BOUNDARY FROM KCTB TO KLWT
(INCLUDING KHVR) AFTER 20Z...BUT THERE IS A BETTER CHANCE FOR
POTENTIALLY LARGE HAIL AND DAMAGING WIND GUSTS THERE. KGTF AND KHLN
WILL LIKELY HAVE WEAKER STORMS. STORMS WILL GRADUALLY DIMINISH FROM
WEST TO EAST THROUGH 06Z...BUT A CHANCE OF SHOWERS WILL PERSIST
OVERNIGHT NEAR KHVR. COULSTON
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 83 55 88 57 / 20 20 20 20
CTB 79 50 83 53 / 20 30 20 20
HLN 86 56 90 58 / 20 20 20 20
BZN 86 50 89 51 / 40 30 20 20
WEY 74 39 75 40 / 50 50 30 30
DLN 79 50 82 52 / 40 30 30 30
HVR 84 52 89 53 / 20 30 20 20
LWT 78 49 83 52 / 30 30 20 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
WEATHER.GOV/GREATFALLS
000
FXUS65 KGGW 041604 AAA
AFDGGW
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GLASGOW MT
1004 AM MDT SAT JUL 4 2009
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH MONDAY...
THE SKY IS SUNNY WITH ONLY A FEW CLOUDS...AND TEMPERATURES ARE
RISING INTO THE MID 60S ACROSS NORTHEAST MONTANA THIS INDEPENDENCE
DAY MORNING. THE SHORTWAVE TROUGH THAT TRIGGERED STRONG TO SEVERE
THUNDERSTORMS YESTERDAY AFTERNOON AND EVENING HAS DEPARTED EAST
OVER NORTH DAKOTA LEAVING THE CWA IN AN AREA OF SUBSIDENCE...HENCE
PRODUCING THE AFOREMENTIONED PLEASANT CONDITIONS. ANOTHER UPPER
LEVEL DISTURBANCE IS PROPAGATING ACROSS NORTH CENTRAL MONTANA THIS
MORNING TRIGGERING SOME WEAK CONVECTION FROM CUT BANK TO LEWISTOWN.
THIS WILL REACH THE LOCAL FORECAST AREA THIS AFTERNOON AND BRING A
FEW THUNDERSTORMS...WITH THE BEST CHANCE SOUTH OF A LINE THROUGH
ZORTMAN AND JORDAN. ANY THUNDERSTORMS ARE NOT EXPECTED TO BE AS
VIGOROUS AS THOSE OF YESTERDAY. A FEW TWEAKS WERE MADE TO THE
FORECAST FOR THE REMAINDER OF THE DAY TO REFLECT CURRENT SATELLITE
TRENDS..BUT OTHERWISE THE OVERALL FORECAST IS IN GOOD SHAPE. AJZ
PREVIOUS SHORT TERM DISCUSSION...
HIGH PRESSURE BEGINS BUILDS UP OVER THE SOUTHWESTERN CORNER OF THE
COUNTRY. AS A RESULT...WINDS ALOFT VEERS MORE TO THE NW TODAY WHICH
WILL CHANNEL DRIER AIR FROM CANADA INTO THE LOCAL AREA. INSTABILITY
WILL NOT BE QUITE AS STRONG AS FRIDAY. HENCE...SPC HAS NOT
INCLUDED NE MT IN THE SLIGHT RISK ZONE FOR SEVERE. HOWEVER
TEMPERATURES ARE EXPECTED TO RISE TO NORMAL FOR THIS TIME OF
YEAR...WHICH IS THE UPPER 70S TO LOWER 80S. THIS IS WARM ENOUGH
WITH LEFT OVER MOISTURE TO POSSIBLY PRODUCE A FEW ISOLATED
STORMS...SO WILL LEAVE SLIGHT CHANCE POPS IN FOR THIS AFTERNOON
AND EVENING.
A WEAK SHORTWAVE TRAVELING ALONG THE EASTERN SLOPE OF THE RIDGE
WILL MOVE SE INTO OUR NW ZONES TONIGHT. THIS COULD PRODUCE SOME
ELEVATED STORMS OVERNIGHT.
SUNDAY THE UPPER RIDGE PEAKS OVER WESTERN MONTANA. THICKNESS
HEIGHTS INCREASE LOCALLY WHICH WILL RAMP UP TEMPERATURES A
BIT INTO THE MID TO UPPER 80S. MODELS PICK UP WEAK DISTURBANCES
ALOFT SO WILL MAINTAIN SLIGHT CHANCE POPS. LEE-SIDE SURFACE TROUGH
OVER THE CENTRAL REGION WILL KEEP MOST ACTIVITY TO OUR WEST
THROUGH SUNDAY NIGHT.
MONDAY...A VIGOROUS CLOSED LOW OFF THE COAST OF WASHINGTON MOVES
ASHORE...SENDING A COLD FRONT INTO WESTERN MONTANA. THE THERMAL
RIDGE NUDGES INTO THE CWA FOR ANOTHER WARM DAY...A REPEAT OF
SUNDAY. THE LEE TROUGH SETS UP OVER NE MT WHICH WILL FOCUS MOST
OF THE STORM ENERGY IN SOUTHERN ALBERTA AND SASKATCHEWAN. WILL
MAINTAIN CHANCE TO SLIGHT CHANCE POPS. SCT
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
UPPER RIDGE MOVES TO THE EAST MONDAY NIGHT AND TUESDAY. A SURFACE
TROUGH OVER THE AREA COMBINED WITH SHORTWAVES ON SOUTHWEST FLOW ALOFT WILL
BRING A CHANCE OF SHOWERS AND THUNDERSTORMS.
MODELS DIFFER ON HOW TO BRING UPPER TROUGH THAT IS FORECASTED TO
BE OFF THE WASHINGTON COAST ON TUESDAY INLAND. THE ECMWF BRINGS THE
TROUGH EAST INTACT PASSING THROUGH EASTERN MONTANA WEDNESDAY
NIGHT. THE GFS SIGNIFICANTLY WEAKENS THE TROUGH AND WAITS UNTIL
FRIDAY TO GET IT TO EASTERN MONTANA. THE ECMWF IS SHOWING BETTER
RUN TO RUN CONSISTENCY WITH THIS SYSTEM. IT LOOKS LIKE THERE COULD
BE A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS WHEN THE TROUGH
COMBINED WITH 100 KNOT JET MOVES THROUGH WEDNESDAY NIGHT. WEAK
SHORTWAVES BEHIND THE TROUGH COULD BRING ANOTHER CHANCE OF SHOWERS
AND THUNDERSTORMS THURSDAY.
THE MODELS DIFFER BETWEEN GFS HAVING ZONAL FLOW WITH WAVES AND
ECMWF HAVING UPPER RIDGE GOING INTO NEXT WEEKEND. WILL MENTION A
SLIGHT CHANCE OF THUNDERSTORMS ON SATURDAY FOR NOW.
&&
.AVIATION...
RAIN SHOWERS AND THUNDERSTORMS HAVE EXITED THE AREA FOR NOW. WILL
SEE AT LEAST A FEW HOURS OF MOSTLY CLEAR SKIES THIS MORNING BEFORE
CUMULUS BUILD WITH DAYTIME HEATING. THE TAF SITES HAVE A CHANCE OF
A SHOWER AND/OR THUNDERSTORM THIS AFTERNOON AND TONIGHT THAT COULD
BRING BRIEF PERIODS OF MVFR CONDITIONS. OTHERWISE...VFR CONDITIONS
WILL DOMINATE.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KMSO 041522
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
922 AM MDT SAT JUL 4 2009
.UPDATE...
AREAL COVERAGE OF THUNDERSTORM ACTIVITY INCREASED FOR REMAINDER OF
MORNING BASED ON OBSERVATIONAL TRENDS.
&&
.PREV DISCUSSION... /ISSUED 446 AM MDT SAT JUL 4 2009/
DISCUSSION...THE BIGGEST CHALLENGE WITH THE FORECAST FOR THE NEXT
TWENTY-FOUR HOURS WILL BE DETERMINING WHERE EXACTLY CONVECTION
WILL OCCUR. AS OF FOUR AM...ISOLATED SHOWERS AND THUNDERSTORMS
HAVE ALREADY BEGUN TO DEVELOP OVER THE BOB MARSHALL WILDERNESS
AREA...SOUTHERN GLACIER NATIONAL PARK AND NORTH OF KALISPELL.
WEAKLY FORCED CONVECTION WILL CONTINUE ALONG THE CONTINENTAL
DIVIDE AND POSSIBLY OVER SOUTHERN IDAHO AND LEMHI COUNTIES THROUGH
THE MORNING HOURS.
AS THE DAY PROGRESSES...THE ATMOSPHERE WILL BECOME INCREASINGLY
MOIST AS MID-LEVEL MONSOONAL MOISTURE PERSISTENTLY WORKS ITS WAY
INTO THE NORTHERN ROCKIES REGION. MODEL ANALYSIS DRAW THE
BOUNDARY OF DEEP MOISTURE NORTH TO BETWEEN MISSOULA AND POLSON BY
LATE THIS AFTERNOON. AS THE UPPER LEVEL 500 MB RIDGE AMPLIFIES AND
MOVES EAST...WEAK EMBEDDED WEATHER DISTURBANCES WILL PROPAGATE
THROUGH THE FLOW. SINCE THE ATMOSPHERE WILL BE MOISTENING AND
WARMING...THE ADDED DYNAMICS OF A POTENTIAL SHORTWAVE WEATHER
DISTURBANCE SHOULD RESULT IN THUNDERSTORM ACTIVITY BEING A LITTLE
MORE WIDESPREAD THAN YESTERDAY. ALTHOUGH MANY OF THESE STORMS WILL
BE WEAK...A FEW OVER SOUTHWEST MONTANA MAY BECOME A LITTLE BIT
STRONGER WITH BRIEF HEAVY RAINFALL...SMALL HAIL AND GUSTY WINDS.
SOME ISOLATED CONVECTION MAY CONTINUE DURING THE OVERNIGHT
HOURS...HOWEVER AM NOT NEARLY AS CONFIDENT IN THIS AS THE RIDGE
AXIS WILL BE MOVING OVER THE DIVIDE BY SUNDAY MORNING LIMITING THE
POTENTIAL FOR LIFT.
CONDITIONS ARE SHAPING UP FOR A MORE WIDESPREAD SHOWER AND
THUNDERSTORM EVENT ON SUNDAY. A TROUGH OF LOW PRESSURE WILL
SLOWLY WORK ITS WAY TOWARDS THE PACIFIC COAST...SUBSEQUENTLY
ENHANCING SOUTHWESTERLY FLOW ALOFT AND DIRECTIONAL AND SPEED SHEER
WITHIN THE ATMOSPHERE. AS THIS OCCURS IT APPEARS AS THOUGH
WIDESPREAD SHOWERS AND THUNDERSTORMS WILL DEVELOP OVER MUCH OF
CENTRAL IDAHO AND WESTERN MONTANA BY LATE SUNDAY MORNING OR EARLY
SUNDAY AFTERNOON. THIS WEATHER SYSTEM SHOULD BE MORE OF THE WETTER
VARIETY...HOWEVER NOT BY TOO MUCH AS THE ATMOSPHERE AS A WHOLE IS
NOT OVERLY MOIST. BUT REGARDLESS OF THE FACT AERIAL COVERAGE WILL
BE RATHER LARGE WITH SOME STORMS BECOME STRONG WITH HEAVY
RAINFALL...SMALL HAIL AND WIND GUSTS TO 40 MPH.
TEMPERATURES TODAY AND SUNDAY WILL BE WELL ABOVE SEASONAL
NORMALS...HOWEVER NOT RECORD SETTING AT THIS TIME. THESE
CONDITIONS WILL BE THE WARMEST TEMPERATURES OF THE YEAR. GIVEN
THIS FACT RECREATIONISTS ARE URGED TO STAY HYDRATED AND TAKE THE
NECESSARY PRECAUTIONS TO STAY COOL.
MONDAY THROUGH FRIDAY...THE UPCOMING WORK WEEK IS EXPECTED TO BE
SIGNIFICANTLY COOLER WITH A GOOD THREAT OF PRECIPITATION AS A
TROUGH PATTERN DEVELOPS OVER THE WESTERN U.S. THERE IS GOOD MODEL
AGREEMENT ON THIS THROUGH MIDWEEK. AN INITIAL SHORTWAVE
DISTURBANCE IS SLATED TO PUSH ACROSS THE NORTHERN ROCKIES MONDAY.
THIS WILL CREATE BREEZY WEST WINDS AS THE DISTURBANCE DRAGS A COLD
FRONT ACROSS THE REGION. MOST OF THE THUNDERSTORM POTENTIAL WITH
THESE FEATURES WILL BE FROM MISSOULA NORTH. A GENERAL SOUTHWEST
FLOW WILL PERSIST BEHIND THIS FIRST WAVE MONDAY NIGHT THROUGH
TUESDAY NIGHT MAINTAINING A SOMEWHAT MOIST AND UNSTABLE AIR MASS.
A MORE MOIST SHORTWAVE IS EXPECTED WEDNESDAY. THIS WILL LIKELY BE
THE COOLEST DAY WITH THE BEST SHOWER COVERAGE THROUGHOUT THE
REGION. MEDIUM RANGE MODELS BEGIN TO DIVERGE THURSDAY AND FRIDAY
WITH THE ECMWF SLOWLY TRANSITIONING TO A DRIER LOW AMPLITUDE RIDGE
AND THE GS HOLDING ONTO SOME TROUGHINESS ALONG THE WEST COAST AND
A WEST-SOUTHWEST FLOW OVER THE NORTHERN ROCKIES. GIVEN THE
STRENGTH AND AMPLITUDE OF THE LONG WAVE TROUGH...THINK THE GFS MAY
BE THE BETTER SOLUTION. THE CURRENT FORECAST OF TRENDING LATE WEEK
PRECIP CHANCES BACK TOWARD CLIMATOLOGY LOOKS GOOD.
AVIATION...AFTERNOON SHOWERS AND THUNDERSTORMS ACROSS MUCH OF
WESTERN MONTANA AND CENTRAL IDAHO WILL PRODUCE HIGH TOPPED
CUMULONIMBUS CLOUDS AND THE LIKELIHOOD FOR GUSTY WINDS TODAY AND
AGAIN ON SUNDAY. WINDS ARE EXPECTED TO BE EVEN STRONGER ON SUNDAY
AIDED BY A STRENGTHENING SURFACE PRESSURE GRADIENT.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&
$$
UPDATE...ZUMPFE
SHORT TERM...DICKERSON
LONG TERM....WHITMORE
AVIATION...DICKERSON
000
FXUS65 KBYZ 041520
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
920 AM MDT SAT JUL 4 2009
.SHORT TERM...VALID FOR TDY AND SUN...
INHERITED FORECAST APPEARS TO BE IN GOOD SHAPE AND ONLY MADE
MINOR ADJUSTMENTS. LATEST RUN OF THE NAM STILL SUPPORTIVE OF
AFTERNOON CONVECTION ACROSS THE REGION. DEEP LAYER SHEAR AROUND
25 KTS IS RATHER WEAK. THEREFORE...SEVERE WEATHER IS NOT
ANTICIPATED ACROSS THE MONTANA PORTION OF THE CWA. PRECIPITABLE
WATERS AROUND ONE INCH WILL CONTINUE TO POSE A THREAT FOR HEAVY
RAIN. GREATER VALUES OF SHEAR ARE FORECAST FURTHER SOUTH ALONG
THE FRONT RANGE OF THE ROCKIES. THE NORTHERN EXTENT OF THIS
INCLUDES SHERIDAN COUNTY. WILL MONITOR AFTERNOON CONVECTION OVER
THE BIG HORNS FOR BETTER STORM ORGANIZATION. SCHUKNECHT
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
THE MODELS CONTINUE TO BE IN PRETTY GOOD AGREEMENT THROUGH ABOUT
THURSDAY...MONDAY IS A TRANSITIONAL DAY AS THE UPPER LEVEL RIDGE
MOVES EAST OF MONTANA AND SOUTHWESTERLY FLOW ALOFT BRINGS A BIT
DRIER AIR TO THE STATE. THUNDERSTORM POTENTIAL REMAINS WITH GOOD
SHEAR AND INSTABILITY MAKING UP FOR SLIGHTLY LESS MOISTURE.
SURFACE MOISTURE FROM PREVIOUS WEATHER WILL ALSO PLAY SIGNIFICANT
ROLE AS COULD KEEP SURFACE HUMIDITIES A BIT HIGHER...AT LEAST
LOCALLY. MONDAY SHOULD ALSO BE THE WARMEST OF THE EXTENDED...WITH
LOW TO MID 90S...AS DOWNSLOPE FLOW AIDS MIXING. WARMEST AIR
APPEARS TO SHIFT EAST BY TUESDAY BEGINNING COOLING TREND. THE DRY
AIR SETTLES ACROSS THE REGION THROUGH WEDNESDAY...BUT THE ATMOSPHERE DOES
SEEM AS SHOULD DESTABILIZE ENOUGH IN AFTERNOON AND EVENING TO
ALLOW THUNDER POTENTIAL...ESPECIALLY IN AREAS WHERE HEAVIER PRECIP
HAD OCCURRED OVER LAST SEVERAL DAYS. PWAT BEGINS TO BUILD BACK INTO
THE AREA WEDNESDAY AS A SFC LOW DEVELOPS IN WY AND HELPS UPSLOPE
DEVELOPMENT IN THE FOOTHILLS AND HIGH TERRAIN. THURSDAY BECOMES A
BIT OF A QUESTION WITH SOME DIFFERENCES IN READ ON THE
PROGRESSION OF THE TROF. GFS BRINGS STRONG WAVE INTO THE AREA ON
THURSDAY...BUT HOLDS MAIN TROF AXIS OF TO THE WEST...WHILE EC
PUSHES TROF THROUGH THE REGION. EITHER WAY THURSDAY LOOKS LIKE A
PRETTY ACTIVE DAY ACROSS THE REGION. FRIDAY LOOKS LIKE A
TRANSITIONAL DAY FOR BOTH MODELS...AS EC BUILD IN ANOTHER UPPER
LEVEL RIDGE AND GFS FAVORS MORE ZONAL FLOW AS AN UPPER LOW MOVES
ACROSS NORTHERN CANADA. GENERALLY SPLIT THE DIFFERENCE FOR
TEMPS...AS EC FAVORS QUICK WARMUP FOLLOWING FRIDAY AND GFS REMAINS
PRETTY COOL. SHOULD REMAIN A CHANCE FOR THUNDER THROUGHOUT...WITH
MULTIPLE SHORTWAVES AND GOOD SURFACE MOISTURE FROM PREVIOUS
SHOWERS. GILSTAD
&&
.AVIATION...
EXPECT THUNDERSTORM ACTIVITY TO DEVELOP THIS AFTERNOON WEST OF
KBIL AND SPREAD EASTWARD DURING THE LATE AFTERNOON AND EVENING.
STORMS WILL BE SLOW MOVING PRODUCING HEAVY RAIN WITH TEMPORARY
RESTRICTIONS TO VISIBILITIES. STORMS WILL DISSIPATE AFTER SUNSET.
