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000
FXUS63 KARX 212110
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
310 PM CST SAT NOV 21 2009
.SHORT TERM...TONIGHT THROUGH MONDAY NIGHT
MAIN FORECAST CONCERN IS ON CHANCES FOR LIGHT PRECIPITATION CHANCES
THROUGH THE PERIOD.
CURRENTLY AS OF 21Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS
SHOWED RIDGING ACROSS THE UPPER MISSISSIPPI VALLEY AND GREAT
LAKES...TROUGHING FROM ALBERTA SOUTH INTO UTAH...AND A MORE POTENT
TROUGH JUST SOUTH OF THE GULF OF ALASKA. SUBSIDENCE UNDER THE UPPER
RIDGE HAS KEPT MUCH OF THE AREA EAST OF THE ROCKIES AND SAY NORTH OF
I-40 PRECIPITATION FREE TODAY. HOWEVER...NUMEROUS ISSUES EXIST THE
CLOUD DEPARTMENT...WHERE A ZONE OF TWO DIFFERENT STRATUS LAYERS CAN
BE SEEN OVER THE CENTRAL PLAINS AND OVER THE FORECAST AREA. BOTH
AREAS HAVE MOSTLY EVOLVED FROM A COMBINATION OF MIXING OUT MORNING
FOG...AND THEN THAT MOISTURE STAYING TRAPPED UNDER THE SUBSIDENCE
INVERSION CAUSED BY THE UPPER RIDGE. THE CLOUDS OVER THE FORECAST
AREA HAVE HELD TEMPERATURES DOWN...WITH READINGS MOSTLY IN THE MID
TO UPPER 40S. RETURN LOW LEVEL FLOW...BETWEEN HIGH PRESSURE OVER THE
OHIO VALLEY AND A LEE TROUGH IS BRINGING 40S DEWPOINTS NORTHWARD
THROUGH THE PLAINS.
TONIGHT...UPPER TROUGH OVER THE INTERMOUNTAIN WEST IS PROGGED TO
PUSH EAST INTO THE WESTERN PLAINS...CAUSING UPPER LEVEL FLOW TO TURN
SOUTHWESTERLY OVER THE AREA. IN RESPONSE IN THE LOW LEVELS...
SOUTHERLY FLOW SHOULD INCREASE...AS THE LEE TROUGH/COLD FRONT MOVES
INTO THE EASTERN DAKOTAS. THIS INCREASING SOUTHERLY FLOW WILL HELP
BRING THE CLOUDS/MOISTURE OVER THE CENTRAL PLAINS INTO THE FORECAST
AREA. PAST AND CURRENT GFS/ECMWF RUNS CONTINUE TO SHOW DEVELOPMENT
OF LIGHT QPF ACROSS THE UPPER MISSISSIPPI VALLEY REGION...ESPECIALLY
AFTER 06Z. HOWEVER...PAST AND CURRENT NAM RUNS REMAIN DRY. LOOKING
AT GFS SOUNDINGS...THE LIGHT QPF LOOKS TO BE A RESULT OF DRIZZLE...
SINCE SATURATION AND LIFT IS CONFINED TO AN AREA AT OR BELOW 5000
FT. PREVIOUS FORECAST WAS DRY...AND WILL CONTINUE THAT IDEA BUT
MAINTAIN A MENTION OF PATCHY DRIZZLE. ONLY AREA THAT MAY NOT SEE
DRIZZLE IS FROM JUNEAU/ADAMS COUNTIES SOUTHWEST INTO GRANT COUNTY...
