[top]
000
FXUS63 KLOT 082127
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
327 PM CST SUN NOV 8 2009
.DISCUSSION...
327 PM CST
MAIN FORECAST FOCUS WILL CONTINUE TO BE ON POTENTIAL OF
RAIN...ESPECIALLY MONDAY NIGHT INTO EARLY TUESDAY.
A WEAK SURFACE COLD FRONT WHICH DROPPED INTO NORTHERN ILLINOIS
LAST NIGHT IS RETREATING BACK TO THE NORTHWARD AS A WARM FRONT AS
SURFACE WAVE LIFTS NORTHEAST ACROSS WESTERN IOWA. SURFACE PRESSURE
FALLS HAVE BEEN STEADILY STRENGTHENING THROUGH THE AFTERNOON
ACROSS SOUTHEAST MINNESOTA/WESTERN WISCONSIN...AND SHOULD CONTINUE
TO SEE THIS WARM FRONT LIFT THROUGH FAR NORTHEAST ILLINOIS THROUGH
REMAINDER OF AFTERNOON. SURFACE RIDGE AXIS IS SPRAWLED FROM WEST
TO EAST FROM LOWER MS RIVER VALLEY INTO THE SOUTHEAST US WITH
POCKET OF VERY DRY LOW LEVEL AIR SAMPLED BY 12Z RAOBS THIS MORNING.
THIS POCKET OF DRY LOW LEVEL AIR WILL ADVECT NORTHWARD THIS
EVENING WITH BETTER MOISTURE RETURN IN CLOSER PROXIMITY TO THE
SURFACE WAVE TRACKING WELL TO THE WEST/NORTHWEST OF THE AREA. HIGH
CLOUDINESS WILL INCREASE THROUGH THE NIGHT WHICH MAY LIMIT FOG
DEVELOPMENT TO THE EXTENT OF LAST NIGHT. WITH THE PROSPECTS OF MORE
SUBSTANTIAL BREAKS IN MID/HIGH CLOUDINESS FOR EASTERN PORTIONS OF
THE FORECAST AREA OVERNIGHT...DID INCLUDE PATCHY FOG MENTION FOR
FAR NORTHEAST ILLINOIS/NORTHWEST INDIANA. IN TERMS OF LOWS
TONIGHT...DEW POINTS HAVE ADVECTED/MIX DOWN INTO THE LOWER AND MID
50S AND WHILE SHOULD SEE SOME DIURNAL DROP IN DEW PTS THIS
EVENING...EXPECTING DEW PTS TOO REMAIN IN THE UPPER 40S OR LOWER
50S. THUS SHOULD SEE AN UNSEASONABLY MILD NIGHT WITH LOWS IN THE
LOWER TO MID 50S.
SURFACE WAVE WILL TRACK INTO SOUTHWEST ONTARIO MONDAY AFTERNOON IN
RESPONSE TO BROAD UPPER LEVEL SHORT WAVE TROUGH MOVING INTO THE
WESTERN GREAT LAKES REGION. THIS WILL ALLOW COLD FRONT TO PUSH
BACK SOUTHWARD ACROSS NORTHERN ILLINOIS TOMORROW AFTERNOON AND
QUESTION IS AVAILABILITY OF LOW LEVEL MOISTURE FOR ANY CHANCES OF
RAIN SHOWERS ASSOCIATED WITH THE FRONT. LOW LEVEL MOISTURE AXIS
SHOULD BECOME PROGRESSIVELY MORE NARROW AS SFC WAVE MOVES INTO
QUEBEC TOMORROW AFTERNOON WITH LITTLE MOVEMENT OF SFC HIGH ACROSS
THE SOUTHEAST. WITH FRONTAL PASSAGE NOW EXPECTED ACROSS FAR
NORTHERN ILLINOIS EARLY IN THE AFTERNOON...DID REMOVE PRECIP
MENTION ACROSS FAR NORTHERN ILLINOIS AND TRIED TO CONFINE MENTION
OF LOW CHANCE POPS FOR RAIN SHOWERS CLOSER TO THE FRONT MONDAY
AFTERNOON. STILL MAINTAINED IDEA OF PREVIOUS FORECAST IN
INCREASING POPS MONDAY NIGHT AS ANOTHER REINFORCING UPPER LEVEL
SHORT WAVE ACTS TO SHARPEN LOW/MID LEVEL FRONTOGENESIS ACROSS THE
AREA WITH BAROCLINIC ZONE DRAPED ACROSS WFO LOT CWA. POTENTIAL FOR
ELEVATED THUNDER MAY BE BETTER JUST SOUTH OF WFO LOT FORECAST
AREA MONDAY NIGHT...BUT FOR REASONS CITED IN PREVIOUS AFD OF UPPER
JET DYNAMICS/FRONTOGENESIS FORCING CANNOT RULE OUT SOME ISOLD
THUNDER.
THIS SECONDARY UPPER TROUGH AXIS IS EXPECTED TO TRACK THROUGH
NORTHERN ILLINOIS EARLY TUESDAY AFTERNOON WHICH SHOULD END CHANCES
OF SHOWERS FROM NORTHWEST TO SOUTHEAST. COOLER TEMPS THEN IN STORE
FOR WEDNESDAY AS SFC HIGH SETTLES INTO THE WESTERN GREAT LAKES
REGION...WITH MAIN MODEL DIFFERENCES BY THIS TIME CONCENTRATED
WELL TO THE SOUTHEAST MORE OVER SOUTHEAST CONUS WITH SFC
CYCLOGENESIS. TEMPS TO MODERATE TOWARD END OF WEEK AS MEDIUM RANGE
MODELS IN FAIR AGREEMENT ON UPPER TROUGHING ACROSS WESTERN CONUS.
DID HAVE TO MAINTAIN BROADBRUSH SLIGHT CHANCE POPS FOR RAIN
SHOWERS FOR THE FRI-SUN PERIOD WITH 12Z ECMWF/GFS BEGINNING TO
COME INTO A BIT BETTER AGREEMENT WITH MORE VIGOROUS SHORT WAVE
EJECTING INTO THE REGION DURING THIS TIME PERIOD...ALTHOUGH WITH
EXPECTED TIMING DISCREPANCIES AT THIS FORECAST DISTANCE.
MARSILI
&&
.AVIATION...
1145 AM CST
1800 UTC TAFS...DIFFUSE SFC WARM FRONT NOW ORIENTED W-E GENLY
ALONG I-80 CORRIDOR. THIS BOUNDARY WILL CONTINUE TO PUSH NWD
ACROSS TERMINAL AREA...AND BE N OF REGION BY 19Z. SATLT IMAGERY
SHOWS A PATCH OF MID/HIGH LVL CLOUDINESS OVR NERN IL...AT LEADING
EDGE OF STRONGER WARM ADVECTION PUNCHING ACROSS UPR MS VLY IN
ADVANCE OF A LOW PRESSURE AREA OVR OMAHA AREA AT 17Z. THIS
CLOUDINESS WILL LIFT NEWD OUT OF AREA BY 19Z. COMBINATION OF
INCREASING INSOLATION AND PUSH OF WARM AIR WILL ALLOW LLVL MIXED
LYR INCR TO ARND 1800 FT BY MID AFTN. AS A RESULT...SSELY WINDS
ARND 10 KT WILL BCM DUE SLY AND INCR A BIT...WITH GUSTS TO NR 20
KTS. WIND SPEED TO SUBSIDE AGAIN BY 23Z AS SFC COOLS WITH SUNSET.
EXPECT CONDITIONS TO REMAIN VFR CLR THROUGH THIS EVENING.
AS COLD FRONT APCHS AREA LATE TONIGHT-MONDAY MORNING...WINDS TO
BCM MORE SWLY WITH SPEEDS DROPPING TO 5-10 KT RANGE. GIVEN HIGH
DEW POINT AIR IN PLACE AHEAD OF THIS FRONT...SUSPECT HAZE/FOG WILL
DVLP AGAIN OVERNIGHT. HOWEVER...DUE TO INCR IN MID/HIGH LVL
CLOUDINESS OVERNIGHT...VIS IS NOT EXPECTED TO DROP BLO MVFR CATEGORY.
COLD FROPA NOT EXPECTED UNTIL AFTER 18Z...XCP OVR N CNTRL IL WHERE
WINDS WILL LIKELY BE IN THE PROCESS OF SHIFTING FROM SW-N ALREADY
BY END OF FCST PERIOD.
MERZLOCK
&&
.MARINE...
1129 AM CST
A FRONTAL TROUGH LYING ACROSS THE SOUTHERN PORTION OF LAKE
MICHIGAN WILL CONTINUE TO LIFT NORTHWARD ACROSS THE LAKE LATE THIS
AFTERNOON AND EVENING...AS A LOW PRESSURE LIFTS NORTHEASTWARD
FROM THE CENTRAL PLAINS TO SOUTHWEST MINNESOTA BY THIS EVENING.
THIS LOW WILL CONTINUE ON ACROSS THE SOO TONIGHT...AND TO WESTERN
QUEBEC ON MONDAY. A TRAILING COLD FRONT WILL PUSH SOUTHWARD ACROSS
LAKE MICHIGAN ON MONDAY...SHIFTING WINDS INTO THE NORTH AND
NORTHEAST. AS A HIGH PRESSURE BUILDS FROM THE NORTHERN PLAINS TO
THE UPPER GREAT LAKES MONDAY NIGHT INTO TUESDAY...A COMBINATION OF
INCREASING PRESSURE RISES AND SUSTAINED COLD AIR FLOW WILL RESULT
IN WINDS INCREASING INTO 15 TO 25 KNOT RANGE.
A FULL LENGTH NORTH NORTHEASTERLY FETCH WILL LEAD TO WAVES
BUILDING TO AROUND 6 FEET ACROSS THE SOUTH END OF THE LAKE MONDAY
NIGHT.
MERZLOCK
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
[top]
000
FXUS63 KILX 082046
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
246 PM CST SUN NOV 8 2009
.DISCUSSION...
ISSUED 224 PM CST SUN NOV 8 2009
HIGH SFC PRESSURE...SOUTHERLY FLOW AND MOSTLY SUNNY SKIES FOR
CENTRAL ILLINOIS RESULTED IN A RATHER UNSEASONABLE DAY. A FRONTAL
BOUNDARY...LIFTING NORTH AS A WARM FRONT HAS PUSHED NORTH OF THE
ILX FA...AS THE ASSOCIATED LOW GETS READY TO MOVE OUT AND BRING
THE CWA THE FIRST ROUND OF PRECIP FOR THE FIRST PORTION OF THE
WEEK. THIS IS THE FIRST MAJOR ISSUE FOR THE FORECAST...WITH THE
SECOND BEING A SYSTEM FOR NEXT WEEKEND. THE FORECAST WAS MOSTLY A
BLEND...AND GIVEN THE GOING ISSUES WITH THE HANDLING OF MOISTURE
OFF OF THE GULF AND HURRICANE IDA...KEPT IT RATHER CONSERVATIVE IN
THE LONG RUN.
SHORT TERM...TONIGHT THROUGH TUESDAY...
LOW MOVING OUT OF THE WEST TONIGHT AND INTO TOMORROW...BRINGING A
SHOT OF RAIN TO THE NW TOMORROW LATE AFTERNOON...SPREADING SE AS
THE EVENING GOES ON. BIG QUESTION MARK REMAINS THE HANDLING OF
MOISTURE FLOW OFF OF THE GULF COAST WITH HURRICANE IDA. MODELS ARE
BRINGING UP A BIT OF MOISTURE AHEAD OF THE FRONTAL BOUNDARY IN
BETWEEN TO RATHER SUBSTANTIAL HIGHS. CURRENTLY...THE MODELS HAVE A
BIT OF AN ENHANCED WAVE IN THE H5 INITIALIZATION THAT COULD BE DUE
TO A BIT OF CONVECTION IN THE AREA OVER WRN TX. WORRIED THAT THIS
MAY BE EFFECTING THE TRACK SOMEWHAT...AND THAT THE MOISTURE
ADVERTISED COULD CHANGE A BIT. THAT BEING SAID...THERE IS WARMER
AND MOISTER AIR MAKING ITS WAY INTO THE MIDWEST NOW TO COLLIDE
WITH THE SYSTEM...JUST KEEPING THE QPFS RATHER LOW FOR NOW UNTIL A
LITTLE MORE AGREEMENT IS SEEN IN THE MODELS.
LONG TERM...WEDNESDAY THROUGH SUNDAY...
GFS AND ECMWF BOTH PULLING A WAVE ACROSS THE MIDWEST NEXT
SATURDAY...THOUGH DIFFERING CONSIDERABLY ON THE DEVELOPMENT AND
DEPTH OF THE LOW. PRECIP SHOWING UP SAT NIGHT/SUN...AND WILL KEEP
THE LOW 30S TO REFLECT THAT... BUT WITH THE SHEER VOLUME OF
VARIABLES...WILL TEMPER IT THERE. OTHER THAN THAT...TEMPS SLOWLY
FALLING IN THE MOS FROM HERE TO THEN...BUT QUITE POSSIBLY WITH
ERROR FROM THE MOS AND ITS CLIMATE. ON THE WARMER SIDE THROUGH THE
EXTENDED.
HJS
&&
.AVIATION...
ISSUED 1119 AM CST SUN NOV 8 2009
NO MAJOR CONCERNS FOR THE FIRST HALF OF THE TAF PERIOD...ASIDE
FROM SOME GUSTY WINDS TO NEAR 20 KNOTS THIS AFTERNOON. BEYOND
THAT...WINDS EXPECTED TO REMAIN HIGH ENOUGH OVERNIGHT TO PRECLUDE
PATCHY DENSE FOG FROM FORMING SIMILAR TO THIS MORNING...HOWEVER
WILL LIKELY SEE VISIBILITIES OF 3-4SM FOR A FEW HOURS BETWEEN
ABOUT 09-14Z. A COLD FRONT WILL APPROACH FROM THE NORTHWEST TOWARD
THE END OF THE FORECAST PERIOD...AND WINDS WILL BE SWINGING AROUND
TO THE WEST AT KPIA/KSPI AS THE TAF PERIOD ENDS. CURRENTLY AM
EXPECTING A DRY FRONTAL PASSAGE...AND CEILINGS ARE EXPECTED TO
REMAIN IN THE VFR RANGE.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
000
FXUS63 KLOT 081802
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1202 PM CST SUN NOV 8 2009
.DISCUSSION...
1112 AM CST
NO SIGNIFICANT CHANGES TO FORECAST PLANNED THIS MORNING.
MSAS DATA INDICATING AREA OF EXPANDING SFC PRESSURE FALLS FROM
EASTERN NEBRASKA INTO NORTHERN IOWA IN RESPONSE TO FRONTAL
BOUNDARY WHICH PASSED ACROSS NORTHERN ILLINOIS LAST NIGHT
BEGINNING TO LIFT BACK NORTHWARD AS A WARM FRONT. THIS WARM ADVECTION
NORTH OF THE FRONT HAS PROMOTED A DECK OF MID/HIGH LEVEL CLOUDS
WITH SOME CONVECTIVE NATURE DUE TO PRESENCE OF STEEP ELEVATED
LAPSE RATES...WITH VIRGA NOTED FROM THESE HIGHER CLOUDS. SATELLITE
TRENDS SUGGEST THIS AREA OF MID/HIGH CLOUDS WILL WORK EAST OF THE
FORECAST AREA THIS AFTERNOON LEAVING MOSTLY SUNNY SKIES. MIXING UP
TO ABOUT 900 HPA FROM ACARS SOUNDINGS COMBINED WITH A FEW MORE
DEGREES OF WARMING TO ACCOUNT FOR LOW LEVEL WARM ADVECTION TODAY
DOES YIELD HIGHS IN THE BALLPARK OF CURRENT FORECAST HIGHS...SO
HAVE MADE NO CHANGES WITH AFTERNOON HIGHS IN THE LOWER TO MID 70S.
UPDATED GRIDS HAVE BEEN SENT TO MAINLY ACCOUNT FOR PATCHY MID/HIGH
CLOUDS AND EARLY MORNING FOG MENTION...BUT NO UPDATED TEXT
FORECAST WILL BE SENT WITH FORECAST IN GOOD SHAPE.
MARSILI
&&
.AVIATION...
1145 AM CST
1800 UTC TAFS...DIFFUSE SFC WARM FRONT NOW ORIENTED W-E GENLY
ALONG I-80 CORRIDOR. THIS BOUNDARY WILL CONTINUE TO PUSH NWD
ACROSS TERMINAL AREA...AND BE N OF REGION BY 19Z. SATLT IMAGERY
SHOWS A PATCH OF MID/HIGH LVL CLOUDINESS OVR NERN IL...AT LEADING
EDGE OF STRONGER WARM ADVECTION PUNCHING ACROSS UPR MS VLY IN
ADVANCE OF A LOW PRESSURE AREA OVR OMAHA AREA AT 17Z. THIS
CLOUDINESS WILL LIFT NEWD OUT OF AREA BY 19Z. COMBINATION OF
INCREASING INSOLATION AND PUSH OF WARM AIR WILL ALLOW LLVL MIXED
LYR INCR TO ARND 1800 FT BY MID AFTN. AS A RESULT...SSELY WINDS
ARND 10 KT WILL BCM DUE SLY AND INCR A BIT...WITH GUSTS TO NR 20
KTS. WIND SPEED TO SUBSIDE AGAIN BY 23Z AS SFC COOLS WITH SUNSET.
EXPECT CONDITIONS TO REMAIN VFR CLR THROUGH THIS EVENING.
AS COLD FRONT APCHS AREA LATE TONIGHT-MONDAY MORNING...WINDS TO
BCM MORE SWLY WITH SPEEDS DROPPING TO 5-10 KT RANGE. GIVEN HIGH
DEW POINT AIR IN PLACE AHEAD OF THIS FRONT...SUSPECT HAZE/FOG WILL
DVLP AGAIN OVERNIGHT. HOWEVER...DUE TO INCR IN MID/HIGH LVL
CLOUDINESS OVERNIGHT...VIS IS NOT EXPECTED TO DROP BLO MVFR CATEGORY.
COLD FROPA NOT EXPECTED UNTIL AFTER 18Z...XCP OVR N CNTRL IL WHERE
WINDS WILL LIKELY BE IN THE PROCESS OF SHIFTING FROM SW-N ALREADY
BY END OF FCST PERIOD.
MERZLOCK
&&
.MARINE...
1129 AM CST
A FRONTAL TROUGH LYING ACROSS THE SOUTHERN PORTION OF LAKE
MICHIGAN WILL CONTINUE TO LIFT NORTHWARD ACROSS THE LAKE LATE THIS
AFTERNOON AND EVENING...AS A LOW PRESSURE LIFTS NORTHEASTWARD
FROM THE CENTRAL PLAINS TO SOUTHWEST MINNESOTA BY THIS EVENING.
THIS LOW WILL CONTINUE ON ACROSS THE SOO TONIGHT...AND TO WESTERN
QUEBEC ON MONDAY. A TRAILING COLD FRONT WILL PUSH SOUTHWARD ACROSS
LAKE MICHIGAN ON MONDAY...SHIFTING WINDS INTO THE NORTH AND
NORTHEAST. AS A HIGH PRESSURE BUILDS FROM THE NORTHERN PLAINS TO
THE UPPER GREAT LAKES MONDAY NIGHT INTO TUESDAY...A COMBINATION OF
INCREASING PRESSURE RISES AND SUSTAINED COLD AIR FLOW WILL RESULT
IN WINDS INCREASING INTO 15 TO 25 KNOT RANGE.
A FULL LENGTH NORTH NORTHEASTERLY FETCH WILL LEAD TO WAVES
BUILDING TO AROUND 6 FEET ACROSS THE SOUTH END OF THE LAKE MONDAY
NIGHT.
MERZLOCK
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
000
FXUS63 KILX 081720
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1120 AM CST SUN NOV 8 2009
.DISCUSSION...
ISSUED 944 AM CST SUN NOV 8 2009
EARLIER FOG HAS BURNED OFF...BUT SKIES STILL A BIT HAZY IN THE
ILLINOIS RIVER VALLEY AROUND PEORIA. SOME SCATTERED MID-LEVEL
CLOUDS HAVE BEEN PUSHING ACROSS MAINLY THE NORTHERN THIRD OF THE
CWA THIS MORNING. TEMPERATURES ARE ALREADY QUITE SIMILAR TO THIS
TIME 24 HOURS AGO...AND 12Z MODEL GUIDANCE DOES NOT SHOW ANY GOOD
REASON WHY TRENDS WILL BE ANY DIFFERENT THE REMAINDER OF THE DAY.
CURRENT FORECAST LOOKS GOOD...AND NO UPDATE IS NEEDED AT THIS TIME.
GEELHART
&&
.AVIATION...
ISSUED 1119 AM CST SUN NOV 8 2009
NO MAJOR CONCERNS FOR THE FIRST HALF OF THE TAF PERIOD...ASIDE
FROM SOME GUSTY WINDS TO NEAR 20 KNOTS THIS AFTERNOON. BEYOND
THAT...WINDS EXPECTED TO REMAIN HIGH ENOUGH OVERNIGHT TO PRECLUDE
PATCHY DENSE FOG FROM FORMING SIMILAR TO THIS MORNING...HOWEVER
WILL LIKELY SEE VISIBILITIES OF 3-4SM FOR A FEW HOURS BETWEEN
ABOUT 09-14Z. A COLD FRONT WILL APPROACH FROM THE NORTHWEST TOWARD
THE END OF THE FORECAST PERIOD...AND WINDS WILL BE SWINGING AROUND
TO THE WEST AT KPIA/KSPI AS THE TAF PERIOD ENDS. CURRENTLY AM
EXPECTING A DRY FRONTAL PASSAGE...AND CEILINGS ARE EXPECTED TO
REMAIN IN THE VFR RANGE.
GEELHART
&&
.PREV DISCUSSION...
ISSUED 325 AM CST SUN NOV 8 2009
FORECAST CHALLENGE IS HOW WARM IT GETS TODAY AND MON AS MET/MAV
GUIDANCE CONTINUES TO GET WARMER. THEN ADDRESSING NEXT CHANCE OF
RAIN SHOWERS EARLY IN THE WORK WEEK AS A COLD FRONT MOVES INTO
IL. 00Z MODELS FAIRLY SIMILAR THROUGH MON NIGHT...THEN DIVERGE
TUE WITH HOW QUICKLY WX SYSTEM EXITS IL. MODELS HAD BEEN TRENDING
SLOWER LAST FEW DAYS WITH COLD FRONT EARLY THIS WORK WEEK. THOUGH
SUSPECT OF NAM/S SLOWER SHORT WAVE MOVING INTO MO BY SUNSET TUE
AND KEEPING SOME LIGHT QPF INTO AREAS SW OF LINCOLN INTO TUE
NIGHT. DID NOT BUY INTO THIS MODEL SOLUTION BUT DID GO SLOWER WITH
WX SYSTEM LATER MON/TUE.
SHORT TERM...TODAY THROUGH TUESDAY NIGHT.
09Z/3 AM SURFACE MAP SHOWS A FRONTAL BOUNDARY OVER THE SOUTHERN
GREAT LAKES INTO NORTHERN IL NEAR GALESBURG TO NEAR THE IA/MO
BORDER AND NORTHERN KS TO 1005 MB LOW PRESSURE IN EASTERN CO THAT
IS DEEPENING. FAIR SKIES OVER IL WITH PASSING THIN CIRRUS
ESPECIALLY FROM I-72 NORTH. PATCHY SHALLOW GROUND FOG DEVELOPING
EARLY THIS MORNING OVER CENTRAL AND NORTHERN IL WITH VISIBILITIES
DOWN TO 2 TO 5 MILES FROM LINCOLN NORTH. PATCHY FOG SHOULD LIFT
BY MID MORNING. ALOFT A STRONG SUBTROPICAL 588 DM 500 MB RIDGE WAS
OVER THE SE STATES AND INTO THE MID MS VALLEY WHILE UPPER LEVEL
TROF OVER THE ROCKIES.
MODELS EJECT LOW PRESSURE FROM EASTERN CO NE INTO WESTERN IA BY
SUNSET LIFTING THE FRONT IN NORTHERN IL BACK NORTH WITH INCREASING
SOUTHERLY FLOW OVER CENTRAL IL. AMPLE SUNSHINE EXPECTED AGAIN WITH
PASSING CIRRUS CLOUDS ESPECIALLY I-74 NORTH. HIGHS TODAY SHOULD BE
SIMILAR TO YESTERDAY IN THE LOW TO MID 70S WHICH IS THE WARMEST
TEMPS OVER IL IN SIX WEEKS SINCE SEP 27. STILL A BIT SHY OF RECORD
HIGHS IN THE UPPER 70S TO AROUND 80F.
LOW PRESSURE WEAKENS AS IT LIFTS NE OF WI BY DAWN MON WHILE
BRINGING A COLD FRONT SE TOWARD THE IL/IA BORDER. STILL DRY
TONIGHT ACROSS IL THOUGH HIGH CLOUDS WILL BE INCREASING OVER THE
IL RIVER VALLEY. LOWS IN THE LOWER 50S THOUGH A BIT COOLER ALONG
THE WABASH RIVER IN SE IL WHERE SOME UPPER 40S POSSIBLE. STRONG
UPPER LEVEL RIDGE NEAR IL WILL SLOW THE COLD FRONT WHICH WEAKENS
TOO AS IT MOVES INTO CENTRAL IL. SHOWERS ARE POST FRONTAL AND
MAINLY NW OF THE IL RIVER MON AFTERNOON. CLOUDS TO CONTINUE TO
INCREASE OVER CENTRAL IL NW OF I-70 MON. WARMED HIGHS UP A FEW
DEGREES MON TOO WITH MID 60S NW OF THE IL RIVER AND UPPER 60S AND
LOWER 70S SE OF THE IL RIVER WITH WARMEST READINGS IN SE IL WHERE
MORE SUNSHINE.
INCREASING CHANCES OF SHOWERS MON NIGHT OVER CENTRAL IL WITH
LIKELY CHANCES FROM PEORIA NORTH WHERE SOME UPPER LEVEL LIFT
PRESENT WHILE SE IL SHOULD REMAIN DRY MON NIGHT CLOSER TO UPPER
LEVEL RIDGE. COLD FRONT WEAKENS FURTHER AS IT MOVES TOWARD THE
OHIO RIVER TUE AFTERNOON WITH CHANCES OF SHOWERS TUE OVER CENTRAL
AND ESPECIALLY EASTERN IL. MOISTURE FROM HURRICANE IDA IN THE GULF
OF MEXICO TO STAY SE OF KY. BUMPED UP HIGHS TUE AS WELL INTO THE
UPPER 50S NW IL AND MID 60S SE IL. HIGH PRESSURE OVER THE PACIFIC
STATES SETTLES INTO THE WESTERN GREAT LAKES BY DAWN WED AND TO
DECREASE CLOUDS DURING TUE NIGHT AND COOLER LOWS IN THE 30S WHICH
IS ACTUALLY CLOSER TO NORMAL FOR MID NOV.
LONG TERM...WEDNESDAY THROUGH SATURDAY.
QUIET WEATHER EXPECTED DURING THIS TIME AS HIGH PRESSURE SLIPS OFF
TO THE EAST WITH RETURN SOUTHERLY FLOW SETTING BACK UP AND KEEPING
TEMPS ABOVE NORMAL THOUGH NOT NEARLY AS WARM AS THIS WEEKEND. THE
NEXT COLD FRONT TO MOVE TOWARD IL LATE THIS WEEK BUT ITS MOISTURE
APPEARS TO STAY NORTH OF CENTRAL/SE IL.
HUETTL
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
000
FXUS63 KLOT 081713
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1113 AM CST SUN NOV 8 2009
.DISCUSSION...
1112 AM CST
NO SIGNIFICANT CHANGES TO FORECAST PLANNED THIS MORNING.
MSAS DATA INDICATING AREA OF EXPANDING SFC PRESSURE FALLS FROM
EASTERN NEBRASKA INTO NORTHERN IOWA IN RESPONSE TO FRONTAL
BOUNDARY WHICH PASSED ACROSS NORTHERN ILLINOIS LAST NIGHT
BEGINNING TO LIFT BACK NORTHWARD AS A WARM FRONT. THIS WARM ADVECTION
NORTH OF THE FRONT HAS PROMOTED A DECK OF MID/HIGH LEVEL CLOUDS
WITH SOME CONVECTIVE NATURE DUE TO PRESENCE OF STEEP ELEVATED
LAPSE RATES...WITH VIRGA NOTED FROM THESE HIGHER CLOUDS. SATELLITE
TRENDS SUGGEST THIS AREA OF MID/HIGH CLOUDS WILL WORK EAST OF THE
FORECAST AREA THIS AFTERNOON LEAVING MOSTLY SUNNY SKIES. MIXING UP
TO ABOUT 900 HPA FROM ACARS SOUNDINGS COMBINED WITH A FEW MORE
DEGREES OF WARMING TO ACCOUNT FOR LOW LEVEL WARM ADVECTION TODAY
DOES YIELD HIGHS IN THE BALLPARK OF CURRENT FORECAST HIGHS...SO
HAVE MADE NO CHANGES WITH AFTERNOON HIGHS IN THE LOWER TO MID 70S.
UPDATED GRIDS HAVE BEEN SENT TO MAINLY ACCOUNT FOR PATCHY MID/HIGH
CLOUDS AND EARLY MORNING FOG MENTION...BUT NO UPDATED TEXT
FORECAST WILL BE SENT WITH FORECAST IN GOOD SHAPE.
MARSILI
&&
.PREV DISCUSSION...
330 AM CST
CERTAINLY SEEMS A LOT MORE LIKE LATE SEPTEMBER THAN THE 2ND WEEK
OF NOVEMBER WITH A HURRICANE MOVING INTO THE GULF OF MEXICO WHILE
THE CHICAGO AREA BASKS IN 70 DEGREE WARMTH. THE UNSEASONABLY WARM
TEMPERATURES ARE CERTAINLY A FAIRLY DRAMATIC CHANGE OF PACE AFTER
THE DAMP...DARK...DREARY...AND DISMALLY COLD OCTOBER.
WEAK HIGH PRESSURE OVER WISCONSIN HAS ALLOWED A FRONT TO SAG
SOUTHWARD INTO NORTHERN ILLINOIS THIS MORNING...HOWEVER LATE
EVENING ACARS SOUNDING FROM RFD SHOW A VERY SHARP SURFACE
INVERSION BENEATH THE UNSEASONABLY WARM TEMPS JUST ABOVE THE
GROUND. ALREADY SEEING SOME RATHER IMPRESSIVE 3HR PRESSURE FALLS
(FOR THIS TIME OF DAY) OVER NEBRASKA AS LOW PRESSURE OVER COLORADO
SITS POISED TO MAKE A RUN NORTHEAST INTO THE UPPER MISSISSIPPI
VALLEY. FRONT CURRENTLY DRAPED ACROSS THE CWA SHOULD LIFT
NORTHWARD LATER THIS MORNING SETTING THE STAGE FOR ANOTHER
UNSEASONABLY WARM NOVEMBER AFTERNOON WITH HIGHS PROBABLY REACHING
THE LOWER 70S MOST AREAS. RECORD HIGH FOR CHICAGO TODAY IS 73
WHICH WE COULD BE WITHIN REASONABLE STRIKING DISTANCE. SOUTHERLY
WINDS SHOULD GRADUALLY FRESHEN UP AND WILL LIKELY SET THE STAGE
TONIGHT FOR A REPEAT OF FRIDAY NIGHT`S MILD CONDITIONS.