REDEVELOPMENT OF THUNDERSTORMS IS EXPECTED ON SUNDAY. BORSUM
&&
.PRELIMINARY POINT TEMP/POPS...
TDY SUN MON TUE WED THU FRI
-------------------------------------------------------
BIL 082 061/088 062/091 060/088 058/083 054/080 057/081
4/T 42/T 21/B 22/T 32/T 32/T 32/T
LVM 082 051/086 052/086 051/084 050/079 047/075 047/079
3/T 43/T 23/T 23/T 22/T 22/T 32/T
HDN 084 057/091 058/094 059/093 057/089 051/083 055/086
3/T 32/T 21/B 22/T 32/T 42/T 32/T
MLS 083 060/090 062/094 063/092 063/087 056/085 060/084
3/T 32/T 21/B 22/T 22/T 42/T 32/T
4BQ 081 058/088 059/093 061/092 061/087 056/078 057/084
3/T 32/T 21/B 22/T 22/T 32/T 32/T
BHK 078 058/086 060/091 060/088 061/083 058/079 058/084
3/T 22/T 21/B 22/T 22/T 42/T 32/T
SHR 078 053/085 054/091 055/089 055/085 049/079 052/081
4/T 43/T 32/T 22/T 22/T 32/T 32/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KTFX 041518
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
900 AM MDT SAT JUL 4 2009
UPDATE...BAND OF ISOLATED SHOWERS...WITH A WEAK THUNDERSTORM OR
TWO...CURRENTLY STRETCHES FROM NRN FERGUS COUNTY NORTHWESTWARD TO
EAST SIDE OF GLACIER NP AND IS MOVING STEADILY EASTWARD. UPDATED
THE 12-18Z POP/WEATHER GRIDS TO MATCH LOCATION OF THIS
ACTIVITY...BUT NO OTHER FORECAST CHANGES MADE AT THIS TIME.
INTENSITY OF AFTN/EVE THUNDERSTORMS STILL THE MAIN CONCERN TODAY.
12Z MODEL DATA SHOWS A BIT LESS WIND SHEAR AND MORE SPOTTY
PRECIPITATION COVERAGE THAN YESTERDAY. BUT WEAKER MORNING INVERSIONS
TODAY...ALONG WITH CURRENT MOSTLY CLEAR SKIES OVER WESTERN HALF OF
CWA...SHOULD PRODUCE MORE HEATING AND INSTABILITY FOR STORM
DEVELOPMENT. THUS WILL KEEP MENTION OF POSSIBLE STRONG STORMS WITH
HAIL AND GUSTY OUTFLOW WINDS IN THE FORECAST FOR AREAS FROM GREAT
FALLS SOUTHWARD. AS WITH PAST FEW DAYS...EXPECT MOST CONVECTIVE
ACTIVITY TO DISSIPATE AROUND SUNSET. WARANAUSKAS
.DISCUSSION...
TODAY THROUGH MONDAY...PACIFIC MOISTURE...MARGINAL INSTABILITY AND
LIGHT UPSLOPE WINDS HAVE ALLOWED FOR ISOLATED SHOWERS AND
THUNDERSTORMS TO DEVELOP ALONG THE CONTINENTAL DIVIDE AND ADJACENT
PLAINS THIS MORNING. CONVECTION WILL STAY MAINLY ISOLATED THIS
MORNING AND THEN BECOME MORE SCATTERED THIS AFTERNOON AS INSTABILITY
AND MOISTURE INCREASE. AT THIS TIME...BEST LIFT AND MOISTURE WILL BE
CONFINED TO SOUTHWEST MONTANA AS LAPSE RATES APPROACH DRY ADIABATIC
AND A WEAK UPPER-LEVEL SHORTWAVE PASSES THROUGH SO HAVE KEPT HIGHEST
POPS THERE. SOME STORMS MAY BECOME STRONG WITH HAIL AND GUSTY WINDS
POSSIBLE THIS AFTERNOON AND EVENING BUT ACTIVITY WILL LIKELY
DIMINISH BY SUNSET AS THE ATMOSPHERE BECOMES MORE STABLE. MODELS
SEEM TO BE IN FAIR AGREEMENT ON SUNDAY FOR AN UPPER-LEVEL RIDGE TO
BUILD OVER THE REGION. AS THE RIDGE AXIS MOVES OVER THE AREA...DRIER
AIR ALOFT WILL LIMIT SHOWER AND THUNDERSTORM ACTIVITY BUT CONTINUED
TO KEEP A SLIGHT CHANCE IN THE FORECAST DUE TO TYPICAL DIURNAL AND
TERRAIN ENHANCEMENT DURING THE AFTERNOON HOURS. TEMPERATURES WILL
REMAIN NEAR AVERAGE FOR TODAY AND THEN CLIMB ABOVE AVERAGE FOR
SUNDAY AND MONDAY WITH READINGS NEAR 90 DEGREES FOR SOME LOCATIONS.
PREDOMINANT SOUTHWEST FLOW WILL ALLOW FOR ABUNDANT PACIFIC MOISTURE
TO STREAM INTO THE REGION ON MONDAY AS A DEEPENING UPPER-LEVEL
TROUGH MOVES INTO THE PACIFIC NORTHWEST...HOWEVER MODELS BEGIN TO
DIVERGE DURING THIS PERIOD IN TERMS OF TIMING AND INTENSITY OF THE
TROUGH. NEVERTHELESS...MODEST INSTABILITY AND WIND SHEAR MAY LEAD TO
ADDITIONAL THUNDERSTORM DEVELOPMENT MONDAY AFTERNOON WITH THE
POTENTIAL FOR SOME STORMS TO BECOME STRONG WITH HAIL AND GUSTY WINDS
SO WILL CONTINUE TO CAREFULLY MONITOR THIS TREND. MLS
MONDAY NIGHT THROUGH THURSDAY NIGHT...THE ECMWF AND GFS MODELS ARE
NOT IN AS GOOD AGREEMENT TONIGHT AS THEY WERE LAST NIGHT. THE MAIN
DIFFERENCE DURING THIS FORECAST PERIOD IS HOW THEY HANDLE AN UPPER
TROUGH OFF THE PACIFIC NORTHWEST COAST LATE MONDAY NIGHT. THE ECMWF
IS MUCH FASTER THAN THE GFS IN MOVING THIS FEATURE THROUGH THE
FORECAST AREA. THE ECMWF HAS IT MOVING THROUGH ON WEDNESDAY WHILE
THE GFS MOVES IT THROUGH THURSDAY NIGHT. DESPITE THIS DIFFERENCE THE
ECMWF AND GFS AGREE ON THE TREND OF INCREASING THE CHANCES OF
PRECIPITATION FROM TUESDAY TO WEDNESDAY. OF COURSE WITH THE ECMWF
THIS TREND IS DUE TO THE UPPER TROUGH MOVING INTO THE AREA. WITH THE
GFS THERE IS A WEAK DISTURBANCE ALOFT THAT TRIGGERS SOME
THUNDERSTORMS ON WEDNESDAY. THIS IDEA REVERSES ON THURSDAY AS THE
GFS HAS THE UPPER TROUGH APPROACHING THE AREA WHICH RESULTS IN SOME
THUNDERSTORMS. THE ECMWF ON THE OTHER HAND HAS A WEAK WEATHER
DISTURBANCE ALOFT THAT TRIGGERS SOME THUNDERSTORMS. THE INHERITED
CHANCE OF PRECIPITATION FORECASTS HANDLE THESE TRENDS WELL SO MADE
ONLY A FEW MINOR CHANGES. ALSO THE INHERITED IDEA OF HAVING COOLER
TEMPERATURES ON WEDNESDAY AND THURSDAY RELATIVE TO TUESDAY LOOKS
GOOD BUT DID LOWER HIGHS FOR THURSDAY OVER THE PLAINS SOME. BLANK
FRIDAY THROUGH SATURDAY....MODELS ARE NOT IN REAL GOOD AGREEMENT
DURING THIS PERIOD. GFS BRINGS A WEAKENING TROUGH OVER A RIDGE
CENTERED OVER THE SOUTHWEST U.S. WHILE THE ECMWF HAS THIS RIDGE
BUILDING OVER WESTERN MONTANA. CONTINUITY FAVORS THE ECMWF WHICH WAS
USED AS THE BASIS OF THIS FORECAST. PARTLY CLOUDY SKIES ARE EXPECTED
FOR MOST LOCATIONS. OVER AND NEAR THE MOUNTAINS SUFFICIENT MOISTURE
AND INSTABILITY RESULT IN MOSTLY CLOUDY SKIES WITH ISOLATED SHOWERS
AND A FEW MAINLY AFTERNOON AND EVENING THUNDERSTORMS. SHOWERS AND
THUNDERSTORMS WILL BE MORE NUMEROUS OVER THE WESTERN MOUNTAINS.
TEMPERATURES ARE EXPECTED TO CLIMB TO NEAR SEASONAL AVERAGES. EK
&&
.AVIATION...
UPDATED 1130Z.
EXPECT GENERALLY VFR CONDITIONS. IT WILL BE ANOTHER DAY WITH MAINLY
AFTERNOON AND EVENING THUNDERSTORMS. ALTHOUGH NOT MENTIONED IN THE
TAFS THERE WILL BE A THREAT OF MVFR CONDITIONS IN LOCALLY HEAVY
RAINFALL ASSOCIATED WITH THE THUNDERSTORMS. EXPECT CLOUDS TO BECOME
CLEAR OR MOSTLY CLEAR AFTER DARK. CONFIDENT THAT WINDS WILL
GENERALLY BE AT OR BELOW 10 KNOTS TODAY THROUGH TONIGHT BUT DO NOT
HAVE MUCH CONFIDENCE IN FORECAST WIND DIRECTIONS. BLANK
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 83 55 88 57 / 20 20 20 20
CTB 79 50 83 53 / 20 30 20 20
HLN 86 56 90 58 / 20 20 20 20
BZN 86 50 89 51 / 40 30 20 20
WEY 74 39 75 40 / 50 50 30 30
DLN 79 50 82 52 / 40 30 30 30
HVR 84 52 89 53 / 20 30 20 20
LWT 78 49 83 52 / 30 30 20 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
WEATHER.GOV/GREATFALLS
000
FXUS65 KTFX 041127
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
530 AM MDT SAT JUL 4 2009
UPDATED AVIATION SECTION
.DISCUSSION...
TODAY THROUGH MONDAY...PACIFIC MOISTURE...MARGINAL INSTABILITY AND
LIGHT UPSLOPE WINDS HAVE ALLOWED FOR ISOLATED SHOWERS AND
THUNDERSTORMS TO DEVELOP ALONG THE CONTINENTAL DIVIDE AND ADJACENT
PLAINS THIS MORNING. CONVECTION WILL STAY MAINLY ISOLATED THIS
MORNING AND THEN BECOME MORE SCATTERED THIS AFTERNOON AS INSTABILITY
AND MOISTURE INCREASE. AT THIS TIME...BEST LIFT AND MOISTURE WILL BE
CONFINED TO SOUTHWEST MONTANA AS LAPSE RATES APPROACH DRY ADIABATIC
AND A WEAK UPPER-LEVEL SHORTWAVE PASSES THROUGH SO HAVE KEPT HIGHEST
POPS THERE. SOME STORMS MAY BECOME STRONG WITH HAIL AND GUSTY WINDS
POSSIBLE THIS AFTERNOON AND EVENING BUT ACTIVITY WILL LIKELY
DIMINISH BY SUNSET AS THE ATMOSPHERE BECOMES MORE STABLE. MODELS
SEEM TO BE IN FAIR AGREEMENT ON SUNDAY FOR AN UPPER-LEVEL RIDGE TO
BUILD OVER THE REGION. AS THE RIDGE AXIS MOVES OVER THE AREA...DRIER
AIR ALOFT WILL LIMIT SHOWER AND THUNDERSTORM ACTIVITY BUT CONTINUED
TO KEEP A SLIGHT CHANCE IN THE FORECAST DUE TO TYPICAL DIURNAL AND
TERRAIN ENHANCEMENT DURING THE AFTERNOON HOURS. TEMPERATURES WILL
REMAIN NEAR AVERAGE FOR TODAY AND THEN CLIMB ABOVE AVERAGE FOR
SUNDAY AND MONDAY WITH READINGS NEAR 90 DEGREES FOR SOME LOCATIONS.
PREDOMINANT SOUTHWEST FLOW WILL ALLOW FOR ABUNDANT PACIFIC MOISTURE
TO STREAM INTO THE REGION ON MONDAY AS A DEEPENING UPPER-LEVEL
TROUGH MOVES INTO THE PACIFIC NORTHWEST...HOWEVER MODELS BEGIN TO
DIVERGE DURING THIS PERIOD IN TERMS OF TIMING AND INTENSITY OF THE
TROUGH. NEVERTHELESS...MODEST INSTABILITY AND WIND SHEAR MAY LEAD TO
ADDITIONAL THUNDERSTORM DEVELOPMENT MONDAY AFTERNOON WITH THE
POTENTIAL FOR SOME STORMS TO BECOME STRONG WITH HAIL AND GUSTY WINDS
SO WILL CONTINUE TO CAREFULLY MONITOR THIS TREND. MLS
MONDAY NIGHT THROUGH THURSDAY NIGHT...THE ECMWF AND GFS MODELS ARE
NOT IN AS GOOD AGREEMENT TONIGHT AS THEY WERE LAST NIGHT. THE MAIN
DIFFERENCE DURING THIS FORECAST PERIOD IS HOW THEY HANDLE AN UPPER
TROUGH OFF THE PACIFIC NORTHWEST COAST LATE MONDAY NIGHT. THE ECMWF
IS MUCH FASTER THAN THE GFS IN MOVING THIS FEATURE THROUGH THE
FORECAST AREA. THE ECMWF HAS IT MOVING THROUGH ON WEDNESDAY WHILE
THE GFS MOVES IT THROUGH THURSDAY NIGHT. DESPITE THIS DIFFERENCE THE
ECMWF AND GFS AGREE ON THE TREND OF INCREASING THE CHANCES OF
PRECIPITATION FROM TUESDAY TO WEDNESDAY. OF COURSE WITH THE ECMWF
THIS TREND IS DUE TO THE UPPER TROUGH MOVING INTO THE AREA. WITH THE
GFS THERE IS A WEAK DISTURBANCE ALOFT THAT TRIGGERS SOME
THUNDERSTORMS ON WEDNESDAY. THIS IDEA REVERSES ON THURSDAY AS THE
GFS HAS THE UPPER TROUGH APPROACHING THE AREA WHICH RESULTS IN SOME
THUNDERSTORMS. THE ECMWF ON THE OTHER HAND HAS A WEAK WEATHER
DISTURBANCE ALOFT THAT TRIGGERS SOME THUNDERSTORMS. THE INHERITED
CHANCE OF PRECIPITATION FORECASTS HANDLE THESE TRENDS WELL SO MADE
ONLY A FEW MINOR CHANGES. ALSO THE INHERITED IDEA OF HAVING COOLER
TEMPERATURES ON WEDNESDAY AND THURSDAY RELATIVE TO TUESDAY LOOKS
GOOD BUT DID LOWER HIGHS FOR THURSDAY OVER THE PLAINS SOME. BLANK
FRIDAY THROUGH SATURDAY....MODELS ARE NOT IN REAL GOOD AGREEMENT
DURING THIS PERIOD. GFS BRINGS A WEAKENING TROUGH OVER A RIDGE
CENTERED OVER THE SOUTHWEST U.S. WHILE THE ECMWF HAS THIS RIDGE
BUILDING OVER WESTERN MONTANA. CONTINUITY FAVORS THE ECMWF WHICH WAS
USED AS THE BASIS OF THIS FORECAST. PARTLY CLOUDY SKIES ARE EXPECTED
FOR MOST LOCATIONS. OVER AND NEAR THE MOUNTAINS SUFFICIENT MOISTURE
AND INSTABILITY RESULT IN MOSTLY CLOUDY SKIES WITH ISOLATED SHOWERS
AND A FEW MAINLY AFTERNOON AND EVENING THUNDERSTORMS. SHOWERS AND
THUNDERSTORMS WILL BE MORE NUMEROUS OVER THE WESTERN MOUNTAINS.
TEMPERATURES ARE EXPECTED TO CLIMB TO NEAR SEASONAL AVERAGES. EK
&&
.AVIATION...
UPDATED 1130Z.
EXPECT GENERALLY VFR CONDITIONS. IT WILL BE ANOTHER DAY WITH MAINLY
AFTERNOON AND EVENING THUNDERSTORMS. ALTHOUGH NOT MENTIONED IN THE
TAFS THERE WILL BE A THREAT OF MVFR CONDITIONS IN LOCALLY HEAVY
RAINFALL ASSOCIATED WITH THE THUNDERSTORMS. EXPECT CLOUDS TO BECOME
CLEAR OR MOSTLY CLEAR AFTER DARK. CONFIDENT THAT WINDS WILL
GENERALLY BE AT OR BELOW 10 KNOTS TODAY THROUGH TONIGHT BUT DO NOT
HAVE MUCH CONFIDENCE IN FORECAST WIND DIRECTIONS. BLANK
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 83 55 88 57 / 20 20 20 20
CTB 79 50 83 53 / 20 30 20 20
HLN 86 56 90 58 / 20 20 20 20
BZN 86 50 89 51 / 40 30 20 20
WEY 74 39 75 40 / 50 50 30 30
DLN 79 50 82 52 / 40 30 30 30
HVR 84 52 89 53 / 20 30 20 20
LWT 78 49 83 52 / 30 30 20 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
WEATHER.GOV/GREATFALLS
000
FXUS65 KMSO 041046
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
446 AM MDT SAT JUL 4 2009
.DISCUSSION...THE BIGGEST CHALLENGE WITH THE FORECAST FOR THE NEXT
TWENTY-FOUR HOURS WILL BE DETERMINING WHERE EXACTLY CONVECTION
WILL OCCUR. AS OF FOUR AM...ISOLATED SHOWERS AND THUNDERSTORMS
HAVE ALREADY BEGUN TO DEVELOP OVER THE BOB MARSHALL WILDERNESS
AREA...SOUTHERN GLACIER NATIONAL PARK AND NORTH OF KALISPELL.
WEAKLY FORCED CONVECTION WILL CONTINUE ALONG THE CONTINENTAL
DIVIDE AND POSSIBLY OVER SOUTHERN IDAHO AND LEMHI COUNTIES THROUGH
THE MORNING HOURS.