WHERE ENOUGH DRIER AIR INFLUENCE FROM CENTRAL ILLINOIS COMING
THROUGH THE RETURN FLOW WILL PREVENT PRECIPITATION. ANOTHER ISSUE TO
DEAL WITH TONIGHT IS THE MOISTURE COMING UP FROM THE SOUTH...RUNNING
INTO A COOLER AIRMASS OVER THE FORECAST AREA. THIS MAY RESULT IN
SOME FOG DEVELOPMENT...ESPECIALLY OVER THE RIDGES OF SOUTHEAST
MINNESOTA AND NORTHEAST IOWA. HAVE MAINTAINED THE GOING AREAS OF
DENSE FOG...BUT DID NOT ISSUE AN ADVISORY AT THIS TIME DUE TO
UNCERTAINTY OF THE FOG BEING WIDESPREAD ENOUGH TO WARRANT THE
ADVISORY. REGARDING LOW TEMPERATURES...WITH THE HIGHER DEWPOINTS
MOVING INTO THE AREA FROM THE SOUTH...LOWS WILL LIKELY BE THIS
EVENING WITH RISING TEMPERATURES AFTERWORDS.
ONE CAVEAT TO WATCH FOR TONIGHT...WITH THE WINDS INCREASING...
DEVELOPING LOW LEVEL SATURATION MAY BE TRICKY AS TEMPERATURES MAY
NOT WANT TO FALL. IF THIS OCCURS...THEN ALL WE COULD END UP WITH IS
SOME PASSING STRATUS CLOUDS WITH BASES AT 3000 FT OR SO...AS SEEN
OVER EASTERN NEBRASKA AND NORTHEAST KANSAS. FUTURE SHIFTS WILL NEED
TO MONITOR CLOUD TRENDS AND DEWPOINT DEPRESSIONS.
SUNDAY...UPPER TROUGH IN THE WESTERN PLAINS AT 12Z WILL CONTINUE ITS
MARCH EASTWARD...AIDED BY THE POTENT TROUGH CURRENTLY SOUTH OF THE
GULF OF ALASKA DIGGING INTO IDAHO AND NORTHERN UTAH. ALTHOUGH THE
UPPER TROUGH IS APPROACHING THE AREA...THE ASSOCIATED COLD FRONT
AHEAD OF IT IS PROGGED TO FALL APART OVER WESTERN MINNESOTA...
POSSIBLY DUE TO NEW LOW PRESSURE FORMING IN WYOMING. IN ANY
EVENT...SOUTHERLY FLOW IS PROGGED TO CONTINUE OVER THE AREA...
BRINGING MORE MOISTURE UP FROM THE SOUTH. SAME SCENARIO EXISTS AGAIN
WITH THE GFS/ECMWF RUNS PRODUCING PRECIPITATION WHILE THE NAM IS
DRY. SOUNDINGS FROM THE GFS OR NAM ARE NOT THAT IMPRESSIVE...WITH
LITTLE LIFT AND HAVE CEILINGS CLIMBING THROUGH THE DAY TO HELP
PREVENT DRIZZLE. ISENTROPIC LIFT PROGS ARE FAIRLY BENIGN TOO WITH
LITTLE IF ANY LIFT. TEMPTED TO DRY OUT THE FORECAST...BUT WITH THE
CONSISTENT SIGNAL BY THE GFS/ECMWF...HAVE MAINTAINED THE LOW
PROBABILITIES OF PRECIPITATION. ANY FOG FROM TONIGHT SHOULD
DISSIPATE BY NOON WITH HEATING AND WARM ADVECTION. REGARDING THAT
WARM ADVECTION...TEMPERATURES SHOULD BE ABLE TO CLIMB INTO THE 50S
IN MOST LOCATIONS.
SUNDAY NIGHT AND MONDAY....UPPER TROUGH THAT WAS MARCHING EASTWARD
TOWARDS THE FORECAST AREA ON SUNDAY SHOULD MOVE THROUGH MONDAY
MORNING...WHILE THE POTENT TROUGH DIGS DOWN INTO NEBRASKA AND
KANSAS. ALTHOUGH THE UPPER TROUGH IS MOVING THROUGH THE AREA...THE
TROUGH IS MUCH WEAKER THAN WHAT IT LOOKS LIKE ON WATER VAPOR...DUE
TO HEIGHTS TRYING TO RISE AHEAD OF THE POTENT TROUGH. THEREFORE...