ANOTHER WEAK FRONT WILL MOVE INTO THE AREA DURING THE DAY
MONDAY...BUT WITH SUCH A WARM START TO THE DAY STILL ANTICIPATE
HIGHS TO CLIMB INTO THE 60S MOST AREAS PRIOR TO FROPA. WHILE SOME
SCT SHOWERS ARE POSSIBLE AS FRONT ARRIVES MONDAY PM...BETTER
SHOWER CHANCES SHOULD COME MONDAY NIGHT AS LOW LEVEL FRONT
SHARPENS UP IN ADVANCE OF APPROACHING SHORTWAVE. MID LEVEL LAPSE
RATES PROGGED TO BE FAIRLY STEEP IN ADVANCE OF THIS SYSTEM WITH A
COUPLE/FEW HUNDRED JOULES OF ELEVATED CAPE PRESENT IN FORECAST
SOUNDINGS FROM BOTH THE GFS AND WRF-NMM. WHILE CERTAINLY NOT THE
MOST DYNAMIC OF SYSTEMS...PRESENCE OF STEEPER LAPSE RATES/WEAK
CAPE IN CONJUNCTION WITH STRENGTHENING LOW LEVEL FRONTOGENESIS AND
PROXIMITY OF RIGHT ENTRANCE REGION OF STRENGTHENING UPPER LEVEL
JET WOULD SUGGEST AT LEAST A MARGINAL THUNDER POTENTIAL AND HAVE
INTRODUCED SMALL THUNDER PROBS INTO GRIDS MONDAY NIGHT AND BUMPED
POPS UP TO LIKELY.
GENERAL TREND IN THE MODELS THE PAST COUPLE RUNS HAS BEEN TO SLOW
DOWN THE ENDING OF THE PRECIP TUESDAY MORNING...AND HAVE BEGUN TO
REFLECT THIS TREND IN OUR GRIDS BY INTRODUCING CHANCE POPS OVER
MUCH OF THE AREA. IF THE CURRENT TREND IN THE MODELS CONTINUES
THEN POPS WILL NEED TO BE UPPER CONSIDERABLY MORE...PARTICULARLY
OVER OUR SE COUNTIES TUESDAY MORNING.
SHOULD SEE A COOL DOWN TO NEAR AVERAGE TEMPERATURES TUES NIGHT
INTO WED NIGHT BEHIND THE COLD FRONT. AIR MASS IN THE WAKE OF THE
FRONT IS OF PACIFIC ORIGINS WHICH SHOULD KEEP THE COOL DOWN FAIRLY
MODEST. HIGH PRESSURE WILL SCOOT OFF TO THE EAST DURING THE DAY
THURSDAY WITH RETURN SOUTHERLY FLOW RESULTING IN A RETURN TO ABOVE
AVERAGE TEMPERATURES AGAIN BY THURSDAY INTO FRIDAY.
IZZI
&&
.AVIATION...
516 AM CDT
1200 UTC TAFS...MAIN WEATHER CONCERNS TO BE WITHIN THE FIRST FEW
HOURS OF TAF ISSUANCE AS SOME FOG HAS DEVELOPED ACROSS THE REGION
IN THE HEART OF THE CALM WINDS DUE TO A STALLED OUT FRONT. THE
THICKEST FOG IS FURTHER SOUTH AND EAST WHERE VIS HAS DROPPED TO
LESS THAN A QUARTER MILE. AS A LOW PRESSURE SYSTEM LIFTS NORTH
ACROSS THE PLAINS TODAY...THIS POCKET OF LOWER VISIBILITIES SHOULD
ALSO COME NORTH AND IS EXPECTED TO DIMINISH AROUND 15Z AS THE
WINDS START TO PICK UP. WIND DIRECTION WILL ALSO BE TRICKY THIS
MORNING WITH THE FRONT IN THE VICINITY. SHOULD START OUT LIGHT AND
VARIABLE AND GO EAST...TO SOUTHEAST...TO SOUTH AND BECOME GUSTY BY
AFTERNOON. WHILE THE GUSTS WILL SHUT OFF AROUND SUNSET...A DECENT
PRESSURE GRADIENT WILL PERSIST OVERNIGHT SUNDAY INTO MONDAY
MORNING AND SHOULD BE ABLE TO REMAIN SUSTAINED AROUND 10KT OUT OF
THE SOUTHWEST. NO PRECIPITATION IS EXPECTED THROUGHOUT THE TAF
PERIOD WITH ONLY SOME PASSING UPPER CLOUDS.
EXPECT ANY SUB-VFR CONDITIONS TO IMPROVE TO VFR LATER THIS MORNING.
HALBACH
&&
.MARINE...
231 AM CST
REMNANT COLD FRONT CURRENTLY ACROSS THE FAR SOUTHERN PORTION OF
LAKE MICHIGAN IS EXPECTED TO TRANSITION TO A WARM FRONT TODAY AS A
LOW PRESSURE SYSTEM DEVELOPING IN EASTERN COLORADO TRACKS NORTH
THROUGH THE PLAINS. WITH THE WARMER AIR MOVING OVER THE
COOLER...STABLE MARINE LAYER IT WILL BE TOUGH FOR MANY GUSTS TO
MAKE IT DOWN TO THE SFC OF THE LAKE ON SUNDAY GIVEN THE SOUTHERLY
WINDS. HOWEVER...AS THIS LOW TRACKS THROUGH THE GREAT LAKES IT
WILL PULL A COLD FRONT ACROSS THE LAKE ON MONDAY. BEHIND THIS
FRONT...AN AREA OF HIGH PRESSURE WILL BE BUILDING IN FROM THE WEST
AND SHOULD SET UP A DECENT PRESSURE GRADIENT ACROSS THE LAKE
MONDAY NIGHT INTO EARLY TUESDAY. GIVEN THE PERSISTENT
NORTH TO NORTHEAST WINDS INTO TUESDAY...SHOULD SEE SOME DECENT
WAVES DEVELOPING ACROSS THE SOUTHERN RIM OF LAKE MICHIGAN WHICH
MAY PROMPT THE ISSUANCE OF A SMALL CRAFT ADVISORY. FOR NOW...BEING
THAT THE WINDS APPEAR MARGINAL AROUND 20KTS AND IT BEING OVER 36
HOURS AWAY...WILL HOLD OFF ON ISSUING ANYTHING.
AFTER THIS...HIGH PRESSURE APPEARS TO TAKE OVER THE GREAT LAKES
REGION THROUGH THE REST OF THE WEEK UNTIL IT SHIFTS OFF TOWARD THE
MID-ATLANTIC REGION AND THE SOUTHERLIES BUILD IN AGAIN.
HALBACH
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
000
FXUS63 KILX 081544
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
944 AM CST SUN NOV 8 2009
.DISCUSSION...
ISSUED 944 AM CST SUN NOV 8 2009
EARLIER FOG HAS BURNED OFF...BUT SKIES STILL A BIT HAZY IN THE
ILLINOIS RIVER VALLEY AROUND PEORIA. SOME SCATTERED MID-LEVEL
CLOUDS HAVE BEEN PUSHING ACROSS MAINLY THE NORTHERN THIRD OF THE
CWA THIS MORNING. TEMPERATURES ARE ALREADY QUITE SIMILAR TO THIS
TIME 24 HOURS AGO...AND 12Z MODEL GUIDANCE DOES NOT SHOW ANY GOOD
REASON WHY TRENDS WILL BE ANY DIFFERENT THE REMAINDER OF THE DAY.
CURRENT FORECAST LOOKS GOOD...AND NO UPDATE IS NEEDED AT THIS TIME.
GEELHART
&&
.AVIATION...
ISSUED 558 AM CST SUN NOV 8 2009...FOR THE 12Z TAFS
LOCALLY DENSE FOG HAS DEVELOPED EARLY THIS MORNING ALONG THE
STATIONARY FRONT IN CENTRAL IL. PIA/BMI/CMI WILL BE AFFECTED THE
MOST...AS THEY ARE ALMOST DIRECTLY UNDER THE FRONT. THOSE TAF
SITES CAN EXPECT LIFR AND VLIFR VIS POSSIBLE THROUGH AROUND
15Z...WITH A VLIFR CIG AT CMI AT TIMES AS WELL. THE FOG IS
SHALLOW...AND SHOULD BURN OFF BY MID MORNING.
THE FRONT WILL LIFT NORTH AS A WARM FRONT TODAY...SETTING UP
SOUTHERLY WINDS FOR ANOTHER DAY IN CENTRAL IL. BUFKIT SOUNDINGS
SHOW MIXING HEIGHTS UP TO 925 MB...WHICH MAY MIX DOWN SOME WIND
GUSTS UP TO 20 KT THIS AFTERNOON. WILL KEEP GUSTS IN ALL TAFS THIS
AFTERNOON.
SHIMON
&&
.PREV DISCUSSION...
ISSUED 325 AM CST SUN NOV 8 2009
FORECAST CHALLENGE IS HOW WARM IT GETS TODAY AND MON AS MET/MAV
GUIDANCE CONTINUES TO GET WARMER. THEN ADDRESSING NEXT CHANCE OF
RAIN SHOWERS EARLY IN THE WORK WEEK AS A COLD FRONT MOVES INTO
IL. 00Z MODELS FAIRLY SIMILAR THROUGH MON NIGHT...THEN DIVERGE
TUE WITH HOW QUICKLY WX SYSTEM EXITS IL. MODELS HAD BEEN TRENDING
SLOWER LAST FEW DAYS WITH COLD FRONT EARLY THIS WORK WEEK. THOUGH
SUSPECT OF NAM/S SLOWER SHORT WAVE MOVING INTO MO BY SUNSET TUE
AND KEEPING SOME LIGHT QPF INTO AREAS SW OF LINCOLN INTO TUE
NIGHT. DID NOT BUY INTO THIS MODEL SOLUTION BUT DID GO SLOWER WITH
WX SYSTEM LATER MON/TUE.
SHORT TERM...TODAY THROUGH TUESDAY NIGHT.
09Z/3 AM SURFACE MAP SHOWS A FRONTAL BOUNDARY OVER THE SOUTHERN
GREAT LAKES INTO NORTHERN IL NEAR GALESBURG TO NEAR THE IA/MO
BORDER AND NORTHERN KS TO 1005 MB LOW PRESSURE IN EASTERN CO THAT
IS DEEPENING. FAIR SKIES OVER IL WITH PASSING THIN CIRRUS
ESPECIALLY FROM I-72 NORTH. PATCHY SHALLOW GROUND FOG DEVELOPING
EARLY THIS MORNING OVER CENTRAL AND NORTHERN IL WITH VISIBILITIES
DOWN TO 2 TO 5 MILES FROM LINCOLN NORTH. PATCHY FOG SHOULD LIFT
BY MID MORNING. ALOFT A STRONG SUBTROPICAL 588 DM 500 MB RIDGE WAS
OVER THE SE STATES AND INTO THE MID MS VALLEY WHILE UPPER LEVEL
TROF OVER THE ROCKIES.
MODELS EJECT LOW PRESSURE FROM EASTERN CO NE INTO WESTERN IA BY
SUNSET LIFTING THE FRONT IN NORTHERN IL BACK NORTH WITH INCREASING
SOUTHERLY FLOW OVER CENTRAL IL. AMPLE SUNSHINE EXPECTED AGAIN WITH
PASSING CIRRUS CLOUDS ESPECIALLY I-74 NORTH. HIGHS TODAY SHOULD BE
SIMILAR TO YESTERDAY IN THE LOW TO MID 70S WHICH IS THE WARMEST
TEMPS OVER IL IN SIX WEEKS SINCE SEP 27. STILL A BIT SHY OF RECORD
HIGHS IN THE UPPER 70S TO AROUND 80F.
LOW PRESSURE WEAKENS AS IT LIFTS NE OF WI BY DAWN MON WHILE
BRINGING A COLD FRONT SE TOWARD THE IL/IA BORDER. STILL DRY
TONIGHT ACROSS IL THOUGH HIGH CLOUDS WILL BE INCREASING OVER THE
IL RIVER VALLEY. LOWS IN THE LOWER 50S THOUGH A BIT COOLER ALONG
THE WABASH RIVER IN SE IL WHERE SOME UPPER 40S POSSIBLE. STRONG
UPPER LEVEL RIDGE NEAR IL WILL SLOW THE COLD FRONT WHICH WEAKENS
TOO AS IT MOVES INTO CENTRAL IL. SHOWERS ARE POST FRONTAL AND
MAINLY NW OF THE IL RIVER MON AFTERNOON. CLOUDS TO CONTINUE TO
INCREASE OVER CENTRAL IL NW OF I-70 MON. WARMED HIGHS UP A FEW
DEGREES MON TOO WITH MID 60S NW OF THE IL RIVER AND UPPER 60S AND
LOWER 70S SE OF THE IL RIVER WITH WARMEST READINGS IN SE IL WHERE
MORE SUNSHINE.
INCREASING CHANCES OF SHOWERS MON NIGHT OVER CENTRAL IL WITH
LIKELY CHANCES FROM PEORIA NORTH WHERE SOME UPPER LEVEL LIFT
PRESENT WHILE SE IL SHOULD REMAIN DRY MON NIGHT CLOSER TO UPPER
LEVEL RIDGE. COLD FRONT WEAKENS FURTHER AS IT MOVES TOWARD THE
OHIO RIVER TUE AFTERNOON WITH CHANCES OF SHOWERS TUE OVER CENTRAL
AND ESPECIALLY EASTERN IL. MOISTURE FROM HURRICANE IDA IN THE GULF
OF MEXICO TO STAY SE OF KY. BUMPED UP HIGHS TUE AS WELL INTO THE
UPPER 50S NW IL AND MID 60S SE IL. HIGH PRESSURE OVER THE PACIFIC
STATES SETTLES INTO THE WESTERN GREAT LAKES BY DAWN WED AND TO
DECREASE CLOUDS DURING TUE NIGHT AND COOLER LOWS IN THE 30S WHICH
IS ACTUALLY CLOSER TO NORMAL FOR MID NOV.
LONG TERM...WEDNESDAY THROUGH SATURDAY.
QUIET WEATHER EXPECTED DURING THIS TIME AS HIGH PRESSURE SLIPS OFF
TO THE EAST WITH RETURN SOUTHERLY FLOW SETTING BACK UP AND KEEPING
TEMPS ABOVE NORMAL THOUGH NOT NEARLY AS WARM AS THIS WEEKEND. THE
NEXT COLD FRONT TO MOVE TOWARD IL LATE THIS WEEK BUT ITS MOISTURE
APPEARS TO STAY NORTH OF CENTRAL/SE IL.
HUETTL
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
000
FXUS63 KILX 081158
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
558 AM CST SUN NOV 8 2009
.DISCUSSION...
ISSUED 325 AM CST SUN NOV 8 2009
FORECAST CHALLENGE IS HOW WARM IT GETS TODAY AND MON AS MET/MAV
GUIDANCE CONTINUES TO GET WARMER. THEN ADDRESSING NEXT CHANCE OF
RAIN SHOWERS EARLY IN THE WORK WEEK AS A COLD FRONT MOVES INTO
IL. 00Z MODELS FAIRLY SIMILAR THROUGH MON NIGHT...THEN DIVERGE
TUE WITH HOW QUICKLY WX SYSTEM EXITS IL. MODELS HAD BEEN TRENDING
SLOWER LAST FEW DAYS WITH COLD FRONT EARLY THIS WORK WEEK. THOUGH
SUSPECT OF NAM/S SLOWER SHORT WAVE MOVING INTO MO BY SUNSET TUE
AND KEEPING SOME LIGHT QPF INTO AREAS SW OF LINCOLN INTO TUE
NIGHT. DID NOT BUY INTO THIS MODEL SOLUTION BUT DID GO SLOWER WITH
WX SYSTEM LATER MON/TUE.
SHORT TERM...TODAY THROUGH TUESDAY NIGHT.
09Z/3 AM SURFACE MAP SHOWS A FRONTAL BOUNDARY OVER THE SOUTHERN
GREAT LAKES INTO NORTHERN IL NEAR GALESBURG TO NEAR THE IA/MO
BORDER AND NORTHERN KS TO 1005 MB LOW PRESSURE IN EASTERN CO THAT
IS DEEPENING. FAIR SKIES OVER IL WITH PASSING THIN CIRRUS
ESPECIALLY FROM I-72 NORTH. PATCHY SHALLOW GROUND FOG DEVELOPING
EARLY THIS MORNING OVER CENTRAL AND NORTHERN IL WITH VISIBILITIES
DOWN TO 2 TO 5 MILES FROM LINCOLN NORTH. PATCHY FOG SHOULD LIFT
BY MID MORNING. ALOFT A STRONG SUBTROPICAL 588 DM 500 MB RIDGE WAS
OVER THE SE STATES AND INTO THE MID MS VALLEY WHILE UPPER LEVEL
TROF OVER THE ROCKIES.
MODELS EJECT LOW PRESSURE FROM EASTERN CO NE INTO WESTERN IA BY
SUNSET LIFTING THE FRONT IN NORTHERN IL BACK NORTH WITH INCREASING
SOUTHERLY FLOW OVER CENTRAL IL. AMPLE SUNSHINE EXPECTED AGAIN WITH
PASSING CIRRUS CLOUDS ESPECIALLY I-74 NORTH. HIGHS TODAY SHOULD BE
SIMILAR TO YESTERDAY IN THE LOW TO MID 70S WHICH IS THE WARMEST
TEMPS OVER IL IN SIX WEEKS SINCE SEP 27. STILL A BIT SHY OF RECORD
HIGHS IN THE UPPER 70S TO AROUND 80F.
LOW PRESSURE WEAKENS AS IT LIFTS NE OF WI BY DAWN MON WHILE
BRINGING A COLD FRONT SE TOWARD THE IL/IA BORDER. STILL DRY
TONIGHT ACROSS IL THOUGH HIGH CLOUDS WILL BE INCREASING OVER THE
IL RIVER VALLEY. LOWS IN THE LOWER 50S THOUGH A BIT COOLER ALONG
THE WABASH RIVER IN SE IL WHERE SOME UPPER 40S POSSIBLE. STRONG
UPPER LEVEL RIDGE NEAR IL WILL SLOW THE COLD FRONT WHICH WEAKENS
TOO AS IT MOVES INTO CENTRAL IL. SHOWERS ARE POST FRONTAL AND
MAINLY NW OF THE IL RIVER MON AFTERNOON. CLOUDS TO CONTINUE TO
INCREASE OVER CENTRAL IL NW OF I-70 MON. WARMED HIGHS UP A FEW
DEGREES MON TOO WITH MID 60S NW OF THE IL RIVER AND UPPER 60S AND
LOWER 70S SE OF THE IL RIVER WITH WARMEST READINGS IN SE IL WHERE
MORE SUNSHINE.
INCREASING CHANCES OF SHOWERS MON NIGHT OVER CENTRAL IL WITH
LIKELY CHANCES FROM PEORIA NORTH WHERE SOME UPPER LEVEL LIFT
PRESENT WHILE SE IL SHOULD REMAIN DRY MON NIGHT CLOSER TO UPPER
LEVEL RIDGE. COLD FRONT WEAKENS FURTHER AS IT MOVES TOWARD THE
OHIO RIVER TUE AFTERNOON WITH CHANCES OF SHOWERS TUE OVER CENTRAL
AND ESPECIALLY EASTERN IL. MOISTURE FROM HURRICANE IDA IN THE GULF
OF MEXICO TO STAY SE OF KY. BUMPED UP HIGHS TUE AS WELL INTO THE
UPPER 50S NW IL AND MID 60S SE IL. HIGH PRESSURE OVER THE PACIFIC
STATES SETTLES INTO THE WESTERN GREAT LAKES BY DAWN WED AND TO
DECREASE CLOUDS DURING TUE NIGHT AND COOLER LOWS IN THE 30S WHICH
IS ACTUALLY CLOSER TO NORMAL FOR MID NOV.
LONG TERM...WEDNESDAY THROUGH SATURDAY.
QUIET WEATHER EXPECTED DURING THIS TIME AS HIGH PRESSURE SLIPS OFF
TO THE EAST WITH RETURN SOUTHERLY FLOW SETTING BACK UP AND KEEPING
TEMPS ABOVE NORMAL THOUGH NOT NEARLY AS WARM AS THIS WEEKEND. THE
NEXT COLD FRONT TO MOVE TOWARD IL LATE THIS WEEK BUT ITS MOISTURE
APPEARS TO STAY NORTH OF CENTRAL/SE IL.
HUETTL
&&
.AVIATION...
ISSUED 558 AM CST SUN NOV 8 2009...FOR THE 12Z TAFS
LOCALLY DENSE FOG HAS DEVELOPED EARLY THIS MORNING ALONG THE
STATIONARY FRONT IN CENTRAL IL. PIA/BMI/CMI WILL BE AFFECTED THE
MOST...AS THEY ARE ALMOST DIRECTLY UNDER THE FRONT. THOSE TAF
SITES CAN EXPECT LIFR AND VLIFR VIS POSSIBLE THROUGH AROUND
15Z...WITH A VLIFR CIG AT CMI AT TIMES AS WELL. THE FOG IS
SHALLOW...AND SHOULD BURN OFF BY MID MORNING.
THE FRONT WILL LIFT NORTH AS A WARM FRONT TODAY...SETTING UP
SOUTHERLY WINDS FOR ANOTHER DAY IN CENTRAL IL. BUFKIT SOUNDINGS
SHOW MIXING HEIGHTS UP TO 925 MB...WHICH MAY MIX DOWN SOME WIND
GUSTS UP TO 20 KT THIS AFTERNOON. WILL KEEP GUSTS IN ALL TAFS THIS
AFTERNOON.
SHIMON
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
000
FXUS63 KLOT 081116
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
516 AM CST SUN NOV 8 2009
.DISCUSSION...
330 AM CST
CERTAINLY SEEMS A LOT MORE LIKE LATE SEPTEMBER THAN THE 2ND WEEK
OF NOVEMBER WITH A HURRICANE MOVING INTO THE GULF OF MEXICO WHILE
THE CHICAGO AREA BASKS IN 70 DEGREE WARMTH. THE UNSEASONABLY WARM
TEMPERATURES ARE CERTAINLY A FAIRLY DRAMATIC CHANGE OF PACE AFTER
THE DAMP...DARK...DREARY...AND DISMALLY COLD OCTOBER.
WEAK HIGH PRESSURE OVER WISCONSIN HAS ALLOWED A FRONT TO SAG
SOUTHWARD INTO NORTHERN ILLINOIS THIS MORNING...HOWEVER LATE
EVENING ACARS SOUNDING FROM RFD SHOW A VERY SHARP SURFACE
INVERSION BENEATH THE UNSEASONABLY WARM TEMPS JUST ABOVE THE
GROUND. ALREADY SEEING SOME RATHER IMPRESSIVE 3HR PRESSURE FALLS
(FOR THIS TIME OF DAY) OVER NEBRASKA AS LOW PRESSURE OVER COLORADO
SITS POISED TO MAKE A RUN NORTHEAST INTO THE UPPER MISSISSIPPI
VALLEY. FRONT CURRENTLY DRAPED ACROSS THE CWA SHOULD LIFT
NORTHWARD LATER THIS MORNING SETTING THE STAGE FOR ANOTHER
UNSEASONABLY WARM NOVEMBER AFTERNOON WITH HIGHS PROBABLY REACHING
THE LOWER 70S MOST AREAS. RECORD HIGH FOR CHICAGO TODAY IS 73
WHICH WE COULD BE WITHIN REASONABLE STRIKING DISTANCE. SOUTHERLY
WINDS SHOULD GRADUALLY FRESHEN UP AND WILL LIKELY SET THE STAGE
TONIGHT FOR A REPEAT OF FRIDAY NIGHT`S MILD CONDITIONS.
ANOTHER WEAK FRONT WILL MOVE INTO THE AREA DURING THE DAY
MONDAY...BUT WITH SUCH A WARM START TO THE DAY STILL ANTICIPATE
HIGHS TO CLIMB INTO THE 60S MOST AREAS PRIOR TO FROPA. WHILE SOME
SCT SHOWERS ARE POSSIBLE AS FRONT ARRIVES MONDAY PM...BETTER
SHOWER CHANCES SHOULD COME MONDAY NIGHT AS LOW LEVEL FRONT
SHARPENS UP IN ADVANCE OF APPROACHING SHORTWAVE. MID LEVEL LAPSE
RATES PROGGED TO BE FAIRLY STEEP IN ADVANCE OF THIS SYSTEM WITH A
COUPLE/FEW HUNDRED JOULES OF ELEVATED CAPE PRESENT IN FORECAST
SOUNDINGS FROM BOTH THE GFS AND WRF-NMM. WHILE CERTAINLY NOT THE
MOST DYNAMIC OF SYSTEMS...PRESENCE OF STEEPER LAPSE RATES/WEAK
CAPE IN CONJUNCTION WITH STRENGTHENING LOW LEVEL FRONTOGENESIS AND
PROXIMITY OF RIGHT ENTRANCE REGION OF STRENGTHENING UPPER LEVEL
JET WOULD SUGGEST AT LEAST A MARGINAL THUNDER POTENTIAL AND HAVE
INTRODUCED SMALL THUNDER PROBS INTO GRIDS MONDAY NIGHT AND BUMPED
POPS UP TO LIKELY.
GENERAL TREND IN THE MODELS THE PAST COUPLE RUNS HAS BEEN TO SLOW
DOWN THE ENDING OF THE PRECIP TUESDAY MORNING...AND HAVE BEGUN TO
REFLECT THIS TREND IN OUR GRIDS BY INTRODUCING CHANCE POPS OVER
MUCH OF THE AREA. IF THE CURRENT TREND IN THE MODELS CONTINUES
THEN POPS WILL NEED TO BE UPPER CONSIDERABLY MORE...PARTICULARLY
OVER OUR SE COUNTIES TUESDAY MORNING.
SHOULD SEE A COOL DOWN TO NEAR AVERAGE TEMPERATURES TUES NIGHT
INTO WED NIGHT BEHIND THE COLD FRONT. AIR MASS IN THE WAKE OF THE
FRONT IS OF PACIFIC ORIGINS WHICH SHOULD KEEP THE COOL DOWN FAIRLY
MODEST. HIGH PRESSURE WILL SCOOT OFF TO THE EAST DURING THE DAY
THURSDAY WITH RETURN SOUTHERLY FLOW RESULTING IN A RETURN TO ABOVE
AVERAGE TEMPERATURES AGAIN BY THURSDAY INTO FRIDAY.
IZZI
&&
.AVIATION...
516 AM CDT
1200 UTC TAFS...MAIN WEATHER CONCERNS TO BE WITHIN THE FIRST FEW
HOURS OF TAF ISSUANCE AS SOME FOG HAS DEVELOPED ACROSS THE REGION
IN THE HEART OF THE CALM WINDS DUE TO A STALLED OUT FRONT. THE
THICKEST FOG IS FURTHER SOUTH AND EAST WHERE VIS HAS DROPPED TO
LESS THAN A QUARTER MILE. AS A LOW PRESSURE SYSTEM LIFTS NORTH
ACROSS THE PLAINS TODAY...THIS POCKET OF LOWER VISIBILITIES SHOULD
ALSO COME NORTH AND IS EXPECTED TO DIMINISH AROUND 15Z AS THE
WINDS START TO PICK UP. WIND DIRECTION WILL ALSO BE TRICKY THIS
MORNING WITH THE FRONT IN THE VICINITY. SHOULD START OUT LIGHT AND
VARIABLE AND GO EAST...TO SOUTHEAST...TO SOUTH AND BECOME GUSTY BY
AFTERNOON. WHILE THE GUSTS WILL SHUT OFF AROUND SUNSET...A DECENT
PRESSURE GRADIENT WILL PERSIST OVERNIGHT SUNDAY INTO MONDAY
MORNING AND SHOULD BE ABLE TO REMAIN SUSTAINED AROUND 10KT OUT OF
THE SOUTHWEST. NO PRECIPITATION IS EXPECTED THROUGHOUT THE TAF
PERIOD WITH ONLY SOME PASSING UPPER CLOUDS.
EXPECT ANY SUB-VFR CONDITIONS TO IMPROVE TO VFR LATER THIS MORNING.
HALBACH
&&
.MARINE...
231 AM CST
REMNANT COLD FRONT CURRENTLY ACROSS THE FAR SOUTHERN PORTION OF
LAKE MICHIGAN IS EXPECTED TO TRANSITION TO A WARM FRONT TODAY AS A
LOW PRESSURE SYSTEM DEVELOPING IN EASTERN COLORADO TRACKS NORTH
THROUGH THE PLAINS. WITH THE WARMER AIR MOVING OVER THE
COOLER...STABLE MARINE LAYER IT WILL BE TOUGH FOR MANY GUSTS TO
MAKE IT DOWN TO THE SFC OF THE LAKE ON SUNDAY GIVEN THE SOUTHERLY
WINDS. HOWEVER...AS THIS LOW TRACKS THROUGH THE GREAT LAKES IT
WILL PULL A COLD FRONT ACROSS THE LAKE ON MONDAY. BEHIND THIS
FRONT...AN AREA OF HIGH PRESSURE WILL BE BUILDING IN FROM THE WEST
AND SHOULD SET UP A DECENT PRESSURE GRADIENT ACROSS THE LAKE
MONDAY NIGHT INTO EARLY TUESDAY. GIVEN THE PERSISTENT
NORTH TO NORTHEAST WINDS INTO TUESDAY...SHOULD SEE SOME DECENT
WAVES DEVELOPING ACROSS THE SOUTHERN RIM OF LAKE MICHIGAN WHICH
MAY PROMPT THE ISSUANCE OF A SMALL CRAFT ADVISORY. FOR NOW...BEING
THAT THE WINDS APPEAR MARGINAL AROUND 20KTS AND IT BEING OVER 36
HOURS AWAY...WILL HOLD OFF ON ISSUING ANYTHING.
AFTER THIS...HIGH PRESSURE APPEARS TO TAKE OVER THE GREAT LAKES
REGION THROUGH THE REST OF THE WEEK UNTIL IT SHIFTS OFF TOWARD THE
MID-ATLANTIC REGION AND THE SOUTHERLIES BUILD IN AGAIN.
HALBACH
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
000
FXUS63 KILX 080930
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
330 AM CST SUN NOV 8 2009
.DISCUSSION...
ISSUED 325 AM CST SUN NOV 8 2009
FORECAST CHALLENGE IS HOW WARM IT GETS TODAY AND MON AS MET/MAV
GUIDANCE CONTINUES TO GET WARMER. THEN ADDRESSING NEXT CHANCE OF
RAIN SHOWERS EARLY IN THE WORK WEEK AS A COLD FRONT MOVES INTO
IL. 00Z MODELS FAIRLY SIMILAR THROUGH MON NIGHT...THEN DIVERGE
TUE WITH HOW QUICKLY WX SYSTEM EXITS IL. MODELS HAD BEEN TRENDING
SLOWER LAST FEW DAYS WITH COLD FRONT EARLY THIS WORK WEEK. THOUGH
SUSPECT OF NAM/S SLOWER SHORT WAVE MOVING INTO MO BY SUNSET TUE
AND KEEPING SOME LIGHT QPF INTO AREAS SW OF LINCOLN INTO TUE
NIGHT. DID NOT BUY INTO THIS MODEL SOLUTION BUT DID GO SLOWER WITH
WX SYSTEM LATER MON/TUE.
SHORT TERM...TODAY THROUGH TUESDAY NIGHT.
09Z/3 AM SURFACE MAP SHOWS A FRONTAL BOUNDARY OVER THE SOUTHERN
GREAT LAKES INTO NORTHERN IL NEAR GALESBURG TO NEAR THE IA/MO
BORDER AND NORTHERN KS TO 1005 MB LOW PRESSURE IN EASTERN CO THAT
IS DEEPENING. FAIR SKIES OVER IL WITH PASSING THIN CIRRUS
ESPECIALLY FROM I-72 NORTH. PATCHY SHALLOW GROUND FOG DEVELOPING
EARLY THIS MORNING OVER CENTRAL AND NORTHERN IL WITH VISIBITILIES
DOWN TO 2 TO 5 MILES FROM LINCOLN NORTH. PATCHY FOG SHOULD LIFT
BY MID MORNING. ALOFT A STRONG SUBTROPICAL 588 DM 500 MB RIDGE WAS
OVER THE SE STATES AND INTO THE MID MS VALLEY WHILE UPPER LEVEL
TROF OVER THE ROCKIES.
MODELS EJECT LOW PRESSURE FROM EASTERN CO NE INTO WESTERN IA BY
SUNSET LIFTING THE FRONT IN NORTHERN IL BACK NORTH WITH INCREASING
SOUTHERLY FLOW OVER CENTRAL IL. AMPLE SUNSHINE EXPECTED AGAIN WITH
PASSING CIRRUS CLOUDS ESPECIALLY I-74 NORTH. HIGHS TODAY SHOULD BE
SIMILAR TO YESTERDAY IN THE LOW TO MID 70S WHICH IS THE WARMEST
TEMPS OVER IL IN SIX WEEKS SINCE SEP 27. STILL A BIT SHY OF RECORD
HIGHS IN THE UPPER 70S TO AROUND 80F.