AS THE DAY PROGRESSES...THE ATMOSPHERE WILL BECOME INCREASINGLY
MOIST AS MID-LEVEL MONSOONAL MOISTURE PERSISTENTLY WORKS ITS WAY
INTO THE NORTHERN ROCKIES REGION. MODEL ANALYSIS DRAW THE
BOUNDARY OF DEEP MOISTURE NORTH TO BETWEEN MISSOULA AND POLSON BY
LATE THIS AFTERNOON. AS THE UPPER LEVEL 500 MB RIDGE AMPLIFIES AND
MOVES EAST...WEAK EMBEDDED WEATHER DISTURBANCES WILL PROPAGATE
THROUGH THE FLOW. SINCE THE ATMOSPHERE WILL BE MOISTENING AND
WARMING...THE ADDED DYNAMICS OF A POTENTIAL SHORTWAVE WEATHER
DISTURBANCE SHOULD RESULT IN THUNDERSTORM ACTIVITY BEING A LITTLE
MORE WIDESPREAD THAN YESTERDAY. ALTHOUGH MANY OF THESE STORMS WILL
BE WEAK...A FEW OVER SOUTHWEST MONTANA MAY BECOME A LITTLE BIT
STRONGER WITH BRIEF HEAVY RAINFALL...SMALL HAIL AND GUSTY WINDS.
SOME ISOLATED CONVECTION MAY CONTINUE DURING THE OVERNIGHT
HOURS...HOWEVER AM NOT NEARLY AS CONFIDENT IN THIS AS THE RIDGE
AXIS WILL BE MOVING OVER THE DIVIDE BY SUNDAY MORNING LIMITING THE
POTENTIAL FOR LIFT.
CONDITIONS ARE SHAPING UP FOR A MORE WIDESPREAD SHOWER AND
THUNDERSTORM EVENT ON SUNDAY. A TROUGH OF LOW PRESSURE WILL
SLOWLY WORK ITS WAY TOWARDS THE PACIFIC COAST...SUBSEQUENTLY
ENHANCING SOUTHWESTERLY FLOW ALOFT AND DIRECTIONAL AND SPEED SHEER
WITHIN THE ATMOSPHERE. AS THIS OCCURS IT APPEARS AS THOUGH
WIDESPREAD SHOWERS AND THUNDERSTORMS WILL DEVELOP OVER MUCH OF
CENTRAL IDAHO AND WESTERN MONTANA BY LATE SUNDAY MORNING OR EARLY
SUNDAY AFTERNOON. THIS WEATHER SYSTEM SHOULD BE MORE OF THE WETTER
VARIETY...HOWEVER NOT BY TOO MUCH AS THE ATMOSPHERE AS A WHOLE IS
NOT OVERLY MOIST. BUT REGARDLESS OF THE FACT AERIAL COVERAGE WILL
BE RATHER LARGE WITH SOME STORMS BECOME STRONG WITH HEAVY
RAINFALL...SMALL HAIL AND WIND GUSTS TO 40 MPH.
TEMPERATURES TODAY AND SUNDAY WILL BE WELL ABOVE SEASONAL
NORMALS...HOWEVER NOT RECORD SETTING AT THIS TIME. THESE
CONDITIONS WILL BE THE WARMEST TEMPERATURES OF THE YEAR. GIVEN
THIS FACT RECREATIONISTS ARE URGED TO STAY HYDRATED AND TAKE THE
NECESSARY PRECAUTIONS TO STAY COOL.
MONDAY THROUGH FRIDAY...THE UPCOMING WORK WEEK IS EXPECTED TO BE
SIGNIFICANTLY COOLER WITH A GOOD THREAT OF PRECIPITATION AS A
TROUGH PATTERN DEVELOPS OVER THE WESTERN U.S. THERE IS GOOD MODEL
AGREEMENT ON THIS THROUGH MIDWEEK. AN INITIAL SHORTWAVE
DISTURBANCE IS SLATED TO PUSH ACROSS THE NORTHERN ROCKIES MONDAY.
THIS WILL CREATE BREEZY WEST WINDS AS THE DISTURBANCE DRAGS A COLD
FRONT ACROSS THE REGION. MOST OF THE THUNDERSTORM POTENTIAL WITH
THESE FEATURES WILL BE FROM MISSOULA NORTH. A GENERAL SOUTHWEST
FLOW WILL PERSIST BEHIND THIS FIRST WAVE MONDAY NIGHT THROUGH
TUESDAY NIGHT MAINTAINING A SOMEWHAT MOIST AND UNSTABLE AIR MASS.
A MORE MOIST SHORTWAVE IS EXPECTED WEDNESDAY. THIS WILL LIKELY BE
THE COOLEST DAY WITH THE BEST SHOWER COVERAGE THROUGHOUT THE
REGION. MEDIUM RANGE MODELS BEGIN TO DIVERGE THURSDAY AND FRIDAY
WITH THE ECMWF SLOWLY TRANSITIONING TO A DRIER LOW AMPLITUDE RIDGE
AND THE GS HOLDING ONTO SOME TROUGHINESS ALONG THE WEST COAST AND
A WEST-SOUTHWEST FLOW OVER THE NORTHERN ROCKIES. GIVEN THE
STRENGTH AND AMPLITUDE OF THE LONG WAVE TROUGH...THINK THE GFS MAY
BE THE BETTER SOLUTION. THE CURRENT FORECAST OF TRENDING LATE WEEK
PRECIP CHANCES BACK TOWARD CLIMATOLOGY LOOKS GOOD.
&&
.AVIATION...AFTERNOON SHOWERS AND THUNDERSTORMS ACROSS MUCH OF
WESTERN MONTANA AND CENTRAL IDAHO WILL PRODUCE HIGH TOPPED
CUMULONIMBUS CLOUDS AND THE LIKELIHOOD FOR GUSTY WINDS TODAY AND
AGAIN ON SUNDAY. WINDS ARE EXPECTED TO BE EVEN STRONGER ON SUNDAY
AIDED BY A STRENGTHENING SURFACE PRESSURE GRADIENT.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&
$$
SHORT TERM...DICKERSON
LONG TERM....WHITMORE
AVIATION...DICKERSON
000
FXUS65 KTFX 041025
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
425 AM MDT SAT JUL 4 2009
.DISCUSSION...
TODAY THROUGH MONDAY...PACIFIC MOISTURE...MARGINAL INSTABILITY AND
LIGHT UPSLOPE WINDS HAVE ALLOWED FOR ISOLATED SHOWERS AND
THUNDERSTORMS TO DEVELOP ALONG THE CONTINENTAL DIVIDE AND ADJACENT
PLAINS THIS MORNING. CONVECTION WILL STAY MAINLY ISOLATED THIS
MORNING AND THEN BECOME MORE SCATTERED THIS AFTERNOON AS INSTABILITY
AND MOISTURE INCREASE. AT THIS TIME...BEST LIFT AND MOISTURE WILL BE
CONFINED TO SOUTHWEST MONTANA AS LAPSE RATES APPROACH DRY ADIABATIC
AND A WEAK UPPER-LEVEL SHORTWAVE PASSES THROUGH SO HAVE KEPT HIGHEST
POPS THERE. SOME STORMS MAY BECOME STRONG WITH HAIL AND GUSTY WINDS
POSSIBLE THIS AFTERNOON AND EVENING BUT ACTIVITY WILL LIKELY
DIMINISH BY SUNSET AS THE ATMOSPHERE BECOMES MORE STABLE. MODELS
SEEM TO BE IN FAIR AGREEMENT ON SUNDAY FOR AN UPPER-LEVEL RIDGE TO
BUILD OVER THE REGION. AS THE RIDGE AXIS MOVES OVER THE AREA...DRIER
AIR ALOFT WILL LIMIT SHOWER AND THUNDERSTORM ACTIVITY BUT CONTINUED
TO KEEP A SLIGHT CHANCE IN THE FORECAST DUE TO TYPICAL DIURNAL AND
TERRAIN ENHANCEMENT DURING THE AFTERNOON HOURS. TEMPERATURES WILL
REMAIN NEAR AVERAGE FOR TODAY AND THEN CLIMB ABOVE AVERAGE FOR
SUNDAY AND MONDAY WITH READINGS NEAR 90 DEGREES FOR SOME LOCATIONS.
PREDOMINANT SOUTHWEST FLOW WILL ALLOW FOR ABUNDANT PACIFIC MOISTURE
TO STREAM INTO THE REGION ON MONDAY AS A DEEPENING UPPER-LEVEL
TROUGH MOVES INTO THE PACIFIC NORTHWEST...HOWEVER MODELS BEGIN TO
DIVERGE DURING THIS PERIOD IN TERMS OF TIMING AND INTENSITY OF THE
TROUGH. NEVERTHELESS...MODEST INSTABILITY AND WIND SHEAR MAY LEAD TO
ADDITIONAL THUNDERSTORM DEVELOPMENT MONDAY AFTERNOON WITH THE
POTENTIAL FOR SOME STORMS TO BECOME STRONG WITH HAIL AND GUSTY WINDS
SO WILL CONTINUE TO CAREFULLY MONITOR THIS TREND. MLS
MONDAY NIGHT THROUGH THURSDAY NIGHT...THE ECMWF AND GFS MODELS ARE
NOT IN AS GOOD AGREEMENT TONIGHT AS THEY WERE LAST NIGHT. THE MAIN
DIFFERENCE DURING THIS FORECAST PERIOD IS HOW THEY HANDLE AN UPPER
TROUGH OFF THE PACIFIC NORTHWEST COAST LATE MONDAY NIGHT. THE ECMWF
IS MUCH FASTER THAN THE GFS IN MOVING THIS FEATURE THROUGH THE
FORECAST AREA. THE ECMWF HAS IT MOVING THROUGH ON WEDNESDAY WHILE
THE GFS MOVES IT THROUGH THURSDAY NIGHT. DESPITE THIS DIFFERENCE THE
ECMWF AND GFS AGREE ON THE TREND OF INCREASING THE CHANCES OF
PRECIPITATION FROM TUESDAY TO WEDNESDAY. OF COURSE WITH THE ECMWF
THIS TREND IS DUE TO THE UPPER TROUGH MOVING INTO THE AREA. WITH THE
GFS THERE IS A WEAK DISTURBANCE ALOFT THAT TRIGGERS SOME
THUNDERSTORMS ON WEDNESDAY. THIS IDEA REVERSES ON THURSDAY AS THE
GFS HAS THE UPPER TROUGH APPROACHING THE AREA WHICH RESULTS IN SOME
THUNDERSTORMS. THE ECMWF ON THE OTHER HAND HAS A WEAK WEATHER
DISTURBANCE ALOFT THAT TRIGGERS SOME THUNDERSTORMS. THE INHERITED
CHANCE OF PRECIPITATION FORECASTS HANDLE THESE TRENDS WELL SO MADE
ONLY A FEW MINOR CHANGES. ALSO THE INHERITED IDEA OF HAVING COOLER
TEMPERATURES ON WEDNESDAY AND THURSDAY RELATIVE TO TUESDAY LOOKS
GOOD BUT DID LOWER HIGHS FOR THURSDAY OVER THE PLAINS SOME. BLANK
FRIDAY THROUGH SATURDAY....MODELS ARE NOT IN REAL GOOD AGREEMENT
DURING THIS PERIOD. GFS BRINGS A WEAKENING TROUGH OVER A RIDGE
CENTERED OVER THE SOUTHWEST U.S. WHILE THE ECMWF HAS THIS RIDGE
BUILDING OVER WESTERN MONTANA. CONTINUITY FAVORS THE ECMWF WHICH WAS
USED AS THE BASIS OF THIS FORECAST. PARTLY CLOUDY SKIES ARE EXPECTED
FOR MOST LOCATIONS. OVER AND NEAR THE MOUNTAINS SUFFICIENT MOISTURE
AND INSTABILITY RESULT IN MOSTLY CLOUDY SKIES WITH ISOLATED SHOWERS
AND A FEW MAINLY AFTERNOON AND EVENING THUNDERSTORMS. SHOWERS AND
THUNDERSTORMS WILL BE MORE NUMEROUS OVER THE WESTERN MOUNTAINS.
TEMPERATURES ARE EXPECTED TO CLIMB TO NEAR SEASONAL AVERAGES. EK
&&
.AVIATION...
UPDATED 0445Z.
VFR CONDITIONS WILL PREVAIL ACROSS THE FORECAST AREA THROUGH
SATURDAY EVENING. HOWEVER...THE AIRMASS IS EXPECTED TO BECOME
MARGINALLY UNSTABLE AGAIN SATURDAY AFTERNOON WITH ISOLATED TO
SCATTERED THUNDERSTORMS DEVELOPING AFTER 18Z AND CONTINUING THROUGH
ABOUT 03Z SUNDAY. ANY STORMS THAT FORM COULD PRODUCE ISOLATED MVFR
CONDITIONS IN LOCALLY HEAVY RAINFALL. MPJ
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 83 55 88 57 / 20 20 20 20
CTB 79 50 83 53 / 20 30 20 20
HLN 86 56 90 58 / 20 20 20 20
BZN 86 50 89 51 / 40 30 20 20
WEY 74 39 75 40 / 50 50 30 30
DLN 79 50 82 52 / 40 30 30 30
HVR 84 52 89 53 / 20 30 20 20
LWT 78 49 83 52 / 30 30 20 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
WEATHER.GOV/GREATFALLS
000
FXUS65 KGGW 040928
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
328 AM MDT SAT JUL 4 2009
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH MONDAY...
HIGH PRESSURE BEGINS BUILDS UP OVER THE SOUTHWESTERN CORNER OF THE
COUNTRY. AS A RESULT...WINDS ALOFT VEERS MORE TO THE NW TODAY WHICH
WILL CHANNEL DRIER AIR FROM CANADA INTO THE LOCAL AREA. INSTABILITY
WILL NOT BE QUITE AS STRONG AS FRIDAY. HENCE...SPC HAS NOT
INCLUDED NE MT IN THE SLIGHT RISK ZONE FOR SEVERE. HOWEVER
TEMPERATURES ARE EXPECTED TO RISE TO NORMAL FOR THIS TIME OF
YEAR...WHICH IS THE UPPER 70S TO LOWER 80S. THIS IS WARM ENOUGH
WITH LEFT OVER MOISTURE TO POSSIBLY PRODUCE A FEW ISOLATED
STORMS...SO WILL LEAVE SLIGHT CHANCE POPS IN FOR THIS AFTERNOON
AND EVENING.
A WEAK SHORTWAVE TRAVELING ALONG THE EASTERN SLOPE OF THE RIDGE
WILL MOVE SE INTO OUR NW ZONES TONIGHT. THIS COULD PRODUCE SOME
ELEVATED STORMS OVERNIGHT.
SUNDAY THE UPPER RIDGE PEAKS OVER WESTERN MONTANA. THICKNESS
HEIGHTS INCREASE LOCALLY WHICH WILL RAMP UP TEMPERATURES A
BIT INTO THE MID TO UPPER 80S. MODELS PICK UP WEAK DISTURBANCES
ALOFT SO WILL MAINTAIN SLIGHT CHANCE POPS. LEE-SIDE SURFACE TROUGH
OVER THE CENTRAL REGION WILL KEEP MOST ACTIVITY TO OUR WEST
THROUGH SUNDAY NIGHT.
MONDAY...A VIGOROUS CLOSED LOW OFF THE COAST OF WASHINGTON MOVES
ASHORE...SENDING A COLD FRONT INTO WESTERN MONTANA. THE THERMAL
RIDGE NUDGES INTO THE CWA FOR ANOTHER WARM DAY...A REPEAT OF
SUNDAY. THE LEE TROUGH SETS UP OVER NE MT WHICH WILL FOCUS MOST
OF THE STORM ENERGY IN SOUTHERN ALBERTA AND SASKATCHEWAN. WILL
MAINTAIN CHANCE TO SLIGHT CHANCE POPS. SCT
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
UPPER RIDGE MOVES TO THE EAST MONDAY NIGHT AND TUESDAY. A SURFACE
TROUGH OVER THE AREA COMBINED WITH SHORTWAVES ON SOUTHWEST FLOW
ALOFT WILL BRING A CHANCE OF SHOWERS AND THUNDERSTORMS.
MODELS DIFFER ON HOW TO BRING UPPER TROUGH THAT IS FORECASTED TO
BE OFF THE WASHINGTON COAST ON TUESDAY INLAND. THE ECMWF BRINGS
THE TROUGH EAST INTACT PASSING THROUGH EASTERN MONTANA WEDNESDAY
NIGHT. THE GFS SIGNIFICANTLY WEAKENS THE TROUGH AND WAITS UNTIL
FRIDAY TO GET IT TO EASTERN MONTANA. THE ECMWF IS SHOWING BETTER
RUN TO RUN CONSISTENCY WITH THIS SYSTEM. IT LOOKS LIKE THERE COULD
BE A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS WHEN THE TROUGH
COMBINED WITH 100 KNOT JET MOVES THROUGH WEDNESDAY NIGHT. WEAK
SHORTWAVES BEHIND THE TROUGH COULD BRING ANOTHER CHANCE OF SHOWERS
AND THUNDERSTORMS THURSDAY.
THE MODELS DIFFER BETWEEN GFS HAVING ZONAL FLOW WITH WAVES AND
ECMWF HAVING UPPER RIDGE GOING INTO NEXT WEEKEND. WILL MENTION A
SLIGHT CHANCE OF THUNDERSTORMS ON SATURDAY FOR NOW.
&&
.AVIATION...
RAIN SHOWERS AND THUNDERSTORMS HAVE EXITED THE AREA FOR NOW. WILL
SEE AT LEAST A FEW HOURS OF MOSTLY CLEAR SKIES THIS MORNING BEFORE
CUMULUS BUILD WITH DAYTIME HEATING. THE TAF SITES HAVE A CHANCE OF
A SHOWER AND/OR THUNDERSTORM THIS AFTERNOON AND TONIGHT THAT COULD
BRING BRIEF PERIODS OF MVFR CONDITIONS. OTHERWISE...VFR CONDITIONS
WILL DOMINATE.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KBYZ 040859
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
259 AM MDT SAT JUL 4 2009
.SHORT TERM...VALID FOR TDY AND SUN...
ANOTHER DAY FOR A FEW ACTIVE THUNDERSTORMS ANTICIPATED WITH
POTENTIAL FOR LOCALLY HEAVY RAIN. CONVECTION ON GOING ACROSS
SOUTHEAST MONTANA EARLY THIS MORNING ON THE TAIL OF SHORT WAVE
ENERGY MOVING ACROSS NORTHERN MONTANA. THESE STORMS STILL
GENERATING SOME LOCALLY HEAVY RAINFALL RATES AND WIND GUSTS TO
AROUND 40 MPH AS THEY DROP SOUTH. THIS ACTIVITY ALSO PUSHING AN
OUTFLOW BOUNDARY SOUTHWEST ACROSS SOUTH CENTRAL MONTANA AS VISIBLE
ON EARLY MORNING RADAR LOOP. BEHIND THIS SYSTEM....EASTERLY LOW
LEVEL UPSLOPE FLOW TO PERSIST ACROSS THE FORECAST AREA AS BOUNDARY
BANKS UP AGAINST MOUNTAINS. THIS WILL KEEP MOISTURE POOLING IN THE
AREA AND GENERATE WEAK TO MODERATE INSTABILITY WITH DAYTIME
HEATING. ALSO WATCHING WATER VAPOR IMAGERY SHOWING ANOTHER IMPULSE
MOVING OUT OF OREGON EARLY THIS MORNING. THIS SYSTEM SHOULD BE
ABLE TO WORK ON INCREASING INSTABILITY FOR MORE SCATTERED
THUNDERSTORMS AS IT MOVES INTO THE REGION LATER TODAY. LAYER PRECIP
WATERS STILL HOVERING AROUND AN INCH...SO WILL INCLUDE ANOTHER DAY
OF LOCALLY HEAVY RAINFALL SIMILAR TO YESTERDAY. ONE STORM ON
NORTHWEST SIDE OF BILLINGS DROPPED ALMOST AN INCH OF RAIN IN A
HALF HOURS TIME YESTERDAY AFTERNOON. SHEAR APPEARS WEAK AND SO SEVERE
THREAT APPEARS MINIMAL BUT NOT OUT OF THE QUESTION.