THE OVERALL DPVA FORCING IS QUITE WEAK OVER THE FORECAST AREA...AS
WELL AS THE ISENTROPIC LIFT. IF ANYWHERE COULD SEE PRECIPITATION
DURING THIS PERIOD...IT LOOKS LIKE NORTHEAST IOWA...SOUTHEAST
MINNESOTA AND INTO CENTRAL WISCONSIN WHERE MOST OF THE WEAK FORCING
IS LOCATED. ELSEWHERE...THIS PERIOD LOOKS MAINLY CLOUDY...THOUGH
WOULD NOT BE SURPRISED TO SEE SOME CLEARING OF THE CLOUDS FROM GRANT
COUNTY NORTHEAST INTO ADAMS. THIS CLEARING IS IN RESPONSE TO A WEDGE
OF DRY AIR IN THE LOW TO MID LEVELS THAT ADVECTS IN ON SOUTHEAST
WINDS. WITH PLENTY OF CLOUDS AND RELATIVELY HIGH DEWPOINTS FOR LATE
NOVEMBER...TEMPERATURES SHOULD REMAIN ON THE MILD SIDE AT NIGHT AND
NOT RISE A WHOLE DURING THE DAY MONDAY. PREVIOUS FORECAST LOWS
SEEMED REASONABLE.
MONDAY NIGHT...TROUGH OVER NEBRASKA AND KANSAS IS PROGGED TO SLOWLY
SHIFT EAST...REACHING A POSITION NEAR KANSAS CITY BY 12Z TUESDAY.
HEIGHT FALLS...ISENTROPIC LIFT AND AN OPEN GULF OF MEXICO FEED OF
MOISTURE AHEAD OF IT WILL ALLOW FOR THE FORMATION OF BOTH WARM AND
COLD CONVEYOR BELTS WITH THE UPPER LOW. MODELS PROG THAT THE WARM
CONVEYOR BELT MAY GET INTO NORTHEAST IOWA AND SOUTHEAST
MINNESOTA...AND HAVE RAISED CHANCES OF PRECIPITATION UP IN THIS
AREA. FARTHER NORTH AND EAST...HAVE MAINTAINED GOING LOW CHANCES OF
PRECIPITATION...MOSTLY DUE TO CONCERNS THAT THE UPPER LOW COULD
PROGRESS A LITTLE BIT FASTER AS THE 21.12Z GFS SHOWS. IMAGINE OVER
TIME THE CHANCES OF PRECIPITATION CAN BE REFINED SUCH THAT LESS AREA
IS AFFECTED...THOUGH. ALONG WITH THE INCOMING WARM CONVEYOR BELT
SHOULD BE A MASS OF AT LEAST HIGH AND MID CLOUDS...IF NOT LOW CLOUDS
TOO. THEREFORE...ANOTHER CLOUDY TIME PERIOD IS EXPECTED...WHICH
SHOULD HELP KEEP LOW TEMPERATURES WELL ABOVE NORMAL.
.LONG TERM...TUESDAY THROUGH SATURDAY
FOCUS OF THIS PERIOD REMAINS ON THE SYSTEM FORECAST IN THE CENTRAL
U.S. TUESDAY MORNING AND ITS IMPACTS INTO THE THANKSGIVING HOLIDAY.
PROBLEM IS...MODELS ARE YET TO COME TO FULL AGREEMENT ON THE TIMING
OF THE SYSTEM. THE 21.06Z GFS AND 21.00Z CANADIAN...ALONG WITH THEIR
RESPECTIVE ENSEMBLES...ALL MOVING THE SYSTEM ALONG FAIRLY QUICKLY.