LOW PRESSURE WEAKENS AS IT LIFTS NE OF WI BY DAWN MON WHILE
BRINGING A COLD FRONT SE TOWARD THE IL/IA BORDER. STILL DRY
TONIGHT ACROSS IL THOUGH HIGH CLOUDS WILL BE INCREASING OVER THE
IL RIVER VALLEY. LOWS IN THE LOWER 50S THOUGH A BIT COOLER ALONG
THE WABASH RIVER IN SE IL WHERE SOME UPPER 40S POSSIBLE. STRONG
UPPER LEVEL RIDGE NEAR IL WILL SLOW THE COLD FRONT WHICH WEAKENS
TOO AS IT MOVES INTO CENTRAL IL. SHOWERS ARE POST FRONTAL AND
MAINLY NW OF THE IL RIVER MON AFTERNOON. CLOUDS TO CONTINUE TO
INCREASE OVER CENTRAL IL NW OF I-70 MON. WARMED HIGHS UP A FEW
DEGREES MON TOO WITH MID 60S NW OF THE IL RIVER AND UPPER 60S AND
LOWER 70S SE OF THE IL RIVER WITH WARMEST READINGS IN SE IL WHERE
MORE SUNSHINE.
INCREASING CHANCES OF SHOWERS MON NIGHT OVER CENTRAL IL WITH
LIKELY CHANCES FROM PEORIA NORTH WHERE SOME UPPER LEVEL LIFT
PRESENT WHILE SE IL SHOULD REMAIN DRY MON NIGHT CLOSER TO UPPER
LEVEL RIDGE. COLD FRONT WEAKENS FURTHER AS IT MOVES TOWARD THE
OHIO RIVER TUE AFTERNOON WITH CHANCES OF SHOWERS TUE OVER CENTRAL
AND ESPECIALLY EASTERN IL. MOISTURE FROM HURRICANE IDA IN THE GULF
OF MEXICO TO STAY SE OF KY. BUMPED UP HIGHS TUE AS WELL INTO THE
UPPER 50S NW IL AND MID 60S SE IL. HIGH PRESSURE OVER THE PACIFIC
STATES SETTLES INTO THE WESTERN GREAT LAKES BY DAWN WED AND TO
DECREASE CLOUDS DURING TUE NIGHT AND COOLER LOWS IN THE 30S WHICH
IS ACTUALLY CLOSER TO NORMAL FOR MID NOV.
LONG TERM...WEDNESDAY THROUGH SATURDAY.
QUIET WEATHER EXPECTED DURING THIS TIME AS HIGH PRESSURE SLIPS OFF
TO THE EAST WITH RETURN SOUTHERLY FLOW SETTING BACK UP AND KEEPING
TEMPS ABOVE NORMAL THOUGH NOT NEARLY AS WARM AS THIS WEEKEND. THE
NEXT COLD FRONT TO MOVE TOWARD IL LATE THIS WEEK BUT ITS MOISTURE
APPEARS TO STAY NORTH OF CENTRAL/SE IL.
HUETTL
&&
.AVIATION...
ISSUED 1125 PM CST SAT NOV 7 2009
LITTLE CHANGE FROM PREVIOUS DISCUSSION...MAIN FORECAST CONCERN WL
BE WITH GROUND FOG DEVELOPMENT IN THE EARLY MRNG HOURS. CURRENT
TEMP DEW POINT SPREADS LOWER ACRS THE NORTH...CLOSER TO A WEAK
STALLED FRONTAL BOUNDARY. FORECAST SOUNDINGS SHOWING PIA AND BMI
HAVING THE HIGHER PROBABILITIES OF SEEING A PERIOD OF MVFR VSBYS
IN FOG. MOISTURE IS VERY SHALLOW SO WHATEVER FOG DOES FORM SHOULD
DISSIPATE QUICKLY AT OR SHORTLY AFTER 15Z SUNDAY. SFC WNDS WL BE
LIGHT...MAINLY FROM A SE TO S DIRECTION AND INTO THE SOUTH AT ALL
TAF SITES ON SUNDAY WITH A FEW GUSTS JUST BELOW 20 KTS IN THE
AFTN.
SMITH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
000
FXUS63 KLOT 080930
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
330 AM CST SUN NOV 8 2009
.DISCUSSION...
330 AM CST
CERTAINLY SEEMS A LOT MORE LIKE LATE SEPTEMBER THAN THE 2ND WEEK
OF NOVEMBER WITH A HURRICANE MOVING INTO THE GULF OF MEXICO WHILE
THE CHICAGO AREA BASKS IN 70 DEGREE WARMTH. THE UNSEASONABLY WARM
TEMPERATURES ARE CERTAINLY A FAIRLY DRAMATIC CHANGE OF PACE AFTER
THE DAMP...DARK...DREARY...AND DISMALLY COLD OCTOBER.
WEAK HIGH PRESSURE OVER WISCONSIN HAS ALLOWED A FRONT TO SAG
SOUTHWARD INTO NORTHERN ILLINOIS THIS MORNING...HOWEVER LATE
EVENING ACARS SOUNDING FROM RFD SHOW A VERY SHARP SURFACE
INVERSION BENEATH THE UNSEASONABLY WARM TEMPS JUST ABOVE THE
GROUND. ALREADY SEEING SOME RATHER IMPRESSIVE 3HR PRESSURE FALLS
(FOR THIS TIME OF DAY) OVER NEBRASKA AS LOW PRESSURE OVER COLORADO
SITS POISED TO MAKE A RUN NORTHEAST INTO THE UPPER MISSISSIPPI
VALLEY. FRONT CURRENTLY DRAPED ACROSS THE CWA SHOULD LIFT
NORTHWARD LATER THIS MORNING SETTING THE STAGE FOR ANOTHER
UNSEASONABLY WARM NOVEMBER AFTERNOON WITH HIGHS PROBABLY REACHING
THE LOWER 70S MOST AREAS. RECORD HIGH FOR CHICAGO TODAY IS 73
WHICH WE COULD BE WITHIN REASONABLE STRIKING DISTANCE. SOUTHERLY
WINDS SHOULD GRADUALLY FRESHEN UP AND WILL LIKELY SET THE STAGE
TONIGHT FOR A REPEAT OF FRIDAY NIGHT`S MILD CONDITIONS.
ANOTHER WEAK FRONT WILL MOVE INTO THE AREA DURING THE DAY
MONDAY...BUT WITH SUCH A WARM START TO THE DAY STILL ANTICIPATE
HIGHS TO CLIMB INTO THE 60S MOST AREAS PRIOR TO FROPA. WHILE SOME
SCT SHOWERS ARE POSSIBLE AS FRONT ARRIVES MONDAY PM...BETTER
SHOWER CHANCES SHOULD COME MONDAY NIGHT AS LOW LEVEL FRONT
SHARPENS UP IN ADVANCE OF APPROACHING SHORTWAVE. MID LEVEL LAPSE
RATES PROGGED TO BE FAIRLY STEEP IN ADVANCE OF THIS SYSTEM WITH A
COUPLE/FEW HUNDRED JOULES OF ELEVATED CAPE PRESENT IN FORECAST
SOUNDINGS FROM BOTH THE GFS AND WRF-NMM. WHILE CERTAINLY NOT THE
MOST DYNAMIC OF SYSTEMS...PRESENCE OF STEEPER LAPSE RATES/WEAK
CAPE IN CONJUNCTION WITH STRENGTHENING LOW LEVEL FRONTOGENESIS AND
PROXIMITY OF RIGHT ENTRANCE REGION OF STRENGTHENING UPPER LEVEL
JET WOULD SUGGEST AT LEAST A MARGINAL THUNDER POTENTIAL AND HAVE
INTRODUCED SMALL THUNDER PROBS INTO GRIDS MONDAY NIGHT AND BUMPED
POPS UP TO LIKELY.
GENERAL TREND IN THE MODELS THE PAST COUPLE RUNS HAS BEEN TO SLOW
DOWN THE ENDING OF THE PRECIP TUESDAY MORNING...AND HAVE BEGUN TO
REFLECT THIS TREND IN OUR GRIDS BY INTRODUCING CHANCE POPS OVER
MUCH OF THE AREA. IF THE CURRENT TREND IN THE MODELS CONTINUES
THEN POPS WILL NEED TO BE UPPER CONSIDERABLY MORE...PARTICULARLY
OVER OUR SE COUNTIES TUESDAY MORNING.
SHOULD SEE A COOL DOWN TO NEAR AVERAGE TEMPERATURES TUES NIGHT
INTO WED NIGHT BEHIND THE COLD FRONT. AIR MASS IN THE WAKE OF THE
FRONT IS OF PACIFIC ORIGINS WHICH SHOULD KEEP THE COOL DOWN FAIRLY
MODEST. HIGH PRESSURE WILL SCOOT OFF TO THE EAST DURING THE DAY
THURSDAY WITH RETURN SOUTHERLY FLOW RESULTING IN A RETURN TO ABOVE
AVERAGE TEMPERATURES AGAIN BY THURSDAY INTO FRIDAY.
IZZI
&&
.AVIATION...
0600 UTC TAFS...MAIN SHORT TERM FORECAST ISSUE IS HAZE/FOG TRENDS
OVERNIGHT AND POTENTIAL FOR PATCHY/TEMPO MVFR/HIGH IFR VISIBILITY
REDUCTIONS.
AS NOTED IN PREVIOUS DISCUSSION...WEAK SFC TROUGH/COLD FRONT
DRIFTING SLOWLY SOUTHEAST ACROSS FCST AREA. WEAK GRADIENT/WIND FIELD
MAKING FRONT DIFFICULT TO ANALYZE HOWEVER...WITH MANY SFC OBS SITES
INDICATING CALM OR LGT/VRBL WINDS. WITH LIGHT WINDS...CLEAR SKIES
AND SHALLOW LOW LEVEL MOISTURE ALONG/VICINITY OF FRONT HAVE SEEN
PATCHY MVFR HAZE DEVELOP EARLIER THAN ANTICIPATED EARLIER THIS
EVENING. HOWEVER...00Z DVN SOUNDING INDICATES DRY AIR/LARGE DEW
POINT DEPRESSIONS JUST ABOVE SHALLOW SFC INVERSION...AND
ASCENT/DESCENT SOUNDINGS FROM KRFD AROUND 04Z ALSO DEPICT EXTREMELY
SHALLOW NATURE OF INVERSION. THUS...DESPITE DECENT JUXTAPOSITION OF
CONDITIONS FOR RADIATIONAL COOLING AND EARLY DEVELOPMENT OF FOG/HAZE
SUSPECT THAT CURRENT PATCHY AND SHALLOW NATURE OF FOG/HAZE WILL
CONTINUE THROUGH SUNDAY MORNING. BASED ON THIS HAVE MAINTAINED
GENERALLY A HIGHER MVFR RESTRICTION AT KORD/KMDW...WHILE MORE LOW
END MVFR/HIGH IFR FOR MORE CLIMATOLOGICALLY FAVORED KDPA/KRFD. IN
FACT KRFD HAS ALREADY BEEN BOUNCING BETWEEN 5 AND AS LOW AS 1 3/4
MILES DURING THE EVENING SO HAVE GONE LOWEST AROUND SUNRISE THERE.
FOG/HAZE SHOULD DISSIPATE BY MID MORNING.
OTHERWISE...WITH DRY AIRMASS FROM ABOVE BOUNDARY LAYER THROUGH MID
LEVELS LITTLE IN WAY OF CLOUD COVER THROUGH PERIOD...SAVE FOR
PATCHES OF HIGH LEVEL CIRRUS ASSOCIATED WITH MINOR AMPLITUDE
WAVES/JET STREAKS RIPPLING THROUGH RELATIVELY ZONAL FLOW ALOFT.
FRONT EXPECTED TO MIX BACK NORTH OF TERMINALS SUNDAY AS WEAK LOW
PRESSURE SYSTEM LIFTS NORTHEAST ACROSS PLAINS. ASSOCIATED INCREASE
IN SFC PRESSURE GRADIENT AND DIURNAL MIXING OF SHALLOW INVERSION
EXPECTED TO RESULT IN SOUTH WINDS WITH GUSTS AROUND OR SLIGHTLY
ABOVE 20 KT SUNDAY AFTERNOON.
RATZER
&&
.MARINE...
231 AM CST
REMNANT COLD FRONT CURRENTLY ACROSS THE FAR SOUTHERN PORTION OF
LAKE MICHIGAN IS EXPECTED TO TRANSITION TO A WARM FRONT TODAY AS A
LOW PRESSURE SYSTEM DEVELOPING IN EASTERN COLORADO TRACKS NORTH
THROUGH THE PLAINS. WITH THE WARMER AIR MOVING OVER THE
COOLER...STABLE MARINE LAYER IT WILL BE TOUGH FOR MANY GUSTS TO
MAKE IT DOWN TO THE SFC OF THE LAKE ON SUNDAY GIVEN THE SOUTHERLY
WINDS. HOWEVER...AS THIS LOW TRACKS THROUGH THE GREAT LAKES IT
WILL PULL A COLD FRONT ACROSS THE LAKE ON MONDAY. BEHIND THIS
FRONT...AN AREA OF HIGH PRESSURE WILL BE BUILDING IN FROM THE WEST
AND SHOULD SET UP A DECENT PRESSURE GRADIENT ACROSS THE LAKE
MONDAY NIGHT INTO EARLY TUESDAY. GIVEN THE PERSISTENT
NORTH TO NORTHEAST WINDS INTO TUESDAY...SHOULD SEE SOME DECENT
WAVES DEVELOPING ACROSS THE SOUTHERN RIM OF LAKE MICHIGAN WHICH
MAY PROMPT THE ISSUANCE OF A SMALL CRAFT ADVISORY. FOR NOW...BEING
THAT THE WINDS APPEAR MARGINAL AROUND 20KTS AND IT BEING OVER 36
HOURS AWAY...WILL HOLD OFF ON ISSUING ANYTHING.
AFTER THIS...HIGH PRESSURE APPEARS TO TAKE OVER THE GREAT LAKES
REGION THROUGH THE REST OF THE WEEK UNTIL IT SHIFTS OFF TOWARD THE
MID-ATLANTIC REGION AND THE SOUTHERLIES BUILD IN AGAIN.
HALBACH
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
000
FXUS63 KLOT 080831
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
231 AM CST SUN NOV 8 2009
.DISCUSSION...
858 PM...EVENING UPDATE...SEVERAL MINOR CONCERNS THIS EVENING
WHICH ALL SEEM TO HINGE ON FRONTAL MOVEMENT/LOCATION. THE COLD
FRONT WILL CONTINUE TO SAG INTO NORTHERN IL AND BECOME STATIONARY
OVERNIGHT...MOVING BACK NORTH AS A WARM FRONT SUNDAY. VISIBILITY
AT RFD HAS ALREADY DROPPED TO 1 3/4SM AND AS THE FRONT SLOWS AND
THEN STALLS...EXPECT MOISTURE TO POOL ALONG/AHEAD OF THE FRONT...
THUS AT LEAST PATCHY FOG WILL BE POSSIBLE...PERHAPS AREAS OF FOG
NEAR THE FRONT. NOT CONFIDENT ON HOW LOW VISIBILITIES WILL GO BUT
MOISTURE APPEARS TO BE QUITE SHALLOW WHICH SUGGESTS MAINLY GROUND
FOG. WILL NEED TO MONITOR TRENDS THROUGH THE NIGHT.
CLEAR SKIES AND LIGHT/CALM WINDS HAVE ALLOWED TEMPS TO DROP OFF
QUICKLY THIS EVENING...COLDEST SPOTS ALREADY IN THE LOWER 40S.
WITH DRIER AIR REMAINING NORTH OF THE FRONT...DON/T THINK LOWS
WILL DROP MUCH MORE THAN LOWER/MID 40S BY MORNING...BUT AGAIN A
LOT HINGES ON FRONTAL LOCATION. HAVE MODIFIED HOURLY GRIDS AND
LOWERED MIN TEMPS A FEW DEGREES. OTHERWISE...CLEAR THIS EVENING
WITH INCREASING THIN CIRRUS OVERNIGHT. CMS
PREVIOUS DISCUSSION...
308 PM CST
WITH MAX TEMPS SURGING TO THE LOWER 70S TODAY AND NOT A CLOUD IN
THE SKY...A PLEASANT DAY WAS IN STORE ACROSS MUCH OF THE REGION.
WITH AN ALREADY MILD START TO THE MORNING AND CLEAR SKIES ACROSS
THE AREA...BUMPED UP MAX TEMPS A COUPLE OF DEGREES TODAY. DESPITE
THE WINDY CONDITIONS FOR PART OF THE DAY TODAY...A WARMER AIR MASS
CONTINUED TO ADVECT INTO THE CWA...CREATING THE MAKINGS FOR A
BEAUTIFUL DAY.
SURFACE TROUGH ALONG WITH WEAK COLD FRONT KNOCKING ON OUR DOOR
JUST TO THE NORTHWEST OF THE CWA WITH TROUGH AXIS EXTENDING FROM
THE UPPER GREAT LAKES SOUTHWEST INTO SOUTHERN IOWA...AND COLD
FRONT EXTENDING INTO SOUTHERN NEBRASKA. SURFACE TROUGH FORECAST TO
EXIT OFF TO THE EAST TONIGHT...ALONG WITH PRESSURE GRADIENT
RELAXING...WILL RESULT IN WINDS CONTINUING TO DIMINISH. FRONT WILL
CONTINUE TO MAKE SOME PROGRESS SOUTHEAST INTO THE FAR NORTHWEST
PORTION OF THE CWA...BUT WITH UPPER LEVEL RIDGE BUILDING ACROSS
THE MIDWEST...WILL STALL TONIGHT. EVEN WITH THE APPROACH OF THIS
FRONT...SKIES WILL REMAIN CLEAR TONIGHT WITH DRIER AIR ALOFT.
ZONAL FLOW WILL TRANSITION TO MORE SOUTHWESTERLY FLOW ALOFT
TONIGHT...AND HELP LIFT THIS WEAK FRONT BACK NORTH ACROSS THE
UPPER MIDWEST EARLY SUNDAY. A SHORT WAVE TROUGH WITHIN THIS FLOW
EJECTING OUT OF THE CENTRAL PLAINS WILL HELP PRODUCE PRESSURE
FALLS AT THE SURFACE...WITH PRESSURE GRADIENT TAKING ON MORE
ORGANIZATION AND WINDS MAINTAINING A SOUTHERLY DIRECTION. THIS
WILL ALL RESULT IN ANOTHER WARM DAY ON SUNDAY WITH ONCE AGAIN
FORECAST HIGH TEMPS RISING INTO THE LOWER 70S.
CLOUD COVER AND PRECIP CHANCES BEGIN TO INCREASE ONCE AGAIN LATE
SUNDAY/EARLY MONDAY AS WEAK SURFACE LOW IS FORECAST TO TRACK
NORTHEAST ALONG THIS BOUNDARY. BUT WITH THIS SURFACE FEATURE
WEAKENING AS IT TRAVERSES THE UPPER MIDWEST...FRONT DOES NOT MAKE
MUCH PR OGRES. AREAS IN FAR NORTHERN ILLINOIS COULD POSSIBLY
OBSERVE EXTENDED CHANCES FOR RAINFALL INTO TUESDAY BEFORE LONG WAVE
TROUGH DIGS SOUTHEAST OUT OF CANADA AND PUSHES THIS FEATURE EAST
OUT OF THE CWA. HIGH PRESSURE BUILDING OUT OF THE CENTRAL PLAINS
BEHIND THIS SYSTEM WILL RETURN CLEAR SKIES AND MORE NORMAL TEMPS
BY MID WEEK.
RODRIGUEZ
&&
.AVIATION...
0600 UTC TAFS...MAIN SHORT TERM FORECAST ISSUE IS HAZE/FOG TRENDS
OVERNIGHT AND POTENTIAL FOR PATCHY/TEMPO MVFR/HIGH IFR VISIBILITY
REDUCTIONS.
AS NOTED IN PREVIOUS DISCUSSION...WEAK SFC TROUGH/COLD FRONT
DRIFTING SLOWLY SOUTHEAST ACROSS FCST AREA. WEAK GRADIENT/WIND FIELD
MAKING FRONT DIFFICULT TO ANALYZE HOWEVER...WITH MANY SFC OBS SITES
INDICATING CALM OR LGT/VRBL WINDS. WITH LIGHT WINDS...CLEAR SKIES
AND SHALLOW LOW LEVEL MOISTURE ALONG/VICINITY OF FRONT HAVE SEEN
PATCHY MVFR HAZE DEVELOP EARLIER THAN ANTICIPATED EARLIER THIS
EVENING. HOWEVER...00Z DVN SOUNDING INDICATES DRY AIR/LARGE DEW
POINT DEPRESSIONS JUST ABOVE SHALLOW SFC INVERSION...AND
ASCENT/DESCENT SOUNDINGS FROM KRFD AROUND 04Z ALSO DEPICT EXTREMELY
SHALLOW NATURE OF INVERSION. THUS...DESPITE DECENT JUXTAPOSITION OF
CONDITIONS FOR RADIATIONAL COOLING AND EARLY DEVELOPMENT OF FOG/HAZE
SUSPECT THAT CURRENT PATCHY AND SHALLOW NATURE OF FOG/HAZE WILL
CONTINUE THROUGH SUNDAY MORNING. BASED ON THIS HAVE MAINTAINED
GENERALLY A HIGHER MVFR RESTRICTION AT KORD/KMDW...WHILE MORE LOW
END MVFR/HIGH IFR FOR MORE CLIMATOLOGICALLY FAVORED KDPA/KRFD. IN
FACT KRFD HAS ALREADY BEEN BOUNCING BETWEEN 5 AND AS LOW AS 1 3/4
MILES DURING THE EVENING SO HAVE GONE LOWEST AROUND SUNRISE THERE.
FOG/HAZE SHOULD DISSIPATE BY MID MORNING.
OTHERWISE...WITH DRY AIRMASS FROM ABOVE BOUNDARY LAYER THROUGH MID
LEVELS LITTLE IN WAY OF CLOUD COVER THROUGH PERIOD...SAVE FOR
PATCHES OF HIGH LEVEL CIRRUS ASSOCIATED WITH MINOR AMPLITUDE
WAVES/JET STREAKS RIPPLING THROUGH RELATIVELY ZONAL FLOW ALOFT.
FRONT EXPECTED TO MIX BACK NORTH OF TERMINALS SUNDAY AS WEAK LOW
PRESSURE SYSTEM LIFTS NORTHEAST ACROSS PLAINS. ASSOCIATED INCREASE
IN SFC PRESSURE GRADIENT AND DIURNAL MIXING OF SHALLOW INVERSION
EXPECTED TO RESULT IN SOUTH WINDS WITH GUSTS AROUND OR SLIGHTLY
ABOVE 20 KT SUNDAY AFTERNOON.
RATZER
&&
.MARINE...
231 AM CST
REMNANT COLD FRONT CURRENTLY ACROSS THE FAR SOUTHERN PORTION OF
LAKE MICHIGAN IS EXPECTED TO TRANSITION TO A WARM FRONT TODAY AS A
LOW PRESSURE SYSTEM DEVELOPING IN EASTERN COLORADO TRACKS NORTH
THROUGH THE PLAINS. WITH THE WARMER AIR MOVING OVER THE
COOLER...STABLE MARINE LAYER IT WILL BE TOUGH FOR MANY GUSTS TO
MAKE IT DOWN TO THE SFC OF THE LAKE ON SUNDAY GIVEN THE SOUTHERLY
WINDS. HOWEVER...AS THIS LOW TRACKS THROUGH THE GREAT LAKES IT
WILL PULL A COLD FRONT ACROSS THE LAKE ON MONDAY. BEHIND THIS
FRONT...AN AREA OF HIGH PRESSURE WILL BE BUILDING IN FROM THE WEST
AND SHOULD SET UP A DECENT PRESSURE GRADIENT ACROSS THE LAKE
MONDAY NIGHT INTO EARLY TUESDAY. GIVEN THE PERSISTENT
NORTH TO NORTHEAST WINDS INTO TUESDAY...SHOULD SEE SOME DECENT
WAVES DEVELOPING ACROSS THE SOUTHERN RIM OF LAKE MICHIGAN WHICH
MAY PROMPT THE ISSUANCE OF A SMALL CRAFT ADVISORY. FOR NOW...BEING
THAT THE WINDS APPEAR MARGINAL AROUND 20KTS AND IT BEING OVER 36
HOURS AWAY...WILL HOLD OFF ON ISSUING ANYTHING.
AFTER THIS...HIGH PRESSURE APPEARS TO TAKE OVER THE GREAT LAKES
REGION THROUGH THE REST OF THE WEEK UNTIL IT SHIFTS OFF TOWARD THE
MID-ATLANTIC REGION AND THE SOUTHERLIES BUILD IN AGAIN.
HALBACH
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
000
FXUS63 KILX 080531
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1131 PM CST SAT NOV 7 2009
.DISCUSSION...
ISSUED 852 PM CST SAT NOV 7 2009
WEAK FRONTAL BOUNDARY ACRS NW IL NOT EXPECTED TO MAKE MUCH MORE
PROGRESS SOUTHEAST OVERNIGHT. LIGHT WINDS AND CLEAR SKIES HAVE
LED TO A QUICK TEMP DECLINCE OVER THE FORECAST AREA THIS EVENING
AS A RESULT...WL HAVE TO ADJUST THE OVERNIGHT LOWS DOWN A CATEGORY.
MAY SEE SOME PATCHY GROUND FOG FORM TOWARDS DAWN AS WELL WITH
THE LIGHT WIND REGIME BUT NOT EXPECTING ANYTHING WIDESPREAD OR
LONG LASTING IN THE MRNG. FRONTAL BOUNDARY SHOULD BEGIN SHIFTING
BACK NORTH AS A WARM FRONT TOMORROW AS UPPER LEVEL HEIGHTS BUILD
IN RESPONSE TO SHORTWAVE ENERGY PUSHING INTO THE PLAINS. NICE
WEATHER TO CONTINUE INTO MONDAY WITH UNSEASONABLY WARM TEMPS.
UPDATED ZONE FORECAST WILL BE OUT BY 915 PM.
&&
.AVIATION...
ISSUED 1125 PM CST SAT NOV 7 2009
LITTLE CHANGE FROM PREVIOUS DISCUSSION...MAIN FORECAST CONCERN WL
BE WITH GROUND FOG DEVELOPMENT IN THE EARLY MRNG HOURS. CURRENT
TEMP DEW POINT SPREADS LOWER ACRS THE NORTH...CLOSER TO A WEAK
STALLED FRONTAL BOUNDARY. FORECAST SOUNDINGS SHOWING PIA AND BMI
HAVING THE HIGHER PROBABILITIES OF SEEING A PERIOD OF MVFR VSBYS
IN FOG. MOISTURE IS VERY SHALLOW SO WHATEVER FOG DOES FORM SHOULD
DISSIPATE QUICKLY AT OR SHORTLY AFTER 15Z SUNDAY. SFC WNDS WL BE
LIGHT...MAINLY FROM A SE TO S DIRECTION AND INTO THE SOUTH AT ALL
TAF SITES ON SUNDAY WITH A FEW GUSTS JUST BELOW 20 KTS IN THE
AFTN.
SMITH
&&
.PREV DISCUSSION...
ISSUED 140 PM CST SAT NOV 7 2009
18Z SURFACE MAP SHOWING WEAK COLD FRONTAL BOUNDARY BEGINNING TO
ENTER FAR NORTHWEST ILLINOIS...EXTENDING SOUTHWEST TO NEAR KANSAS
CITY. TEMPERATURES HAVE SURGED INTO THE MID 70S ACROSS THE WESTERN
CWA EARLY THIS AFTERNOON...AND WERE AROUND 70 IN THE EAST. THE
ENTIRE REGION WAS DEVOID OF CLOUDS...ASIDE FROM A FEW CIRRUS
CLOUDS MOVING NORTHEAST ACROSS MISSOURI.
MAIN FORECAST ISSUES FOR THE DAY INVOLVE FRONTAL PASSAGES IN THE
MONDAY/TUESDAY TIME FRAME...AS WELL AS LATE NEXT WEEK.
SHORT TERM...TONIGHT THROUGH TUESDAY...
CURRENT COLD FRONT EXPECTED TO BECOME STATIONARY OVERNIGHT...NORTH
OF THE CWA...THEN LIFT BACK NORTH ON SUNDAY. ANOTHER UNSEASONABLY
MILD DAY IS ANTICIPATED ACROSS THE AREA ON SUNDAY...WITH HIGHS
AGAIN REACHING THE 70S. SKIES EXPECTED TO BECOME PARTLY CLOUDY
LATE TONIGHT AS THE FRONT APPROACHES...THEN CLEAR UP AGAIN ON
SUNDAY.
LOW PRESSURE EXPECTED TO FORM IN KANSAS ON SUNDAY AND MOVE
NORTHEAST INTO THE MIDWEST. A COLD FRONT WILL SHARPEN UP AS A
RESULT AS IT MOVES EAST TOWARD THE CWA. MODELS IN REASONABLE
AGREEMENT THROUGH 48 HOURS...THEN THE NAM BECOMES SHARPLY
DIVERGENT WITH THE SPEED OF THIS FRONT...AND RATHER GLARING WITH
ITS DIFFERENCES BY TUESDAY. WILL SIDE WITH THE SLOWER SUITE OF
GUIDANCE AS A RESULT...BRINGING THE FRONT THROUGH THE AREA MONDAY
NIGHT AND EXITING TUESDAY MORNING. EXTRATROPICAL LOW IN THE
NORTHERN GULF OF MEXICO TO PRECLUDE MUCH MOISTURE RETURN AHEAD OF
THE FRONT. WILL CONTINUE WITH SLIGHT CHANCES ACROSS THE NORTHWEST
CWA ON MONDAY...WITH RAIN CHANCES SPREADING OVER THE CWA MONDAY
NIGHT. SOUTHEAST CWA MAY STAY DRY UNTIL TUESDAY MORNING. DID BUMP
UP POPS A BIT MONDAY NIGHT INTO THE 40 PERCENT RANGE...PRIMARILY
WEST OF I-55. A CLEARING TREND IS EXPECTED ON TUESDAY AND TUESDAY
NIGHT...AS HIGH PRESSURE BUILDS INTO THE MID-MISSISSIPPI VALLEY
BEHIND THE FRONT.
LONG TERM...WEDNESDAY THROUGH SATURDAY...
UPPER LEVEL RIDGING TO ADVANCE EAST ACROSS THE CONUS MIDWEEK...AS
A TROUGH BEGINS TO DIG ACROSS THE WESTERN STATES IN RESPONSE TO
LEFTOVER ENERGY FROM A POWERFUL LOW MOVING SOUTHEAST FROM THE
GULF OF ALASKA. LONGER RANGE MODELS BEGIN TO DIVERGE SIGNIFICANTLY BY
FRIDAY. THE GFS IS RATHER AGRESSIVE IN DEVELOPING A STRONG UPPER
LOW ACROSS THE NORTHERN PLAINS...WITH SHARPLY COLDER CONDITIONS
SPREADING IN BEHIND A FRONT ON SATURDAY. MEANWHILE...THE NEWLY
ARRIVED ECMWF HAS A BOUNDARY OSCILLATING ACROSS THE AREA THROUGH
THE WEEKEND...BEFORE FINALLY PUSHING THROUGH SUNDAY EVENING. AT
THIS POINT...WILL SIDE MORE WITH THE ECMWF...KEEPING THE CWA DRY
THROUGH FRIDAY NIGHT AND INCLUDING ONLY SILENT 20 POPS FOR
SATURDAY AS THE MODELS TRY TO RESOLVE THEIR DIFFERENCES.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
000
FXUS63 KLOT 080511
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1111 PM CST SAT NOV 7 2009
.DISCUSSION...
858 PM...EVENING UPDATE...SEVERAL MINOR CONCERNS THIS EVENING
WHICH ALL SEEM TO HINGE ON FRONTAL MOVEMENT/LOCATION. THE COLD
FRONT WILL CONTINUE TO SAG INTO NORTHERN IL AND BECOME STATIONARY
OVERNIGHT...MOVING BACK NORTH AS A WARM FRONT SUNDAY. VISIBILITY
AT RFD HAS ALREADY DROPPED TO 1 3/4SM AND AS THE FRONT SLOWS AND
THEN STALLS...EXPECT MOISTURE TO POOL ALONG/AHEAD OF THE FRONT...