BY SUNDAY...SLIGHT SHIFT IN THE PATTERN EXPECTED AS UPPER HEIGHTS
BEGIN BUILDING IN RESPONSE TO DIGGING TROUGH ALONG WEST COAST...
WHICH WILL TRY TO SUPPRESS CONVECTION. STILL CANT COMPLETELY RULE
OUT A STORM AS WEAK IMPULSES TOP THE RIDGE. ALTHOUGH...INSTABILITY
SHOULD BE WEAK AS AIRMASS BEGINS TO DRY WITH OVERALL DOWNSLOPE
PATTERN DEVELOPING. HAVE MAINTAINED ISOLATED STORM CHANCES.
AS FOR TEMPERATURES...A SLIGHTLY COOLER THAN AVERAGE DAY
ANTICIPATED AGAIN TODAY WITH THE INCREASE IN CLOUDS AND STORMS.
SUNDAY WILL BEGIN A WARMUP WITH TEMPERATURES CLOSING IN ON 90
DEGREES MANY LOWER ELEVATIONS. FRIEDERS
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
THE MODELS CONTINUE TO BE IN PRETTY GOOD AGREEMENT THROUGH ABOUT
THURSDAY...MONDAY IS A TRANSITIONAL DAY AS THE UPPER LEVEL RIDGE
MOVES EAST OF MONTANA AND SOUTHWESTERLY FLOW ALOFT BRINGS A BIT
DRIER AIR TO THE STATE. THUNDERSTORM POTENTIAL REMAINS WITH GOOD
SHEAR AND INSTABILITY MAKING UP FOR SLIGHTLY LESS MOISTURE.
SURFACE MOISTURE FROM PREVIOUS WEATHER WILL ALSO PLAY SIGNIFICANT
ROLE AS COULD KEEP SURFACE HUMIDITIES A BIT HIGHER...AT LEAST
LOCALLY. MONDAY SHOULD ALSO BE THE WARMEST OF THE EXTENDED...WITH
LOW TO MID 90S...AS DOWNSLOPE FLOW AIDS MIXING. WARMEST AIR
APPEARS TO SHIFT EAST BY TUESDAY BEGINNING COOLING TREND. THE DRY
AIR SETTLES ACROSS THE REGION THROUGH WEDNESDAY...BUT THE ATMOSPHERE DOES
SEEM TO DESTABILIZE ENOUGH IN AFTERNOON AND EVENING TO ALLOW
THUNDER POTENTIAL...ESPECIALLY IN AREAS WHERE HEAVIER PRECIP HAD
OCCURRED OVER LAST SEVERAL DAYS. PWAT BEGINS TO BUILD BACK INTO
THE AREA WEDNESDAY AS A SFC LOW DEVELOPS IN WY AND HELPS UPSLOPE
DEVELOPMENT IN THE FOOTHILLS AND HIGH TERRAIN. THURSDAY BECOMES A
BIT OF A QUESTION WITH SOME DIFFERENCES IN READ ON THE PROGRESSION
OF THE TROF. GFS BRINGS STRONG WAVE INTO THE AREA ON
THURSDAY...BUT HOLDS MAIN TROF AXIS OF TO THE WEST...WHILE EC
PUSHES TROF THROUGH THE REGION. EITHER WAY THURSDAY LOOKS LIKE A
PRETTY ACTIVE DAY ACROSS THE REGION. FRIDAY LOOKS LIKE A
TRANSITIONAL DAY FOR BOTH MODELS...AS EC BUILD IN ANOTHER UPPER
LEVEL RIDGE AND GFS FAVORS MORE ZONAL FLOW AS AN UPPER LOW MOVES
ACROSS NORTHERN CANADA. GENERALLY SPLIT THE DIFFERENCE FOR
TEMPS...AS EC FAVORS QUICK WARMUP FOLLOWING FRIDAY AND GFS REMAINS
PRETTY COOL. SHOULD REMAIN A CHANCE FOR THUNDER THROUGHOUT...WITH
MULTIPLE SHORTWAVES AND GOOD SURFACE MOISTURE FROM PREVIOUS
SHOWERS. GILSTAD
&&
.AVIATION...
AN AREA OF SHOWERS AND THUNDERSTORMS CONTINUE ACROSS EASTERN
ROUTES...PRODUCING HEAVY RAIN AND GUSTY WINDS...AND REDUCING FLIGHT
CONDITIONS TO IFR RANGE DUE TO LOWERED CEILINGS AND REDUCED
VISIBILITIES IN AND AROUND THUNDERSTORMS. OTHERWISE VFR FLIGHT
CONDITIONS WILL PREVAIL ACROSS THE REGION THROUGH EARLY MORNING.
FOG DEVELOPMENT WILL BE POSSIBLE IN THE EARLY MORNING HOURS ACROSS
MUCH OF THE FORECAST AREA. FOG WILL BE POSSIBLE ACROSS THE
REGION...INCLUDING THE KLVM...KBIL...KSHR...KMLS AND KBHK
AIRPORTS...AND ESPECIALLY IN RIVER VALLEYS...AND ALONG THE EAST
AND NORTHERN SLOPES OF AREA MOUNTAINS...CAUSING IFR OR LOWER
FLIGHT CONDITIONS. ADDITIONAL SCATTERED SHOWERS AND THUNDERSTORMS
ARE EXPECTED THROUGH THIS AFTERNOON AND EVENING AS ANOTHER UPPER
LEVEL DISTURBANCE PUSHES THROUGH THE AREA. GILSTAD
&&
.PRELIMINARY POINT TEMP/POPS...
TDY SUN MON TUE WED THU FRI
-------------------------------------------------------
BIL 082 061/088 062/091 060/088 058/083 054/080 057/081
4/T 42/T 21/B 22/T 32/T 32/T 32/T
LVM 082 051/086 052/086 051/084 050/079 047/075 047/079
3/T 43/T 23/T 23/T 22/T 22/T 32/T
HDN 084 057/091 058/094 059/093 057/089 051/083 055/086
3/T 32/T 21/B 22/T 32/T 42/T 32/T
MLS 083 060/090 062/094 063/092 063/087 056/085 060/084
3/T 32/T 21/B 22/T 22/T 42/T 32/T
4BQ 081 058/088 059/093 061/092 061/087 056/078 057/084
3/T 32/T 21/B 22/T 22/T 32/T 32/T
BHK 078 058/086 060/091 060/088 061/083 058/079 058/084
3/T 22/T 21/B 22/T 22/T 42/T 32/T
SHR 078 053/085 054/091 055/089 055/085 049/079 052/081
4/T 43/T 32/T 22/T 22/T 32/T 32/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KTFX 040441
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1040 PM MDT FRI JUL 3 2009
.UPDATE...NO MAJOR GRID CHANGES TONIGHT WITH SHORT TERM FORECAST
LOOKING PRETTY GOOD. SOME ISOLATED THUNDERSTORMS ARE STILL MOVING
AROUND OVER PORTIONS OF THE SOUTHWEST AND NORTHEAST CORNERS OF THE
CWA. THE POTENTIAL FOR SEVERE WEATHER DOES EXIST WITH THESE STORMS
AND WILL CONTINUE TO BE MONITORED CLOSELY. THE STORMS WILL
CONTINUE TO BE ACTIVE FOR A COUPLE HOURS BUT EXPECT THEM TO TAPER
OFF IN THE EARLY MORNING HOURS.
&&
.AVIATION...
UPDATED 0445Z.
VFR CONDITIONS WILL PREVAIL ACROSS THE FORECAST AREA THROUGH
SATURDAY EVENING. HOWEVER...THE AIRMASS IS EXPECTED TO BECOME
MARGINALLY UNSTABLE AGAIN SATURDAY AFTERNOON WITH ISOLATED TO
SCATTERED THUNDERSTORMS DEVELOPING AFTER 18Z AND CONTINUING THROUGH
ABOUT 03Z SUNDAY. ANY STORMS THAT FORM COULD PRODUCE ISOLATED MVFR
CONDITIONS IN LOCALLY HEAVY RAINFALL. MPJ
&&
.PREV DISCUSSION...
/ISSUED 548 PM MDT FRI JUL 3 2009/
TODAY THROUGH SUNDAY EVENING...UPPER RIDGE THAT WAS
CENTERED OVER THE FOUR CORNERS AREA A FEW DAYS AGO HAS NOW DRIFTED
EAST WITH ITS AXIS NOW OVER THE GREAT PLAINS. SOUTHWEST FLOW ON THE
RIDGE`S WEST SIDE CONTINUES TO PUSH PACIFIC MOISTURE INTO
MONTANA...LEADING TO ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS THIS
AFTN/EVE OVER CENTRAL AND SOUTHWEST PORTIONS OF THE CWA. LATEST
MODEL DATA HAS SLIGHTLY REDUCED THE POTENTIAL FOR STRONG-TO-SEVERE
STORMS DUE IN PART TO COOLER-THAN-FORECAST SURFACE TEMPERATURES.
HOWEVER...POTENTIAL IS STILL HIGH ENOUGH FOR POSSIBLE STRONG STORMS
BEARING HAIL AND GUSTY OUTFLOW WINDS LATER THIS AFTN. WHATEVER
CONVECTION DEVELOPS SHOULD DISSIPATE TOWARD SUNSET AS AIRMASS
BECOMES MORE STABLE. GOOD AGREEMENT IN MODELS ON LITTLE CHANGE IN
CONDITIONS FOR TOMORROW...WITH SOUTHWEST FLOW ALOFT BRINGING IN
ADDITIONAL MOISTURE FOR ONE MORE ROUND OF SHOWERS AND
THUNDERSTORMS. SOME STORMS COULD BE STRONG WITH HAIL AND GUSTY
WINDS. LOOKS LIKE REGION WILL GET A BREAK FROM THE STORMS ON SUNDAY
AS THE UPPER RIDGE REBUILDS OVER THE NORTHERN ROCKIES AND MOIST
PACIFIC FLOW LESSENS. SOME CONVECTION IS POSSIBLE BUT WILL BE MORE
ISOLATED IN COVERAGE. TEMPERATURES WILL REMAIN 4 TO 7 DEG ABOVE
NORMAL THROUGH THE WEEKEND. WARANAUSKAS
SUNDAY NIGHT THROUGH WEDNESDAY NIGHT...ECMWF AND GFS MODELS AGREE IN
STARTING THE PERIOD WITH AN UPPER RIDGE OVER THE FORECAST AREA.
THEREAFTER EXPECT SOUTHWEST FLOW ALOFT. THOSE TWO MODELS ALSO AGREE
ON ROTATING A WEATHER DISTURBANCE ALOFT THROUGH THE FORECAST AREA
MONDAY NIGHT. AHEAD OF THE DISTURBANCE MODELS DEVELOP GOOD LIFT AND
MOISTURE..MAINLY IN THE NORTH. SO INCREASED POPS FOR THAT AREA.
ECMWF AND GFS ALSO AGREE IN DEVELOPING AN UPPER LOW OVER THE PACIFIC
NORTHWEST ON WEDNESDAY WITH INCREASED MOISTURE FOR NORTHWEST
MONTANA. IN LINE WITH THIS INCREASED THE CHANCES OF PRECIPITATION
FOR THE ROCKY MOUNTAIN FRONT. INHERITED TREND OF COOLING HIGH
TEMPERATURES FROM MONDAY TO WEDNESDAY LOOKS FINE BUT STARTED OFF
WARMER ON MONDAY WITH HIGHS WELL ABOVE NORMAL. BY WEDNESDAY LOWERED
INHERITED HIGH TEMPERATURES ON THE ORDER OF 5 TO 10 DEGREES OVER THE
PLAINS. BLANK
THURSDAY THROUGH FRIDAY....MODELS REMAIN IN FAIR AGREEMENT DURING
THIS PERIOD...WITH SOME DIFFERENCES IN TIMING OF FEATURES. A
LONGWAVE UPPER LEVEL TROUGH PERSISTS ALONG THE WEST COAST RESULTING
IN A SOUTHWESTERLY FLOW ALOFT ACROSS THE FORECAST AREA. WEAK
DISTURBANCES IN THIS SOMEWHAT MOIST AND UNSTABLE FLOW WILL BE
RESPONSIBLE FOR PARTLY TO MOSTLY CLOUDY SKIES WITH ISOLATED SHOWERS
AND MAINLY AFTERNOON AND EVENING THUNDERSTORMS. SHOWERS AND
THUNDERSTORMS WILL BE MORE NUMEROUS OVER THE MOUNTAINS. THE WARMEST
AIR STAYS MOSTLY SOUTH AND EAST OF THE FORECAST AREA...HOWEVER
TEMPERATURES ARE EXPECTED TO CLIMB TO NEAR SEASONAL AVERAGES. EK
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 53 83 55 86 / 30 20 20 20
CTB 48 80 50 84 / 20 10 20 10
HLN 55 87 56 89 / 30 20 20 20
BZN 53 86 53 89 / 40 30 30 30
WEY 43 72 43 75 / 50 40 40 30
DLN 51 79 52 82 / 40 30 30 30
HVR 52 84 52 89 / 30 20 30 20
LWT 51 77 52 82 / 40 30 30 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GUSTAFSON
LONG TERM...COULSTON/EK
AVIATION...MPJ
WEATHER.GOV/GREATFALLS
000
FXUS65 KGGW 040318
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
918 PM MDT FRI JUL 3 2009
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SUNDAY...
AREA OF THUNDERSTORMS HAVE MOVED INTO RICHLAND AND MCCONE COUNTIES.
JUST HEAVY RAIN BEING REPORTED WITH GUSTS TO 50 MPH (NORTH OF ENID
IN RICHLAND CO) AT MOST. NO WORRIES WITH RAINFALL AS FLASH FLOOD
GUIDANCE IS ABOUT 3 INCHES. SEVERE STORM IN NORTHERN BLAINE COUNTY
FELL APART BEFORE REACHING NORTH PHILLIPS. HAVE LOWERED POPS TO
SLIGHT CHC BEHIND LINE. INSTABILITY LOOKS GOOD FOR SE ZONES SO
SHOWERS/STORMS MAY HANG ON FOR A FEW MORE HOURS. REST OF FORECAST
LOOKS IN GOOD SHAPE. PRODUCTS HAVE BEEN ISSUED. JAMBA
PREVIOUS DISCUSSION...
A SHORTWAVE TROUGH WILL SWEEP ACROSS NORTHEAST MONTANA OVERNIGHT
BRINGING A ROUND OF THUNDERSTORMS...SOME OF WHICH COULD BE SEVERE
IN THE EVENING. PRECIPITABLE WATER VALUES WILL BE NEAR ONE
INCH...SO HEAVY RAIN IS POSSIBLE IN ANY STORMS. FLASH FLOOD
GUIDANCE IS HIGH ACROSS MOST OF THE AREA. HOWEVER...IT IS MUCH
LOWER IN RICHLAND...WIBAUX...AND EASTERN DAWSON COUNTIES AS THEY
RECENTLY RECEIVED SEVERE THUNDERSTORMS WITH HEAVY RAIN. FLASH
FLOODING COULD BE A THREAT THERE OVERNIGHT IF THEY RECEIVE HEAVY
RAIN.
A DRIER NORTHERLY PUSH OF CANADIAN AIR DEVELOPS BEHIND THE
DEPARTING SHORTWAVE TROUGH SATURDAY. THIS WILL REDUCE INSTABILITY
ACROSS THE AREA...EXCEPT FOR THE FAR SOUTHWEST CORNER OF THE CWA.
12Z MODEL SUITE CASTS DOUBT ON THUNDERSTORM POTENTIAL. HOWEVER...RECENT
MODEL RUNS HAVE BEEN...AND TYPICALLY ARE...FICKLE WITH
MOISTURE...SO A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS WILL BE
MAINTAINED WITH ENERGETIC WEST-SOUTHWEST FLOW ALOFT. MAXIMUM
TEMPERATURES WILL RANGE FROM THE UPPER 70S TO MID 80S ACROSS THE
AREA...WHICH IS NEAR AVERAGE FOR EARLY JULY.
A WEAK SHORTWAVE TRAVERSES ACROSS NORTHEAST MONTANA SATURDAY NIGHT
RESULTING IN STEEPENING MID-LEVEL LAPSE RATES. THIS COULD RESULT
IN A FEW ELEVATED NOCTURNAL THUNDERSTORMS. 500MB HEIGHTS AND
1000-500MB THICKNESS VALUES BEGIN TO CLIMB ON SUNDAY AS AN UPPER
RIDGE BUILDS OVER THE NORTHERN HIGH PLAINS. THIS WILL SEND MAXIMUM
TEMPERATURES WELL INTO THE 80S...AND PERHAPS LOW 90S. THE LEE-SIDE
SURFACE TROUGH BECOMES RE-INVIGORATED OVER CENTRAL MONTANA IN A
WARMING AIRMASS ALLOWING SOUTHEASTERLY FLOW TO EXPAND OVER THE
REGION...AND HENCE...REFRESH LOW LEVEL MOISTURE IN THE AREA. THE
MID AND UPPER LEVELS WILL BE MORE STABLE SUNDAY...BUT A SLIGHT
CHANCE OF THUNDERSTORMS WILL BE MAINTAINED WITH INCREASING
INSTABILITY. AJZ
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...
LITTLE CHANGE FOR THE EXTENDED FORECAST AS MODELS IN GOOD
AGREEMENT WITH MAIN PATTERN...OF UPPER FLOW BACKING TO THE
SOUTHWEST EARLY NEXT WEEK. MADE SLIGHT ADJUSTMENT TO POPS FOR
COLLABORATIVE PURPOSES...WHILE THE REMAINDER OF THE FORECAST LOOKS
ON TRACK. EBERT
PREVIOUS LONG TERM FORECAST DISCUSSION...THE UPPER LEVEL RIDGE
WILL PASS OVER THE AREA SUNDAY NIGHT AND MONDAY BACKING THE
INITIAL NW FLOW ALOFT TO THE WEST. UPPER FLOW WILL CONTINUE
BACKING TO THE SOUTHWEST THROUGH THE REMAINDER OF THE WEEK AS
STRONG HIGH PRESSURE BUILDS UP OVER THE SOUTHWESTERN STATES WHILE
AN UPPER LEVEL TROUGH MOVES INTO THE PACNW.
MONDAY AND MONDAY NIGHT...A THERMAL RIDGE PUSHES INTO THE
AREA...RAMPING UP TEMPERATURES. INSTABILITY COULD INITIATE TS
ACTIVITY BY AFTERNOON. TIMING DIFFERENCES BETWEEN GFS AND EC
CONTINUE...WITH THE EC PUSHING THE RIDGE AXIS EAST OF THE AREA BY
AFTERNOON...ALLOWING MORE MOISTURE INTO THE UNSTABLE AREA. THE GEM
SIDES WITH THE EC...SO IT SEEMS REASONABLE TO INCLUDE AT LEAST
SLIGHT CHANCE POPS. AN INVERTED SURFACE TROUGH WILL PUSH THE BEST
AREA FOR POPS INTO THE NORTHERN ZONES AND CANADA.
TUESDAY AND TUESDAY NIGHT...THERMAL RIDGE MOVES EAST OF THE AREA
AND SW FLOW ALOFT SENDS MORE CLOUDS OUR WAY...LOWERING
TEMPERATURES A BIT CLOSER TO NORMAL. OTHERWISE UNSTABLE CONDITIONS
WILL CONTINUE TO CREATE AT LEAST A SLIGHT CHANCE FOR
THUNDERSTORMS.
WEDNESDAY AND WEDNESDAY NIGHT...THE UPPER LEVEL LOW CONTINUES TO
SPIN OVER WASHINGTON STATE SENDING A STRONG UPPER JET OVER
CENTRAL MONTANA. THE RESULT WILL BE CONTINUED INJECTION OF
MOISTURE. BOTH EC AND GFS SHOW A COLD FRONT NUDGING CLOSE TO OUR
WESTERN BORDER. THE RESULT COULD BE HEAVIER SHOWERS PUSHING INTO
THE CWA. THERE WILL BE A TREND TOWARDS TEMPERATURES NEAR NORMAL
THROUGH THE REMAINDER OF THE EXTENDED PERIOD.
THURSDAY THE UPPER LOW LIFTS INTO THE CENTRAL CANADIAN PRAIRIE
TAKING MOST OF THE SHOWER ACTIVITY WITH IT. THE RESULT LOCALLY
WILL BE NEAR NORMAL TEMPERATURES. SCT
&&
.AVIATION...
ISOLATED TO SCATTERED RAIN SHOWERS AND THUNDERSTORMS WILL MOVE
ACROSS THE REGION TODAY AND THE INCREASINGLY UNSTABLE AFTERNOON
CONDITIONS COULD PRODUCE SOME SEVERE THUNDERSTORMS...MAINLY TO THE
SOUTHWEST OF THE TAF SITES...INTO EARLY EVENING WITH STRONG GUSTY
WINDS AND POSSIBLY LARGE HAIL. OTHERWISE GENERALLY VFR THROUGH
TONIGHT WITH SOUTHEAST WINDS DIMINISHING AROUND SUNSET. RAE
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KBYZ 040255
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
855 PM MDT FRI JUL 3 2009
.SHORT TERM...VALID FOR SAT AND SUN...
UPDATE TO ZONES AND AFP THIS EVENING. ISOLATED TO SCATTERED
THUNDERSTORMS WILL CONTINUE ACROSS THE ENTIRE AREA TONIGHT. THE
THREAT FOR SEVERE WEATHER HAS ENDED BUT POTENTIAL STILL EXIST FOR
THUNDERSTORMS WITH VERY HEAVY RAIN AS PW`S REMAINING OVER AN
INCH. WATER VAPOR SHOWING STRONG SHORT WAVE MOVING IN FROM
EASTERN IDAHO THIS EVENING. MODELS SEEM TO BE UNDER DOING THE
STRENGTH OF THIS WAVE AND WILL CONTINUE HIGH SCATTERED POPS GOING
IN CURRENT FORECAST TONIGHT. MOIST UPSLOPE FLOW TO CONTINUE INTO
SOUTHEAST MONTANA TONIGHT AND PATCHY FOG IS EXPECTED OVER THESE
AREAS AFTER MIDNIGHT. TEMPERATURE FORECAST LOOKS GOOD AND NO
CHANGES MADE. RICHMOND
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
MONDAY A TRANSITIONAL DAY AS THE UPPER LEVEL RIDGE MOVES EAST OF
MONTANA AND SOUTHWESTERLY FLOW ALOFT BRINGS A BIT DRIER AIR TO THE
STATE. STILL WILL SEE POTENTIAL FOR THUNDERSTORMS ON MONDAY AS
WIND SHEAR WILL OVERCOMPENSATE FOR THE REDUCTION IN MOISTURE.
COULD BE A PRETTY STORMY DAY IF ENOUGH LOW LEVEL MOISTURE FROM
PREVIOUS STORMS HELPS KEEP ELEVATED DEW POINTS OVER THE REGION.
MONDAY SHOULD BE THE WARMEST DAY AS SOME DOWNSLOPE FLOW HELPS
IMPROVE MIXING AND LOWER TO MID 90S LOOK LIKELY. BY TUESDAY
WARMEST AIR SHIFTS EAST AND DRIER AIR BECOMES MORE ENTRENCHED
THROUGH AIRMASS SHOULD DESTABILIZE ENOUGH FOR SOME POSSIBLE
CONVECTION...FAVORING THE AFTERNOON AND EVENING HOURS. WEDNESDAY
LOOKS UNCERTAIN AS THE ECMWF PUSHES A STRONG WAVE THROUGH ALBERTA
SUPPRESSING HEIGHTS WHILE THE GFS PRODUCES A SHORTWAVE RIDGE OVER
THE AREA. GFS SOLUTION WOULD PROMOTE RETURN FLOW MOISTURE INTO
SOUTHEAST MONTANA BUT IT LOOKS CONVECTIVE FEEDBACK CONTAMINATED SO
WILL HOLD OFF ON INTRODUCING TOO MUCH THUNDER THREAT AT THIS TIME.
BOTH MODELS ARE INDICATING A LESS AMPLIFIED FLOW PATTERN FOR
THURSDAY AND FRIDAY WHICH WOULD ENSURE A COOL DOWN IN
TEMPERATURES. PATTERN WILL LIKELY FAVOR MOUNTAIN CONVECTION WITH
SOME ACTIVITY REACHING THE ADJACENT PLAINS. BOTH MODELS ARE
INDICATING HEIGHTS RISING FOR FRIDAY SO HAVE SLIGHTLY LOWER POPS
THAT DAY. BORSUM
&&
.AVIATION...
SCATTERED THUNDERSTORMS WILL CONTINUE ACROSS THE AREA FOR MUCH OF
THE NIGHT AS ANOTHER UPPER LEVEL DISTURBANCE CROSSES THE REGION
FROM WEST TO EAST. A VERY MOIST ATMOSPHERE IS IN PLACE ACROSS THE
AREA THIS EVENING...THUS IFR CONDITIONS IN HEAVY RAIN CAN BE
EXPECTED WITH ANY THUNDERSTORMS TONIGHT. MVFR CEILINGS CURRENTLY
IMPACTING KBHK AIRPORT WILL CONTINUE OVERNIGHT...WITH FOG
DEVELOPMENT LIKELY LATE TONIGHT RESULTING IN IFR OR LOWER
CONDITIONS. BY THE EARLY MORNING HOURS FOG DEVELOPMENT WILL BE
POSSIBLE ACROSS MUCH OF THE FORECAST AREA. THERE IS A SLIGHT
CHANCE OF IFR OR LOWER VISIBILITIES WITH FOG ALONG AREA RIVERS
AND STREAMS...AS WELL AS ALONG THE EAST AND NORTH SLOPES OF AREA
MOUNTAINS...WHICH MAY ALSO RESULT IN OVERNIGHT MOUNTAIN
OBSCURATION. THE SLIGHT CHANCE OF IFR OR LOWER VISIBILITIES DUE
TO FOG INCLUDE THE KLVM...KBIL...KSHR...KMLS AND KBHK AIRPORTS.
CHAMBERS
&&
.PRELIMINARY POINT TEMP/POPS...
SAT SUN MON TUE WED THU FRI
-----------------------------------------------------------
BIL 060/082 061/086 062/089 060/087 059/085 057/081 057/081
44/T 42/T 22/T 22/T 32/T 32/T 22/T
LVM 049/082 051/084 052/083 051/081 050/081 048/077 047/079
43/T 43/T 22/T 23/T 22/T 23/T 32/T
HDN 058/084 057/089 058/094 056/091 055/088 053/086 052/086
43/T 32/T 22/T 22/T 32/T 32/T 22/T
MLS 061/083 060/088 062/092 063/090 062/088 062/084 061/084
42/T 32/T 22/T 22/T 22/T 32/T 22/T
4BQ 058/081 058/086 059/093 059/091 060/088 057/082 057/084
43/T 32/T 21/B 22/T 22/T 22/T 22/T
BHK 057/078 058/084 060/089 059/089 060/086 056/079 057/084
32/T 22/T 21/B 22/T 22/T 32/T 22/T
SHR 055/078 053/083 054/090 054/088 053/086 052/079 051/081
44/T 43/T 32/T 22/T 22/T 22/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KTFX 040255
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
855 PM MDT FRI JUL 3 2009
.UPDATE...NO MAJOR GRID CHANGES TONIGHT WITH SHORT TERM FORECAST
LOOKING PRETTY GOOD. SOME ISOLATED THUNDERSTORMS ARE STILL MOVING
AROUND OVER PORTIONS OF THE SOUTHWEST AND NORTHEAST CORNERS OF THE
CWA. THE POTENTIAL FOR SEVERE WEATHER DOES EXIST WITH THESE STORMS
AND WILL CONTINUE TO BE MONITORED CLOSELY. THE STORMS WILL
CONTINUE TO BE ACTIVE FOR A COUPLE HOURS BUT EXPECT THEM TO TAPER
OFF IN THE EARLY MORNING HOURS.
&&
.AVIATION...
UPDATED 2350Z.
VFR CONDITIONS WILL PREVAIL ACROSS THE FORECAST AREA THROUGH
SATURDAY AFTERNOON. HOWEVER...ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS WILL CONTINUE TO AFFECT PORTIONS OF SOUTHWEST
MONTANA AND NORTHEASTERN PORTIONS OF CENTRAL MONTANA WITH LOCAL
MVFR CONDITIONS IN BRIEF HEAVY RAINFALL THROUGH 03Z SATURDAY.
CONDITIONS WILL STABILIZE OVERNIGHT BUT THE AIRMASS IS EXPECTED TO
BECOME MARGINALLY UNSTABLE AGAIN SATURDAY AFTERNOON WITH ISOLATED
TO SCATTERED THUNDERSTORMS DEVELOPING AFTER 18Z. MPJ
&&
.PREV DISCUSSION...
/ISSUED 548 PM MDT FRI JUL 3 2009/
TODAY THROUGH SUNDAY EVENING...UPPER RIDGE THAT WAS
CENTERED OVER THE FOUR CORNERS AREA A FEW DAYS AGO HAS NOW DRIFTED
EAST WITH ITS AXIS NOW OVER THE GREAT PLAINS. SOUTHWEST FLOW ON THE
RIDGE`S WEST SIDE CONTINUES TO PUSH PACIFIC MOISTURE INTO
MONTANA...LEADING TO ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS THIS
AFTN/EVE OVER CENTRAL AND SOUTHWEST PORTIONS OF THE CWA. LATEST
MODEL DATA HAS SLIGHTLY REDUCED THE POTENTIAL FOR STRONG-TO-SEVERE
STORMS DUE IN PART TO COOLER-THAN-FORECAST SURFACE TEMPERATURES.
HOWEVER...POTENTIAL IS STILL HIGH ENOUGH FOR POSSIBLE STRONG STORMS
BEARING HAIL AND GUSTY OUTFLOW WINDS LATER THIS AFTN. WHATEVER
CONVECTION DEVELOPS SHOULD DISSIPATE TOWARD SUNSET AS AIRMASS
BECOMES MORE STABLE. GOOD AGREEMENT IN MODELS ON LITTLE CHANGE IN
CONDITIONS FOR TOMORROW...WITH SOUTHWEST FLOW ALOFT BRINGING IN
ADDITIONAL MOISTURE FOR ONE MORE ROUND OF SHOWERS AND
THUNDERSTORMS. SOME STORMS COULD BE STRONG WITH HAIL AND GUSTY
WINDS. LOOKS LIKE REGION WILL GET A BREAK FROM THE STORMS ON SUNDAY
AS THE UPPER RIDGE REBUILDS OVER THE NORTHERN ROCKIES AND MOIST
PACIFIC FLOW LESSENS. SOME CONVECTION IS POSSIBLE BUT WILL BE MORE
ISOLATED IN COVERAGE. TEMPERATURES WILL REMAIN 4 TO 7 DEG ABOVE
NORMAL THROUGH THE WEEKEND. WARANAUSKAS
SUNDAY NIGHT THROUGH WEDNESDAY NIGHT...ECMWF AND GFS MODELS AGREE IN
STARTING THE PERIOD WITH AN UPPER RIDGE OVER THE FORECAST AREA.
THEREAFTER EXPECT SOUTHWEST FLOW ALOFT. THOSE TWO MODELS ALSO AGREE
ON ROTATING A WEATHER DISTURBANCE ALOFT THROUGH THE FORECAST AREA
MONDAY NIGHT. AHEAD OF THE DISTURBANCE MODELS DEVELOP GOOD LIFT AND
MOISTURE..MAINLY IN THE NORTH. SO INCREASED POPS FOR THAT AREA.
ECMWF AND GFS ALSO AGREE IN DEVELOPING AN UPPER LOW OVER THE PACIFIC
NORTHWEST ON WEDNESDAY WITH INCREASED MOISTURE FOR NORTHWEST
MONTANA. IN LINE WITH THIS INCREASED THE CHANCES OF PRECIPITATION
FOR THE ROCKY MOUNTAIN FRONT. INHERITED TREND OF COOLING HIGH
TEMPERATURES FROM MONDAY TO WEDNESDAY LOOKS FINE BUT STARTED OFF
WARMER ON MONDAY WITH HIGHS WELL ABOVE NORMAL. BY WEDNESDAY LOWERED
INHERITED HIGH TEMPERATURES ON THE ORDER OF 5 TO 10 DEGREES OVER THE
PLAINS. BLANK
THURSDAY THROUGH FRIDAY....MODELS REMAIN IN FAIR AGREEMENT DURING
THIS PERIOD...WITH SOME DIFFERENCES IN TIMING OF FEATURES. A
LONGWAVE UPPER LEVEL TROUGH PERSISTS ALONG THE WEST COAST RESULTING
IN A SOUTHWESTERLY FLOW ALOFT ACROSS THE FORECAST AREA. WEAK
DISTURBANCES IN THIS SOMEWHAT MOIST AND UNSTABLE FLOW WILL BE
RESPONSIBLE FOR PARTLY TO MOSTLY CLOUDY SKIES WITH ISOLATED SHOWERS
AND MAINLY AFTERNOON AND EVENING THUNDERSTORMS. SHOWERS AND
THUNDERSTORMS WILL BE MORE NUMEROUS OVER THE MOUNTAINS. THE WARMEST
AIR STAYS MOSTLY SOUTH AND EAST OF THE FORECAST AREA...HOWEVER
TEMPERATURES ARE EXPECTED TO CLIMB TO NEAR SEASONAL AVERAGES. EK
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 53 83 55 86 / 30 20 20 20
CTB 48 80 50 84 / 20 10 20 10
HLN 55 87 56 89 / 30 20 20 20
BZN 53 86 53 89 / 40 30 30 30
WEY 43 72 43 75 / 50 40 40 30
DLN 51 79 52 82 / 40 30 30 30
HVR 52 84 52 89 / 30 20 30 20
LWT 51 77 52 82 / 40 30 30 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GUSTAFSON
LONG TERM...COULSTON
AVIATION...MPJ
WEATHER.GOV/GREATFALLS
000
FXUS65 KBYZ 040255
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
855 PM MDT FRI JUL 3 2009
.SHORT TERM...VALID FOR SAT AND SUN...
UPDATE TO ZONES AND AFP THIS EVENING. ISOLATED TO SCATTERED
THUNDERSTORMS WILL CONTINUE ACROSS THE ENTIRE AREA TONIGHT. THE
THREAT FOR SEVERE WEATHER HAS ENDED BUT POTENTIAL STILL EXIST FOR
THUNDERSTORMS WITH VERY HEAVY RAIN AS PW`S REMAINING OVER AN
INCH. WATER VAPOR SHOWING STRONG SHORT WAVE MOVING IN FROM
EASTERN IDAHO THIS EVENING. MODELS SEEM TO BE UNDER DOING THE
STRENGTH OF THIS WAVE AND WILL CONTINUE HIGH SCATTERED POPS GOING
IN CURRENT FORECAST TONIGHT. MOIST UPSLOPE FLOW TO CONTINUE INTO
SOUTHEAST MONTANA TONIGHT AND PATCHY FOG IS EXPECTED OVER THESE
AREAS AFTER MIDNIGHT. TEMPERATURE FORECAST LOOKS GOOD AND NO
CHANGES MADE. RICHMOND
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
MONDAY A TRANSITIONAL DAY AS THE UPPER LEVEL RIDGE MOVES EAST OF
MONTANA AND SOUTHWESTERLY FLOW ALOFT BRINGS A BIT DRIER AIR TO THE
STATE. STILL WILL SEE POTENTIAL FOR THUNDERSTORMS ON MONDAY AS
WIND SHEAR WILL OVERCOMPENSATE FOR THE REDUCTION IN MOISTURE.
COULD BE A PRETTY STORMY DAY IF ENOUGH LOW LEVEL MOISTURE FROM
PREVIOUS STORMS HELPS KEEP ELEVATED DEW POINTS OVER THE REGION.
MONDAY SHOULD BE THE WARMEST DAY AS SOME DOWNSLOPE FLOW HELPS
IMPROVE MIXING AND LOWER TO MID 90S LOOK LIKELY. BY TUESDAY
WARMEST AIR SHIFTS EAST AND DRIER AIR BECOMES MORE ENTRENCHED
THROUGH AIRMASS SHOULD DESTABILIZE ENOUGH FOR SOME POSSIBLE
CONVECTION...FAVORING THE AFTERNOON AND EVENING HOURS. WEDNESDAY
LOOKS UNCERTAIN AS THE ECMWF PUSHES A STRONG WAVE THROUGH ALBERTA
SUPPRESSING HEIGHTS WHILE THE GFS PRODUCES A SHORTWAVE RIDGE OVER
THE AREA. GFS SOLUTION WOULD PROMOTE RETURN FLOW MOISTURE INTO
SOUTHEAST MONTANA BUT IT LOOKS CONVECTIVE FEEDBACK CONTAMINATED SO
WILL HOLD OFF ON INTRODUCING TOO MUCH THUNDER THREAT AT THIS TIME.
BOTH MODELS ARE INDICATING A LESS AMPLIFIED FLOW PATTERN FOR
THURSDAY AND FRIDAY WHICH WOULD ENSURE A COOL DOWN IN
TEMPERATURES. PATTERN WILL LIKELY FAVOR MOUNTAIN CONVECTION WITH
SOME ACTIVITY REACHING THE ADJACENT PLAINS. BOTH MODELS ARE
INDICATING HEIGHTS RISING FOR FRIDAY SO HAVE SLIGHTLY LOWER POPS
THAT DAY. BORSUM
&&
.AVIATION...