THUS AT LEAST PATCHY FOG WILL BE POSSIBLE...PERHAPS AREAS OF FOG
NEAR THE FRONT. NOT CONFIDENT ON HOW LOW VISIBILITIES WILL GO BUT
MOISTURE APPEARS TO BE QUITE SHALLOW WHICH SUGGESTS MAINLY GROUND
FOG. WILL NEED TO MONITOR TRENDS THROUGH THE NIGHT.
CLEAR SKIES AND LIGHT/CALM WINDS HAVE ALLOWED TEMPS TO DROP OFF
QUICKLY THIS EVENING...COLDEST SPOTS ALREADY IN THE LOWER 40S.
WITH DRIER AIR REMAINING NORTH OF THE FRONT...DON/T THINK LOWS
WILL DROP MUCH MORE THAN LOWER/MID 40S BY MORNING...BUT AGAIN A
LOT HINGES ON FRONTAL LOCATION. HAVE MODIFIED HOURLY GRIDS AND
LOWERED MIN TEMPS A FEW DEGREES. OTHERWISE...CLEAR THIS EVENING
WITH INCREASING THIN CIRRUS OVERNIGHT. CMS
PREVIOUS DISCUSSION...
308 PM CST
WITH MAX TEMPS SURGING TO THE LOWER 70S TODAY AND NOT A CLOUD IN
THE SKY...A PLEASANT DAY WAS IN STORE ACROSS MUCH OF THE REGION.
WITH AN ALREADY MILD START TO THE MORNING AND CLEAR SKIES ACROSS
THE AREA...BUMPED UP MAX TEMPS A COUPLE OF DEGREES TODAY. DESPITE
THE WINDY CONDITIONS FOR PART OF THE DAY TODAY...A WARMER AIR MASS
CONTINUED TO ADVECT INTO THE CWA...CREATING THE MAKINGS FOR A
BEAUTIFUL DAY.
SURFACE TROUGH ALONG WITH WEAK COLD FRONT KNOCKING ON OUR DOOR
JUST TO THE NORTHWEST OF THE CWA WITH TROUGH AXIS EXTENDING FROM
THE UPPER GREAT LAKES SOUTHWEST INTO SOUTHERN IOWA...AND COLD
FRONT EXTENDING INTO SOUTHERN NEBRASKA. SURFACE TROUGH FORECAST TO
EXIT OFF TO THE EAST TONIGHT...ALONG WITH PRESSURE GRADIENT
RELAXING...WILL RESULT IN WINDS CONTINUING TO DIMINISH. FRONT WILL
CONTINUE TO MAKE SOME PROGRESS SOUTHEAST INTO THE FAR NORTHWEST
PORTION OF THE CWA...BUT WITH UPPER LEVEL RIDGE BUILDING ACROSS
THE MIDWEST...WILL STALL TONIGHT. EVEN WITH THE APPROACH OF THIS
FRONT...SKIES WILL REMAIN CLEAR TONIGHT WITH DRIER AIR ALOFT.
ZONAL FLOW WILL TRANSITION TO MORE SOUTHWESTERLY FLOW ALOFT
TONIGHT...AND HELP LIFT THIS WEAK FRONT BACK NORTH ACROSS THE
UPPER MIDWEST EARLY SUNDAY. A SHORT WAVE TROUGH WITHIN THIS FLOW
EJECTING OUT OF THE CENTRAL PLAINS WILL HELP PRODUCE PRESSURE
FALLS AT THE SURFACE...WITH PRESSURE GRADIENT TAKING ON MORE
ORGANIZATION AND WINDS MAINTAINING A SOUTHERLY DIRECTION. THIS
WILL ALL RESULT IN ANOTHER WARM DAY ON SUNDAY WITH ONCE AGAIN
FORECAST HIGH TEMPS RISING INTO THE LOWER 70S.
CLOUD COVER AND PRECIP CHANCES BEGIN TO INCREASE ONCE AGAIN LATE
SUNDAY/EARLY MONDAY AS WEAK SURFACE LOW IS FORECAST TO TRACK
NORTHEAST ALONG THIS BOUNDARY. BUT WITH THIS SURFACE FEATURE
WEAKENING AS IT TRAVERSES THE UPPER MIDWEST...FRONT DOES NOT MAKE
MUCH PR OGRES. AREAS IN FAR NORTHERN ILLINOIS COULD POSSIBLY
OBSERVE EXTENDED CHANCES FOR RAINFALL INTO TUESDAY BEFORE LONG WAVE
TROUGH DIGS SOUTHEAST OUT OF CANADA AND PUSHES THIS FEATURE EAST
OUT OF THE CWA. HIGH PRESSURE BUILDING OUT OF THE CENTRAL PLAINS
BEHIND THIS SYSTEM WILL RETURN CLEAR SKIES AND MORE NORMAL TEMPS
BY MID WEEK.
RODRIGUEZ
&&
.AVIATION...
0600 UTC TAFS...MAIN SHORT TERM FORECAST ISSUE IS HAZE/FOG TRENDS
OVERNIGHT AND POTENTIAL FOR PATCHY/TEMPO MVFR/HIGH IFR VISIBILITY
REDUCTIONS.
AS NOTED IN PREVIOUS DISCUSSION...WEAK SFC TROUGH/COLD FRONT
DRIFTING SLOWLY SOUTHEAST ACROSS FCST AREA. WEAK GRADIENT/WIND FIELD
MAKING FRONT DIFFICULT TO ANALYZE HOWEVER...WITH MANY SFC OBS SITES
INDICATING CALM OR LGT/VRBL WINDS. WITH LIGHT WINDS...CLEAR SKIES
AND SHALLOW LOW LEVEL MOISTURE ALONG/VICINITY OF FRONT HAVE SEEN
PATCHY MVFR HAZE DEVELOP EARLIER THAN ANTICIPATED EARLIER THIS
EVENING. HOWEVER...00Z DVN SOUNDING INDICATES DRY AIR/LARGE DEW
POINT DEPRESSIONS JUST ABOVE SHALLOW SFC INVERSION...AND
ASCENT/DESCENT SOUNDINGS FROM KRFD AROUND 04Z ALSO DEPICT EXTREMELY
SHALLOW NATURE OF INVERSION. THUS...DESPITE DECENT JUXTAPOSITION OF
CONDITIONS FOR RADIATIONAL COOLING AND EARLY DEVELOPMENT OF FOG/HAZE
SUSPECT THAT CURRENT PATCHY AND SHALLOW NATURE OF FOG/HAZE WILL
CONTINUE THROUGH SUNDAY MORNING. BASED ON THIS HAVE MAINTAINED
GENERALLY A HIGHER MVFR RESTRICTION AT KORD/KMDW...WHILE MORE LOW
END MVFR/HIGH IFR FOR MORE CLIMATOLOGICALLY FAVORED KDPA/KRFD. IN
FACT KRFD HAS ALREADY BEEN BOUNCING BETWEEN 5 AND AS LOW AS 1 3/4
MILES DURING THE EVENING SO HAVE GONE LOWEST AROUND SUNRISE THERE.
FOG/HAZE SHOULD DISSIPATE BY MID MORNING.
OTHERWISE...WITH DRY AIRMASS FROM ABOVE BOUNDARY LAYER THROUGH MID
LEVELS LITTLE IN WAY OF CLOUD COVER THROUGH PERIOD...SAVE FOR
PATCHES OF HIGH LEVEL CIRRUS ASSOCIATED WITH MINOR AMPLITUDE
WAVES/JET STREAKS RIPPLING THROUGH RELATIVELY ZONAL FLOW ALOFT.
FRONT EXPECTED TO MIX BACK NORTH OF TERMINALS SUNDAY AS WEAK LOW
PRESSURE SYSTEM LIFTS NORTHEAST ACROSS PLAINS. ASSOCIATED INCREASE
IN SFC PRESSURE GRADIENT AND DIURNAL MIXING OF SHALLOW INVERSION
EXPECTED TO RESULT IN SOUTH WINDS WITH GUSTS AROUND OR SLIGHTLY
ABOVE 20 KT SUNDAY AFTERNOON.
RATZER
&&
.MARINE...
1148 AM CST
A LOW PRESSURE APPROACHING HUDSON BAY WILL CONTINUE TO TRACK
NORTHEAST TODAY AND TONIGHT. A TRAILING TROUGH OF LOW PRESSURE
WILL DROP SOUTHEASTWARD ACROSS LAKE MICHIGAN THIS AFTERNOON AS IT
SLOWLY WEAKENS. A WEAK RIDGE OF HIGH PRESSURE WILL THEN BUILD
ACROSS THE NORTHERN PLAINS...REACHING THE GREAT LAKES REGION
TONIGHT. ON SUNDAY...ANOTHER WEAK AREA OF LOW PRESSURE IS EXPECTED
LIFT FROM THE CENTRAL PLAINS STATES...NORTHEASTWARD ACROSS THE
UPPER MIDWEST. THIS WILL SWING WINDS BACK INTO THE S AND SE WITH
SPEEDS INCREASING INTO 15 TO 25 KT RANGE...BUT STAYING MUCH
LIGHTER THAN WINDS YESTERDAY AND LAST NIGHT. A MORE SIGNIFICANT
WEATHER DISTURBANCE WILL TO MOVE ACROSS SOUTHERN CANADA ON MONDAY.
IN RESPONSE...SFC HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN
PLAINS AND UPPER MISSISSIPPI VALLEY ALLOWING A STRONGER...MORE
SUSTAINED NORTH TO NORTHWEST AIR FLOW TO EVOLVE HEADING INTO MID
WEEK.
MERZLOCK
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
000
FXUS63 KLOT 080258
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
858 PM CST SAT NOV 7 2009
.DISCUSSION...
858 PM...EVENING UPDATE...SEVERAL MINOR CONCERNS THIS EVENING
WHICH ALL SEEM TO HINGE ON FRONTAL MOVEMENT/LOCATION. THE COLD
FRONT WILL CONTINUE TO SAG INTO NORTHERN IL AND BECOME STATIONARY
OVERNIGHT...MOVING BACK NORTH AS A WARM FRONT SUNDAY. VISIBILITY
AT RFD HAS ALREADY DROPPED TO 1 3/4SM AND AS THE FRONT SLOWS AND
THEN STALLS...EXPECT MOISTURE TO POOL ALONG/AHEAD OF THE FRONT...
THUS AT LEAST PATCHY FOG WILL BE POSSIBLE...PERHAPS AREAS OF FOG
NEAR THE FRONT. NOT CONFIDENT ON HOW LOW VISIBILITIES WILL GO BUT
MOISTURE APPEARS TO BE QUITE SHALLOW WHICH SUGGESTS MAINLY GROUND
FOG. WILL NEED TO MONITOR TRENDS THROUGH THE NIGHT.
CLEAR SKIES AND LIGHT/CALM WINDS HAVE ALLOWED TEMPS TO DROP OFF
QUICKLY THIS EVENING...COLDEST SPOTS ALREADY IN THE LOWER 40S.
WITH DRIER AIR REMAINING NORTH OF THE FRONT...DON/T THINK LOWS
WILL DROP MUCH MORE THAN LOWER/MID 40S BY MORNING...BUT AGAIN A
LOT HINGES ON FRONTAL LOCATION. HAVE MODIFIED HOURLY GRIDS AND
LOWERED MIN TEMPS A FEW DEGREES. OTHERWISE...CLEAR THIS EVENING
WITH INCREASING THIN CIRRUS OVERNIGHT. CMS
PREVIOUS DISCUSSION...
308 PM CST
WITH MAX TEMPS SURGING TO THE LOWER 70S TODAY AND NOT A CLOUD IN
THE SKY...A PLEASANT DAY WAS IN STORE ACROSS MUCH OF THE REGION.
WITH AN ALREADY MILD START TO THE MORNING AND CLEAR SKIES ACROSS
THE AREA...BUMPED UP MAX TEMPS A COUPLE OF DEGREES TODAY. DESPITE
THE WINDY CONDITIONS FOR PART OF THE DAY TODAY...A WARMER AIR MASS
CONTINUED TO ADVECT INTO THE CWA...CREATING THE MAKINGS FOR A
BEAUTIFUL DAY.
SURFACE TROUGH ALONG WITH WEAK COLD FRONT KNOCKING ON OUR DOOR
JUST TO THE NORTHWEST OF THE CWA WITH TROUGH AXIS EXTENDING FROM
THE UPPER GREAT LAKES SOUTHWEST INTO SOUTHERN IOWA...AND COLD
FRONT EXTENDING INTO SOUTHERN NEBRASKA. SURFACE TROUGH FORECAST TO
EXIT OFF TO THE EAST TONIGHT...ALONG WITH PRESSURE GRADIENT
RELAXING...WILL RESULT IN WINDS CONTINUING TO DIMINISH. FRONT WILL
CONTINUE TO MAKE SOME PROGRESS SOUTHEAST INTO THE FAR NORTHWEST
PORTION OF THE CWA...BUT WITH UPPER LEVEL RIDGE BUILDING ACROSS
THE MIDWEST...WILL STALL TONIGHT. EVEN WITH THE APPROACH OF THIS
FRONT...SKIES WILL REMAIN CLEAR TONIGHT WITH DRIER AIR ALOFT.
ZONAL FLOW WILL TRANSITION TO MORE SOUTHWESTERLY FLOW ALOFT
TONIGHT...AND HELP LIFT THIS WEAK FRONT BACK NORTH ACROSS THE
UPPER MIDWEST EARLY SUNDAY. A SHORT WAVE TROUGH WITHIN THIS FLOW
EJECTING OUT OF THE CENTRAL PLAINS WILL HELP PRODUCE PRESSURE
FALLS AT THE SURFACE...WITH PRESSURE GRADIENT TAKING ON MORE
ORGANIZATION AND WINDS MAINTAINING A SOUTHERLY DIRECTION. THIS
WILL ALL RESULT IN ANOTHER WARM DAY ON SUNDAY WITH ONCE AGAIN
FORECAST HIGH TEMPS RISING INTO THE LOWER 70S.
CLOUD COVER AND PRECIP CHANCES BEGIN TO INCREASE ONCE AGAIN LATE
SUNDAY/EARLY MONDAY AS WEAK SURFACE LOW IS FORECAST TO TRACK
NORTHEAST ALONG THIS BOUNDARY. BUT WITH THIS SURFACE FEATURE
WEAKENING AS IT TRAVERSES THE UPPER MIDWEST...FRONT DOES NOT MAKE
MUCH PR OGRES. AREAS IN FAR NORTHERN ILLINOIS COULD POSSIBLY
OBSERVE EXTENDED CHANCES FOR RAINFALL INTO TUESDAY BEFORE LONG WAVE
TROUGH DIGS SOUTHEAST OUT OF CANADA AND PUSHES THIS FEATURE EAST
OUT OF THE CWA. HIGH PRESSURE BUILDING OUT OF THE CENTRAL PLAINS
BEHIND THIS SYSTEM WILL RETURN CLEAR SKIES AND MORE NORMAL TEMPS
BY MID WEEK.
RODRIGUEZ
&&
.AVIATION...
0000 UTC TAFS...MAIN CONCERNS FOR AVIATION FORECASTS THIS EVENING
DEAL WITH WEAK TROF/COLD FRONTAL PASSAGE THIS EVENING...HAZE/FOG
POTENTIAL EARLY SUNDAY AND RETURN TO GUSTY SOUTH WINDS SUNDAY
AFTERNOON.
LATEST SFC ANALYSIS DEPICTS WEAK SFC TROF/FRONT DRIFTING SOUTHEAST
ACROSS NORTHWEST IL/CENTRAL WI. DIURNAL DECOUPLING ALREADY TAKING
PLACE WITH WIND SPEEDS BECOMING LIGHT/VARIABLE OR CALM...SO WIND
SHIFT EXPECTED TO BE RATHER BENIGN...THOUGH OVERALL VEERING FROM
LIGHT WEST TO LIGHT EASTERLY EXPECTED DURING LATE EVENING/OVERNIGHT
HOURS AND WITH CURRENT WEAK WIND FIELD...LIGHT AND VARIABLE SEEMS
SUFFICIENT THROUGH EARLY SUNDAY.
MAINLY CLEAR SKIES COUPLED LIGHT/CALM WINDS WILL ALLOW FOR GOOD
RADIATIONAL COOLING CONDITIONS...WHICH ALONG WITH EXISTING ALTHOUGH
LIMITED MOISTURE IN VICINITY OF STALLING TROUGH/FRONT WILL LIKELY
SUPPORT AT LEAST SOME POTENTIAL FOR PATCHY HAZE/SHALLOW FOG
ESPECIALLY AT LESS URBANIZED TERMINALS. WRF/NAM GUIDANCE ACTUALLY
DEPICTS LIFR VISIBILITY CONDITIONS DEVELOPING BY SUNRISE...THOUGH
BOUNDARY LAYER MOISTURE PROFILE OF WRF FORECAST SOUNDINGS APPEARS
SUSPECT IN DEVELOPING SUCH IMPRESSIVE SATURATION. THUS HAVE
STAYED CLOSE TO PREVIOUS FORECAST TREND/MAV GUIDANCE WHICH WOULD
SUGGEST HIGHER END MVFR VISIBILITY CONDITIONS. DIURNAL MIXING
AFTER SUNRISE SHOULD ALLOW FOG/HAZE TO DISSIPATE BY MID MORNING.
WEAK LOW PRESSURE WAVE LIFTING NORTHEAST ACROSS PLAINS SUNDAY
EXPECTED TO TIGHTEN SFC PRESSURE GRADIENT AND LIFT FRONT BACK NORTH
OF TERMINALS BY AFTERNOON. THIS SUPPORTS SHIFT BACK TO SOUTH...WITH
FORECAST SOUNDINGS INDICATING BOUNDARY LAYER WINDS SUPPORTING GUSTS
ABOVE 20 KTS BY MID/LATE AFTERNOON.
GUSEMAN/RATZER
&&
.MARINE...
1148 AM CST
A LOW PRESSURE APPROACHING HUDSON BAY WILL CONTINUE TO TRACK
NORTHEAST TODAY AND TONIGHT. A TRAILING TROUGH OF LOW PRESSURE
WILL DROP SOUTHEASTWARD ACROSS LAKE MICHIGAN THIS AFTERNOON AS IT
SLOWLY WEAKENS. A WEAK RIDGE OF HIGH PRESSURE WILL THEN BUILD
ACROSS THE NORTHERN PLAINS...REACHING THE GREAT LAKES REGION
TONIGHT. ON SUNDAY...ANOTHER WEAK AREA OF LOW PRESSURE IS EXPECTED
LIFT FROM THE CENTRAL PLAINS STATES...NORTHEASTWARD ACROSS THE
UPPER MIDWEST. THIS WILL SWING WINDS BACK INTO THE S AND SE WITH
SPEEDS INCREASING INTO 15 TO 25 KT RANGE...BUT STAYING MUCH
LIGHTER THAN WINDS YESTERDAY AND LAST NIGHT. A MORE SIGNIFICANT
WEATHER DISTURBANCE WILL TO MOVE ACROSS SOUTHERN CANADA ON MONDAY.
IN RESPONSE...SFC HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN
PLAINS AND UPPER MISSISSIPPI VALLEY ALLOWING A STRONGER...MORE
SUSTAINED NORTH TO NORTHWEST AIR FLOW TO EVOLVE HEADING INTO MID
WEEK.
MERZLOCK
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
000
FXUS63 KILX 080255
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
855 PM CST SAT NOV 7 2009
.DISCUSSION...
ISSUED 852 PM CST SAT NOV 7 2009
WEAK FRONTAL BOUNDARY ACRS NW IL NOT EXPECTED TO MAKE MUCH MORE
PROGRESS SOUTHEAST OVERNIGHT. LIGHT WINDS AND CLEAR SKIES HAVE
LED TO A QUICK TEMP DECLINCE OVER THE FORECAST AREA THIS EVENING
AS A RESULT...WL HAVE TO ADJUST THE OVERNIGHT LOWS DOWN A CATEGORY.
MAY SEE SOME PATCHY GROUND FOG FORM TOWARDS DAWN AS WELL WITH
THE LIGHT WIND REGIME BUT NOT EXPECTING ANYTHING WIDESPREAD OR
LONG LASTING IN THE MRNG. FRONTAL BOUNDARY SHOULD BEGIN SHIFTING
BACK NORTH AS A WARM FRONT TOMORROW AS UPPER LEVEL HEIGHTS BUILD
IN RESPONSE TO SHORTWAVE ENERGY PUSHING INTO THE PLAINS. NICE
WEATHER TO CONTINUE INTO MONDAY WITH UNSEASONABLY WARM TEMPS.
UPDATED ZONE FORECAST WILL BE OUT BY 915 PM.
SMITH
&&
.AVIATION...
ISSUED 515 PM CST SAT NOV 7 2009
MAIN FORECAST CONCERN WILL BE WITH THE POTENTIAL FOR SOME GROUND
FOG DEVELOPMENT AFTR 09Z TNT. OTHERWISE...VFR CONDITIONS ARE
EXPECTED FOR THE REMAINDER OF THIS FORECAST PERIOD. WEAK FRONTAL
BOUNDARY JUST TO OUR WEST IS EXPECTED TO HOLD NEARLY STATIONARY
OVERNIGHT BEFORE RETURNING NWD AS A WARM FRONT TOMORROW. SFC WNDS
HAVE DECREASED CONSIDERABLY OVER THE PAST 12 TO 18 HOURS AND EXPCT
LIGHT SE WINDS AND MOSTLY CLEAR SKIES TNT INTO SUN MRNG. AS THE
FRONT SHIFTS WELL NORTH OF OUR AREA ON SUNDAY...SURFACE WINDS WL
INCREASE OUT OF THE SOUTH BY LATE MRNG WITH A FEW GUSTS ARND 20 KTS.
SMITH
&&
.PREV DISCUSSION...
ISSUED 140 PM CST SAT NOV 7 2009
18Z SURFACE MAP SHOWING WEAK COLD FRONTAL BOUNDARY BEGINNING TO
ENTER FAR NORTHWEST ILLINOIS...EXTENDING SOUTHWEST TO NEAR KANSAS
CITY. TEMPERATURES HAVE SURGED INTO THE MID 70S ACROSS THE WESTERN
CWA EARLY THIS AFTERNOON...AND WERE AROUND 70 IN THE EAST. THE
ENTIRE REGION WAS DEVOID OF CLOUDS...ASIDE FROM A FEW CIRRUS
CLOUDS MOVING NORTHEAST ACROSS MISSOURI.
MAIN FORECAST ISSUES FOR THE DAY INVOLVE FRONTAL PASSAGES IN THE
MONDAY/TUESDAY TIME FRAME...AS WELL AS LATE NEXT WEEK.
SHORT TERM...TONIGHT THROUGH TUESDAY...
CURRENT COLD FRONT EXPECTED TO BECOME STATIONARY OVERNIGHT...NORTH
OF THE CWA...THEN LIFT BACK NORTH ON SUNDAY. ANOTHER UNSEASONABLY
MILD DAY IS ANTICIPATED ACROSS THE AREA ON SUNDAY...WITH HIGHS
AGAIN REACHING THE 70S. SKIES EXPECTED TO BECOME PARTLY CLOUDY
LATE TONIGHT AS THE FRONT APPROACHES...THEN CLEAR UP AGAIN ON
SUNDAY.
LOW PRESSURE EXPECTED TO FORM IN KANSAS ON SUNDAY AND MOVE
NORTHEAST INTO THE MIDWEST. A COLD FRONT WILL SHARPEN UP AS A
RESULT AS IT MOVES EAST TOWARD THE CWA. MODELS IN REASONABLE
AGREEMENT THROUGH 48 HOURS...THEN THE NAM BECOMES SHARPLY
DIVERGENT WITH THE SPEED OF THIS FRONT...AND RATHER GLARING WITH
ITS DIFFERENCES BY TUESDAY. WILL SIDE WITH THE SLOWER SUITE OF
GUIDANCE AS A RESULT...BRINGING THE FRONT THROUGH THE AREA MONDAY
NIGHT AND EXITING TUESDAY MORNING. EXTRATROPICAL LOW IN THE
NORTHERN GULF OF MEXICO TO PRECLUDE MUCH MOISTURE RETURN AHEAD OF
THE FRONT. WILL CONTINUE WITH SLIGHT CHANCES ACROSS THE NORTHWEST
CWA ON MONDAY...WITH RAIN CHANCES SPREADING OVER THE CWA MONDAY
NIGHT. SOUTHEAST CWA MAY STAY DRY UNTIL TUESDAY MORNING. DID BUMP
UP POPS A BIT MONDAY NIGHT INTO THE 40 PERCENT RANGE...PRIMARILY
WEST OF I-55. A CLEARING TREND IS EXPECTED ON TUESDAY AND TUESDAY
NIGHT...AS HIGH PRESSURE BUILDS INTO THE MID-MISSISSIPPI VALLEY
BEHIND THE FRONT.
LONG TERM...WEDNESDAY THROUGH SATURDAY...
UPPER LEVEL RIDGING TO ADVANCE EAST ACROSS THE CONUS MIDWEEK...AS
A TROUGH BEGINS TO DIG ACROSS THE WESTERN STATES IN RESPONSE TO
LEFTOVER ENERGY FROM A POWERFUL LOW MOVING SOUTHEAST FROM THE
GULF OF ALASKA. LONGER RANGE MODELS BEGIN TO DIVERGE SIGNIFICANTLY BY
FRIDAY. THE GFS IS RATHER AGRESSIVE IN DEVELOPING A STRONG UPPER
LOW ACROSS THE NORTHERN PLAINS...WITH SHARPLY COLDER CONDITIONS
SPREADING IN BEHIND A FRONT ON SATURDAY. MEANWHILE...THE NEWLY
ARRIVED ECMWF HAS A BOUNDARY OSCILLATING ACROSS THE AREA THROUGH
THE WEEKEND...BEFORE FINALLY PUSHING THROUGH SUNDAY EVENING. AT
THIS POINT...WILL SIDE MORE WITH THE ECMWF...KEEPING THE CWA DRY
THROUGH FRIDAY NIGHT AND INCLUDING ONLY SILENT 20 POPS FOR
SATURDAY AS THE MODELS TRY TO RESOLVE THEIR DIFFERENCES.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
000
FXUS63 KLOT 080103 CCA
AFDLOT
AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
702 PM CST SAT NOV 7 2009
.DISCUSSION...
308 PM CST
WITH MAX TEMPS SURGING TO THE LOWER 70S TODAY AND NOT A CLOUD IN
THE SKY...A PLEASANT DAY WAS IN STORE ACROSS MUCH OF THE REGION.
WITH AN ALREADY MILD START TO THE MORNING AND CLEAR SKIES ACROSS
THE AREA...BUMPED UP MAX TEMPS A COUPLE OF DEGREES TODAY. DESPITE
THE WINDY CONDITIONS FOR PART OF THE DAY TODAY...A WARMER AIR MASS
CONTINUED TO ADVECT INTO THE CWA...CREATING THE MAKINGS FOR A
BEAUTIFUL DAY.
SURFACE TROUGH ALONG WITH WEAK COLD FRONT KNOCKING ON OUR DOOR
JUST TO THE NORTHWEST OF THE CWA WITH TROUGH AXIS EXTENDING FROM
THE UPPER GREAT LAKES SOUTHWEST INTO SOUTHERN IOWA...AND COLD
FRONT EXTENDING INTO SOUTHERN NEBRASKA. SURFACE TROUGH FORECAST TO
EXIT OFF TO THE EAST TONIGHT...ALONG WITH PRESSURE GRADIENT
RELAXING...WILL RESULT IN WINDS CONTINUING TO DIMINISH. FRONT WILL
CONTINUE TO MAKE SOME PROGRESS SOUTHEAST INTO THE FAR NORTHWEST
PORTION OF THE CWA...BUT WITH UPPER LEVEL RIDGE BUILDING ACROSS
THE MIDWEST...WILL STALL TONIGHT. EVEN WITH THE APPROACH OF THIS
FRONT...SKIES WILL REMAIN CLEAR TONIGHT WITH DRIER AIR ALOFT.
ZONAL FLOW WILL TRANSITION TO MORE SOUTHWESTERLY FLOW ALOFT
TONIGHT...AND HELP LIFT THIS WEAK FRONT BACK NORTH ACROSS THE
UPPER MIDWEST EARLY SUNDAY. A SHORT WAVE TROUGH WITHIN THIS FLOW
EJECTING OUT OF THE CENTRAL PLAINS WILL HELP PRODUCE PRESSURE
FALLS AT THE SURFACE...WITH PRESSURE GRADIENT TAKING ON MORE
ORGANIZATION AND WINDS MAINTAINING A SOUTHERLY DIRECTION. THIS
WILL ALL RESULT IN ANOTHER WARM DAY ON SUNDAY WITH ONCE AGAIN
FORECAST HIGH TEMPS RISING INTO THE LOWER 70S.
CLOUD COVER AND PRECIP CHANCES BEGIN TO INCREASE ONCE AGAIN LATE
SUNDAY/EARLY MONDAY AS WEAK SURFACE LOW IS FORECAST TO TRACK
NORTHEAST ALONG THIS BOUNDARY. BUT WITH THIS SURFACE FEATURE
WEAKENING AS IT TRAVERSES THE UPPER MIDWEST...FRONT DOES NOT MAKE
MUCH PR OGRES. AREAS IN FAR NORTHERN ILLINOIS COULD POSSIBLY
OBSERVE EXTENDED CHANCES FOR RAINFALL INTO TUESDAY BEFORE LONG WAVE
TROUGH DIGS SOUTHEAST OUT OF CANADA AND PUSHES THIS FEATURE EAST
OUT OF THE CWA. HIGH PRESSURE BUILDING OUT OF THE CENTRAL PLAINS
BEHIND THIS SYSTEM WILL RETURN CLEAR SKIES AND MORE NORMAL TEMPS
BY MID WEEK.
RODRIGUEZ
&&
.AVIATION...
0000 UTC TAFS...MAIN CONCERNS FOR AVIATION FORECASTS THIS EVENING
DEAL WITH WEAK TROF/COLD FRONTAL PASSAGE THIS EVENING...HAZE/FOG
POTENTIAL EARLY SUNDAY AND RETURN TO GUSTY SOUTH WINDS SUNDAY
AFTERNOON.
LATEST SFC ANALYSIS DEPICTS WEAK SFC TROF/FRONT DRIFTING SOUTHEAST
ACROSS NORTHWEST IL/CENTRAL WI. DIURNAL DECOUPLING ALREADY TAKING
PLACE WITH WIND SPEEDS BECOMING LIGHT/VARIABLE OR CALM...SO WIND
SHIFT EXPECTED TO BE RATHER BENIGN...THOUGH OVERALL VEERING FROM
LIGHT WEST TO LIGHT EASTERLY EXPECTED DURING LATE EVENING/OVERNIGHT
HOURS AND WITH CURRENT WEAK WIND FIELD...LIGHT AND VARIABLE SEEMS
SUFFICIENT THROUGH EARLY SUNDAY.
MAINLY CLEAR SKIES COUPLED LIGHT/CALM WINDS WILL ALLOW FOR GOOD
RADIATIONAL COOLING CONDITIONS...WHICH ALONG WITH EXISTING ALTHOUGH
LIMITED MOISTURE IN VICINITY OF STALLING TROUGH/FRONT WILL LIKELY
SUPPORT AT LEAST SOME POTENTIAL FOR PATCHY HAZE/SHALLOW FOG
ESPECIALLY AT LESS URBANIZED TERMINALS. WRF/NAM GUIDANCE ACTUALLY
DEPICTS LIFR VISIBILITY CONDITIONS DEVELOPING BY SUNRISE...THOUGH
BOUNDARY LAYER MOISTURE PROFILE OF WRF FORECAST SOUNDINGS APPEARS
SUSPECT IN DEVELOPING SUCH IMPRESSIVE SATURATION. THUS HAVE
STAYED CLOSE TO PREVIOUS FORECAST TREND/MAV GUIDANCE WHICH WOULD
SUGGEST HIGHER END MVFR VISIBILITY CONDITIONS. DIURNAL MIXING
AFTER SUNRISE SHOULD ALLOW FOG/HAZE TO DISSIPATE BY MID MORNING.
WEAK LOW PRESSURE WAVE LIFTING NORTHEAST ACROSS PLAINS SUNDAY
EXPECTED TO TIGHTEN SFC PRESSURE GRADIENT AND LIFT FRONT BACK NORTH
OF TERMINALS BY AFTERNOON. THIS SUPPORTS SHIFT BACK TO SOUTH...WITH
FORECAST SOUNDINGS INDICATING BOUNDARY LAYER WINDS SUPPORTING GUSTS
ABOVE 20 KTS BY MID/LATE AFTERNOON.
GUSEMAN/RATZER
RATZER
&&
.MARINE...
1148 AM CST
A LOW PRESSURE APPROACHING HUDSON BAY WILL CONTINUE TO TRACK
NORTHEAST TODAY AND TONIGHT. A TRAILING TROUGH OF LOW PRESSURE
WILL DROP SOUTHEASTWARD ACROSS LAKE MICHIGAN THIS AFTERNOON AS IT
SLOWLY WEAKENS. A WEAK RIDGE OF HIGH PRESSURE WILL THEN BUILD
ACROSS THE NORTHERN PLAINS...REACHING THE GREAT LAKES REGION
TONIGHT. ON SUNDAY...ANOTHER WEAK AREA OF LOW PRESSURE IS EXPECTED
LIFT FROM THE CENTRAL PLAINS STATES...NORTHEASTWARD ACROSS THE
UPPER MIDWEST. THIS WILL SWING WINDS BACK INTO THE S AND SE WITH
SPEEDS INCREASING INTO 15 TO 25 KT RANGE...BUT STAYING MUCH
LIGHTER THAN WINDS YESTERDAY AND LAST NIGHT. A MORE SIGNIFICANT
WEATHER DISTURBANCE WILL TO MOVE ACROSS SOUTHERN CANADA ON MONDAY.
IN RESPONSE...SFC HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN
PLAINS AND UPPER MISSISSIPPI VALLEY ALLOWING A STRONGER...MORE
SUSTAINED NORTH TO NORTHWEST AIR FLOW TO EVOLVE HEADING INTO MID
WEEK.
MERZLOCK
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
000
FXUS63 KLOT 080038
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
638 PM CST SAT NOV 7 2009
.DISCUSSION...
308 PM CST
WITH MAX TEMPS SURGING TO THE LOWER 70S TODAY AND NOT A CLOUD IN
THE SKY...A PLEASANT DAY WAS IN STORE ACROSS MUCH OF THE REGION.
WITH AN ALREADY MILD START TO THE MORNING AND CLEAR SKIES ACROSS
THE AREA...BUMPED UP MAX TEMPS A COUPLE OF DEGREES TODAY. DESPITE
THE WINDY CONDITIONS FOR PART OF THE DAY TODAY...A WARMER AIR MASS
CONTINUED TO ADVECT INTO THE CWA...CREATING THE MAKINGS FOR A
BEAUTIFUL DAY.
SURFACE TROUGH ALONG WITH WEAK COLD FRONT KNOCKING ON OUR DOOR
JUST TO THE NORTHWEST OF THE CWA WITH TROUGH AXIS EXTENDING FROM
THE UPPER GREAT LAKES SOUTHWEST INTO SOUTHERN IOWA...AND COLD
FRONT EXTENDING INTO SOUTHERN NEBRASKA. SURFACE TROUGH FORECAST TO
EXIT OFF TO THE EAST TONIGHT...ALONG WITH PRESSURE GRADIENT
RELAXING...WILL RESULT IN WINDS CONTINUING TO DIMINISH. FRONT WILL
CONTINUE TO MAKE SOME PROGRESS SOUTHEAST INTO THE FAR NORTHWEST
PORTION OF THE CWA...BUT WITH UPPER LEVEL RIDGE BUILDING ACROSS
THE MIDWEST...WILL STALL TONIGHT. EVEN WITH THE APPROACH OF THIS
FRONT...SKIES WILL REMAIN CLEAR TONIGHT WITH DRIER AIR ALOFT.
ZONAL FLOW WILL TRANSITION TO MORE SOUTHWESTERLY FLOW ALOFT
TONIGHT...AND HELP LIFT THIS WEAK FRONT BACK NORTH ACROSS THE
UPPER MIDWEST EARLY SUNDAY. A SHORT WAVE TROUGH WITHIN THIS FLOW
EJECTING OUT OF THE CENTRAL PLAINS WILL HELP PRODUCE PRESSURE
FALLS AT THE SURFACE...WITH PRESSURE GRADIENT TAKING ON MORE
ORGANIZATION AND WINDS MAINTAINING A SOUTHERLY DIRECTION. THIS
WILL ALL RESULT IN ANOTHER WARM DAY ON SUNDAY WITH ONCE AGAIN
FORECAST HIGH TEMPS RISING INTO THE LOWER 70S.
CLOUD COVER AND PRECIP CHANCES BEGIN TO INCREASE ONCE AGAIN LATE
SUNDAY/EARLY MONDAY AS WEAK SURFACE LOW IS FORECAST TO TRACK
NORTHEAST ALONG THIS BOUNDARY. BUT WITH THIS SURFACE FEATURE
WEAKENING AS IT TRAVERSES THE UPPER MIDWEST...FRONT DOES NOT MAKE
MUCH PR OGRES. AREAS IN FAR NORTHERN ILLINOIS COULD POSSIBLY
OBSERVE EXTENDED CHANCES FOR RAINFALL INTO TUESDAY BEFORE LONG WAVE
TROUGH DIGS SOUTHEAST OUT OF CANADA AND PUSHES THIS FEATURE EAST
OUT OF THE CWA. HIGH PRESSURE BUILDING OUT OF THE CENTRAL PLAINS
BEHIND THIS SYSTEM WILL RETURN CLEAR SKIES AND MORE NORMAL TEMPS
BY MID WEEK.
RODRIGUEZ
&&
.AVIATION...
0000 UTC TAFS...MAIN CONCERNS FOR AVIATION FORECASTS THIS EVENING
DEAL WITH WEAK TROF/COLD FRONTAL PASSAGE THIS EVENING...HAZE/FOG
POTENTIAL EARLY SUNDAY AND RETURN TO GUSTY SOUTH WINDS SUNDAY
AFTERNOON.
LATEST SFC ANALYSIS DEPICTS WEAK SFC TROF/FRONT DRIFTING SOUTHEAST
ACROSS NORTHWEST IL/CENTRAL WI. DIURNAL DECOUPLING ALREADY TAKING
PLACE WITH WIND SPEEDS BECOMING LIGHT/VARIABLE OR CALM...SO WIND
SHIFT EXPECTED TO BE RATHER BENIGN...THOUGH OVERALL VEERING FROM
LIGHT WEST TO LIGHT EASTERLY EXPECTED DURING LATE EVENING/OVERNIGHT
HOURS AND WITH CURRENT WEAK WIND FIELD...LIGHT AND VARIABLE SEEMS
SUFFICIENT THROUGH EARLY SUNDAY.
MAINLY CLEAR SKIES COUPLED LIGHT/CALM WINDS WILL ALLOW FOR GOOD
RADIATIONAL COOLING CONDITIONS...WHICH ALONG WITH EXISTING THOUGH
LIMITED MOISTURE IN VICINITY OF STALLING TROUGH/FRONT WILL LIKELY
SUPPORT AT LEAST SOME POTENTIAL FOR PATCHY HAZE/SHALLOW FOG
ESPECIALLY AT LESS URBANIZED TERMINALS. WRF/NAM GUIDANCE ACTUALLY
DEPICTS LIFR VISIBILITY CONDITIONS DEVELOPING BY SUNRISE...THOUGH
BOUNDARY LAYER MOISTURE PROFILE OF WRF FORECAST SOUNDINGS APPEARS
SUSPECT IN DEVELOP SUCH IMPRESSIVE SATURATION. THUS HAVE STAYED
CLOSE TO PREVIOUS FORECAST TREND/MAV GUIDANCE WHICH WOULD SUGGEST
HIGHER END MVFR VISIBILITY CONDITIONS. DIURNAL MIXING AFTER SUNRISE
SHOULD ALLOW FOG/HAZE TO DISSIPATE BY MID MORNING.
WEAK LOW PRESSURE WAVE LIFTING NORTHEAST ACROSS PLAINS SUNDAY
EXPECTED TO TIGHTEN SFC PRESSURE GRADIENT AND LIFT FRONT BACK NORTH
OF TERMINALS BY AFTERNOON. THIS SUPPORTS SHIFT BACK TO SOUTH...WITH
FORECAST SOUNDINGS INDICATING BOUNDARY LAYER WINDS SUPPORTING GUSTS
ABOVE 20 KTS BY MID/LATE AFTERNOON.
GUSEMAN/RATZER
RATZER
&&
.MARINE...
1148 AM CST
A LOW PRESSURE APPROACHING HUDSON BAY WILL CONTINUE TO TRACK
NORTHEAST TODAY AND TONIGHT. A TRAILING TROUGH OF LOW PRESSURE
WILL DROP SOUTHEASTWARD ACROSS LAKE MICHIGAN THIS AFTERNOON AS IT
SLOWLY WEAKENS. A WEAK RIDGE OF HIGH PRESSURE WILL THEN BUILD
ACROSS THE NORTHERN PLAINS...REACHING THE GREAT LAKES REGION
TONIGHT. ON SUNDAY...ANOTHER WEAK AREA OF LOW PRESSURE IS EXPECTED
LIFT FROM THE CENTRAL PLAINS STATES...NORTHEASTWARD ACROSS THE
UPPER MIDWEST. THIS WILL SWING WINDS BACK INTO THE S AND SE WITH
SPEEDS INCREASING INTO 15 TO 25 KT RANGE...BUT STAYING MUCH
LIGHTER THAN WINDS YESTERDAY AND LAST NIGHT. A MORE SIGNIFICANT
WEATHER DISTURBANCE WILL TO MOVE ACROSS SOUTHERN CANADA ON MONDAY.
IN RESPONSE...SFC HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN
PLAINS AND UPPER MISSISSIPPI VALLEY ALLOWING A STRONGER...MORE
SUSTAINED NORTH TO NORTHWEST AIR FLOW TO EVOLVE HEADING INTO MID
WEEK.
MERZLOCK
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
000
FXUS63 KILX 072325
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
525 PM CST SAT NOV 7 2009
.DISCUSSION...
ISSUED 140 PM CST SAT NOV 7 2009
18Z SURFACE MAP SHOWING WEAK COLD FRONTAL BOUNDARY BEGINNING TO
ENTER FAR NORTHWEST ILLINOIS...EXTENDING SOUTHWEST TO NEAR KANSAS
CITY. TEMPERATURES HAVE SURGED INTO THE MID 70S ACROSS THE WESTERN
CWA EARLY THIS AFTERNOON...AND WERE AROUND 70 IN THE EAST. THE
ENTIRE REGION WAS DEVOID OF CLOUDS...ASIDE FROM A FEW CIRRUS
CLOUDS MOVING NORTHEAST ACROSS MISSOURI.
MAIN FORECAST ISSUES FOR THE DAY INVOLVE FRONTAL PASSAGES IN THE
MONDAY/TUESDAY TIME FRAME...AS WELL AS LATE NEXT WEEK.
SHORT TERM...TONIGHT THROUGH TUESDAY...
CURRENT COLD FRONT EXPECTED TO BECOME STATIONARY OVERNIGHT...NORTH
OF THE CWA...THEN LIFT BACK NORTH ON SUNDAY. ANOTHER UNSEASONABLY
MILD DAY IS ANTICIPATED ACROSS THE AREA ON SUNDAY...WITH HIGHS
AGAIN REACHING THE 70S. SKIES EXPECTED TO BECOME PARTLY CLOUDY
LATE TONIGHT AS THE FRONT APPROACHES...THEN CLEAR UP AGAIN ON
SUNDAY.
LOW PRESSURE EXPECTED TO FORM IN KANSAS ON SUNDAY AND MOVE
NORTHEAST INTO THE MIDWEST. A COLD FRONT WILL SHARPEN UP AS A
RESULT AS IT MOVES EAST TOWARD THE CWA. MODELS IN REASONABLE
AGREEMENT THROUGH 48 HOURS...THEN THE NAM BECOMES SHARPLY
DIVERGENT WITH THE SPEED OF THIS FRONT...AND RATHER GLARING WITH
ITS DIFFERENCES BY TUESDAY. WILL SIDE WITH THE SLOWER SUITE OF
GUIDANCE AS A RESULT...BRINGING THE FRONT THROUGH THE AREA MONDAY
NIGHT AND EXITING TUESDAY MORNING. EXTRATROPICAL LOW IN THE
NORTHERN GULF OF MEXICO TO PRECLUDE MUCH MOISTURE RETURN AHEAD OF
THE FRONT. WILL CONTINUE WITH SLIGHT CHANCES ACROSS THE NORTHWEST
CWA ON MONDAY...WITH RAIN CHANCES SPREADING OVER THE CWA MONDAY
NIGHT. SOUTHEAST CWA MAY STAY DRY UNTIL TUESDAY MORNING. DID BUMP
UP POPS A BIT MONDAY NIGHT INTO THE 40 PERCENT RANGE...PRIMARILY
WEST OF I-55. A CLEARING TREND IS EXPECTED ON TUESDAY AND TUESDAY
NIGHT...AS HIGH PRESSURE BUILDS INTO THE MID-MISSISSIPPI VALLEY
BEHIND THE FRONT.
LONG TERM...WEDNESDAY THROUGH SATURDAY...
UPPER LEVEL RIDGING TO ADVANCE EAST ACROSS THE CONUS MIDWEEK...AS
A TROUGH BEGINS TO DIG ACROSS THE WESTERN STATES IN RESPONSE TO
LEFTOVER ENERGY FROM A POWERFUL LOW MOVING SOUTHEAST FROM THE
GULF OF ALASKA. LONGER RANGE MODELS BEGIN TO DIVERGE SIGNIFICANTLY BY
FRIDAY. THE GFS IS RATHER AGRESSIVE IN DEVELOPING A STRONG UPPER
LOW ACROSS THE NORTHERN PLAINS...WITH SHARPLY COLDER CONDITIONS
SPREADING IN BEHIND A FRONT ON SATURDAY. MEANWHILE...THE NEWLY
ARRIVED ECMWF HAS A BOUNDARY OSCILLATING ACROSS THE AREA THROUGH
THE WEEKEND...BEFORE FINALLY PUSHING THROUGH SUNDAY EVENING. AT
THIS POINT...WILL SIDE MORE WITH THE ECMWF...KEEPING THE CWA DRY
THROUGH FRIDAY NIGHT AND INCLUDING ONLY SILENT 20 POPS FOR
SATURDAY AS THE MODELS TRY TO RESOLVE THEIR DIFFERENCES.
GEELHART
&&
.AVIATION...
ISSUED 515 PM CST SAT NOV 7 2009
MAIN FORECAST CONCERN WILL BE WITH THE POTENTIAL FOR SOME GROUND
FOG DEVELOPMENT AFTR 09Z TNT. OTHERWISE...VFR CONDITIONS ARE
EXPECTED FOR THE REMAINDER OF THIS FORECAST PERIOD. WEAK FRONTAL
BOUNDARY JUST TO OUR WEST IS EXPECTED TO HOLD NEARLY STATIONARY
OVERNIGHT BEFORE RETURNING NWD AS A WARM FRONT TOMORROW. SFC WNDS
HAVE DECREASED CONSIDERABLY OVER THE PAST 12 TO 18 HOURS AND EXPCT
LIGHT SE WINDS AND MOSTLY CLEAR SKIES TNT INTO SUN MRNG. AS THE
FRONT SHIFTS WELL NORTH OF OUR AREA ON SUNDAY...SURFACE WINDS WL
INCREASE OUT OF THE SOUTH BY LATE MRNG WITH A FEW GUSTS ARND 20 KTS.
SMITH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
000
FXUS63 KLOT 072143
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
343 PM CST SAT NOV 7 2009
.DISCUSSION...
308 PM CST
WITH MAX TEMPS SURGING TO THE LOWER 70S TODAY AND NOT A CLOUD IN
THE SKY...A PLEASANT DAY WAS IN STORE ACROSS MUCH OF THE REGION.
WITH AN ALREADY MILD START TO THE MORNING AND CLEAR SKIES ACROSS
THE AREA...BUMPED UP MAX TEMPS A COUPLE OF DEGREES TODAY. DESPITE
THE WINDY CONDITIONS FOR PART OF THE DAY TODAY...A WARMER AIR MASS
CONTINUED TO ADVECT INTO THE CWA...CREATING THE MAKINGS FOR A
BEAUTIFUL DAY.
SURFACE TROUGH ALONG WITH WEAK COLD FRONT KNOCKING ON OUR DOOR
JUST TO THE NORTHWEST OF THE CWA WITH TROUGH AXIS EXTENDING FROM
THE UPPER GREAT LAKES SOUTHWEST INTO SOUTHERN IOWA...AND COLD
FRONT EXTENDING INTO SOUTHERN NEBRASKA. SURFACE TROUGH FORECAST TO
EXIT OFF TO THE EAST TONIGHT...ALONG WITH PRESSURE GRADIENT
RELAXING...WILL RESULT IN WINDS CONTINUING TO DIMINISH. FRONT WILL
CONTINUE TO MAKE SOME PROGRESS SOUTHEAST INTO THE FAR NORTHWEST
PORTION OF THE CWA...BUT WITH UPPER LEVEL RIDGE BUILDING ACROSS
THE MIDWEST...WILL STALL TONIGHT. EVEN WITH THE APPROACH OF THIS
FRONT...SKIES WILL REMAIN CLEAR TONIGHT WITH DRIER AIR ALOFT.
ZONAL FLOW WILL TRANSITION TO MORE SOUTHWESTERLY FLOW ALOFT
TONIGHT...AND HELP LIFT THIS WEAK FRONT BACK NORTH ACROSS THE
UPPER MIDWEST EARLY SUNDAY. A SHORT WAVE TROUGH WITHIN THIS FLOW
EJECTING OUT OF THE CENTRAL PLAINS WILL HELP PRODUCE PRESSURE
FALLS AT THE SURFACE...WITH PRESSURE GRADIENT TAKING ON MORE
ORGANIZATION AND WINDS MAINTAINING A SOUTHERLY DIRECTION. THIS
WILL ALL RESULT IN ANOTHER WARM DAY ON SUNDAY WITH ONCE AGAIN
FORECAST HIGH TEMPS RISING INTO THE LOWER 70S.
CLOUD COVER AND PRECIP CHANCES BEGIN TO INCREASE ONCE AGAIN LATE
SUNDAY/EARLY MONDAY AS WEAK SURFACE LOW IS FORECAST TO TRACK
NORTHEAST ALONG THIS BOUNDARY. BUT WITH THIS SURFACE FEATURE
WEAKENING AS IT TRAVERSES THE UPPER MIDWEST...FRONT DOES NOT MAKE
MUCH PR OGRES. AREAS IN FAR NORTHERN ILLINOIS COULD POSSIBLY
OBSERVE EXTENDED CHANCES FOR RAINFALL INTO TUESDAY BEFORE LONG WAVE
TROUGH DIGS SOUTHEAST OUT OF CANADA AND PUSHES THIS FEATURE EAST
OUT OF THE CWA. HIGH PRESSURE BUILDING OUT OF THE CENTRAL PLAINS
BEHIND THIS SYSTEM WILL RETURN CLEAR SKIES AND MORE NORMAL TEMPS
BY MID WEEK.
RODRIGUEZ
&&
.AVIATION...
1200 PM CST
1800 UTC TAFS...MAIN CONCERN AGAIN TODAY IS WITH WIND FCST.
CURRENT SFC ANALYSIS SHOWS A RATHER WEAK AND DIFFUSE COLD FRONTAL
BOUNDARY WORKING ITS WAY SEWD ACROSS ERN WI AND NWRN IL. THIS
FEATURE WILL CONTINUE TO WEAKEN AS IT SETTLES ACROSS REMAINDER OF
AREA THIS AFTN. AS THE FRONT APPROACHES...STRONGER SWLY
WINDS...GUSTING TO AOA 20 KTS...WILL BEGIN TO DIMINISH. WE/RE
ALREADY SEEING THIS OCCUR ACROSS NRN IL...TO W OF FOX RIVER
VALLEY. WINDS TO DIMINISH FURTHER HEADING INTO THIS EVENING. WITH
CLR SKIES AND WEAKENING GRADIENT...SFC/BOUNDARY LYR AIR WILL
DECOUPLE EARLY THIS EVENING ALLOWING WINDS TO DROP OFF TO LGT AND
VRBL. BY LATE TONIGHT...COMBINATION OF SFC RIDGE MOVING E OF
AREA...AND WEAK LOW PRESSURE FORMING ACROSS CNTRL PLAINS...WILL
RESULT IN PREVAILING WIND BCMG SELY BLO 10 KTS BY SUNRISE
SUNDAY...THEN TURNING SLY AND INCRG TO 10-20 KT RANGE BY 18Z AS
TODAY/S COLD FRONT LIFTS BACK NWD AND AREA ONCE AGAIN LIES WITHIN
WARM SECTOR.
SATLT IMAGERY SHOWS NEAREST UPSTREAM CLOUDS OVER 500 MI AWAY...SO
WILL GO WITH VFR CLR CONDITIONS THROUGH THIS EVENING. AS WARM
ADVECTION RE-STRENGTHENS LATER TONIGHT AHEAD OF NEXT
WAVE...SUSPECT SOME MID LVL CLOUDINESS WILL INCR ACROSS MID MS VLY
AND SRN GRTLKS REGION. THIS WILL LIFT N OF REGION BY 18Z AS WARM
FRONT LIFTS THRU.
OF MORE CONCERN TONIGHT WILL BE VIS. UNLIKE LAST NIGHT WHEN SFC
WINDS STAYED ELEVATED THROUGH HE NIGHT...DECOUPLING OF LLVL AIR
MASS...LIGHT WINDS AND SFC DEW POINTS NR 50 F SUGGEST HAZE/FOG
WILL DVLP OVERNIGHT. THIS DOESN/T LOOK LIKE A DENSE FOG SITN...BUT
WE PROBABLY WILL HAVE VIS DROPPING INTO MVFR RANGE LATE TONIGHT
THROUGH EARLY SUNDAY.
MERZLOCK
&&
.MARINE...
1148 AM CST
A LOW PRESSURE APPROACHING HUDSON BAY WILL CONTINUE TO TRACK
NORTHEAST TODAY AND TONIGHT. A TRAILING TROUGH OF LOW PRESSURE
WILL DROP SOUTHEASTWARD ACROSS LAKE MICHIGAN THIS AFTERNOON AS IT
SLOWLY WEAKENS. A WEAK RIDGE OF HIGH PRESSURE WILL THEN BUILD
ACROSS THE NORTHERN PLAINS...REACHING THE GREAT LAKES REGION
TONIGHT. ON SUNDAY...ANOTHER WEAK AREA OF LOW PRESSURE IS EXPECTED
LIFT FROM THE CENTRAL PLAINS STATES...NORTHEASTWARD ACROSS THE
UPPER MIDWEST. THIS WILL SWING WINDS BACK INTO THE S AND SE WITH
SPEEDS INCREASING INTO 15 TO 25 KT RANGE...BUT STAYING MUCH
LIGHTER THAN WINDS YESTERDAY AND LAST NIGHT. A MORE SIGNIFICANT
WEATHER DISTURBANCE WILL TO MOVE ACROSS SOUTHERN CANADA ON MONDAY.
IN RESPONSE...SFC HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN
PLAINS AND UPPER MISSISSIPPI VALLEY ALLOWING A STRONGER...MORE
SUSTAINED NORTH TO NORTHWEST AIR FLOW TO EVOLVE HEADING INTO MID
WEEK.
MERZLOCK
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
000
FXUS63 KILX 071942
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
142 PM CST SAT NOV 7 2009
.DISCUSSION...
ISSUED 140 PM CST SAT NOV 7 2009
18Z SURFACE MAP SHOWING WEAK COLD FRONTAL BOUNDARY BEGINNING TO
ENTER FAR NORTHWEST ILLINOIS...EXTENDING SOUTHWEST TO NEAR KANSAS
CITY. TEMPERATURES HAVE SURGED INTO THE MID 70S ACROSS THE WESTERN
CWA EARLY THIS AFTERNOON...AND WERE AROUND 70 IN THE EAST. THE
ENTIRE REGION WAS DEVOID OF CLOUDS...ASIDE FROM A FEW CIRRUS
CLOUDS MOVING NORTHEAST ACROSS MISSOURI.
MAIN FORECAST ISSUES FOR THE DAY INVOLVE FRONTAL PASSAGES IN THE
MONDAY/TUESDAY TIME FRAME...AS WELL AS LATE NEXT WEEK.
SHORT TERM...TONIGHT THROUGH TUESDAY...
CURRENT COLD FRONT EXPECTED TO BECOME STATIONARY OVERNIGHT...NORTH
OF THE CWA...THEN LIFT BACK NORTH ON SUNDAY. ANOTHER UNSEASONABLY
MILD DAY IS ANTICIPATED ACROSS THE AREA ON SUNDAY...WITH HIGHS
AGAIN REACHING THE 70S. SKIES EXPECTED TO BECOME PARTLY CLOUDY
LATE TONIGHT AS THE FRONT APPROACHES...THEN CLEAR UP AGAIN ON
SUNDAY.
LOW PRESSURE EXPECTED TO FORM IN KANSAS ON SUNDAY AND MOVE
NORTHEAST INTO THE MIDWEST. A COLD FRONT WILL SHARPEN UP AS A
RESULT AS IT MOVES EAST TOWARD THE CWA. MODELS IN REASONABLE
AGREEMENT THROUGH 48 HOURS...THEN THE NAM BECOMES SHARPLY
DIVERGENT WITH THE SPEED OF THIS FRONT...AND RATHER GLARING WITH
ITS DIFFERENCES BY TUESDAY. WILL SIDE WITH THE SLOWER SUITE OF
GUIDANCE AS A RESULT...BRINGING THE FRONT THROUGH THE AREA MONDAY
NIGHT AND EXITING TUESDAY MORNING. EXTRATROPICAL LOW IN THE
NORTHERN GULF OF MEXICO TO PRECLUDE MUCH MOISTURE RETURN AHEAD OF
THE FRONT. WILL CONTINUE WITH SLIGHT CHANCES ACROSS THE NORTHWEST
CWA ON MONDAY...WITH RAIN CHANCES SPREADING OVER THE CWA MONDAY
NIGHT. SOUTHEAST CWA MAY STAY DRY UNTIL TUESDAY MORNING. DID BUMP
UP POPS A BIT MONDAY NIGHT INTO THE 40 PERCENT RANGE...PRIMARILY
WEST OF I-55. A CLEARING TREND IS EXPECTED ON TUESDAY AND TUESDAY
NIGHT...AS HIGH PRESSURE BUILDS INTO THE MID-MISSISSIPPI VALLEY
BEHIND THE FRONT.
LONG TERM...WEDNESDAY THROUGH SATURDAY...
UPPER LEVEL RIDGING TO ADVANCE EAST ACROSS THE CONUS MIDWEEK...AS
A TROUGH BEGINS TO DIG ACROSS THE WESTERN STATES IN RESPONSE TO
LEFTOVER ENERGY FROM A POWERFUL LOW MOVING SOUTHEAST FROM THE
GULF OF ALASKA. LONGER RANGE MODELS BEGIN TO DIVERGE SIGNIFICANTLY BY
FRIDAY. THE GFS IS RATHER AGRESSIVE IN DEVELOPING A STRONG UPPER
LOW ACROSS THE NORTHERN PLAINS...WITH SHARPLY COLDER CONDITIONS
SPREADING IN BEHIND A FRONT ON SATURDAY. MEANWHILE...THE NEWLY
ARRIVED ECMWF HAS A BOUNDARY OSCILLATING ACROSS THE AREA THROUGH
THE WEEKEND...BEFORE FINALLY PUSHING THROUGH SUNDAY EVENING. AT
THIS POINT...WILL SIDE MORE WITH THE ECMWF...KEEPING THE CWA DRY
THROUGH FRIDAY NIGHT AND INCLUDING ONLY SILENT 20 POPS FOR
SATURDAY AS THE MODELS TRY TO RESOLVE THEIR DIFFERENCES.
GEELHART
&&
.AVIATION...
ISSUED 1130 AM CST SAT NOV 7 2009
CLEAR SKIES TO CONTINUE. ONLY ISSUE IS WIND FLOW. PRESSURE
GRADIENT AHEAD OF APPROACHING FRONT WILL KEEP WINDS GUSTY TODAY.
WILL SEE SOME START TO DROP OFF TOWARD EVENING AS GRADIENT
WEAKENS. TOWARD MORNING TONIGHT...WITH THE APPROACH OF THE
FRONT...LIGHT WINDS JUST AHEAD OF FRONT AND NEARLY CLEAR
CONDITIONS MAY ALLOW SOME FOG DEVELOPMENT. FEEL ONLY WILL BE MVFR
THOUGH...JUST AS OCCURRED LAST NIGHT IN IA NEAR APPROACH OF FRONT.
GOETSCH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
000
FXUS63 KLOT 071831
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1231 PM CST SAT NOV 7 2009
.DISCUSSION...
152 AM CST
MODELS APPEAR TO HOLD ON TO CONSISTENCY WITH THE SFC TROF ACROSS
THE UPPER MS VLY AND GREAT LAKES REGION FLATTENING OUT AND
EJECTING NE INTO ONTARIO TODAY WHILE DRAPING A WEAK FRONTAL
BOUNDARY DOWN ACROSS NRN IL. THIS FRONT IS LITTLE MORE THAN A WEAK
WIND SHIFT TO THE WEST IN AN OTHERWISE WEAK PRESSURE GRADIENT AND
SUBSEQUENT LIGHTER WIND PATTERN BE ESTABLISHED BY LATE AFTN.
HOWEVER BRISK WINDS THIS EARLY MRNG SHUD KEEP LOW TEMPS UP TO
AROUND 50 IN MOST LOCATIONS...PROVIDING A GOOD START FOR AMPLE
SUNSHINE TO PUSH HIGHS TO AROUND 70 THIS AFTN.
ON A SIDE NOTE...PREVIOUS DISCUSSION WAS CONCERNED ABOUT LOW STRATUS
FORMING OVERNIGHT AND CAUSING A CLOUDY START TO THE MRNG. HOWEVER
MIXING STILL GOING STRONG IN VIGOROUS WIND FIELD AND NO SIGNS OF
BLACK STRATUS ON SATL FOG PRODUCT AS YET. THUS APPEARS NOT TO BE A
CONCERN THIS MRNG AND WILL EXPECT A SUNNY START TO THE DAY.
WITH HIGH PRESSURE BUILDING BACK INTO THE MIDWEST AND GREAT LAKES
REGION TONIGHT...WILL MAINTAIN CLEAR SKIES. ABSENCE OF POST FRONTAL
COLD AIR ADVECTION WILL LIKELY ONLY DROP LOWS TO AROUND 50 WITH SOME
LOW LYING MID 40S POSSIBLE CONSIDERING WEAKER WIND PATTERN.
SUNDAY IS STILL REINFORCING UPPER RIDGING EAST OF THE MS RIVER VLY
AND TILTING UPPER FLOW TO A MORE SWLY PATTERN OVER THE PLAINS AND
MIDWEST. AND OF COURSE A LEE SIDE LOW PRESSURE SYSTEM IS FORECAST TO
EJECT NE ALONG THIS UPPER PATTERN FROM THE HIGH PLAINS LATE TONIGHT
AND SUNDAY. THIS WILL PUSH OUR WEAK COLD FRONT BACK NORTH ON SUNDAY
AS A WARM FRONT. HIGHS NEAR 70 ARE AGAIN PROBABLE FOR SUNDAY AS A
RESULT DESPITE AN EXPECTED INCREASE IN AFTN WAA CLOUD COVER AHEAD OF
THIS SYSTEM. AS THE FRONT CONTINUES TO LIFT NORTH LATE SUNDAY...MODELS
DEPICTING RISING HEIGHTS OVER ILLINOIS...HELPING TO PUSH WAA
CLOUDINESS NORTHWARD. AN INTENSIFYING LLJ FROM THE GULF THRU THE
SRN PLAINS TO THE MID AND UPR MS VLY SHUD FEED GULF MSTR INTO THE
REGION SUNDAY INTO MONDAY. ANY OVERRUNNING PCPN SUNDAY WILL BE IN
THE COOLER AIR NORTH OF THIS OLD FRONTAL BOUNDARY IN WISCONSIN.