SCATTERED THUNDERSTORMS WILL CONTINUE ACROSS THE AREA FOR MUCH OF
THE NIGHT AS ANOTHER UPPER LEVEL DISTURBANCE CROSSES THE REGION
FROM WEST TO EAST. A VERY MOIST ATMOSPHERE IS IN PLACE ACROSS THE
AREA THIS EVENING...THUS IFR CONDITIONS IN HEAVY RAIN CAN BE
EXPECTED WITH ANY THUNDERSTORMS TONIGHT. MVFR CEILINGS CURRENTLY
IMPACTING KBHK AIRPORT WILL CONTINUE OVERNIGHT...WITH FOG
DEVELOPMENT LIKELY LATE TONIGHT RESULTING IN IFR OR LOWER
CONDITIONS. BY THE EARLY MORNING HOURS FOG DEVELOPMENT WILL BE
POSSIBLE ACROSS MUCH OF THE FORECAST AREA. THERE IS A SLIGHT
CHANCE OF IFR OR LOWER VISIBILITIES WITH FOG ALONG AREA RIVERS
AND STREAMS...AS WELL AS ALONG THE EAST AND NORTH SLOPES OF AREA
MOUNTAINS...WHICH MAY ALSO RESULT IN OVERNIGHT MOUNTAIN
OBSCURATION. THE SLIGHT CHANCE OF IFR OR LOWER VISIBILITIES DUE
TO FOG INCLUDE THE KLVM...KBIL...KSHR...KMLS AND KBHK AIRPORTS.
CHAMBERS
&&
.PRELIMINARY POINT TEMP/POPS...
SAT SUN MON TUE WED THU FRI
-----------------------------------------------------------
BIL 060/082 061/086 062/089 060/087 059/085 057/081 057/081
44/T 42/T 22/T 22/T 32/T 32/T 22/T
LVM 049/082 051/084 052/083 051/081 050/081 048/077 047/079
43/T 43/T 22/T 23/T 22/T 23/T 32/T
HDN 058/084 057/089 058/094 056/091 055/088 053/086 052/086
43/T 32/T 22/T 22/T 32/T 32/T 22/T
MLS 061/083 060/088 062/092 063/090 062/088 062/084 061/084
42/T 32/T 22/T 22/T 22/T 32/T 22/T
4BQ 058/081 058/086 059/093 059/091 060/088 057/082 057/084
43/T 32/T 21/B 22/T 22/T 22/T 22/T
BHK 057/078 058/084 060/089 059/089 060/086 056/079 057/084
32/T 22/T 21/B 22/T 22/T 32/T 22/T
SHR 055/078 053/083 054/090 054/088 053/086 052/079 051/081
44/T 43/T 32/T 22/T 22/T 22/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KTFX 040255
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
855 PM MDT FRI JUL 3 2009
.UPDATE...NO MAJOR GRID CHANGES TONIGHT WITH SHORT TERM FORECAST
LOOKING PRETTY GOOD. SOME ISOLATED THUNDERSTORMS ARE STILL MOVING
AROUND OVER PORTIONS OF THE SOUTHWEST AND NORTHEAST CORNERS OF THE
CWA. THE POTENTIAL FOR SEVERE WEATHER DOES EXIST WITH THESE STORMS
AND WILL CONTINUE TO BE MONITORED CLOSELY. THE STORMS WILL
CONTINUE TO BE ACTIVE FOR A COUPLE HOURS BUT EXPECT THEM TO TAPER
OFF IN THE EARLY MORNING HOURS.
&&
.AVIATION...
UPDATED 2350Z.
VFR CONDITIONS WILL PREVAIL ACROSS THE FORECAST AREA THROUGH
SATURDAY AFTERNOON. HOWEVER...ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS WILL CONTINUE TO AFFECT PORTIONS OF SOUTHWEST
MONTANA AND NORTHEASTERN PORTIONS OF CENTRAL MONTANA WITH LOCAL
MVFR CONDITIONS IN BRIEF HEAVY RAINFALL THROUGH 03Z SATURDAY.
CONDITIONS WILL STABILIZE OVERNIGHT BUT THE AIRMASS IS EXPECTED TO
BECOME MARGINALLY UNSTABLE AGAIN SATURDAY AFTERNOON WITH ISOLATED
TO SCATTERED THUNDERSTORMS DEVELOPING AFTER 18Z. MPJ
&&
.PREV DISCUSSION...
/ISSUED 548 PM MDT FRI JUL 3 2009/
TODAY THROUGH SUNDAY EVENING...UPPER RIDGE THAT WAS
CENTERED OVER THE FOUR CORNERS AREA A FEW DAYS AGO HAS NOW DRIFTED
EAST WITH ITS AXIS NOW OVER THE GREAT PLAINS. SOUTHWEST FLOW ON THE
RIDGE`S WEST SIDE CONTINUES TO PUSH PACIFIC MOISTURE INTO
MONTANA...LEADING TO ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS THIS
AFTN/EVE OVER CENTRAL AND SOUTHWEST PORTIONS OF THE CWA. LATEST
MODEL DATA HAS SLIGHTLY REDUCED THE POTENTIAL FOR STRONG-TO-SEVERE
STORMS DUE IN PART TO COOLER-THAN-FORECAST SURFACE TEMPERATURES.
HOWEVER...POTENTIAL IS STILL HIGH ENOUGH FOR POSSIBLE STRONG STORMS
BEARING HAIL AND GUSTY OUTFLOW WINDS LATER THIS AFTN. WHATEVER
CONVECTION DEVELOPS SHOULD DISSIPATE TOWARD SUNSET AS AIRMASS
BECOMES MORE STABLE. GOOD AGREEMENT IN MODELS ON LITTLE CHANGE IN
CONDITIONS FOR TOMORROW...WITH SOUTHWEST FLOW ALOFT BRINGING IN
ADDITIONAL MOISTURE FOR ONE MORE ROUND OF SHOWERS AND
THUNDERSTORMS. SOME STORMS COULD BE STRONG WITH HAIL AND GUSTY
WINDS. LOOKS LIKE REGION WILL GET A BREAK FROM THE STORMS ON SUNDAY
AS THE UPPER RIDGE REBUILDS OVER THE NORTHERN ROCKIES AND MOIST
PACIFIC FLOW LESSENS. SOME CONVECTION IS POSSIBLE BUT WILL BE MORE
ISOLATED IN COVERAGE. TEMPERATURES WILL REMAIN 4 TO 7 DEG ABOVE
NORMAL THROUGH THE WEEKEND. WARANAUSKAS
SUNDAY NIGHT THROUGH WEDNESDAY NIGHT...ECMWF AND GFS MODELS AGREE IN
STARTING THE PERIOD WITH AN UPPER RIDGE OVER THE FORECAST AREA.
THEREAFTER EXPECT SOUTHWEST FLOW ALOFT. THOSE TWO MODELS ALSO AGREE
ON ROTATING A WEATHER DISTURBANCE ALOFT THROUGH THE FORECAST AREA
MONDAY NIGHT. AHEAD OF THE DISTURBANCE MODELS DEVELOP GOOD LIFT AND
MOISTURE..MAINLY IN THE NORTH. SO INCREASED POPS FOR THAT AREA.
ECMWF AND GFS ALSO AGREE IN DEVELOPING AN UPPER LOW OVER THE PACIFIC
NORTHWEST ON WEDNESDAY WITH INCREASED MOISTURE FOR NORTHWEST
MONTANA. IN LINE WITH THIS INCREASED THE CHANCES OF PRECIPITATION
FOR THE ROCKY MOUNTAIN FRONT. INHERITED TREND OF COOLING HIGH
TEMPERATURES FROM MONDAY TO WEDNESDAY LOOKS FINE BUT STARTED OFF
WARMER ON MONDAY WITH HIGHS WELL ABOVE NORMAL. BY WEDNESDAY LOWERED
INHERITED HIGH TEMPERATURES ON THE ORDER OF 5 TO 10 DEGREES OVER THE
PLAINS. BLANK
THURSDAY THROUGH FRIDAY....MODELS REMAIN IN FAIR AGREEMENT DURING
THIS PERIOD...WITH SOME DIFFERENCES IN TIMING OF FEATURES. A
LONGWAVE UPPER LEVEL TROUGH PERSISTS ALONG THE WEST COAST RESULTING
IN A SOUTHWESTERLY FLOW ALOFT ACROSS THE FORECAST AREA. WEAK
DISTURBANCES IN THIS SOMEWHAT MOIST AND UNSTABLE FLOW WILL BE
RESPONSIBLE FOR PARTLY TO MOSTLY CLOUDY SKIES WITH ISOLATED SHOWERS
AND MAINLY AFTERNOON AND EVENING THUNDERSTORMS. SHOWERS AND
THUNDERSTORMS WILL BE MORE NUMEROUS OVER THE MOUNTAINS. THE WARMEST
AIR STAYS MOSTLY SOUTH AND EAST OF THE FORECAST AREA...HOWEVER
TEMPERATURES ARE EXPECTED TO CLIMB TO NEAR SEASONAL AVERAGES. EK
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 53 83 55 86 / 30 20 20 20
CTB 48 80 50 84 / 20 10 20 10
HLN 55 87 56 89 / 30 20 20 20
BZN 53 86 53 89 / 40 30 30 30
WEY 43 72 43 75 / 50 40 40 30
DLN 51 79 52 82 / 40 30 30 30
HVR 52 84 52 89 / 30 20 30 20
LWT 51 77 52 82 / 40 30 30 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GUSTAFSON
LONG TERM...COULSTON
AVIATION...MPJ
WEATHER.GOV/GREATFALLS
000
FXUS65 KTFX 032348
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
548 PM MDT FRI JUL 3 2009
...UPDATE TO AVIATION...
.DISCUSSION...
TODAY THROUGH SUNDAY EVENING...UPPER RIDGE THAT WAS
CENTERED OVER THE FOUR CORNERS AREA A FEW DAYS AGO HAS NOW DRIFTED
EAST WITH ITS AXIS NOW OVER THE GREAT PLAINS. SOUTHWEST FLOW ON THE
RIDGE`S WEST SIDE CONTINUES TO PUSH PACIFIC MOISTURE INTO
MONTANA...LEADING TO ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS THIS
AFTN/EVE OVER CENTRAL AND SOUTHWEST PORTIONS OF THE CWA. LATEST
MODEL DATA HAS SLIGHTLY REDUCED THE POTENTIAL FOR STRONG-TO-SEVERE
STORMS DUE IN PART TO COOLER-THAN-FORECAST SURFACE TEMPERATURES.
HOWEVER...POTENTIAL IS STILL HIGH ENOUGH FOR POSSIBLE STRONG STORMS
BEARING HAIL AND GUSTY OUTFLOW WINDS LATER THIS AFTN. WHATEVER
CONVECTION DEVELOPS SHOULD DISSIPATE TOWARD SUNSET AS AIRMASS
BECOMES MORE STABLE. GOOD AGREEMENT IN MODELS ON LITTLE CHANGE IN
CONDITIONS FOR TOMORROW...WITH SOUTHWEST FLOW ALOFT BRINGING IN
ADDITIONAL MOISTURE FOR ONE MORE ROUND OF SHOWERS AND
THUNDERSTORMS. SOME STORMS COULD BE STRONG WITH HAIL AND GUSTY
WINDS. LOOKS LIKE REGION WILL GET A BREAK FROM THE STORMS ON SUNDAY
AS THE UPPER RIDGE REBUILDS OVER THE NORTHERN ROCKIES AND MOIST
PACIFIC FLOW LESSENS. SOME CONVECTION IS POSSIBLE BUT WILL BE MORE
ISOLATED IN COVERAGE. TEMPERATURES WILL REMAIN 4 TO 7 DEG ABOVE
NORMAL THROUGH THE WEEKEND. WARANAUSKAS
SUNDAY NIGHT THROUGH WEDNESDAY NIGHT...ECMWF AND GFS MODELS AGREE IN
STARTING THE PERIOD WITH AN UPPER RIDGE OVER THE FORECAST AREA.
THEREAFTER EXPECT SOUTHWEST FLOW ALOFT. THOSE TWO MODELS ALSO AGREE
ON ROTATING A WEATHER DISTURBANCE ALOFT THROUGH THE FORECAST AREA
MONDAY NIGHT. AHEAD OF THE DISTURBANCE MODELS DEVELOP GOOD LIFT AND
MOISTURE..MAINLY IN THE NORTH. SO INCREASED POPS FOR THAT AREA.
ECMWF AND GFS ALSO AGREE IN DEVELOPING AN UPPER LOW OVER THE PACIFIC
NORTHWEST ON WEDNESDAY WITH INCREASED MOISTURE FOR NORTHWEST
MONTANA. IN LINE WITH THIS INCREASED THE CHANCES OF PRECIPITATION
FOR THE ROCKY MOUNTAIN FRONT. INHERITED TREND OF COOLING HIGH
TEMPERATURES FROM MONDAY TO WEDNESDAY LOOKS FINE BUT STARTED OFF
WARMER ON MONDAY WITH HIGHS WELL ABOVE NORMAL. BY WEDNESDAY LOWERED
INHERITED HIGH TEMPERATURES ON THE ORDER OF 5 TO 10 DEGREES OVER THE
PLAINS. BLANK
THURSDAY THROUGH FRIDAY....MODELS REMAIN IN FAIR AGREEMENT DURING
THIS PERIOD...WITH SOME DIFFERENCES IN TIMING OF FEATURES. A
LONGWAVE UPPER LEVEL TROUGH PERSISTS ALONG THE WEST COAST RESULTING
IN A SOUTHWESTERLY FLOW ALOFT ACROSS THE FORECAST AREA. WEAK
DISTURBANCES IN THIS SOMEWHAT MOIST AND UNSTABLE FLOW WILL BE
RESPONSIBLE FOR PARTLY TO MOSTLY CLOUDY SKIES WITH ISOLATED SHOWERS
AND MAINLY AFTERNOON AND EVENING THUNDERSTORMS. SHOWERS AND
THUNDERSTORMS WILL BE MORE NUMEROUS OVER THE MOUNTAINS. THE WARMEST
AIR STAYS MOSTLY SOUTH AND EAST OF THE FORECAST AREA...HOWEVER
TEMPERATURES ARE EXPECTED TO CLIMB TO NEAR SEASONAL AVERAGES. EK
&&
.AVIATION...
UPDATED 2350Z.
VFR CONDITIONS WILL PREVAIL ACROSS THE FORECAST AREA THROUGH
SATURDAY AFTERNOON. HOWEVER...ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS WILL CONTINUE TO AFFECT PORTIONS OF SOUTHWEST
MONTANA AND NORTHEASTERN PORTIONS OF CENTRAL MONTANA WITH LOCAL
MVFR CONDITIONS IN BRIEF HEAVY RAINFALL THROUGH 03Z SATURDAY.
CONDITIONS WILL STABILIZE OVERNIGHT BUT THE AIRMASS IS EXPECTED TO
BECOME MARGINALLY UNSTABLE AGAIN SATURDAY AFTERNOON WITH ISOLATED
TO SCATTERED THUNDERSTORMS DEVELOPING AFTER 18Z. MPJ
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 53 83 55 86 / 30 20 20 20
CTB 48 80 50 84 / 20 10 20 10
HLN 55 87 56 89 / 30 20 20 20
BZN 53 86 53 89 / 40 30 30 30
WEY 43 72 43 75 / 50 40 40 30
DLN 51 79 52 82 / 50 30 30 30
HVR 52 84 52 89 / 20 20 30 20
LWT 51 77 52 82 / 40 30 30 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...WARANAUSKAS
LONG TERM...BLANK/EK
AVIATION...MPJ
WEATHER.GOV/GREATFALLS
000
FXUS65 KMSO 032218
AFDMSO
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MISSOULA MT
418 PM MDT FRI JUL 3 2009
.UPDATE...ADDED MENTIONING OF THUNDERSTORMS POSSIBLE IN THE
FLATHEAD VALLEY THROUGH THIS EVENING.
&&
.DISCUSSION...LATEST RADAR SCANS HAVE SHOWED THUNDERSTORM
DEVELOPMENT OCCURRING IN THE FLATHEAD VALLEY. THESE STORMS SHOULD
REMAIN FAIRLY SMALL IN SIZE AND ARE EXPECTED TO DISSIPATE BY
SUNDOWN THIS EVENING. AS A RESULT OF THIS
DEVELOPMENT...THUNDERSTORM WORDING HAS BEEN ADDED TO THE
FORECAST THROUGH TONIGHT.
&&
.AVIATION...HIGH PRESSURE WILL BE THE DOMINANT WEATHER FEATURE PRESENT DURING
THE NEXT 24 HOURS. INSTABILITY AND MOISTURE MOVING THROUGH THE
RIDGE OF HIGH PRESSURE WILL BRING THUNDERSTORMS NEAR KGPI...KSMN...AND
KBTM THROUGH THIS EVENING. VARIABLE AND GUSTY WINDS ARE LIKELY IN
THE VICINITY OF THUNDERSTORMS.
&&
.PREV DISCUSSION... /ISSUED 234 PM MDT FRI JUL 3 2009/
DISCUSSION...
TONIGHT THROUGH SUNDAY...AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL
BE THE MAIN FEATURE PRESENT DURING THE NEXT COUPLE OF DAYS. THE
RIDGE IS ANTICIPATED TO BE MOST PRONOUNCED DURING SUNDAY
AFTERNOON...COINCIDING WITH THE WARMEST DAYTIME TEMPERATURES SO
FAR THIS SUMMER. MOISTURE TRANSPORTED THROUGH THE RIDGE FROM THE
DESERT SOUTHWEST WILL CONTINUE TO COMBINE WITH DAYTIME HEATING FOR
DEVELOPING THUNDERSTORMS...MAINLY OVER SOUTHWEST MONTANA AND NORTH
CENTRAL IDAHO...EACH AFTERNOON AND EVENING. MEANWHILE...A CLOSED
LOW PRESSURE CIRCULATION DEVELOPING OFF THE PACIFIC NORTHWEST
COAST WILL CREEP CLOSER TO NORTHERN U.S. ROCKIES DURING THIS
TIME...WITH A PRONOUNCED INCREASE IN OVERNIGHT TEMPERATURES AT
HIGHER ELEVATIONS.
SUNDAY NIGHT AND MONDAY...THE UPPER RIDGE WILL SHIFT EAST AND ALLOW
A MOIST SOUTHWEST FLOW TO MOVE INTO THE INTERMOUNTAIN REGION. MODELS
STILL INDICATE A POSSIBLE STRONG WIND EVENT ACROSS NORTH CENTRAL
IDAHO AND WESTERN MONTANA AS A COOLER AIRMASS APPROACHES THE
INTERMOUNTAIN REGION. HAVE THEREFORE INCREASED WIND SPEEDS IN THE
FORECAST AND WILL CONTINUE TO MONITOR THROUGH THE WEEKEND. ALSO WITH
THE CHANGE IN AIRMASS...THUNDERSTORMS CLOUD DEVELOP SUNDAY EVENING
AND CONTINUE THROUGH MONDAY...ESPECIALLY ACROSS THE NORTHERN
CLEARWATER MOUNTAINS AND NORTHWEST MONTANA WHERE BEST MOISTURE LOOKS
TO RESIDE.
TUESDAY THROUGH THURSDAY...SOUTHWEST FLOW WILL TRANSITION TO AN
UPPER TROUGH MOVING OVER NORTH CENTRAL IDAHO AND WESTERN MONTANA.
THIS WILL KEEP TEMPERATURES FALLING EACH DAY WITH READINGS WELL
BELOW AVERAGE WEDNESDAY AND THURSDAY. MODELS IN DECENT AGREEMENT
THAT TUESDAY NIGHT AND WEDNESDAY LOOK TO BE THE BEST DAY FOR
WIDESPREAD SHOWERS AND THUNDERSTORMS AS THE UPPER TROUGH MOVES OVER
THE INTERMOUNTAIN REGION.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&
$$
UPDATE...ALLEGRETTO
SHORT TERM...ZUMPFE
LONG TERM....KOLATA
AVIATION...ZUMPFE
000
FXUS65 KBYZ 032127
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
327 PM MDT FRI JUL 3 2009
.SHORT TERM...VALID FOR SAT AND SUN...
THUNDERSTORMS ARE EXPECTED TO CONTINUE TO SPREAD ACROSS THE
PLAINS INTO THE EVENING. PERSISTENT CLOUD COVER HAS TEMPERED
INSTABILITY A BIT FOR THIS AFTERNOON. TRENDED MAX TEMP FORECAST
DOWN SLIGHTLY IN RESPONSE. HOWEVER...NO DRASTIC CHANGES HAVE BEEN
MADE AS SOME BREAKS IN THE CLOUDS EXIST. DID NOT REMOVE SEVERE
WORDING FROM THUNDERSTORM FORECAST AS A NUMBER OF THESE CELLS MAY
REACH SEVERE THRESHOLDS. ALTHOUGH 0-3 KM BULK SHEAR IS RATHER
LOW...DEEP LAYER SHEAR AROUND 30 KTS SHOULD AID IN STORM
ORGANIZATION. SUFFICIENT CAPE AND MODERATELY-STEEP MID-LVL LAPSE
RATES WILL CONTINUE TO POSE A HAIL THREAT. THE HEAVY RAINFALL
THREAT WILL CONTINUE AS PWATS REMAIN BETWEEN 0.75 - 1.00 INCH.
STRONG WINDS WILL ALSO BE POSSIBLE WITH THESE STORMS. KEPT CHANCE
POPS OVERNIGHT AS MODELS DEPICT SOME ELEVATED INSTABILITY AFTER
06Z. FOR THE 4TH OF JULY...INCREASED POPS OVER THE HIGHER TERRAIN
AS AFTERNOON THUNDERSTORMS ARE EXPECTED. SOME OF THESE STORMS MAY
DRIFT ONTO THE PLAINS SO KEPT CHANCE POPS THROUGH THE EVENING.
LOWER PRECIPITATION CHANCES ARE IN STORE FOR SUNDAY AND SHOULD BE
CENTERED MAINLY ALONG THE HIGHER TERRAIN. SCHUKNECHT
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
MONDAY A TRANSITIONAL DAY AS THE UPPER LEVEL RIDGE MOVES EAST OF
MONTANA AND SOUTHWESTERLY FLOW ALOFT BRINGS A BIT DRIER AIR TO THE
STATE. STILL WILL SEE POTENTIAL FOR THUNDERSTORMS ON MONDAY AS
WIND SHEAR WILL OVERCOMPENSATE FOR THE REDUCTION IN MOISTURE.
COULD BE A PRETTY STORMY DAY IF ENOUGH LOW LEVEL MOISTURE FROM
PREVIOUS STORMS HELPS KEEP ELEVATED DEW POINTS OVER THE REGION.
MONDAY SHOULD BE THE WARMEST DAY AS SOME DOWNSLOPE FLOW HELPS
IMPROVE MIXING AND LOWER TO MID 90S LOOK LIKELY. BY TUESDAY
WARMEST AIR SHIFTS EAST AND DRIER AIR BECOMES MORE ENTRENCHED
THROUGH AIRMASS SHOULD DESTABILIZE ENOUGH FOR SOME POSSIBLE
CONVECTION...FAVORING THE AFTERNOON AND EVENING HOURS. WEDNESDAY
LOOKS UNCERTAIN AS THE ECMWF PUSHES A STRONG WAVE THROUGH ALBERTA
SUPPRESSING HEIGHTS WHILE THE GFS PRODUCES A SHORTWAVE RIDGE OVER
THE AREA. GFS SOLUTION WOULD PROMOTE RETURN FLOW MOISTURE INTO
SOUTHEAST MONTANA BUT IT LOOKS CONVECTIVE FEEDBACK CONTAMINATED SO
WILL HOLD OFF ON INTRODUCING TOO MUCH THUNDER THREAT AT THIS TIME.
BOTH MODELS ARE INDICATING A LESS AMPLIFIED FLOW PATTERN FOR
THURSDAY AND FRIDAY WHICH WOULD ENSURE A COOL DOWN IN
TEMPERATURES. PATTERN WILL LIKELY FAVOR MOUNTAIN CONVECTION WITH
SOME ACTIVITY REACHING THE ADJACENT PLAINS. BOTH MODELS ARE
INDICATING HEIGHTS RISING FOR FRIDAY SO HAVE SLIGHTLY LOWER POPS
THAT DAY. BORSUM
&&
.AVIATION...
THUNDERSTORMS WILL IMPACT THE REGION THIS AFTERNOON AND EVENING.
SOME STORMS WILL PRODUCE VERY HEAVY RAINS AND HAIL CAUSING
TEMPORARY REDUCTIONS IN VISIBILITIES AND CEILINGS. CONVECTION WILL
DECREASE TONIGHT BEFORE ANOTHER ROUND OF THUNDERSTORMS DEVELOP ON
SATURDAY. PATCHY FOG IS POSSIBLE AROUND SUNRISE MAINLY ALONG THE
RIVER BOTTOMS. BORSUM
&&
.PRELIMINARY POINT TEMP/POPS...
SAT SUN MON TUE WED THU FRI
-----------------------------------------------------------
BIL 059/082 061/086 062/089 060/087 059/085 057/081 057/081
54/T 42/T 22/T 22/T 32/T 32/T 22/T
LVM 048/082 051/084 052/083 051/081 050/081 048/077 047/079
43/T 43/T 22/T 23/T 22/T 23/T 32/T
HDN 057/084 057/089 058/094 056/091 055/088 053/086 052/086
43/T 32/T 22/T 22/T 32/T 32/T 22/T
MLS 060/083 060/088 062/092 063/090 062/088 062/084 061/084
42/T 32/T 22/T 22/T 22/T 32/T 22/T
4BQ 057/081 058/086 059/093 059/091 060/088 057/082 057/084
43/T 32/T 21/B 22/T 22/T 22/T 22/T
BHK 056/078 058/084 060/089 059/089 060/086 056/079 057/084
32/T 22/T 21/B 22/T 22/T 32/T 22/T
SHR 054/078 053/083 054/090 054/088 053/086 052/079 051/081
54/T 43/T 32/T 22/T 22/T 22/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KTFX 032118
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
318 PM MDT FRI JUL 3 2009
.DISCUSSION...
TODAY THROUGH SUNDAY EVENING...UPPER RIDGE THAT WAS
CENTERED OVER THE FOUR CORNERS AREA A FEW DAYS AGO HAS NOW DRIFTED
EAST WITH ITS AXIS NOW OVER THE GREAT PLAINS. SOUTHWEST FLOW ON THE
RIDGE`S WEST SIDE CONTINUES TO PUSH PACIFIC MOISTURE INTO
MONTANA...LEADING TO ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS THIS
AFTN/EVE OVER CENTRAL AND SOUTHWEST PORTIONS OF THE CWA. LATEST
MODEL DATA HAS SLIGHTLY REDUCED THE POTENTIAL FOR STRONG-TO-SEVERE
STORMS DUE IN PART TO COOLER-THAN-FORECAST SURFACE TEMPERATURES.
HOWEVER...POTENTIAL IS STILL HIGH ENOUGH FOR POSSIBLE STRONG STORMS
BEARING HAIL AND GUSTY OUTFLOW WINDS LATER THIS AFTN. WHATEVER
CONVECTION DEVELOPS SHOULD DISSIPATE TOWARD SUNSET AS AIRMASS
BECOMES MORE STABLE. GOOD AGREEMENT IN MODELS ON LITTLE CHANGE IN
CONDITIONS FOR TOMORROW...WITH SOUTHWEST FLOW ALOFT BRINGING IN
ADDITIONAL MOISTURE FOR ONE MORE ROUND OF SHOWERS AND
THUNDERSTORMS. SOME STORMS COULD BE STRONG WITH HAIL AND GUSTY
WINDS. LOOKS LIKE REGION WILL GET A BREAK FROM THE STORMS ON SUNDAY
AS THE UPPER RIDGE REBUILDS OVER THE NORTHERN ROCKIES AND MOIST
PACIFIC FLOW LESSENS. SOME CONVECTION IS POSSIBLE BUT WILL BE MORE
ISOLATED IN COVERAGE. TEMPERATURES WILL REMAIN 4 TO 7 DEG ABOVE
NORMAL THROUGH THE WEEKEND. WARANAUSKAS
SUNDAY NIGHT THROUGH WEDNESDAY NIGHT...ECMWF AND GFS MODELS AGREE IN
STARTING THE PERIOD WITH AN UPPER RIDGE OVER THE FORECAST AREA.
THEREAFTER EXPECT SOUTHWEST FLOW ALOFT. THOSE TWO MODELS ALSO AGREE
ON ROTATING A WEATHER DISTURBANCE ALOFT THROUGH THE FORECAST AREA
MONDAY NIGHT. AHEAD OF THE DISTURBANCE MODELS DEVELOP GOOD LIFT AND
MOISTURE..MAINLY IN THE NORTH. SO INCREASED POPS FOR THAT AREA.
ECMWF AND GFS ALSO AGREE IN DEVELOPING AN UPPER LOW OVER THE PACIFIC
NORTHWEST ON WEDNESDAY WITH INCREASED MOISTURE FOR NORTHWEST
MONTANA. IN LINE WITH THIS INCREASED THE CHANCES OF PRECIPITATION
FOR THE ROCKY MOUNTAIN FRONT. INHERITED TREND OF COOLING HIGH
TEMPERATURES FROM MONDAY TO WEDNESDAY LOOKS FINE BUT STARTED OFF
WARMER ON MONDAY WITH HIGHS WELL ABOVE NORMAL. BY WEDNESDAY LOWERED
INHERITED HIGH TEMPERATURES ON THE ORDER OF 5 TO 10 DEGREES OVER THE
PLAINS. BLANK
THURSDAY THROUGH FRIDAY....MODELS REMAIN IN FAIR AGREEMENT DURING
THIS PERIOD...WITH SOME DIFFERENCES IN TIMING OF FEATURES. A
LONGWAVE UPPER LEVEL TROUGH PERSISTS ALONG THE WEST COAST RESULTING
IN A SOUTHWESTERLY FLOW ALOFT ACROSS THE FORECAST AREA. WEAK
DISTURBANCES IN THIS SOMEWHAT MOIST AND UNSTABLE FLOW WILL BE
RESPONSIBLE FOR PARTLY TO MOSTLY CLOUDY SKIES WITH ISOLATED SHOWERS
AND MAINLY AFTERNOON AND EVENING THUNDERSTORMS. SHOWERS AND
THUNDERSTORMS WILL BE MORE NUMEROUS OVER THE MOUNTAINS. THE WARMEST
AIR STAYS MOSTLY SOUTH AND EAST OF THE FORECAST AREA...HOWEVER
TEMPERATURES ARE EXPECTED TO CLIMB TO NEAR SEASONAL AVERAGES. EK
&&
.AVIATION...
UPDATED 1805Z.
VFR CONDITIONS WILL GENERALLY CONTINUE ACROSS SOUTHWEST...CENTRAL...
AND NORTH CENTRAL MONTANA THROUGH 18Z SATURDAY...UNLESS OTHERWISE
NOTED BELOW. A DISTURBANCE IN THE MOIST AND MODERATE WESTERLY FLOW
ALOFT WILL BRING ISOLATED THUNDERSTORMS WITH ASSOCIATED MVFR
CONDITIONS IN BRIEF HEAVY RAINFALL TO THE KLWT TERMINAL AREA THROUGH
AROUND 20Z. OTHERWISE...THE FLOW WILL BECOME INCREASINGLY UNSTABLE
THROUGH THE AFTERNOON FOR SCATTERED SHOWER AND THUNDERSTORM
DEVELOPMENT ACROSS MOST OF THE AREA. BRIEF HEAVY RAINFALL WITH
OCCASIONAL MVFR CONDITIONS...HAIL...AND GUSTY WINDS WILL BE THE MAIN
THREAT FROM THESE STORMS. THE GREATEST THREAT FOR LARGE HAIL AND
WIND GUSTS OF 50 KT OR MORE WILL BE SOUTH AND EAST OF A
KHVR-KLWT-KBZN LINE...MAINLY AFFECTING THE KLWT TERMINAL. THE
AIRMASS WILL GENERALLY STABILIZE FROM THE WEST BETWEEN 00Z AND 04Z
FOR DECREASING CLOUDS AND STORMS. ONLY THE KCTB TERMINAL WILL BE
EXEMPT FROM THUNDERSTORM ACTIVITY TODAY. COULSTON
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 53 83 55 86 / 30 20 20 20
CTB 48 80 50 84 / 20 10 20 10
HLN 55 87 56 89 / 30 20 20 20
BZN 53 86 53 89 / 40 30 30 30
WEY 43 72 43 75 / 50 40 40 30
DLN 51 79 52 82 / 50 30 30 30
HVR 52 84 52 89 / 20 20 30 20
LWT 51 77 52 82 / 40 30 30 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...WARANAUSKAS
LONG TERM...BLANK/KURDY
AVIATION...COULSTON
WEATHER.GOV/GREATFALLS
000
FXUS65 KGGW 032038
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
238 PM MDT FRI JUL 3 2009
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SUNDAY...
A SHORTWAVE TROUGH WILL SWEEP ACROSS NORTHEAST MONTANA OVERNIGHT
BRINGING A ROUND OF THUNDERSTORMS...SOME OF WHICH COULD BE SEVERE
IN THE EVENING. PRECIPITABLE WATER VALUES WILL BE NEAR ONE
INCH...SO HEAVY RAIN IS POSSIBLE IN ANY STORMS. FLASH FLOOD
GUIDANCE IS HIGH ACROSS MOST OF THE AREA. HOWEVER...IT IS MUCH
LOWER IN RICHLAND...WIBAUX...AND EASTERN DAWSON COUNTIES AS
THEY RECENTLY RECEIVED SEVERE THUNDERSTORMS WITH HEAVY RAIN.
FLASH FLOODING COULD BE A THREAT THERE OVERNIGHT IF THEY RECEIVE
HEAVY RAIN.
A DRIER NORTHERLY PUSH OF CANADIAN AIR DEVELOPS BEHIND THE
DEPARTING SHORTWAVE TROUGH SATURDAY. THIS WILL REDUCE INSTABILITY
ACROSS THE AREA...EXCEPT FOR THE FAR SOUTHWEST CORNER OF THE CWA.
12Z MODEL SUITE CASTS DOUBT ON THUNDERSTORM POTENTIAL. HOWEVER...RECENT
MODEL RUNS HAVE BEEN...AND TYPICALLY ARE...FICKLE WITH
MOISTURE...SO A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS WILL BE
MAINTAINED WITH ENERGETIC WEST-SOUTHWEST FLOW ALOFT. MAXIMUM
TEMPERATURES WILL RANGE FROM THE UPPER 70S TO MID 80S ACROSS THE
AREA...WHICH IS NEAR AVERAGE FOR EARLY JULY.
A WEAK SHORTWAVE TRAVERSES ACROSS NORTHEAST MONTANA SATURDAY NIGHT
RESULTING IN STEEPENING MID-LEVEL LAPSE RATES. THIS COULD RESULT
IN A FEW ELEVATED NOCTURNAL THUNDERSTORMS. 500MB HEIGHTS AND
1000-500MB THICKNESS VALUES BEGIN TO CLIMB ON SUNDAY AS AN UPPER
RIDGE BUILDS OVER THE NORTHERN HIGH PLAINS. THIS WILL SEND MAXIMUM
TEMPERATURES WELL INTO THE 80S...AND PERHAPS LOW 90S. THE LEE-SIDE
SURFACE TROUGH BECOMES RE-INVIGORATED OVER CENTRAL MONTANA IN A
WARMING AIRMASS ALLOWING SOUTHEASTERLY FLOW TO EXPAND OVER THE
REGION...AND HENCE...REFRESH LOW LEVEL MOISTURE IN THE AREA. THE
MID AND UPPER LEVELS WILL BE MORE STABLE SUNDAY...BUT A SLIGHT
CHANCE OF THUNDERSTORMS WILL BE MAINTAINED WITH INCREASING
INSTABILITY. AJZ
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...
LITTLE CHANGE FOR THE EXTENDED FORECAST AS MODELS IN GOOD
AGREEMENT WITH MAIN PATTERN...OF UPPER FLOW BACKING TO THE
SOUTHWEST EARLY NEXT WEEK. MADE SLIGHT ADJUSTMENT TO POPS FOR
COLLABORATIVE PURPOSES...WHILE THE REMAINDER OF THE FORECAST LOOKS
ON TRACK. EBERT
PREVIOUS LONG TERM FORECAST DISCUSSION...THE UPPER LEVEL RIDGE
WILL PASS OVER THE AREA SUNDAY NIGHT AND MONDAY BACKING THE
INITIAL NW FLOW ALOFT TO THE WEST. UPPER FLOW WILL CONTINUE
BACKING TO THE SOUTHWEST THROUGH THE REMAINDER OF THE WEEK AS
STRONG HIGH PRESSURE BUILDS UP OVER THE SOUTHWESTERN STATES WHILE
AN UPPER LEVEL TROUGH MOVES INTO THE PACNW.
MONDAY AND MONDAY NIGHT...A THERMAL RIDGE PUSHES INTO THE
AREA...RAMPING UP TEMPERATURES. INSTABILITY COULD INITIATE TS
ACTIVITY BY AFTERNOON. TIMING DIFFERENCES BETWEEN GFS AND EC
CONTINUE...WITH THE EC PUSHING THE RIDGE AXIS EAST OF THE AREA BY
AFTERNOON...ALLOWING MORE MOISTURE INTO THE UNSTABLE AREA. THE GEM
SIDES WITH THE EC...SO IT SEEMS REASONABLE TO INCLUDE AT LEAST
SLIGHT CHANCE POPS. AN INVERTED SURFACE TROUGH WILL PUSH THE BEST
AREA FOR POPS INTO THE NORTHERN ZONES AND CANADA.