THE WARM FEED OF GULF MSTR INTO ILLINOIS WILL LIKELY KEEP NIGHTTIME
TEMPS UP TO AROUND 50 SUNDAY NIGHT.
THINGS CHANGE ON MONDAY HOWEVER AS A DEEPENING UPR TROF DIVES SE
FROM WRN CANADA AND SETS THIS PLAINS SYSTEM IN MOTION TO THE SE. A
SHOT OF RAIN IS POSSIBLE MONDAY THRU EARLY TUESDAY AS THIS SYSTEM IS
PUSHED SE BY THIS DIVING AMPLIFIED UPR TROF. POST FRONTAL CAA WILL
PUT AN END TO ANYMORE 60S FOR DAYTIME HIGHS THIS WEEK. WHILE A
WARMUP APPEARS TO BE SETTING UP FOR THURSDAY...ANOTHER SHOT OF RAIN
AND POST FRONTAL CAA ON FRIDAY APPEARS TO FOIL ANY WEEKEND PROSPECTS
FOR A RETURN OF THESE CONDITIONS.
RLB
&&
.AVIATION...
1200 PM CST
1800 UTC TAFS...MAIN CONCERN AGAIN TODAY IS WITH WIND FCST.
CURRENT SFC ANALYSIS SHOWS A RATHER WEAK AND DIFFUSE COLD FRONTAL
BOUNDARY WORKING ITS WAY SEWD ACROSS ERN WI AND NWRN IL. THIS
FEATURE WILL CONTINUE TO WEAKEN AS IT SETTLES ACROSS REMAINDER OF
AREA THIS AFTN. AS THE FRONT APPROACHES...STRONGER SWLY
WINDS...GUSTING TO AOA 20 KTS...WILL BEGIN TO DIMINISH. WE/RE
ALREADY SEEING THIS OCCUR ACROSS NRN IL...TO W OF FOX RIVER
VALLEY. WINDS TO DIMINISH FURTHER HEADING INTO THIS EVENING. WITH
CLR SKIES AND WEAKENING GRADIENT...SFC/BOUNDARY LYR AIR WILL
DECOUPLE EARLY THIS EVENING ALLOWING WINDS TO DROP OFF TO LGT AND
VRBL. BY LATE TONIGHT...COMBINATION OF SFC RIDGE MOVING E OF
AREA...AND WEAK LOW PRESSURE FORMING ACROSS CNTRL PLAINS...WILL
RESULT IN PREVAILING WIND BCMG SELY BLO 10 KTS BY SUNRISE
SUNDAY...THEN TURNING SLY AND INCRG TO 10-20 KT RANGE BY 18Z AS
TODAY/S COLD FRONT LIFTS BACK NWD AND AREA ONCE AGAIN LIES WITHIN
WARM SECTOR.
SATLT IMAGERY SHOWS NEAREST UPSTREAM CLOUDS OVER 500 MI AWAY...SO
WILL GO WITH VFR CLR CONDITIONS THROUGH THIS EVENING. AS WARM
ADVECTION RE-STRENGTHENS LATER TONIGHT AHEAD OF NEXT
WAVE...SUSPECT SOME MID LVL CLOUDINESS WILL INCR ACROSS MID MS VLY
AND SRN GRTLKS REGION. THIS WILL LIFT N OF REGION BY 18Z AS WARM
FRONT LIFTS THRU.
OF MORE CONCERN TONIGHT WILL BE VIS. UNLIKE LAST NIGHT WHEN SFC
WINDS STAYED ELEVATED THROUGH HE NIGHT...DECOUPLING OF LLVL AIR
MASS...LIGHT WINDS AND SFC DEW POINTS NR 50 F SUGGEST HAZE/FOG
WILL DVLP OVERNIGHT. THIS DOESN/T LOOK LIKE A DENSE FOG SITN...BUT
WE PROBABLY WILL HAVE VIS DROPPING INTO MVFR RANGE LATE TONIGHT
THROUGH EARLY SUNDAY.
MERZLOCK
&&
.MARINE...
1148 AM CST
A LOW PRESSURE APPROACHING HUDSON BAY WILL CONTINUE TO TRACK
NORTHEAST TODAY AND TONIGHT. A TRAILING TROUGH OF LOW PRESSURE
WILL DROP SOUTHEASTWARD ACROSS LAKE MICHIGAN THIS AFTERNOON AS IT
SLOWLY WEAKENS. A WEAK RIDGE OF HIGH PRESSURE WILL THEN BUILD
ACROSS THE NORTHERN PLAINS...REACHING THE GREAT LAKES REGION
TONIGHT. ON SUNDAY...ANOTHER WEAK AREA OF LOW PRESSURE IS EXPECTED
LIFT FROM THE CENTRAL PLAINS STATES...NORTHEASTWARD ACROSS THE
UPPER MIDWEST. THIS WILL SWING WINDS BACK INTO THE S AND SE WITH
SPEEDS INCREASING INTO 15 TO 25 KT RANGE...BUT STAYING MUCH
LIGHTER THAN WINDS YESTERDAY AND LAST NIGHT. A MORE SIGNIFICANT
WEATHER DISTURBANCE WILL TO MOVE ACROSS SOUTHERN CANADA ON MONDAY.
IN RESPONSE...SFC HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN
PLAINS AND UPPER MISSISSIPPI VALLEY ALLOWING A STRONGER...MORE
SUSTAINED NORTH TO NORTHWEST AIR FLOW TO EVOLVE HEADING INTO MID
WEEK.
MERZLOCK
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL NOON SATURDAY.
&&
$$
000
FXUS63 KILX 071732
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1132 AM CST SAT NOV 7 2009
.DISCUSSION...
ISSUED 1015 AM CST SAT NOV 7 2009
MORNING MSAS SURFACE ANALYSIS SHOWS FRONTAL SYSTEM FROM WI OVER
EASTERN IA INTO CENTRAL KS. TIGHT PRESSURE GRADIENT AHEAD OF THE
SYSTEM WILL KEEP GUSTY WINDS FROM THE SOUTH SOUTHWEST OVER THE
REGION TODAY. HOWEVER AS THE HIGH TO THE EAST RETREATS...GRADIENT
WEAKENS BY LATE AFTERNOON AND SO WILL SEE SOME DROP IN WINDS. NEW
NAM AND GFS MODELS ALSO CONDITION TO SUPPORT THIS TREND. HIGH
TEMPS FOR TODAY ON TRACK WITH CURRENT FORECAST SO NO UPDATE NEEDED.
&&
.AVIATION...
ISSUED 1130 AM CST SAT NOV 7 2009
CLEAR SKIES TO CONTINUE. ONLY ISSUE IS WIND FLOW. PRESSURE
GRADIENT AHEAD OF APPROACHING FRONT WILL KEEP WINDS GUSTY TODAY.
WILL SEE SOME START TO DROP OFF TOWARD EVENING AS GRADIENT
WEAKENS. TOWARD MORNING TONIGHT...WITH THE APPROACH OF THE
FRONT...LIGHT WINDS JUST AHEAD OF FRONT AND NEARLY CLEAR
CONDITIONS MAY ALLOW SOME FOG DEVELOPMENT. FEEL ONLY WILL BE MVFR
THOUGH...JUST AS OCCURRED LAST NIGHT IN IA NEAR APPROACH OF FRONT.
GOETSCH
&&
.PREV DISCUSSION...
ISSUED 330 AM CST SAT NOV 7 2009
FORECAST CONCERN IS HOW WARM IT GETS THIS WEEKEND WITH UPPER LEVEL
RIDGE OVER IL. THEN NEXT CHANCE OF RAIN SHOWERS EARLY NEXT WORK
WEEK WITH MODELS TRENDING SLOWER WITH THIS COLD FRONT.
SHORT TERM...TODAY THROUGH TUESDAY
09Z/3 AM SURFACE MAP SHOWS STRONG 981 MB LOW PRESSURE OVER
NORTHERN MANITOBA WITH A COLD FRONT EXTENDING SOUTHWARD ACROSS
WESTERN MN TO CENTRAL KS. 1027 MB HIGH PRESSURE WAS ACROSS THE
ATLANTIC STATES. TIGHT PRESSURE GRADIENT OVER IL GIVING BREEZY SSW
WINDS 10 TO 17 MPH AND GUSTS OF 17 TO 23 MPH. CIRRUS CLOUDS PASSED
EAST OF IL. MILD TEMPS WERE IN THE LOW TO MID 50S. DEWPOINTS
RANGED FROM THE MID TO UPPER 30S FROM I-57 EAST TO THE UPPER 40S
FROM I-55 WEST. ALOFT NEARLY ZONAL UPPER LEVEL FLOW ACROSS THE
MIDWEST WITH 586 DM 500 MB HIGH OVER THE GULF COAST STATES...573
DM 500 MB LOW NEAR BAJA AND UPPER LEVEL TROF OVER WESTERN CANADA.
MODELS SIMILAR IN WEAKENING THE COLD FRONT AS IT MOVES INTO
NORTHERN IL BY SUNSET WITH PRESSURE GRADIENT WEAKENING AS IT
APPROACHES CENTRAL IL LATE TODAY. BREEZY SSW WINDS INTO MID
AFTERNOON TO DIMINISH DURING THIS AFTERNOON FROM NW TO SE. AMPLE
SUNSHINE EXPECTED TODAY AND MILDER HIGHS IN THE LOWER 70S WITH
WARMEST READINGS IN WESTERN IL WHERE WARMER 850-925 TEMPS.
LOW PRESSURE AROUND SE CO AND NE NM LATER TONIGHT INTO SUNDAY TO
LIFT THE WEAK FRONT BACK NORTH WITH IL BACK IN AN INCREASING
SOUTHERLY FLOW. MILD HIGHS AGAIN IN THE LOWER 70S WITH MOSTLY
SUNNY SKIES. A BIT COOLER HIGHS IN THE MID TO UPPER 60S MON WITH
INCREASING CLOUDS AHEAD OF APPROACHING COLD FRONT.
00Z MODELS TRENDING SLOWER WITH COLD FRONT MOVING SE TOWARD NW IL
BY SUNSET MON AND HAVING POST FRONTAL QPF/SHOWERS WHICH MAINLY
MOVES ACROSS IL MON NIGHT. JUST HAVE SLIGHT CHANCE OF SHOWERS MON
AFTERNOON WEST OF I-57 AND THEN CHANCE OF SHOWERS ACROSS CENTRAL
IL MON NIGHT AND IN EASTERN IL TUE AS WEAKENING COLD FRONT MOVES
TOWARD THE OHIO RIVER. MODELS KEEPING TROPICAL MOISTURE OVER THE
GULF OF MEXICO SE OF KY AND NOT INFLUENCING IL.
LONG TERM...TUESDAY NIGHT THROUGH FRIDAY
LITTLE CHANGES MADE TO THE EXTENDED FORECAST WITH DRY CONDITIONS
STILL EXPECTED DURING THIS TIME. COOLED THE LOWS A FEW DEGREES TUE
NIGHT INTO THE 30S AS 1034 MB HIGH PRESSURE SETTLES OVER IL BY DAWN
WED. HIGH PRESSURE DRIFTS EAST OF IL WED/THU SETTING UP A RETURN
SOUTHERLY FLOW AND TEMPERATURES RISING BACK ABOVE NORMAL...THOUGH
NOT AS WARM AS THIS WEEKEND. NEXT CHANCE OF SHOWERS APPEARS TO BE
NEXT WEEKEND WITH THE ARRIVAL OF THE NEXT COLD FRONT...THOUGH
STILL SOME DIFFERENCES WITH TIMING OF THIS FRONT.
HUETTL
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
000
FXUS63 KILX 071617
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1017 AM CST SAT NOV 7 2009
.DISCUSSION...
ISSUED 1015 AM CST SAT NOV 7 2009
MORNING MSAS SURFACE ANALYSIS SHOWS FRONTAL SYSTEM FROM WI OVER
EASTERN IA INTO CENTRAL KS. TIGHT PRESSURE GRADIENT AHEAD OF THE
SYSTEM WILL KEEP GUSTY WINDS FROM THE SOUTH SOUTHWEST OVER THE
REGION TODAY. HOWEVER AS THE HIGH TO THE EAST RETREATS...GRADIENT
WEAKENS BY LATE AFTERNOON AND SO WILL SEE SOME DROP IN WINDS. NEW
NAM AND GFS MODELS ALSO CONDITION TO SUPPORT THIS TREND. HIGH
TEMPS FOR TODAY ON TRACK WITH CURRENT FORECAST SO NO UPDATE NEEDED.
GOETSCH
&&
.AVIATION...
ISSUED 541 AM CST SAT NOV 7 2009...FOR THE 12Z TAFS
WINDS WILL CONTINUE TO BE THE MAIN CONCERN FOR AVIATION TODAY.
LOW LEVEL WIND SHEAR CONDITIONS WILL PERSIST UNTIL MIXING DEVELOPS
IN THE HEATING OF THE DAY. 45 TO 50KTS OF LOW LEVEL WIND ARE
PRESENT AT 1600FT ABOVE GROUND...JUST ABOVE THE DECOUPLED BOUNDARY
LAYER WINDS. WENT WITH WIND SHEAR FROM THE SOUTHWEST IN ALL TAFS
THROUGH 15Z.
WINDS WILL BACK FARTHER SOUTHWEST TODAY...THEN WEAKEN AND RETURN
MORE SOUTHERLY AS THE COLD FRONT DROPS SOUTH INTO NORTHERN
ILLINOIS LATE THIS AFTERNOON AND EVENING.
VISIBILITY MAY DROP TO NEAR MVFR CONDITIONS LATE SATURDAY
NIGHT...BUT DID NOT INTRODUCE THAT WITH THIS ISSUANCE. WILL SEE
WHAT MOISTURE MAKES IT THIS FAR NORTH...AND HOW CLOSE THE FRONT
GETS BEFORE IT STALLS OUT...THEN LIFTS NORTH AS A WARM FRONT.
FOGGIER CONDITIONS WILL BE MORE LIKELY CLOSER TO THE FRONT.
SHIMON
&&
.PREV DISCUSSION...
ISSUED 330 AM CST SAT NOV 7 2009
FORECAST CONCERN IS HOW WARM IT GETS THIS WEEKEND WITH UPPER LEVEL
RIDGE OVER IL. THEN NEXT CHANCE OF RAIN SHOWERS EARLY NEXT WORK
WEEK WITH MODELS TRENDING SLOWER WITH THIS COLD FRONT.
SHORT TERM...TODAY THROUGH TUESDAY
09Z/3 AM SURFACE MAP SHOWS STRONG 981 MB LOW PRESSURE OVER
NORTHERN MANITOBA WITH A COLD FRONT EXTENDING SOUTHWARD ACROSS
WESTERN MN TO CENTRAL KS. 1027 MB HIGH PRESSURE WAS ACROSS THE
ATLANTIC STATES. TIGHT PRESSURE GRADIENT OVER IL GIVING BREEZY SSW
WINDS 10 TO 17 MPH AND GUSTS OF 17 TO 23 MPH. CIRRUS CLOUDS PASSED
EAST OF IL. MILD TEMPS WERE IN THE LOW TO MID 50S. DEWPOINTS
RANGED FROM THE MID TO UPPER 30S FROM I-57 EAST TO THE UPPER 40S
FROM I-55 WEST. ALOFT NEARLY ZONAL UPPER LEVEL FLOW ACROSS THE
MIDWEST WITH 586 DM 500 MB HIGH OVER THE GULF COAST STATES...573
DM 500 MB LOW NEAR BAJA AND UPPER LEVEL TROF OVER WESTERN CANADA.
MODELS SIMILAR IN WEAKENING THE COLD FRONT AS IT MOVES INTO
NORTHERN IL BY SUNSET WITH PRESSURE GRADIENT WEAKENING AS IT
APPROACHES CENTRAL IL LATE TODAY. BREEZY SSW WINDS INTO MID
AFTERNOON TO DIMINISH DURING THIS AFTERNOON FROM NW TO SE. AMPLE
SUNSHINE EXPECTED TODAY AND MILDER HIGHS IN THE LOWER 70S WITH
WARMEST READINGS IN WESTERN IL WHERE WARMER 850-925 TEMPS.
LOW PRESSURE AROUND SE CO AND NE NM LATER TONIGHT INTO SUNDAY TO
LIFT THE WEAK FRONT BACK NORTH WITH IL BACK IN AN INCREASING
SOUTHERLY FLOW. MILD HIGHS AGAIN IN THE LOWER 70S WITH MOSTLY
SUNNY SKIES. A BIT COOLER HIGHS IN THE MID TO UPPER 60S MON WITH
INCREASING CLOUDS AHEAD OF APPROACHING COLD FRONT.
00Z MODELS TRENDING SLOWER WITH COLD FRONT MOVING SE TOWARD NW IL
BY SUNSET MON AND HAVING POST FRONTAL QPF/SHOWERS WHICH MAINLY
MOVES ACROSS IL MON NIGHT. JUST HAVE SLIGHT CHANCE OF SHOWERS MON
AFTERNOON WEST OF I-57 AND THEN CHANCE OF SHOWERS ACROSS CENTRAL
IL MON NIGHT AND IN EASTERN IL TUE AS WEAKENING COLD FRONT MOVES
TOWARD THE OHIO RIVER. MODELS KEEPING TROPICAL MOISTURE OVER THE
GULF OF MEXICO SE OF KY AND NOT INFLUENCING IL.
LONG TERM...TUESDAY NIGHT THROUGH FRIDAY
LITTLE CHANGES MADE TO THE EXTENDED FORECAST WITH DRY CONDITIONS
STILL EXPECTED DURING THIS TIME. COOLED THE LOWS A FEW DEGREES TUE
NIGHT INTO THE 30S AS 1034 MB HIGH PRESSURE SETTLES OVER IL BY DAWN
WED. HIGH PRESSURE DRIFTS EAST OF IL WED/THU SETTING UP A RETURN
SOUTHERLY FLOW AND TEMPERATURES RISING BACK ABOVE NORMAL...THOUGH
NOT AS WARM AS THIS WEEKEND. NEXT CHANCE OF SHOWERS APPEARS TO BE
NEXT WEEKEND WITH THE ARRIVAL OF THE NEXT COLD FRONT...THOUGH
STILL SOME DIFFERENCES WITH TIMING OF THIS FRONT.
HUETTL
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
000
FXUS63 KILX 071141
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
541 AM CST SAT NOV 7 2009
.DISCUSSION...
ISSUED 330 AM CST SAT NOV 7 2009
FORECAST CONCERN IS HOW WARM IT GETS THIS WEEKEND WITH UPPER LEVEL
RIDGE OVER IL. THEN NEXT CHANCE OF RAIN SHOWERS EARLY NEXT WORK
WEEK WITH MODELS TRENDING SLOWER WITH THIS COLD FRONT.
SHORT TERM...TODAY THROUGH TUESDAY
09Z/3 AM SURFACE MAP SHOWS STRONG 981 MB LOW PRESSURE OVER
NORTHERN MANITOBA WITH A COLD FRONT EXTENDING SOUTHWARD ACROSS
WESTERN MN TO CENTRAL KS. 1027 MB HIGH PRESSURE WAS ACROSS THE
ATLANTIC STATES. TIGHT PRESSURE GRADIENT OVER IL GIVING BREEZY SSW
WINDS 10 TO 17 MPH AND GUSTS OF 17 TO 23 MPH. CIRRUS CLOUDS PASSED
EAST OF IL. MILD TEMPS WERE IN THE LOW TO MID 50S. DEWPOINTS
RANGED FROM THE MID TO UPPER 30S FROM I-57 EAST TO THE UPPER 40S
FROM I-55 WEST. ALOFT NEARLY ZONAL UPPER LEVEL FLOW ACROSS THE
MIDWEST WITH 586 DM 500 MB HIGH OVER THE GULF COAST STATES...573
DM 500 MB LOW NEAR BAJA AND UPPER LEVEL TROF OVER WESTERN CANADA.
MODELS SIMILAR IN WEAKENING THE COLD FRONT AS IT MOVES INTO
NORTHERN IL BY SUNSET WITH PRESSURE GRADIENT WEAKENING AS IT
APPROACHES CENTRAL IL LATE TODAY. BREEZY SSW WINDS INTO MID
AFTERNOON TO DIMINISH DURING THIS AFTERNOON FROM NW TO SE. AMPLE
SUNSHINE EXPECTED TODAY AND MILDER HIGHS IN THE LOWER 70S WITH
WARMEST READINGS IN WESTERN IL WHERE WARMER 850-925 TEMPS.
LOW PRESSURE AROUND SE CO AND NE NM LATER TONIGHT INTO SUNDAY TO
LIFT THE WEAK FRONT BACK NORTH WITH IL BACK IN AN INCREASING
SOUTHERLY FLOW. MILD HIGHS AGAIN IN THE LOWER 70S WITH MOSTLY
SUNNY SKIES. A BIT COOLER HIGHS IN THE MID TO UPPER 60S MON WITH
INCREASING CLOUDS AHEAD OF APPROACHING COLD FRONT.
00Z MODELS TRENDING SLOWER WITH COLD FRONT MOVING SE TOWARD NW IL
BY SUNSET MON AND HAVING POST FRONTAL QPF/SHOWERS WHICH MAINLY
MOVES ACROSS IL MON NIGHT. JUST HAVE SLIGHT CHANCE OF SHOWERS MON
AFTERNOON WEST OF I-57 AND THEN CHANCE OF SHOWERS ACROSS CENTRAL
IL MON NIGHT AND IN EASTERN IL TUE AS WEAKENING COLD FRONT MOVES
TOWARD THE OHIO RIVER. MODELS KEEPING TROPICAL MOISTURE OVER THE
GULF OF MEXICO SE OF KY AND NOT INFLUENCING IL.
LONG TERM...TUESDAY NIGHT THROUGH FRIDAY
LITTLE CHANGES MADE TO THE EXTENDED FORECAST WITH DRY CONDITIONS
STILL EXPECTED DURING THIS TIME. COOLED THE LOWS A FEW DEGREES TUE
NIGHT INTO THE 30S AS 1034 MB HIGH PRESSURE SETTLES OVER IL BY DAWN
WED. HIGH PRESSURE DRIFTS EAST OF IL WED/THU SETTING UP A RETURN
SOUTHERLY FLOW AND TEMPERATURES RISING BACK ABOVE NORMAL...THOUGH
NOT AS WARM AS THIS WEEKEND. NEXT CHANCE OF SHOWERS APPEARS TO BE
NEXT WEEKEND WITH THE ARRIVAL OF THE NEXT COLD FRONT...THOUGH
STILL SOME DIFFERENCES WITH TIMING OF THIS FRONT.
HUETTL
&&
.AVIATION...
ISSUED 541 AM CST SAT NOV 7 2009...FOR THE 12Z TAFS
WINDS WILL CONTINUE TO BE THE MAIN CONCERN FOR AVIATION TODAY.
LOW LEVEL WIND SHEAR CONDITIONS WILL PERSIST UNTIL MIXING DEVELOPS
IN THE HEATING OF THE DAY. 45 TO 50KTS OF LOW LEVEL WIND ARE
PRESENT AT 1600FT ABOVE GROUND...JUST ABOVE THE DECOUPLED BOUNDARY
LAYER WINDS. WENT WITH WIND SHEAR FROM THE SOUTHWEST IN ALL TAFS
THROUGH 15Z.
WINDS WILL BACK FARTHER SOUTHWEST TODAY...THEN WEAKEN AND RETURN
MORE SOUTHERLY AS THE COLD FRONT DROPS SOUTH INTO NORTHERN
ILLINOIS LATE THIS AFTERNOON AND EVENING.
VISIBILITY MAY DROP TO NEAR MVFR CONDITIONS LATE SATURDAY
NIGHT...BUT DID NOT INTRODUCE THAT WITH THIS ISSUANCE. WILL SEE
WHAT MOISTURE MAKES IT THIS FAR NORTH...AND HOW CLOSE THE FRONT
GETS BEFORE IT STALLS OUT...THEN LIFTS NORTH AS A WARM FRONT.
FOGGIER CONDITIONS WILL BE MORE LIKELY CLOSER TO THE FRONT.
SHIMON
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
000
FXUS63 KLOT 071133
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
533 AM CST SAT NOV 7 2009
.DISCUSSION...
152 AM CST
MODELS APPEAR TO HOLD ON TO CONSISTENCY WITH THE SFC TROF ACROSS
THE UPPER MS VLY AND GREAT LAKES REGION FLATTENING OUT AND
EJECTING NE INTO ONTARIO TODAY WHILE DRAPING A WEAK FRONTAL
BOUNDARY DOWN ACROSS NRN IL. THIS FRONT IS LITTLE MORE THAN A WEAK
WIND SHIFT TO THE WEST IN AN OTHERWISE WEAK PRESSURE GRADIENT AND
SUBSEQUENT LIGHTER WIND PATTERN BE ESTABLISHED BY LATE AFTN.
HOWEVER BRISK WINDS THIS EARLY MRNG SHUD KEEP LOW TEMPS UP TO
AROUND 50 IN MOST LOCATIONS...PROVIDING A GOOD START FOR AMPLE
SUNSHINE TO PUSH HIGHS TO AROUND 70 THIS AFTN.
ON A SIDE NOTE...PREVIOUS DISCUSSION WAS CONCERNED ABOUT LOW STRATUS
FORMING OVERNIGHT AND CAUSING A CLOUDY START TO THE MRNG. HOWEVER
MIXING STILL GOING STRONG IN VIGOROUS WIND FIELD AND NO SIGNS OF
BLACK STRATUS ON SATL FOG PRODUCT AS YET. THUS APPEARS NOT TO BE A
CONCERN THIS MRNG AND WILL EXPECT A SUNNY START TO THE DAY.
WITH HIGH PRESSURE BUILDING BACK INTO THE MIDWEST AND GREAT LAKES
REGION TONIGHT...WILL MAINTAIN CLEAR SKIES. ABSENCE OF POST FRONTAL
COLD AIR ADVECTION WILL LIKELY ONLY DROP LOWS TO AROUND 50 WITH SOME
LOW LYING MID 40S POSSIBLE CONSIDERING WEAKER WIND PATTERN.
SUNDAY IS STILL REINFORCING UPPER RIDGING EAST OF THE MS RIVER VLY
AND TILTING UPPER FLOW TO A MORE SWLY PATTERN OVER THE PLAINS AND
MIDWEST. AND OF COURSE A LEE SIDE LOW PRESSURE SYSTEM IS FORECAST TO
EJECT NE ALONG THIS UPPER PATTERN FROM THE HIGH PLAINS LATE TONIGHT
AND SUNDAY. THIS WILL PUSH OUR WEAK COLD FRONT BACK NORTH ON SUNDAY
AS A WARM FRONT. HIGHS NEAR 70 ARE AGAIN PROBABLE FOR SUNDAY AS A
RESULT DESPITE AN EXPECTED INCREASE IN AFTN WAA CLOUD COVER AHEAD OF
THIS SYSTEM. AS THE FRONT CONTINUES TO LIFT NORTH LATE SUNDAY...MODELS
DEPICTING RISING HEIGHTS OVER ILLINOIS...HELPING TO PUSH WAA
CLOUDINESS NORTHWARD. AN INTENSIFYING LLJ FROM THE GULF THRU THE
SRN PLAINS TO THE MID AND UPR MS VLY SHUD FEED GULF MSTR INTO THE
REGION SUNDAY INTO MONDAY. ANY OVERRUNNING PCPN SUNDAY WILL BE IN
THE COOLER AIR NORTH OF THIS OLD FRONTAL BOUNDARY IN WISCONSIN.
THE WARM FEED OF GULF MSTR INTO ILLINOIS WILL LIKELY KEEP NIGHTTIME
TEMPS UP TO AROUND 50 SUNDAY NIGHT.
THINGS CHANGE ON MONDAY HOWEVER AS A DEEPENING UPR TROF DIVES SE
FROM WRN CANADA AND SETS THIS PLAINS SYSTEM IN MOTION TO THE SE. A
SHOT OF RAIN IS POSSIBLE MONDAY THRU EARLY TUESDAY AS THIS SYSTEM IS
PUSHED SE BY THIS DIVING AMPLIFIED UPR TROF. POST FRONTAL CAA WILL
PUT AN END TO ANYMORE 60S FOR DAYTIME HIGHS THIS WEEK. WHILE A
WARMUP APPEARS TO BE SETTING UP FOR THURSDAY...ANOTHER SHOT OF RAIN
AND POST FRONTAL CAA ON FRIDAY APPEARS TO FOIL ANY WEEKEND PROSPECTS
FOR A RETURN OF THESE CONDITIONS.
RLB
&&
.AVIATION...
12Z TAFS...MAIN CONCERN FOR THE PERIOD CONTINUES TO FOCUS ON WINDS.
THE PRESSURE GRADIENT WILL REMAIN STRONG FOR THE MORNING HOURS AS
HIGH PRESSURE REMAINS PARKED OVER THE MID ATLANTIC REGION AND A
TROUGH OF LOW PRESSURE AND WEAK COLD FRONT APPROACH FROM THE WEST.
AT ISSUANCE TIME...THE TROUGH IS APPROACHING THE MISSISSIPPI
VALLEY AND WINDS OVER NRN IL/IN ARE VEERING SSWLY. EXPECT WINDS TO
REMAIN GUSTY TO ARND 20KT UNTIL THE TROUGH CROSSES THE REGION...AT
WHICH POINT...THE GRADIENT WILL WEAKEN CONSIDERABLY. WINDS WILL
VEER WSWLY-WLY WITH THE FROPA...BUT WITH WEAK PRESSURE RISES
BEHIND THE FRONT AND LITTLE IN THE WAY OF COLD ADVECTION...WINDS
WILL ACTUALLY WEAKEN THROUGH THE LATE MORNING AND AFTERNOON HOURS.
AS WEAK HIGH PRESSURE BUILDS IN FOR THE EVENING AND OVERNIGHT
HOURS...WINDS WILL BECOME LIGHT AND VARIABLE.
MODEL RH TIME SECTIONS SHOW A VERY DRY PROFILE...SO EXPECT LITTLE
IN THE WAY OF CLOUD COVER THROUGH THE PERIOD...MAINLY JUST SOME
VARIABLE CIRRUS.
THE LATEST SFC ANALYSIS SHOWS SOME MOISTURE INFLUX AHEAD OF THE
APPROACHING FRONT...WITH DEWPOINTS CLIMBING INTO THE UPPER 40S. THE
MODEST LOW LEVEL MOISTURE SHOULD REMAIN IN PLACE OVERNIGHT...AND
WITH WEAK WINDS AND MOSTLY CLEAR SKIES...SOME BR DEVELOPMENT IS
POSSIBLE. THE LATEST GUIDANCE SUGGESTS THAT DEWPOINT DEPRESSIONS
WILL NOT REACH SATURATION...SO HAVE ONLY INTRODUCED 4SM FOR RFD
AND DPA...WITH THE OTHER SITES ONLY DROPPING TO 6SM DUE TO URBAN
HEAT ISLAND CONSIDERATIONS.
KREIN
&&
.MARINE...
300 AM CST
MARGINAL GALES EXPECTED TO CONTINUE UNTIL EARLY THIS MORNING AS A
STRONG PRESSURE GRADIENT REMAINS IN PLACE OVER THE LAKE.
HOWEVER...LATER THIS MORNING A WEAKENING TROUGH AND COLD FRONT
WILL SWEEP ACROSS THE LAKE...RELAXING THE GRADIENT AND TURNING
WINDS WESTERLY BY THIS AFTERNOON. A WEAK RIDGE OF HIGH PRESSURE
WILL BUILD OVER THE LAKE TONIGHT AND TOMORROW...ALLOWING WINDS TO
FURTHER DECREASE TO ARND 5 TO 10KT. A WEAK LOW PRESSURE SYSTEM
WILL TRACK NORTHEAST OUT OF THE CENTRAL PLAINS AND ACROSS THE NRN
PORTION OF THE LAKE ON MONDAY. AS THIS LOW PASSES TO THE EAST...IT
WILL DRAG ANOTHER FRONT DOWN THE LENGTH OF THE LAKE MONDAY
NIGHT...BRINGING A PERIOD OF NORTH WINDS FOR MONDAY NIGHT AND TUESDAY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 6 AM SATURDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 10 AM SATURDAY.