TUESDAY AND TUESDAY NIGHT...THERMAL RIDGE MOVES EAST OF THE AREA
AND SW FLOW ALOFT SENDS MORE CLOUDS OUR WAY...LOWERING
TEMPERATURES A BIT CLOSER TO NORMAL. OTHERWISE UNSTABLE CONDITIONS
WILL CONTINUE TO CREATE AT LEAST A SLIGHT CHANCE FOR
THUNDERSTORMS.
WEDNESDAY AND WEDNESDAY NIGHT...THE UPPER LEVEL LOW CONTINUES TO
SPIN OVER WASHINGTON STATE SENDING A STRONG UPPER JET OVER
CENTRAL MONTANA. THE RESULT WILL BE CONTINUED INJECTION OF
MOISTURE. BOTH EC AND GFS SHOW A COLD FRONT NUDGING CLOSE TO OUR
WESTERN BORDER. THE RESULT COULD BE HEAVIER SHOWERS PUSHING INTO
THE CWA. THERE WILL BE A TREND TOWARDS TEMPERATURES NEAR NORMAL
THROUGH THE REMAINDER OF THE EXTENDED PERIOD.
THURSDAY THE UPPER LOW LIFTS INTO THE CENTRAL CANADIAN PRAIRIE
TAKING MOST OF THE SHOWER ACTIVITY WITH IT. THE RESULT LOCALLY
WILL BE NEAR NORMAL TEMPERATURES. SCT
&&
.AVIATION...
ISOLATED TO SCATTERED RAIN SHOWERS AND THUNDERSTORMS WILL MOVE
ACROSS THE REGION TODAY AND THE INCREASINGLY UNSTABLE AFTERNOON
CONDITIONS COULD PRODUCE SOME SEVERE THUNDERSTORMS...MAINLY TO THE
SOUTHWEST OF THE TAF SITES...INTO EARLY EVENING WITH STRONG GUSTY
WINDS AND POSSIBLY LARGE HAIL. OTHERWISE GENERALLY VFR THROUGH
TONIGHT WITH SOUTHEAST WINDS DIMINISHING AROUND SUNSET. RAE
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KMSO 032034
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
234 PM MDT FRI JUL 3 2009
.DISCUSSION...
TONIGHT THROUGH SUNDAY...AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL
BE THE MAIN FEATURE PRESENT DURING THE NEXT COUPLE OF DAYS. THE
RIDGE IS ANTICIPATED TO BE MOST PRONOUNCED DURING SUNDAY
AFTERNOON...COINCIDING WITH THE WARMEST DAYTIME TEMPERATURES SO
FAR THIS SUMMER. MOISTURE TRANSPORTED THROUGH THE RIDGE FROM THE
DESERT SOUTHWEST WILL CONTINUE TO COMBINE WITH DAYTIME HEATING FOR
DEVELOPING THUNDERSTORMS...MAINLY OVER SOUTHWEST MONTANA AND NORTH
CENTRAL IDAHO...EACH AFTERNOON AND EVENING. MEANWHILE...A CLOSED
LOW PRESSURE CIRCULATION DEVELOPING OFF THE PACIFIC NORTHWEST
COAST WILL CREEP CLOSER TO NORTHERN U.S. ROCKIES DURING THIS
TIME...WITH A PRONOUNCED INCREASE IN OVERNIGHT TEMPERATURES AT
HIGHER ELEVATIONS.
SUNDAY NIGHT AND MONDAY...THE UPPER RIDGE WILL SHIFT EAST AND ALLOW
A MOIST SOUTHWEST FLOW TO MOVE INTO THE INTERMOUNTAIN REGION. MODELS
STILL INDICATE A POSSIBLE STRONG WIND EVENT ACROSS NORTH CENTRAL
IDAHO AND WESTERN MONTANA AS A COOLER AIRMASS APPROACHES THE
INTERMOUNTAIN REGION. HAVE THEREFORE INCREASED WIND SPEEDS IN THE
FORECAST AND WILL CONTINUE TO MONITOR THROUGH THE WEEKEND. ALSO WITH
THE CHANGE IN AIRMASS...THUNDERSTORMS CLOUD DEVELOP SUNDAY EVENING
AND CONTINUE THROUGH MONDAY...ESPECIALLY ACROSS THE NORTHERN
CLEARWATER MOUNTAINS AND NORTHWEST MONTANA WHERE BEST MOISTURE LOOKS
TO RESIDE.
TUESDAY THROUGH THURSDAY...SOUTHWEST FLOW WILL TRANSITION TO AN
UPPER TROUGH MOVING OVER NORTH CENTRAL IDAHO AND WESTERN MONTANA.
THIS WILL KEEP TEMPERATURES FALLING EACH DAY WITH READINGS WELL
BELOW AVERAGE WEDNESDAY AND THURSDAY. MODELS IN DECENT AGREEMENT
THAT TUESDAY NIGHT AND WEDNESDAY LOOK TO BE THE BEST DAY FOR
WIDESPREAD SHOWERS AND THUNDERSTORMS AS THE UPPER TROUGH MOVES OVER
THE INTERMOUNTAIN REGION.
&&
.AVIATION...
HIGH PRESSURE WILL BE THE DOMINANT WEATHER FEATURE PRESENT DURING
THE NEXT 24 HOURS. INSTABILITY AND MOISTURE MOVING THROUGH THE RIDGE
WILL BRING THUNDERSTORMS NEAR KSMN AND KBTM THROUGH 04/0400...AND
COMMENCING ONCE AGAIN AFTER 04/1800. VARIABLE AND GUSTY WINDS ARE
LIKELY IN THE VICINITY OF THUNDERSTORMS.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&
$$
SHORT TERM...ZUMPFE
LONG TERM....KOLATA
AVIATION...ZUMPFE
000
FXUS65 KMSO 031809
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
1209 PM MDT FRI JUL 3 2009
.UPDATE...
THUNDERSTORM COVERAGE HAS BEEN EXPANDED NORTHWARD AND ALONG
CONTINENTAL DIVIDE FOR REST OF THIS AFTERNOON AND EVENING...CITING
RECENT OBSERVATIONS AND TRENDS.
&&
.PREV DISCUSSION... /ISSUED 345 AM MDT FRI JUL 3 2009/
..HOT HOLIDAY WEEKEND WITH MOTHER NATURES FIREWORKS ACROSS THE
SOUTH FRIDAY AND SATURDAY...
DISCUSSION...TODAY THROUGH TONIGHT...LOW-LEVEL MOISTURE HAS BEEN
STEADILY INCREASING ACROSS THE NORTHERN ROCKIES AND KEPT LIGHT
SHOWER ACTIVITY ACROSS CENTRAL IDAHO AND SOUTHWEST MONTANA INTO
THE EARLY MORNING HOURS. ISOLATED LIGHT SHOWER ACTIVITY WILL
CONTINUE THROUGH MID MORNING ACROSS THE BITTERROOT VALLEY AND TO A
LESSER DEGREE ACROSS THE BUTTE BLACKFOOT AREA. TEMPERATURES WILL
REMAIN WARM...ABOVE SEASONAL NORMALS AGAIN TODAY...UNDER WEAK HIGH
PRESSURE.
THE POTENTIAL FOR AFTERNOON THUNDERSTORMS ACROSS THE SOUTH CONTINUES TODAY
WITH HIGH PRECIPITABLE WATER VALUES AND MODERATE UPPER LEVEL WIND
DYNAMICS IN PLACE WITHIN THE ALREADY WARM AIRMASS. THE
THUNDERSTORM BOUNDARY WILL BE CONCENTRATED ACROSS THE SOUTHERN
HALF OF THE BITTERROOT VALLEY TO DRUMMOND AND ALL POINTS SOUTH.
SOUTHEASTERN IDAHO COUNTY AND ALL OF LEMHI COUNTY SHOULD ALSO SEE
THUNDERSTORM ACTIVITY IN THE AFTERNOON. SMALL HAIL...PERIODS OF
HEAVY RAIN AND GUSTY WINDS WILL BE POSSIBLE WITH THUNDERSTORMS
THIS AFTERNOON.
SATURDAY AND SUNDAY WILL BE VERY SIMILAR TO FRIDAY WITH GRADUAL
WARMING EACH DAY. SUNDAY NIGHT AND MONDAY...THE UPPER RIDGE WILL
SHIFT EAST AND ALLOW A MOIST SOUTHWEST FLOW TO MOVE INTO THE
INTERMOUNTAIN REGION. MODELS STILL INDICATE A POSSIBLE STRONG WIND
EVENT ACROSS NORTH CENTRAL IDAHO AND WESTERN MONTANA AS A COOLER
AIRMASS APPROACHES THE INTERMOUNTAIN REGION. HAVE THEREFORE
INCREASED WIND SPEEDS IN THE FORECAST AND WILL CONTINUE TO MONITOR
THROUGH THE WEEKEND. ALSO WITH THE CHANGE IN
AIRMASS...THUNDERSTORMS CLOUD DEVELOP SUNDAY EVENING AND CONTINUE
THROUGH MONDAY...ESPECIALLY ACROSS THE NORTHERN CLEARWATER
MOUNTAINS AND NORTHWEST MONTANA WHERE BEST MOISTURE LOOKS TO
RESIDE.
TUESDAY THROUGH THURSDAY...SOUTHWEST FLOW WILL TRANSITION TO AN
UPPER TROUGH MOVING OVER NORTH CENTRAL IDAHO AND WESTERN MONTANA.
THIS WILL KEEP TEMPERATURES FALLING EACH DAY WITH READINGS WELL
BELOW AVERAGE WEDNESDAY AND THURSDAY. MODELS IN DECENT AGREEMENT
THAT TUESDAY NIGHT AND WEDNESDAY LOOK TO BE THE BEST DAY FOR
WIDESPREAD SHOWERS AND THUNDERSTORMS AS THE UPPER TROUGH MOVES OVER
THE INTERMOUNTAIN REGION.
AVIATION...BUILDING UPPER LEVEL HIGH PRESSURE WILL KEEP SKIES
MOSTLY CLEAR AND WINDS LIGHT THROUGH MIDDAY FRIDAY. BREEZY NORTHEAST
WINDS AT KGPI WILL LAST UNTIL NOON...AS THE SURFACE PRESSURE
GRADIENT ACROSS THE GREAT DIVIDE TIGHTENS. BREEZY WINDS AT KMSO
WILL LAST THROUGH SUNSET IN THE MIXED AFTERNOON ATMOSPHERE.
THUNDERSTORM POTENTIAL NEAR KSMN AND KBTM IS GREATER TODAY...WITH
SMALL HAIL...PERIODS OF BRIEF HEAVY RAIN AND GUSTY WINDS POSSIBLE
WITH THE STRONGEST STORMS. SHOWER ACTIVITY...WITH SOME RUMBLES OF
THUNDER...COULD LINGER OVER THE HIGHER TERRAIN AFTER SUNSET.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&
$$
UPDATE...ZUMPFE
SHORT TERM...NOLTE/MEAD
LONG TERM....MEAD
AVIATION...NOLTE
000
FXUS65 KTFX 031807
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1205 PM MDT FRI JUL 3 2009
...UPDATE TO AVIATION...
UPDATE...BAND OF RAINSHOWERS WITH SOME WEAK SHORT-LIVED EMBEDDED
THUNDERSTORMS CURRENTLY MOVING ACROSS CENTRAL AND SOUTHWEST PARTS OF
THE FORECAST AREA. UPDATED CURRENT POP GRID TO BETTER MATCH RADAR
IMAGERY. ALSO SLIGHTLY INCREASED POP GRID FOR THIS AFTN FOR AREAS
SOUTH AND EAST OF GREAT FALLS. STORM INDICATORS FROM 12Z MODEL RUNS
STILL SHOWING FAVORABLE CONDITIONS FOR SCATTERED STRONG AND SOME
SEVERE THUNDERSTORMS OVER CENTRAL AND SOUTHWEST COUNTIES THIS
AFTN/EVE...WITH HAIL AND GUSTY OUTFLOW WINDS BEING THE PRIMARY
THREATS. STORMS SHOULD BE MORE ISOLATED AND LESS INTENSE ALONG THE
HILINE. STORM ACTIVITY WILL DISSIPATE TOWARD SUNSET.
WARANAUSKAS
.DISCUSSION...
FRIDAY THROUGH SUNDAY...ISOLATED SHOWERS AND THUNDERSTORMS ARE
PASSING OVER PARTS OF SOUTHWEST MONTANA THIS MORNING AS WEAK ENERGY
AND MOISTURE ROTATE ALONG A DAMPENING UPPER-LEVEL RIDGE. THERE WILL
BE A LULL IN ACTIVITY THROUGH EARLY THIS AFTERNOON...HOWEVER PACIFIC
MOISTURE WILL CONTINUE TO STREAM INTO THE REGION AS FLOW TURNS MORE
ZONAL. MOISTURE AND DIFFLUENT FLOW ALOFT WILL COMBINE WITH DIURNAL
INSTABILITY TO GENERATE SCATTERED THUNDERSTORMS THIS AFTERNOON WITH
POSSIBLE STRONG-TO-SEVERE STORMS OVER SOUTHWEST MONTANA AND EASTERN
PORTIONS OF THE FORECAST AREA...MAINLY ALONG AND EAST FROM A BZN-LWT
LINE HOWEVER STRONG STORMS ARE POSSIBLE FARTHER NORTH FROM GTF-HVR.
EVEN THOUGH ABUNDANT PAC MOISTURE IS AVAILABLE AND TEMPERATURES WILL
BE ABOVE AVERAGE...WEAK WIND SHEAR MAY NOT SUPPORT LARGE UPDRAFTS.
BEST LIFT WILL PRIMARILY BE OVER THE MOUNTAINS...BUT AS STORMS
PROPAGATE ONTO THE ADJACENT PLAINS THERE IS THE THREAT FOR LARGE
HAIL AND STRONG WINDS. THUNDERSTORM ACTIVITY WILL LIKELY DISSIPATE
AND MOVE OUT OF THE FORECAST AREA BY SUNSET.
MODELS CONTINUE TO INDICATE THAT THIS UNSETTLED PATTERN WILL PERSIST
THROUGH THE WEEKEND AS UPPER-LEVEL RIDGE BUILDS BACK OVER THE
REGION. MOISTURE AND EMBEDDED SHORTWAVES WILL PROMOTE AFTERNOON
SHOWER AND THUNDERSTORM DEVELOPMENT SATURDAY AND SUNDAY WITH NEAR
AVERAGE HIGH TEMPERATURES EXPECTED ON THE 4TH OF JULY AND ABOVE
AVERAGE TEMPERATURES ON SUNDAY. MLS
SUNDAY NIGHT THROUGH WEDNESDAY NIGHT...ECMWF AND GFS MODELS AGREE IN
STARTING THE PERIOD WITH AN UPPER RIDGE OVER THE FORECAST AREA.
THEREAFTER EXPECT SOUTHWEST FLOW ALOFT. THOSE TWO MODELS ALSO AGREE
ON ROTATING A WEATHER DISTURBANCE ALOFT THROUGH THE FORECAST AREA
MONDAY NIGHT. AHEAD OF THE DISTURBANCE MODELS DEVELOP GOOD LIFT AND
MOISTURE..MAINLY IN THE NORTH. SO INCREASED POPS FOR THAT AREA.
ECMWF AND GFS ALSO AGREE IN DEVELOPING AN UPPER LOW OVER THE PACIFIC
NORTHWEST ON WEDNESDAY WITH INCREASED MOISTURE FOR NORTHWEST
MONTANA. IN LINE WITH THIS INCREASED THE CHANCES OF PRECIPITATION
FOR THE ROCKY MOUNTAIN FRONT. INHERITED TREND OF COOLING HIGH
TEMPERATURES FROM MONDAY TO WEDNESDAY LOOKS FINE BUT STARTED OFF
WARMER ON MONDAY WITH HIGHS WELL ABOVE NORMAL. BY WEDNESDAY LOWERED
INHERITED HIGH TEMPERATURES ON THE ORDER OF 5 TO 10 DEGREES OVER THE
PLAINS. BLANK
THURSDAY THROUGH FRIDAY....MODELS REMAIN IN FAIR AGREEMENT DURING
THIS PERIOD...WITH SOME DIFFERENCES IN TIMING OF FEATURES. A
LONGWAVE UPPER LEVEL TROUGH PERSISTS ALONG THE WEST COAST RESULTING
IN A SOUTHWESTERLY FLOW ALOFT ACROSS THE FORECAST AREA. WEAK
DISTURBANCES IN THIS SOMEWHAT MOIST AND UNSTABLE FLOW WILL BE
RESPONSIBLE FOR PARTLY TO MOSTLY CLOUDY SKIES WITH ISOLATED SHOWERS
AND MAINLY AFTERNOON AND EVENING THUNDERSTORMS. SHOWERS AND
THUNDERSTORMS WILL BE MORE NUMEROUS OVER THE MOUNTAINS. THE WARMEST
AIR STAYS MOSTLY SOUTH AND EAST OF THE FORECAST AREA...HOWEVER
TEMPERATURES ARE EXPECTED TO CLIMB TO NEAR SEASONAL AVERAGES. EK
&&
.AVIATION...
UPDATED 1805Z.
VFR CONDITIONS WILL GENERALLY CONTINUE ACROSS SOUTHWEST...CENTRAL...
AND NORTH CENTRAL MONTANA THROUGH 18Z SATURDAY...UNLESS OTHERWISE
NOTED BELOW. A DISTURBANCE IN THE MOIST AND MODERATE WESTERLY FLOW
ALOFT WILL BRING ISOLATED THUNDERSTORMS WITH ASSOCIATED MVFR
CONDITIONS IN BRIEF HEAVY RAINFALL TO THE KLWT TERMINAL AREA THROUGH
AROUND 20Z. OTHERWISE...THE FLOW WILL BECOME INCREASINGLY UNSTABLE
THROUGH THE AFTERNOON FOR SCATTERED SHOWER AND THUNDERSTORM
DEVELOPMENT ACROSS MOST OF THE AREA. BRIEF HEAVY RAINFALL WITH
OCCASIONAL MVFR CONDITIONS...HAIL...AND GUSTY WINDS WILL BE THE MAIN
THREAT FROM THESE STORMS. THE GREATEST THREAT FOR LARGE HAIL AND
WIND GUSTS OF 50 KT OR MORE WILL BE SOUTH AND EAST OF A
KHVR-KLWT-KBZN LINE...MAINLY AFFECTING THE KLWT TERMINAL. THE
AIRMASS WILL GENERALLY STABILIZE FROM THE WEST BETWEEN 00Z AND 04Z
FOR DECREASING CLOUDS AND STORMS. ONLY THE KCTB TERMINAL WILL BE
EXEMPT FROM THUNDERSTORM ACTIVITY TODAY. COULSTON
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 80 54 83 55 / 20 30 20 20
CTB 77 48 80 50 / 20 20 20 20
HLN 85 55 86 56 / 30 30 20 20
BZN 86 52 85 53 / 40 40 30 30
WEY 73 42 71 42 / 50 50 40 40
DLN 78 50 78 52 / 40 50 30 30
HVR 83 52 83 52 / 20 20 20 30
LWT 76 51 77 52 / 40 40 30 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
WEATHER.GOV/GREATFALLS
| 