&&
$$
000
FXUS63 KILX 070928
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
328 AM CST SAT NOV 7 2009
.DISCUSSION...
ISSUED 330 AM CST SAT NOV 7 2009
FORECAST CONCERN IS HOW WARM IT GETS THIS WEEKEND WITH UPPER LEVEL
RIDGE OVER IL. THEN NEXT CHANCE OF RAIN SHOWERS EARLY NEXT WORK
WEEK WITH MODELS TRENDING SLOWER WITH THIS COLD FRONT.
SHORT TERM...TODAY THROUGH TUESDAY
09Z/3 AM SURFACE MAP SHOWS STRONG 981 MB LOW PRESSURE OVER
NORTHERN MANITOBA WITH A COLD FRONT EXTENDING SOUTHWARD ACROSS
WESTERN MN TO CENTRAL KS. 1027 MB HIGH PRESSURE WAS ACROSS THE
ATLANTIC STATES. TIGHT PRESSURE GRADIENT OVER IL GIVING BREEZY SSW
WINDS 10 TO 17 MPH AND GUSTS OF 17 TO 23 MPH. CIRRUS CLOUDS PASSED
EAST OF IL. MILD TEMPS WERE IN THE LOW TO MID 50S. DEWPOINTS
RANGED FROM THE MID TO UPPER 30S FROM I-57 EAST TO THE UPPER 40S
FROM I-55 WEST. ALOFT NEARLY ZONAL UPPER LEVEL FLOW ACROSS THE
MIDWEST WITH 586 DM 500 MB HIGH OVER THE GULF COAST STATES...573
DM 500 MB LOW NEAR BAJA AND UPPER LEVEL TROF OVER WESTERN CANADA.
MODELS SIMILAR IN WEAKENING THE COLD FRONT AS IT MOVES INTO
NORTHERN IL BY SUNSET WITH PRESSURE GRADIENT WEAKENING AS IT
APPROACHES CENTRAL IL LATE TODAY. BREEZY SSW WINDS INTO MID
AFTERNOON TO DIMINISH DURING THIS AFTERNOON FROM NW TO SE. AMPLE
SUNSHINE EXPECTED TODAY AND MILDER HIGHS IN THE LOWER 70S WITH
WARMEST READINGS IN WESTERN IL WHERE WARMER 850-925 TEMPS.
LOW PRESSURE AROUND SE CO AND NE NM LATER TONIGHT INTO SUNDAY TO
LIFT THE WEAK FRONT BACK NORTH WITH IL BACK IN AN INCREASING
SOUTHERLY FLOW. MILD HIGHS AGAIN IN THE LOWER 70S WITH MOSTLY
SUNNY SKIES. A BIT COOLER HIGHS IN THE MID TO UPPER 60S MON WITH
INCREASING CLOUDS AHEAD OF APPROACHING COLD FRONT.
00Z MODELS TRENDING SLOWER WITH COLD FRONT MOVING SE TOWARD NW IL
BY SUNSET MON AND HAVING POST FRONTAL QPF/SHOWERS WHICH MAINLY
MOVES ACROSS IL MON NIGHT. JUST HAVE SLIGHT CHANCE OF SHOWERS MON
AFTERNOON WEST OF I-57 AND THEN CHANCE OF SHOWERS ACROSS CENTRAL
IL MON NIGHT AND IN EASTERN IL TUE AS WEAKENING COLD FRONT MOVES
TOWARD THE OHIO RIVER. MODELS KEEPING TROPICAL MOISTURE OVER THE
GULF OF MEXICO SE OF KY AND NOT INFLUENCING IL.
LONG TERM...TUESDAY NIGHT THROUGH FRIDAY
LITTLE CHANGES MADE TO THE EXTENDED FORECAST WITH DRY CONDITIONS
STILL EXPECTED DURING THIS TIME. COOLED THE LOWS A FEW DEGREES TUE
NIGHT INTO THE 30S AS 1034 MB HIGH PRESSURE SETTLES OVER IL BY DAWN
WED. HIGH PRESSURE DRIFTS EAST OF IL WED/THU SETTING UP A RETURN
SOUTHERLY FLOW AND TEMPERATURES RISING BACK ABOVE NORMAL...THOUGH
NOT AS WARM AS THIS WEEKEND. NEXT CHANCE OF SHOWERS APPEARS TO BE
NEXT WEEKEND WITH THE ARRIVAL OF THE NEXT COLD FRONT...THOUGH
STILL SOME DIFFERENCES WITH TIMING OF THIS FRONT.
HUETTL
&&
.AVIATION...
ISSUED 1125 PM CST FRI NOV 6 2009
SOUTHERLY WINDS GRDLY DIMINISHING ACRS THE AREA...HOWEVER WIND
PROFILERS SHOWING 1500-2000 FOOT WINDS OUT OF THE SOUTHWEST
AT 35-45 KTS SO WL CONTINUE WITH THE LLWS STARTING WITH THE
06Z TAF ISSUANCE. OTHERWISE...MODELS HAVE BACKED OFF SOME ON
THE POTENTIAL FOR SOME LOWER CIGS DEVELOPING BY MRNG. WL CONTINUE
WITH VFR CONDITIONS THRU THIS FCST PERIOD. SFC WNDS WL REMAIN OUT
OF THE SOUTH TNT AT 10 TO 15 KTS...AND THEN VEER MORE INTO THE
SOUTHWEST ON SATURDAY. WEAK FRONTAL BOUNDARY FORECAST TO APPROACH
OUR NRN TAF SITES LATER TMRW EVENING WHICH MAY HELP TO BACK THE
WINDS MORE INTO THE SOUTH AND SOUTHEAST AFTER DARK. FORECAST
SOUNDINGS AND TIME HEIGHT CROSS SECTIONS INDICATE SOME INCREASE
IN MOISTURE ARND 2500-3500 FEET JUST AHEAD OF THE BNDRY LATE TMRW
NIGHT...BUT IT APPEARS THAT WL NOT AFFECT OUR TAF SITES UNTIL JUST
AFTER THIS FORECAST PERIOD.
SMITH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
000
FXUS63 KLOT 070855
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
255 AM CST SAT NOV 7 2009
.DISCUSSION...
152 AM CST
MODELS APPEAR TO HOLD ON TO CONSISTENCY WITH THE SFC TROF ACROSS
THE UPPER MS VLY AND GREAT LAKES REGION FLATTENING OUT AND
EJECTING NE INTO ONTARIO TODAY WHILE DRAPING A WEAK FRONTAL
BOUNDARY DOWN ACROSS NRN IL. THIS FRONT IS LITTLE MORE THAN A WEAK
WIND SHIFT TO THE WEST IN AN OTHERWISE WEAK PRESSURE GRADIENT AND
SUBSEQUENT LIGHTER WIND PATTERN BE ESTABLISHED BY LATE AFTN.
HOWEVER BRISK WINDS THIS EARLY MRNG SHUD KEEP LOW TEMPS UP TO
AROUND 50 IN MOST LOCATIONS...PROVIDING A GOOD START FOR AMPLE
SUNSHINE TO PUSH HIGHS TO AROUND 70 THIS AFTN.
ON A SIDE NOTE...PREVIOUS DISCUSSION WAS CONCERNED ABOUT LOW STRATUS
FORMING OVERNIGHT AND CAUSING A CLOUDY START TO THE MRNG. HOWEVER
MIXING STILL GOING STRONG IN VIGOROUS WIND FIELD AND NO SIGNS OF
BLACK STRATUS ON SATL FOG PRODUCT AS YET. THUS APPEARS NOT TO BE A
CONCERN THIS MRNG AND WILL EXPECT A SUNNY START TO THE DAY.
WITH HIGH PRESSURE BUILDING BACK INTO THE MIDWEST AND GREAT LAKES
REGION TONIGHT...WILL MAINTAIN CLEAR SKIES. ABSENCE OF POST FRONTAL
COLD AIR ADVECTION WILL LIKELY ONLY DROP LOWS TO AROUND 50 WITH SOME
LOW LYING MID 40S POSSIBLE CONSIDERING WEAKER WIND PATTERN.
SUNDAY IS STILL REINFORCING UPPER RIDGING EAST OF THE MS RIVER VLY
AND TILTING UPPER FLOW TO A MORE SWLY PATTERN OVER THE PLAINS AND
MIDWEST. AND OF COURSE A LEE SIDE LOW PRESSURE SYSTEM IS FORECAST TO
EJECT NE ALONG THIS UPPER PATTERN FROM THE HIGH PLAINS LATE TONIGHT
AND SUNDAY. THIS WILL PUSH OUR WEAK COLD FRONT BACK NORTH ON SUNDAY
AS A WARM FRONT. HIGHS NEAR 70 ARE AGAIN PROBABLE FOR SUNDAY AS A
RESULT DESPITE AN EXPECTED INCREASE IN AFTN WAA CLOUD COVER AHEAD OF
THIS SYSTEM. AS THE FRONT CONTINUES TO LIFT NORTH LATE SUNDAY...MODELS
DEPICTING RISING HEIGHTS OVER ILLINOIS...HELPING TO PUSH WAA
CLOUDINESS NORTHWARD. AN INTENSIFYING LLJ FROM THE GULF THRU THE
SRN PLAINS TO THE MID AND UPR MS VLY SHUD FEED GULF MSTR INTO THE
REGION SUNDAY INTO MONDAY. ANY OVERRUNNING PCPN SUNDAY WILL BE IN
THE COOLER AIR NORTH OF THIS OLD FRONTAL BOUNDARY IN WISCONSIN.
THE WARM FEED OF GULF MSTR INTO ILLINOIS WILL LIKELY KEEP NIGHTTIME
TEMPS UP TO AROUND 50 SUNDAY NIGHT.
THINGS CHANGE ON MONDAY HOWEVER AS A DEEPENING UPR TROF DIVES SE
FROM WRN CANADA AND SETS THIS PLAINS SYSTEM IN MOTION TO THE SE. A
SHOT OF RAIN IS POSSIBLE MONDAY THRU EARLY TUESDAY AS THIS SYSTEM IS
PUSHED SE BY THIS DIVING AMPLIFIED UPR TROF. POST FRONTAL CAA WILL
PUT AN END TO ANYMORE 60S FOR DAYTIME HIGHS THIS WEEK. WHILE A
WARMUP APPEARS TO BE SETTING UP FOR THURSDAY...ANOTHER SHOT OF RAIN
AND POST FRONTAL CAA ON FRIDAY APPEARS TO FOIL ANY WEEKEND PROSPECTS
FOR A RETURN OF THESE CONDITIONS.
RLB
&&
.AVIATION...
06Z TAFS...FORECAST CONCERNS REMAIN WIND SPEEDS THRU SATURDAY
MORNING ALONG WITH LOW LEVEL WIND SHEAR OVERNIGHT.
SOUTHERLY WINDS HAVE BEEN SLOW TO DIMINISH WITH MANY LOCATIONS
STILL GUSTING TO 20KTS OR HIGHER. TIGHT PRESSURE GRADIENT ALONG
WITH A LOW INVERSION NOT ALLOWING SFC TO DECOUPLE THUS WIND GUSTS
18-20KTS LIKELY TO CONTINUE THRU EARLY MORNING...PERHAPS DROPPING
OFF SOME TOWARD SUNRISE. BUT AS A WEAK FRONT/TROUGH SWINGS ACROSS
THE REGION...WINDS WILL BECOME SOUTHWESTERLY AND EXPECT GUSTS IN
THE 18-20KT RANGE THRU MUCH OF THE MORNING. WINDS TURN WESTERLY
SATURDAY AFTERNOON AND GRADUALLY DIMINISH TO LIGHT AND VRB BY
EVENING AS A WEAK RIDGE OF HIGH PRESSURE BUILDS ACROSS THE AREA.
EVENTUALLY...WINDS WILL SHIFT LIGHT EASTERLY LATE SATURDAY NIGHT
INTO SUNDAY MORNING.
PROFILERS AND VAD WIND DATA SUPPORT WIND SPEEDS IN THE 40-45KT
RANGE AROUND 2KFT. 00Z NAM SOUNDINGS ALSO SUPPORT THESE SPEEDS
CONTINUING THOUGH MUCH OF THE NIGHT. ALTHOUGH WILL BE ADDING
PREVAILING GUSTS TO THE SFC WINDS WILL MAINTAIN LOW LEVEL WIND
SHEAR DURING THE OVERNIGHT HRS AND EXPECT THESE SPEEDS TO SLOWLY
DIMINISH AFTER 12Z.
LARGE AREA OF BKN/OVC CIRRUS CONTINUES TO SHIFT EAST WITH MORE
CIRRUS FURTHER NORTHWEST. APPEARS SKC WILL LIKELY PREVAIL THRU
THE EARLY MORNING HRS. EARLIER CONCERN OF LOW/IFR CIGS APPEAR TO
BE WANING AS THE NAM/MET GUIDANCE HAS BACKED AWAY FROM PREVIOUS
PESSIMISTIC FORECASTS...THOUGH STILL DOES SHOW A BRIEF PERIOD OF
MVFR CIGS AFTER SUNRISE. GIVEN VERY LOW INVERSION HEIGHTS...IF
ANY CLOUDS WERE TO DEVELOP...WOULD LIKELY BE BELOW 1KFT. AT THIS
POINT...WITH LITTLE TO SUPPORT THEM...HAVE DECIDED TO REMOVE ALL
MENTION OF LOW CLOUDS BUT WILL CERTAINLY NEED TO BE MONITORED
THRU THE NIGHT. CMS
&&
.MARINE...
300 AM CST
MARGINAL GALES EXPECTED TO CONTINUE UNTIL EARLY THIS MORNING AS A
STRONG PRESSURE GRADIENT REMAINS IN PLACE OVER THE LAKE.
HOWEVER...LATER THIS MORNING A WEAKENING TROUGH AND COLD FRONT
WILL SWEEP ACROSS THE LAKE...RELAXING THE GRADIENT AND TURNING
WINDS WESTERLY BY THIS AFTERNOON. A WEAK RIDGE OF HIGH PRESSURE
WILL BUILD OVER THE LAKE TONIGHT AND TOMORROW...ALLOWING WINDS TO
FURTHER DECREASE TO ARND 5 TO 10KT. A WEAK LOW PRESSURE SYSTEM
WILL TRACK NORTHEAST OUT OF THE CENTRAL PLAINS AND ACROSS THE NRN
PORTION OF THE LAKE ON MONDAY. AS THIS LOW PASSES TO THE EAST...IT
WILL DRAG ANOTHER FRONT DOWN THE LENGTH OF THE LAKE MONDAY
NIGHT...BRINGING A PERIOD OF NORTH WINDS FOR MONDAY NIGHT AND TUESDAY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 6 AM SATURDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 10 AM SATURDAY.
&&
$$
000
FXUS63 KLOT 070752
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
152 AM CST SAT NOV 7 2009
.DISCUSSION...
152 AM CST
MODELS APPEAR TO HOLD ON TO CONSISTENCY WITH THE SFC TROF ACROSS
THE UPPER MS VLY AND GREAT LAKES REGION FLATTENING OUT AND
EJECTING NE INTO ONTARIO TODAY WHILE DRAPING A WEAK FRONTAL
BOUNDARY DOWN ACROSS NRN IL. THIS FRONT IS LITTLE MORE THAN A WEAK
WIND SHIFT TO THE WEST IN AN OTHERWISE WEAK PRESSURE GRADIENT AND
SUBSEQUENT LIGHTER WIND PATTERN BE ESTABLISHED BY LATE AFTN.
HOWEVER BRISK WINDS THIS EARLY MRNG SHUD KEEP LOW TEMPS UP TO
AROUND 50 IN MOST LOCATIONS...PROVIDING A GOOD START FOR AMPLE
SUNSHINE TO PUSH HIGHS TO AROUND 70 THIS AFTN.
ON A SIDE NOTE...PREVIOUS DISCUSSION WAS CONCERNED ABOUT LOW STRATUS
FORMING OVERNIGHT AND CAUSING A CLOUDY START TO THE MRNG. HOWEVER
MIXING STILL GOING STRONG IN VIGOROUS WIND FIELD AND NO SIGNS OF
BLACK STRATUS ON SATL FOG PRODUCT AS YET. THUS APPEARS NOT TO BE A
CONCERN THIS MRNG AND WILL EXPECT A SUNNY START TO THE DAY.
WITH HIGH PRESSURE BUILDING BACK INTO THE MIDWEST AND GREAT LAKES
REGION TONIGHT...WILL MAINTAIN CLEAR SKIES. ABSENCE OF POST FRONTAL
COLD AIR ADVECTION WILL LIKELY ONLY DROP LOWS TO AROUND 50 WITH SOME
LOW LYING MID 40S POSSIBLE CONSIDERING WEAKER WIND PATTERN.
SUNDAY IS STILL REINFORCING UPPER RIDGING EAST OF THE MS RIVER VLY
AND TILTING UPPER FLOW TO A MORE SWLY PATTERN OVER THE PLAINS AND
MIDWEST. AND OF COURSE A LEE SIDE LOW PRESSURE SYSTEM IS FORECAST TO
EJECT NE ALONG THIS UPPER PATTERN FROM THE HIGH PLAINS LATE TONIGHT
AND SUNDAY. THIS WILL PUSH OUR WEAK COLD FRONT BACK NORTH ON SUNDAY
AS A WARM FRONT. HIGHS NEAR 70 ARE AGAIN PROBABLE FOR SUNDAY AS A
RESULT DESPITE AN EXPECTED INCREASE IN AFTN WAA CLOUD COVER AHEAD OF
THIS SYSTEM. AS THE FRONT CONTINUES TO LIFT NORTH LATE SUNDAY...MODELS
DEPICTING RISING HEIGHTS OVER ILLINOIS...HELPING TO PUSH WAA
CLOUDINESS NORTHWARD. AN INTENSIFYING LLJ FROM THE GULF THRU THE
SRN PLAINS TO THE MID AND UPR MS VLY SHUD FEED GULF MSTR INTO THE
REGION SUNDAY INTO MONDAY. ANY OVERRUNNING PCPN SUNDAY WILL BE IN
THE COOLER AIR NORTH OF THIS OLD FRONTAL BOUNDARY IN WISCONSIN.
THE WARM FEED OF GULF MSTR INTO ILLINOIS WILL LIKELY KEEP NIGHTTIME
TEMPS UP TO AROUND 50 SUNDAY NIGHT.
THINGS CHANGE ON MONDAY HOWEVER AS A DEEPENING UPR TROF DIVES SE
FROM WRN CANADA AND SETS THIS PLAINS SYSTEM IN MOTION TO THE SE. A
SHOT OF RAIN IS POSSIBLE MONDAY THRU EARLY TUESDAY AS THIS SYSTEM IS
PUSHED SE BY THIS DIVING AMPLIFIED UPR TROF. POST FRONTAL CAA WILL
PUT AN END TO ANYMORE 60S FOR DAYTIME HIGHS THIS WEEK. WHILE A
WARMUP APPEARS TO BE SETTING UP FOR THURSDAY...ANOTHER SHOT OF RAIN
AND POST FRONTAL CAA ON FRIDAY APPEARS TO FOIL ANY WEEKEND PROSPECTS
FOR A RETURN OF THESE CONDITIONS.
RLB
&&
.AVIATION...
06Z TAFS...FORECAST CONCERNS REMAIN WIND SPEEDS THRU SATURDAY
MORNING ALONG WITH LOW LEVEL WIND SHEAR OVERNIGHT.
SOUTHERLY WINDS HAVE BEEN SLOW TO DIMINISH WITH MANY LOCATIONS
STILL GUSTING TO 20KTS OR HIGHER. TIGHT PRESSURE GRADIENT ALONG
WITH A LOW INVERSION NOT ALLOWING SFC TO DECOUPLE THUS WIND GUSTS
18-20KTS LIKELY TO CONTINUE THRU EARLY MORNING...PERHAPS DROPPING
OFF SOME TOWARD SUNRISE. BUT AS A WEAK FRONT/TROUGH SWINGS ACROSS
THE REGION...WINDS WILL BECOME SOUTHWESTERLY AND EXPECT GUSTS IN
THE 18-20KT RANGE THRU MUCH OF THE MORNING. WINDS TURN WESTERLY
SATURDAY AFTERNOON AND GRADUALLY DIMINISH TO LIGHT AND VRB BY
EVENING AS A WEAK RIDGE OF HIGH PRESSURE BUILDS ACROSS THE AREA.
EVENTUALLY...WINDS WILL SHIFT LIGHT EASTERLY LATE SATURDAY NIGHT
INTO SUNDAY MORNING.
PROFILERS AND VAD WIND DATA SUPPORT WIND SPEEDS IN THE 40-45KT
RANGE AROUND 2KFT. 00Z NAM SOUNDINGS ALSO SUPPORT THESE SPEEDS
CONTINUING THOUGH MUCH OF THE NIGHT. ALTHOUGH WILL BE ADDING
PREVAILING GUSTS TO THE SFC WINDS WILL MAINTAIN LOW LEVEL WIND
SHEAR DURING THE OVERNIGHT HRS AND EXPECT THESE SPEEDS TO SLOWLY
DIMINISH AFTER 12Z.
LARGE AREA OF BKN/OVC CIRRUS CONTINUES TO SHIFT EAST WITH MORE
CIRRUS FURTHER NORTHWEST. APPEARS SKC WILL LIKELY PREVAIL THRU
THE EARLY MORNING HRS. EARLIER CONCERN OF LOW/IFR CIGS APPEAR TO
BE WANING AS THE NAM/MET GUIDANCE HAS BACKED AWAY FROM PREVIOUS
PESSIMISTIC FORECASTS...THOUGH STILL DOES SHOW A BRIEF PERIOD OF
MVFR CIGS AFTER SUNRISE. GIVEN VERY LOW INVERSION HEIGHTS...IF
ANY CLOUDS WERE TO DEVELOP...WOULD LIKELY BE BELOW 1KFT. AT THIS
POINT...WITH LITTLE TO SUPPORT THEM...HAVE DECIDED TO REMOVE ALL
MENTION OF LOW CLOUDS BUT WILL CERTAINLY NEED TO BE MONITORED
THRU THE NIGHT. CMS
&&
.MARINE...
205 PM CST
A TIGHT PRESSURE GRADIENT REMAINS SITUATED FROM THE LOWER MIDWEST
NORTHEAST INTO THE UPPER GREAT LAKES REGION...IN RESPONSE TO A
DEPARTING AREA OF HIGH PRESSURE AND SURFACE TROUGH IN THE CENTRAL
PLAINS. THIS SETUP HAS PROVIDED SOUTH TO SOUTHEAST GUSTS ALONG THE
LAKE. GUSTS WILL STILL INCREASE THROUGH TONIGHT WITH SOUTH GALES
POSSIBLE BEFORE SATURDAY MORNING. AS THE SURFACE TROUGH EXITS TO
THE EAST...PRESSURE GRADIENT WILL RELAX FOR THE TIME BEING ALONG
WITH WIND GUSTS...BEFORE A WEAK AREA OF LOW PRESSURE MOVES
NORTHEAST ACROSS THE LAKE. ON THE BACKSIDE OF THIS SYSTEM...A COLD
FRONT WILL MOVE DOWN THE LAKE RETURNING THE WINDS BACK TO MORE OF
A NORTHERLY DIRECTION BY MONDAY.
RODRIGUEZ
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 6 AM SATURDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 10 AM SATURDAY.
&&
$$
000
FXUS63 KILX 070526
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1126 PM CST FRI NOV 6 2009
.DISCUSSION...
ISSUED 835 PM CST FRI NOV 6 2009
FRONTAL BOUNDARY OUT TO OUR WEST WILL CONTINUE TO EDGE TOWARDS
CENTRAL ILLINOIS OVERNIGHT. AHEAD OF THIS FEATURE...SOUTHERLY
WINDS CONTINUE TO GUST AOA 20 MPH IN A FEW LOCATIONS BUT EXPECT
THE GRADIENT TO WEAKEN LATE TNT AS THE BNDRY PUSHES TOWARDS
THE REGION. LOW LEVEL WARM AXIS NOTED ON THE LATEST SURFACE
ANALYSIS PUSHING NE INTO WRN IL SUGGESTING TEMPS WON`T BE FALLING
OFF MUCH IF ANY OVERNIGHT. CURRENT FORECAST HAS STEADY OR SLOWLY
RISING TEMPS OVERNIGHT AND BASED ON UPSTREAM TEMPS THAT SEEMS
REASONABLE AT THIS POINT. MAY SEE WINDS DECOUPLE ENOUGH AFTER
MIDNIGHT WHERE WE MAY ACTUALLY SEE SOME TEMPS DROP OFF A FEW
DEGREES. LATEST WATER VAPOR AND IR LOOPS SHOWING THE BAND OF
CIRRUS SHOULD PUSH EAST OF CENTRAL IL AFTR MIDNIGHT SO WL MAKE
SOME MINOR TWEAKS TO THE SKY GRIDS...OTHERWISE...THE REST OF
THE FORECAST IS IN GOOD SHAPE. NO EVENING ZFP UPDATE WILL BE
NEEDED.
&&
.AVIATION...
ISSUED 1125 PM CST FRI NOV 6 2009
SOUTHERLY WINDS GRDLY DIMINISHING ACRS THE AREA...HOWEVER WIND
PROFILERS SHOWING 1500-2000 FOOT WINDS OUT OF THE SOUTHWEST
AT 35-45 KTS SO WL CONTINUE WITH THE LLWS STARTING WITH THE
06Z TAF ISSUANCE. OTHERWISE...MODELS HAVE BACKED OFF SOME ON
THE POTENTIAL FOR SOME LOWER CIGS DEVELOPING BY MRNG. WL CONTINUE
WITH VFR CONDITIONS THRU THIS FCST PERIOD. SFC WNDS WL REMAIN OUT
OF THE SOUTH TNT AT 10 TO 15 KTS...AND THEN VEER MORE INTO THE
SOUTHWEST ON SATURDAY. WEAK FRONTAL BOUNDARY FORECAST TO APPROACH
OUR NRN TAF SITES LATER TMRW EVENING WHICH MAY HELP TO BACK THE
WINDS MORE INTO THE SOUTH AND SOUTHEAST AFTER DARK. FORECAST
SOUNDINGS AND TIME HEIGHT CROSS SECTIONS INDICATE SOME INCREASE
IN MOISTURE ARND 2500-3500 FEET JUST AHEAD OF THE BNDRY LATE TMRW
NIGHT...BUT IT APPEARS THAT WL NOT AFFECT OUR TAF SITES UNTIL JUST
AFTER THIS FORECAST PERIOD.
SMITH
&&
.PREV DISCUSSION...
ISSUED 140 PM CST FRI NOV 6 2009
A BREEZY SOUTHERLY FLOW HAS BROUGHT TEMPERATURES WELL INTO THE 60S
ACROSS THE CWA EARLY THIS AFTERNOON...NUDGING 70 DEGREES ACROSS
THE WEST. PRESSURE GRADIENT OF ABOUT 10 MB FROM NORTHWEST TO
SOUTHEAST ACROSS ILLINOIS...BETWEEN A SURFACE HIGH NEAR WASHINGTON
DC AND A WEAK TROUGH MOVING ACROSS THE NORTHERN AND CENTRAL PLAINS.
LOW-LEVEL JET AT 850 MB AROUND 40 KNOTS OUT OF THE SOUTHWEST...HELPING
TO BRING A SURGE OF 50S DEWPOINTS INTO MISSOURI AND SOUTHERN IOWA.
MAIN FORECAST ISSUES FOR THIS PACKAGE INCLUDE TEMPERATURES OVER
THE WEEKEND...AS WELL AS THE ARRIVAL OF A COLD FRONT LATER ON
MONDAY.
SHORT TERM...TODAY THROUGH MONDAY...
UNSEASONABLY MILD WEATHER EXPECTED THE NEXT COUPLE DAYS...AS A
SOUTH TO SOUTHWEST FLOW CONTINUES. NORTHERN END OF THE SURFACE
TROUGH CURRENTLY IN THE PLAINS EXPECTED TO PASS NORTH OF THE AREA
SATURDAY MORNING...WITH ONLY A PERIOD OF INCREASED CLOUDINESS
EXPECTED IN THE NORTHERN CWA...WHILE SOUTHERN END GETS PINCHED OFF
BY HIGH PRESSURE MOVING INTO SOUTH DAKOTA. 50 KNOT JET AT 925 MB
TO MOVE ACROSS THE AREA TONIGHT...HELPING TO KEEP WINDS GUSTY AT
THE SURFACE AND TEMPERATURES STEADY OR SLOWLY RISING AFTER
MIDNIGHT. TEMPERATURES EXPECTED TO REACH THE LOWER 70S OVER MOST
OF THE CWA BOTH SATURDAY AND SUNDAY...A GOOD 15 DEGREES ABOVE
NORMAL BUT STILL WELL SHY OF THE RECORDS WHICH ARE AROUND 80.
FAIRLY ZONAL FLOW ALOFT EXPECTED THROUGH THE WEEKEND...WITH A
SHORTWAVE TRACKING ALONG THE CANADIAN BORDER. MODELS IN GENERAL
AGREEMENT THROUGH MONDAY MORNING ON THE TRACK OF THE ASSOCIATED
SURFACE BOUNDARY...BUT SOUTHWEST EXTENT OF IT STILL A BIT OF A
QUESTION AS IT SQUEEZES BETWEEN DUAL SURFACE HIGHS TO THE NORTHWEST
AND SOUTHEAST. MOISTURE RETURN WILL NOT BE VERY PLENTIFUL...WITH A
QUASI-TROPICAL SYSTEM IN THE NORTHERN GULF CUTTING OFF ANY FLOW
INTO THE MIDWEST. WILL CONTINUE WITH SLIGHT CHANCE POPS OVER MUCH
OF THE CWA ON MONDAY...AND LOW CHANCES OF 25-30 PERCENT MONDAY
NIGHT.
LONG TERM...TUESDAY THROUGH FRIDAY...
UPPER PATTERN EXPECTED TO BECOME MORE AMPLIFIED AS THE WEEK
PROGRESSES...WITH RIDGING MOVING EASTWARD ACROSS THE CONUS AND
FLOW BECOMING MORE SOUTHWESTERLY. SURFACE CYCLONE EXPECTED TO
DEVELOP NEAR THE KANSAS/COLORADO BORDER BY THURSDAY EVENING...WITH
A FRONTAL BOUNDARY EXTENDING NORTHEAST INTO WISCONSIN. SOUTHERN
PUSH OF THE BOUNDARY IN QUESTION...WITH THE NEW 12Z ECMWF KEEPING
IT NORTH OF THE CWA THROUGH EARLY SATURDAY MORNING...AND THE GFS
BRINGING IT THROUGH OVER 24 HOURS EARLIER. LEANED TOWARD THE
SLOWER SOLUTION AT THIS TIME...AND KEPT FRIDAY DRY. TEMPERATURES
STILL EXPECTED TO BE ABOVE NORMAL THROUGH THE END OF THE WEEK...
ALTHOUGH NOT TO THE DEGREE OF THE FIRST PART OF THE FORECAST.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
000
FXUS63 KLOT 070444
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1044 PM CST FRI NOV 6 2009
.DISCUSSION...
740 PM CST
MADE SOME ADJUSTMENTS TO SKY COVER GRIDS BASED ON SATELLITE TRENDS.
GFS 500-250 MB RH SEEMS TO HAVE A GOOD HANDLE ON IT. UNLESS STRATUS
DEVELOPS...SKIES SHOULD BECOME MOSTLY CLEAR OVERNIGHT. TEMPS HAVE
BEEN SLOW TO FALL THIS EVENING WITH CLOUD COVER AND BRISK WINDS.
WINDS WILL SLOWLY FALL OFF AND CLOUDS WILL CLEAR LATER SO TEMPS
SHOULD FALL INTO MID-UPPER 40S AS FORECAST.
ALLSOPP
.PREVIOUS DISCUSSION...
231 PM CST
NO MAJOR CHANGES TO INHERITED FCST. CURRENT SATLT IMAGERY SHOWS
HIGH LVL CLOUDINESS ASSD WITH SHEARED OUT SHORT WAVE FROM UPR MS
VLY...WSWWD TO SERN CO. THIS FEATURE WILL CONTINUE EWD
TONIGHT...SPREADING MID/HIGH CLOUDINESS ACROSS AREA. IN
ADDITION...GUIDANCE SUGGESTS SOME LOWER CLOUDS WILL DEVELOP
OVERNIGHT AS HIGHER DEW POINT AIR STREAMING NWD TO W OF MS RVR
ADVECTS INTO REGION. THOUGH NO LOWER CLOUDS UPSTREAM AS OF
YET...EXPECT THEY WILL FORM LATER THIS EVENING AND OVERNIGHT AS
BOUNDARY LYR COOLS AND INVERSION DEVELOPS ONCE AGAIN. CLIMATOLOGY
WOULD ALSO SUPPORT THIS SCENARIO. MORE VIGOROUS SHORT WAVE MOVING
ACROSS SRN CANADA TONIGHT WILL PUSH AN ASSD SFC COLD FRONT SEWD
ACROSS THE UPR GRTLKS/UPR MS VLY OVERNIGHT. THIS WILL HELP TO KEEP
WINDS SOMEWHAT ELEVATED...AT LEAST THROUGH THIS EVENING...UNTIL
BOUNDARY LYR COOLS AND DECOUPLES OVERNIGHT. WEAKENING FRONT TO
PUSH THROUGH FA ON SATURDAY...BUT WITH THIS FRONT BECOMING MORE
ALIGNED WITH MID LVL FLOW...EXPECT LTL MORE THAN A WINDSHIFT TO W
TO MARK ITS PASSAGE. POST FRONTAL AIR MASS WILL BE FAIRLY DRY AND
THIS SHOULD ALLOW FOR AT LEAST PARTIAL CLEARING OF ANY RESIDUAL
CLOUDINESS.
SATURDAY NIGHT INTO SUNDAY MORNING...LEE SIDE LOW OVER CNTRL HIGH
PLAINS IS FCST TO DAMPEN AND EJECT NEWD TOWARD UPR MS VLY. THIS
WILL BRING TOMORROW/S COLD FRONT BACK N AS A WARM FRONT...AND WILL
ALSO RESULT IN RENEWED LLVL WARM ADVECTION SAT NIGHT INTO SUNDAY
MORNING BRINGING IN MORE WAA CLOUDINESS. HOWEVER...AS FRONT LIFTS
BACK TO N BY MID DAY SUNDAY...ENOUGH SUNSHINE IS EXPECTED TO
EMERGE...AND ACT ON UNSEASONABLY WARM LLVL AIR MASS...TO BOOST
TEMPS TO NEARLY 20 DEG ABV NORMAL. LOOKS LIKE WE HAD NOVEMBER IN
OCTOBER AND WE/RE GETTING EARLY OCTOBER WX IN NOVEMBER. IN
ADDITION...LLVLS ARE EXPECTED TO MOISTEN UP...WITH H85 DEW POINTS
FCST TO REACH 8-10 DEG C BY EARLY MONDAY. THIS SUPPORTS FAVORING
LOW TEMPS WAY ABV NORMAL SUNDAY NIGHT WITH OVERNIGHT LOWS ONLY
LOWERING TO ABOUT WHAT NORMAL HIGHS ARE FOR THE SECOND WEEK OF
NOVEMBER. SLY WINDS SHOULD ALSO REMAIN ELEVATED SUN NIGHT AS NEXT
COOL FRONT APCHS. MORE VIGOROUS SHORT WAVE IS FCST TO DROP ESEWD
TOWARD UPPER GRTLKS ON MONDAY. THIS IS EXPECTED TO PRODUCE OUR
NEXT CHANCE FOR RAIN AS FRONTAL CLOUD BAND DEVELOPS AND MOVES SEWD
INTO NRN IL MONDAY MORNING...AND ACROSS REMAINDER OF REGION BY MON
AFTN. ASSD SHORT WAVE IS FCST TO REMAIN POSITIVELY TILTED...AND
WITH LACK OF ANY STRONG DYNAMICS...WILL KEEP POPS IN CHC CATEGORY
MON-MON NIGHT. FOLLOWING THIS FROPA ON MONDAY...MORE SUSTAINED
COLD ADVECTION TO OCCUR MONDAY NIGHT-TUESDAY AS HIGH PRESSURE
BUILDS UPSTREAM...OVR UPR MIDWEST...TO BRING TEMPS BACK DOWN
CLOSER TO...BUT STILL ABOVE...NORMAL MUCH OF THE REMAINDER OF THE
FCST PERIOD. OVERALL PATTERN HEADING INTO EXTENDED PERIOD
SUGGESTING CONTINUATION OF TROUGHING IN WRN CONUS AND RIDGING IN
THE EAST SO TREND WILL BE FOR MILD NOVEMBER TO CONTINUE.
MERZLOCK
&&
.AVIATION...
06Z TAFS...FORECAST CONCERNS REMAIN WIND SPEEDS THRU SATURDAY
MORNING ALONG WITH LOW LEVEL WIND SHEAR OVERNIGHT.
SOUTHERLY WINDS HAVE BEEN SLOW TO DIMINISH WITH MANY LOCATIONS
STILL GUSTING TO 20KTS OR HIGHER. TIGHT PRESSURE GRADIENT ALONG
WITH A LOW INVERSION NOT ALLOWING SFC TO DECOUPLE THUS WIND GUSTS
18-20KTS LIKELY TO CONTINUE THRU EARLY MORNING...PERHAPS DROPPING
OFF SOME TOWARD SUNRISE. BUT AS A WEAK FRONT/TROUGH SWINGS ACROSS
THE REGION...WINDS WILL BECOME SOUTHWESTERLY AND EXPECT GUSTS IN
THE 18-20KT RANGE THRU MUCH OF THE MORNING. WINDS TURN WESTERLY
SATURDAY AFTERNOON AND GRADUALLY DIMINISH TO LIGHT AND VRB BY
EVENING AS A WEAK RIDGE OF HIGH PRESSURE BUILDS ACROSS THE AREA.
EVENTUALLY...WINDS WILL SHIFT LIGHT EASTERLY LATE SATURDAY NIGHT
INTO SUNDAY MORNING.
PROFILERS AND VAD WIND DATA SUPPORT WIND SPEEDS IN THE 40-45KT
RANGE AROUND 2KFT. 00Z NAM SOUNDINGS ALSO SUPPORT THESE SPEEDS
CONTINUING THOUGH MUCH OF THE NIGHT. ALTHOUGH WILL BE ADDING
PREVAILING GUSTS TO THE SFC WINDS WILL MAINTAIN LOW LEVEL WIND
SHEAR DURING THE OVERNIGHT HRS AND EXPECT THESE SPEEDS TO SLOWLY
DIMINISH AFTER 12Z.
LARGE AREA OF BKN/OVC CIRRUS CONTINUES TO SHIFT EAST WITH MORE
CIRRUS FURTHER NORTHWEST. APPEARS SKC WILL LIKELY PREVAIL THRU
THE EARLY MORNING HRS. EARLIER CONCERN OF LOW/IFR CIGS APPEAR TO
BE WANING AS THE NAM/MET GUIDANCE HAS BACKED AWAY FROM PREVIOUS
PESSIMISTIC FORECASTS...THOUGH STILL DOES SHOW A BRIEF PERIOD OF
MVFR CIGS AFTER SUNRISE. GIVEN VERY LOW INVERSION HEIGHTS...IF
ANY CLOUDS WERE TO DEVELOP...WOULD LIKELY BE BELOW 1KFT. AT THIS
POINT...WITH LITTLE TO SUPPORT THEM...HAVE DECIDED TO REMOVE ALL
MENTION OF LOW CLOUDS BUT WILL CERTAINLY NEED TO BE MONITORED
THRU THE NIGHT. CMS
&&
.MARINE...
205 PM CST
A TIGHT PRESSURE GRADIENT REMAINS SITUATED FROM THE LOWER MIDWEST
NORTHEAST INTO THE UPPER GREAT LAKES REGION...IN RESPONSE TO A
DEPARTING AREA OF HIGH PRESSURE AND SURFACE TROUGH IN THE CENTRAL
PLAINS. THIS SETUP HAS PROVIDED SOUTH TO SOUTHEAST GUSTS ALONG THE
LAKE. GUSTS WILL STILL INCREASE THROUGH TONIGHT WITH SOUTH GALES
POSSIBLE BEFORE SATURDAY MORNING. AS THE SURFACE TROUGH EXITS TO
THE EAST...PRESSURE GRADIENT WILL RELAX FOR THE TIME BEING ALONG
WITH WIND GUSTS...BEFORE A WEAK AREA OF LOW PRESSURE MOVES
NORTHEAST ACROSS THE LAKE. ON THE BACKSIDE OF THIS SYSTEM...A COLD
FRONT WILL MOVE DOWN THE LAKE RETURNING THE WINDS BACK TO MORE OF
A NORTHERLY DIRECTION BY MONDAY.
RODRIGUEZ
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 6 AM SATURDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 10 AM SATURDAY.
&&
$$
000
FXUS63 KILX 070244
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
844 PM CST FRI NOV 6 2009
.DISCUSSION...
ISSUED 835 PM CST FRI NOV 6 2009
FRONTAL BOUNDARY OUT TO OUR WEST WILL CONTINUE TO EDGE TOWARDS
CENTRAL ILLINOIS OVERNIGHT. AHEAD OF THIS FEATURE...SOUTHERLY
WINDS CONTINUE TO GUST AOA 20 MPH IN A FEW LOCATIONS BUT EXPECT
THE GRADIENT TO WEAKEN LATE TNT AS THE BNDRY PUSHES TOWARDS
THE REGION. LOW LEVEL WARM AXIS NOTED ON THE LATEST SURFACE
ANALYSIS PUSHING NE INTO WRN IL SUGGESTING TEMPS WON`T BE FALLING
OFF MUCH IF ANY OVERNIGHT. CURRENT FORECAST HAS STEADY OR SLOWLY
RISING TEMPS OVERNIGHT AND BASED ON UPSTREAM TEMPS THAT SEEMS
REASONABLE AT THIS POINT. MAY SEE WINDS DECOUPLE ENOUGH AFTER
MIDNIGHT WHERE WE MAY ACTUALLY SEE SOME TEMPS DROP OFF A FEW
DEGREES. LATEST WATER VAPOR AND IR LOOPS SHOWING THE BAND OF
CIRRUS SHOULD PUSH EAST OF CENTRAL IL AFTR MIDNIGHT SO WL MAKE
SOME MINOR TWEAKS TO THE SKY GRIDS...OTHERWISE...THE REST OF
THE FORECAST IS IN GOOD SHAPE. NO EVENING ZFP UPDATE WILL BE
NEEDED.
SMITH
&&
.AVIATION...
ISSUED 535 PM CST FRI NOV 6 2009
TIGHT PRESSURE GRADIENT TO ONLY SLOWLY RELAX LATE TNT WHICH SHOULD
HELP KEEP WINDS UP THRU MOST OF THE NIGHT. THE GUSTS SHOULD PULL
BACK SOME AFTR DARK BUT WL INCLUDE SOME INTO THE EARLY MRNG HOURS
BEFORE DIMINISHING. WITH THE WINDS EXPECTED TO SLOWLY DIMINISH
OVERNIGHT...THE NEXT CONCERN WL BE WITH LOW LEVEL WIND SHEAR AS
MODEL SOUNDINGS SHOWING 40KTS JUST OFF THE DECK. WL CONTINUE FROM
THE PREVIOUS FCST IN BRINGING IN THE LLWS AFTR 06Z AND THEN ENDING
BY 14Z SAT. MODELS STILL INSIST ON BRINGING LOW LEVEL MOISTURE/CLOUDS
INTO AT LEAST THE NRN PART OF THE FCST AREA BUT AM NOT SEEING ANY
EVIDENCE OF THIS OUT TO OUR WEST SO WL CONTINUE WITH THE VFR
CONDITIONS THRU THIS FCST PERIOD. SFC WNDS WL GRDLY VEER INTO THE
WEST DURING THE DAY SATURDAY.
SMITH
&&
.PREV DISCUSSION...
ISSUED 140 PM CST FRI NOV 6 2009
A BREEZY SOUTHERLY FLOW HAS BROUGHT TEMPERATURES WELL INTO THE 60S
ACROSS THE CWA EARLY THIS AFTERNOON...NUDGING 70 DEGREES ACROSS
THE WEST. PRESSURE GRADIENT OF ABOUT 10 MB FROM NORTHWEST TO
SOUTHEAST ACROSS ILLINOIS...BETWEEN A SURFACE HIGH NEAR WASHINGTON
DC AND A WEAK TROUGH MOVING ACROSS THE NORTHERN AND CENTRAL PLAINS.
LOW-LEVEL JET AT 850 MB AROUND 40 KNOTS OUT OF THE SOUTHWEST...HELPING
TO BRING A SURGE OF 50S DEWPOINTS INTO MISSOURI AND SOUTHERN IOWA.
MAIN FORECAST ISSUES FOR THIS PACKAGE INCLUDE TEMPERATURES OVER
THE WEEKEND...AS WELL AS THE ARRIVAL OF A COLD FRONT LATER ON
MONDAY.
SHORT TERM...TODAY THROUGH MONDAY...
UNSEASONABLY MILD WEATHER EXPECTED THE NEXT COUPLE DAYS...AS A
SOUTH TO SOUTHWEST FLOW CONTINUES. NORTHERN END OF THE SURFACE
TROUGH CURRENTLY IN THE PLAINS EXPECTED TO PASS NORTH OF THE AREA
SATURDAY MORNING...WITH ONLY A PERIOD OF INCREASED CLOUDINESS
EXPECTED IN THE NORTHERN CWA...WHILE SOUTHERN END GETS PINCHED OFF
BY HIGH PRESSURE MOVING INTO SOUTH DAKOTA. 50 KNOT JET AT 925 MB
TO MOVE ACROSS THE AREA TONIGHT...HELPING TO KEEP WINDS GUSTY AT
THE SURFACE AND TEMPERATURES STEADY OR SLOWLY RISING AFTER
MIDNIGHT. TEMPERATURES EXPECTED TO REACH THE LOWER 70S OVER MOST
OF THE CWA BOTH SATURDAY AND SUNDAY...A GOOD 15 DEGREES ABOVE
NORMAL BUT STILL WELL SHY OF THE RECORDS WHICH ARE AROUND 80.
FAIRLY ZONAL FLOW ALOFT EXPECTED THROUGH THE WEEKEND...WITH A
SHORTWAVE TRACKING ALONG THE CANADIAN BORDER. MODELS IN GENERAL
AGREEMENT THROUGH MONDAY MORNING ON THE TRACK OF THE ASSOCIATED
SURFACE BOUNDARY...BUT SOUTHWEST EXTENT OF IT STILL A BIT OF A
QUESTION AS IT SQUEEZES BETWEEN DUAL SURFACE HIGHS TO THE NORTHWEST
AND SOUTHEAST. MOISTURE RETURN WILL NOT BE VERY PLENTIFUL...WITH A
QUASI-TROPICAL SYSTEM IN THE NORTHERN GULF CUTTING OFF ANY FLOW
INTO THE MIDWEST. WILL CONTINUE WITH SLIGHT CHANCE POPS OVER MUCH
OF THE CWA ON MONDAY...AND LOW CHANCES OF 25-30 PERCENT MONDAY
NIGHT.
LONG TERM...TUESDAY THROUGH FRIDAY...
UPPER PATTERN EXPECTED TO BECOME MORE AMPLIFIED AS THE WEEK
PROGRESSES...WITH RIDGING MOVING EASTWARD ACROSS THE CONUS AND
FLOW BECOMING MORE SOUTHWESTERLY. SURFACE CYCLONE EXPECTED TO
DEVELOP NEAR THE KANSAS/COLORADO BORDER BY THURSDAY EVENING...WITH
A FRONTAL BOUNDARY EXTENDING NORTHEAST INTO WISCONSIN. SOUTHERN
PUSH OF THE BOUNDARY IN QUESTION...WITH THE NEW 12Z ECMWF KEEPING
IT NORTH OF THE CWA THROUGH EARLY SATURDAY MORNING...AND THE GFS
BRINGING IT THROUGH OVER 24 HOURS EARLIER. LEANED TOWARD THE
SLOWER SOLUTION AT THIS TIME...AND KEPT FRIDAY DRY. TEMPERATURES
STILL EXPECTED TO BE ABOVE NORMAL THROUGH THE END OF THE WEEK...
ALTHOUGH NOT TO THE DEGREE OF THE FIRST PART OF THE FORECAST.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
000
FXUS63 KLOT 070144
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
740 PM CST FRI NOV 6 2009
.DISCUSSION UPDATE...
740 PM CST
MADE SOME ADJUSTMENTS TO SKY COVER GRIDS BASED ON SATELLITE TRENDS.
GFS 500-250 MB RH SEEMS TO HAVE A GOOD HANDLE ON IT. UNLESS STRATUS
DEVELOPS...SKIES SHOULD BECOME MOSTLY CLEAR OVERNIGHT. TEMPS HAVE
BEEN SLOW TO FALL THIS EVENING WITH CLOUD COVER AND BRISK WINDS.
WINDS WILL SLOWLY FALL OFF AND CLOUDS WILL CLEAR LATER SO TEMPS
SHOULD FALL INTO MID-UPPER 40S AS FORECAST.
ALLSOPP
.PREVIOUS DISCUSSION...
231 PM CST
NO MAJOR CHANGES TO INHERITED FCST. CURRENT SATLT IMAGERY SHOWS
HIGH LVL CLOUDINESS ASSD WITH SHEARED OUT SHORT WAVE FROM UPR MS
VLY...WSWWD TO SERN CO. THIS FEATURE WILL CONTINUE EWD
TONIGHT...SPREADING MID/HIGH CLOUDINESS ACROSS AREA. IN
ADDITION...GUIDANCE SUGGESTS SOME LOWER CLOUDS WILL DEVELOP
OVERNIGHT AS HIGHER DEW POINT AIR STREAMING NWD TO W OF MS RVR
ADVECTS INTO REGION. THOUGH NO LOWER CLOUDS UPSTREAM AS OF
YET...EXPECT THEY WILL FORM LATER THIS EVENING AND OVERNIGHT AS
BOUNDARY LYR COOLS AND INVERSION DEVELOPS ONCE AGAIN. CLIMATOLOGY
WOULD ALSO SUPPORT THIS SCENARIO. MORE VIGOROUS SHORT WAVE MOVING
ACROSS SRN CANADA TONIGHT WILL PUSH AN ASSD SFC COLD FRONT SEWD
ACROSS THE UPR GRTLKS/UPR MS VLY OVERNIGHT. THIS WILL HELP TO KEEP
WINDS SOMEWHAT ELEVATED...AT LEAST THROUGH THIS EVENING...UNTIL
BOUNDARY LYR COOLS AND DECOUPLES OVERNIGHT. WEAKENING FRONT TO
PUSH THROUGH FA ON SATURDAY...BUT WITH THIS FRONT BECOMING MORE
ALIGNED WITH MID LVL FLOW...EXPECT LTL MORE THAN A WINDSHIFT TO W
TO MARK ITS PASSAGE. POST FRONTAL AIR MASS WILL BE FAIRLY DRY AND
THIS SHOULD ALLOW FOR AT LEAST PARTIAL CLEARING OF ANY RESIDUAL
CLOUDINESS.
SATURDAY NIGHT INTO SUNDAY MORNING...LEE SIDE LOW OVER CNTRL HIGH
PLAINS IS FCST TO DAMPEN AND EJECT NEWD TOWARD UPR MS VLY. THIS
WILL BRING TOMORROW/S COLD FRONT BACK N AS A WARM FRONT...AND WILL
ALSO RESULT IN RENEWED LLVL WARM ADVECTION SAT NIGHT INTO SUNDAY
MORNING BRINGING IN MORE WAA CLOUDINESS. HOWEVER...AS FRONT LIFTS
BACK TO N BY MID DAY SUNDAY...ENOUGH SUNSHINE IS EXPECTED TO
EMERGE...AND ACT ON UNSEASONABLY WARM LLVL AIR MASS...TO BOOST
TEMPS TO NEARLY 20 DEG ABV NORMAL. LOOKS LIKE WE HAD NOVEMBER IN
OCTOBER AND WE/RE GETTING EARLY OCTOBER WX IN NOVEMBER. IN
ADDITION...LLVLS ARE EXPECTED TO MOISTEN UP...WITH H85 DEW POINTS
FCST TO REACH 8-10 DEG C BY EARLY MONDAY. THIS SUPPORTS FAVORING
LOW TEMPS WAY ABV NORMAL SUNDAY NIGHT WITH OVERNIGHT LOWS ONLY
LOWERING TO ABOUT WHAT NORMAL HIGHS ARE FOR THE SECOND WEEK OF
NOVEMBER. SLY WINDS SHOULD ALSO REMAIN ELEVATED SUN NIGHT AS NEXT
COOL FRONT APCHS. MORE VIGOROUS SHORT WAVE IS FCST TO DROP ESEWD
TOWARD UPPER GRTLKS ON MONDAY. THIS IS EXPECTED TO PRODUCE OUR
NEXT CHANCE FOR RAIN AS FRONTAL CLOUD BAND DEVELOPS AND MOVES SEWD
INTO NRN IL MONDAY MORNING...AND ACROSS REMAINDER OF REGION BY MON
AFTN. ASSD SHORT WAVE IS FCST TO REMAIN POSITIVELY TILTED...AND
WITH LACK OF ANY STRONG DYNAMICS...WILL KEEP POPS IN CHC CATEGORY
MON-MON NIGHT. FOLLOWING THIS FROPA ON MONDAY...MORE SUSTAINED
COLD ADVECTION TO OCCUR MONDAY NIGHT-TUESDAY AS HIGH PRESSURE
BUILDS UPSTREAM...OVR UPR MIDWEST...TO BRING TEMPS BACK DOWN
CLOSER TO...BUT STILL ABOVE...NORMAL MUCH OF THE REMAINDER OF THE
FCST PERIOD. OVERALL PATTERN HEADING INTO EXTENDED PERIOD
SUGGESTING CONTINUATION OF TROUGHING IN WRN CONUS AND RIDGING IN
THE EAST SO TREND WILL BE FOR MILD NOVEMBER TO CONTINUE.
MERZLOCK
&&
.AVIATION...
00Z TAFS...SEVERAL FORECAST CONCERNS THIS EVENING...INCLUDING
WINDS THIS EVENING...LOW LEVEL WIND SHEAR OVERNIGHT AND POTENTIAL
FOR LOW CIGS SATURDAY MORNING.
STRONGEST PRESSURE GRADIENT CURRENTLY MOVING ACROSS THE REGION
EARLY THIS EVENING. GUSTS SHOULD GRADUALLY DIMINISH DURING THE
EVENING HRS AS AN INVERSION DEVELOPS...THOUGH LOWEST LEVELS DO
REMAIN QUITE BREEZY THRU EVENING. ABOVE THIS INVERSION...LOW LEVEL
WINDS WILL CONTINUE TO INCREASE THRU THE EVENING AND CONTINUE
OVERNIGHT. CONFIDENCE NOT PARTICULARLY HIGH ON HOW STRONG THESE
WINDS WILL BECOME AND AT WHAT HEIGHT. SO HAVE MAINTAINED LOW LEVEL
WIND SHEAR WITH THIS FORECAST AND HOPE TO REFINE THIS WITH ACARS
SOUNDINGS EITHER THRU THE EVENING OR WITH THE 06Z TAFS.
MODELS SHOW INCREASING LOW LEVEL MOISTURE OVERNIGHT WITH A PEAK
OCCURRING AROUND SUNRISE AND JUST AHEAD OF A WEAK FRONT/TROUGH THAT
PASSES ACROSS THE REGION SATURDAY MORNING. WOULD EXPECT ANY LOW
CLOUDS THAT DO DEVELOP TO BE RATHER LOW CONSIDERING THE LOW HEIGHT
OF THE INVERSION BUT NOT SURE IF THEY WILL FORM. BECAUSE OF THIS
HAVE BACKED OFF TO SCATTERED MENTION BUT LOWERED CLOUD HEIGHTS
UNDER 1KFT. IF THEY FORM...BKN/OVC IFR CIGS WILL LIKELY PREVAIL
FOR A FEW HRS AHEAD OF THE FRONT LIFTING AND THEN SCATTERING OUT.
SOUTHERLY WINDS THIS EVENING WILL TURN MORE SOUTHWESTERLY
OVERNIGHT STILL IN THE 10-15KT RANGE THEN SHIFT WESTERLY BEHIND
THE FRONT BY SATURDAY AFTERNOON. EXPECT SOME HIGHER GUSTS FOR A
TIME SATURDAY MORNING BUT AS A WEAK RIDGE BUILDS ACROSS PARTS OF
THE MIDWEST SATURDAY EVENING...EXPECT WINDS TO GO LIGHT AND VRB
TOWARD THE END OF THE PERIOD. CMS
&&
.MARINE...
205 PM CST
A TIGHT PRESSURE GRADIENT REMAINS SITUATED FROM THE LOWER MIDWEST
NORTHEAST INTO THE UPPER GREAT LAKES REGION...IN RESPONSE TO A
DEPARTING AREA OF HIGH PRESSURE AND SURFACE TROUGH IN THE CENTRAL
PLAINS. THIS SETUP HAS PROVIDED SOUTH TO SOUTHEAST GUSTS ALONG THE
LAKE. GUSTS WILL STILL INCREASE THROUGH TONIGHT WITH SOUTH GALES
POSSIBLE BEFORE SATURDAY MORNING. AS THE SURFACE TROUGH EXITS TO
THE EAST...PRESSURE GRADIENT WILL RELAX FOR THE TIME BEING ALONG
WITH WIND GUSTS...BEFORE A WEAK AREA OF LOW PRESSURE MOVES
NORTHEAST ACROSS THE LAKE. ON THE BACKSIDE OF THIS SYSTEM...A COLD
FRONT WILL MOVE DOWN THE LAKE RETURNING THE WINDS BACK TO MORE OF
A NORTHERLY DIRECTION BY MONDAY.
RODRIGUEZ
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 6 AM SATURDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 10 AM SATURDAY.
&&
$$
000
FXUS63 KILX 062347
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
547 PM CST FRI NOV 6 2009
.DISCUSSION...
ISSUED 140 PM CST FRI NOV 6 2009
A BREEZY SOUTHERLY FLOW HAS BROUGHT TEMPERATURES WELL INTO THE 60S
ACROSS THE CWA EARLY THIS AFTERNOON...NUDGING 70 DEGREES ACROSS
THE WEST. PRESSURE GRADIENT OF ABOUT 10 MB FROM NORTHWEST TO
SOUTHEAST ACROSS ILLINOIS...BETWEEN A SURFACE HIGH NEAR WASHINGTON
DC AND A WEAK TROUGH MOVING ACROSS THE NORTHERN AND CENTRAL PLAINS.
LOW-LEVEL JET AT 850 MB AROUND 40 KNOTS OUT OF THE SOUTHWEST...HELPING
TO BRING A SURGE OF 50S DEWPOINTS INTO MISSOURI AND SOUTHERN IOWA.
MAIN FORECAST ISSUES FOR THIS PACKAGE INCLUDE TEMPERATURES OVER
THE WEEKEND...AS WELL AS THE ARRIVAL OF A COLD FRONT LATER ON
MONDAY.
SHORT TERM...TODAY THROUGH MONDAY...
UNSEASONABLY MILD WEATHER EXPECTED THE NEXT COUPLE DAYS...AS A
SOUTH TO SOUTHWEST FLOW CONTINUES. NORTHERN END OF THE SURFACE
TROUGH CURRENTLY IN THE PLAINS EXPECTED TO PASS NORTH OF THE AREA
SATURDAY MORNING...WITH ONLY A PERIOD OF INCREASED CLOUDINESS
EXPECTED IN THE NORTHERN CWA...WHILE SOUTHERN END GETS PINCHED OFF
BY HIGH PRESSURE MOVING INTO SOUTH DAKOTA. 50 KNOT JET AT 925 MB
TO MOVE ACROSS THE AREA TONIGHT...HELPING TO KEEP WINDS GUSTY AT
THE SURFACE AND TEMPERATURES STEADY OR SLOWLY RISING AFTER
MIDNIGHT. TEMPERATURES EXPECTED TO REACH THE LOWER 70S OVER MOST
OF THE CWA BOTH SATURDAY AND SUNDAY...A GOOD 15 DEGREES ABOVE
NORMAL BUT STILL WELL SHY OF THE RECORDS WHICH ARE AROUND 80.
FAIRLY ZONAL FLOW ALOFT EXPECTED THROUGH THE WEEKEND...WITH A
SHORTWAVE TRACKING ALONG THE CANADIAN BORDER. MODELS IN GENERAL
AGREEMENT THROUGH MONDAY MORNING ON THE TRACK OF THE ASSOCIATED
SURFACE BOUNDARY...BUT SOUTHWEST EXTENT OF IT STILL A BIT OF A
QUESTION AS IT SQUEEZES BETWEEN DUAL SURFACE HIGHS TO THE NORTHWEST
AND SOUTHEAST. MOISTURE RETURN WILL NOT BE VERY PLENTIFUL...WITH A
QUASI-TROPICAL SYSTEM IN THE NORTHERN GULF CUTTING OFF ANY FLOW
INTO THE MIDWEST. WILL CONTINUE WITH SLIGHT CHANCE POPS OVER MUCH
OF THE CWA ON MONDAY...AND LOW CHANCES OF 25-30 PERCENT MONDAY
NIGHT.
LONG TERM...TUESDAY THROUGH FRIDAY...
UPPER PATTERN EXPECTED TO BECOME MORE AMPLIFIED AS THE WEEK
PROGRESSES...WITH RIDGING MOVING EASTWARD ACROSS THE CONUS AND
FLOW BECOMING MORE SOUTHWESTERLY. SURFACE CYCLONE EXPECTED TO
DEVELOP NEAR THE KANSAS/COLORADO BORDER BY THURSDAY EVENING...WITH
A FRONTAL BOUNDARY EXTENDING NORTHEAST INTO WISCONSIN. SOUTHERN
PUSH OF THE BOUNDARY IN QUESTION...WITH THE NEW 12Z ECMWF KEEPING
IT NORTH OF THE CWA THROUGH EARLY SATURDAY MORNING...AND THE GFS
BRINGING IT THROUGH OVER 24 HOURS EARLIER. LEANED TOWARD THE
SLOWER SOLUTION AT THIS TIME...AND KEPT FRIDAY DRY. TEMPERATURES
STILL EXPECTED TO BE ABOVE NORMAL THROUGH THE END OF THE WEEK...
ALTHOUGH NOT TO THE DEGREE OF THE FIRST PART OF THE FORECAST.
GEELHART
&&
.AVIATION...
ISSUED 535 PM CST FRI NOV 6 2009
TIGHT PRESSURE GRADIENT TO ONLY SLOWLY RELAX LATE TNT WHICH SHOULD
HELP KEEP WINDS UP THRU MOST OF THE NIGHT. THE GUSTS SHOULD PULL
BACK SOME AFTR DARK BUT WL INCLUDE SOME INTO THE EARLY MRNG HOURS
BEFORE DIMINISHING. WITH THE WINDS EXPECTED TO SLOWLY DIMINISH
OVERNIGHT...THE NEXT CONCERN WL BE WITH LOW LEVEL WIND SHEAR AS
MODEL SOUNDINGS SHOWING 40KTS JUST OFF THE DECK. WL CONTINUE FROM
THE PREVIOUS FCST IN BRINGING IN THE LLWS AFTR 06Z AND THEN ENDING
BY 14Z SAT. MODELS STILL INSIST ON BRINGING LOW LEVEL MOISTURE/CLOUDS
INTO AT LEAST THE NRN PART OF THE FCST AREA BUT AM NOT SEEING ANY
EVIDENCE OF THIS OUT TO OUR WEST SO WL CONTINUE WITH THE VFR
CONDITIONS THRU THIS FCST PERIOD. SFC WNDS WL GRDLY VEER INTO THE
WEST DURING THE DAY SATURDAY.
SMITH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
| 