BY 12Z WEDNESDAY...THEY SHOW THE SYSTEM IN LOWER MICHIGAN. OF NOTE
IS THAT THE CANADIAN...WHICH A FEW DAYS AGO WAS ONE OF THE
SLOWEST...HAS NOW TURNED TO THE FASTEST SCENARIO. THE 21.00Z ECMWF
AS WELL AS THE 20.12Z ECMWF ENSEMBLES...ARE THE SLOWEST...REACHING
ONLY THE CHICAGO AREA AROUND 00Z THURSDAY. THE TIMING OF THIS SYSTEM
IS CRITICAL TOO...SINCE ALL MODELS SHOW A FAIRLY POTENT SHORTWAVE
TROUGH IN THE NORTHERN STREAM FLOW DROPPING DOWN INTO THE UPPER
MISSISSIPPI VALLEY LATE WEDNESDAY. THIS TROUGH WILL HELP BRING
COLDER AIR IN...AND IF THE SYSTEM IS STILL LINGERING AROUND LIKE THE
21.00Z ECMWF SHOWS...A BETTER CHANCE EXISTS FOR AN ACCUMULATING
SNOW. FOR NOW...THE PREFERRED OPTION IS TO STAY CLOSER TO THE 21.00Z
ECMWF...AS PER HPC PROGS. INTERESTING THAT THE 21.12Z ECMWF HAS COME
IN FASTER. THEREFORE...WITH THE WIDE MODEL VARIETY...THE TUESDAY
THROUGH THURSDAY TIME FRAME IS DEFINITELY SUBJECT TO CHANGE. ENOUGH
CONFIDENCE EXISTS TO RAISE CHANCES OF PRECIPITATION TO 60-70 ON
TUESDAY...DESPITE THE TIMING DIFFERENCES...AS MAJORITY OF MODELS
SHOW THE AREA AFFECTED BY A WARM CONVEYOR BELT. AFTER TUESDAY...HAVE
KEPT THE PRECIPITATION CHANCES NO HIGHER THAN 50 UNTIL CERTAINTY
INCREASES. WILL START CHANGING THE PRECIPITATION TYPE OVER TO SNOW
TOWARDS WEDNESDAY NIGHT...THOUGH...AS THAT NORTHERN STREAM TROUGH
DROPS IN. HAVE EXTENDED CHANCES OF PRECIPITATION INTO THANKSGIVING
AS WELL...BUT ONLY LOW PROBABILITIES AT THIS POINT.
FOR THURSDAY NIGHT THROUGH SATURDAY...MODELS AND ENSEMBLES DEPICT
RIDGING OVER THE WESTERN U.S. PUSHING EAST INTO THE UPPER
MISSISSIPPI VALLEY...ALBEIT FLATTENING OUT. THIS RIDGE IS BEING
PUSHED EAST BY A TROUGH MOVING INTO THE WESTERN U.S.. LOOKS OF THIS
TROUGH APPEARS TO BE ONE OF A MORE PROGRESSIVE NATURE...ESPECIALLY
GIVEN THE FLATTENING RIDGE AHEAD OF IT. HOWEVER...IT APPEARS ANY
PRECIPITATION ASSOCIATED WITH IT SHOULD NOT ARRIVE UNTIL AFTER
SATURDAY. THEREFORE...THE FORECAST FOR THIS TIME FRAME WILL STAY
DRY. LOOKING FOR A COOL THURSDAY NIGHT AS A SURFACE RIDGE BUILDS
IN...AND COULD BE EVEN COOLER IF SNOW COVER EXISTS. GRADUAL WARMING
IS THEN PLANNED FOR FRIDAY INTO SATURDAY AS RETURN FLOW SETS UP IN
THE WAKE OF THE RIDGE. IT SHOULD BE NOTED THAT A COLD FRONTAL
BOUNDARY MAY BE ENTERING THE PICTURE FOR SATURDAY...AHEAD OF THE
WESTERN TROUGH PUSHING EASTWARD.
&&
.AVIATION...TONIGHT AND SUNDAY
NOT A HIGH CONFIDENCE FORECAST FOR THE NEXT 24 HOURS WHICH BEGINS
WITH POORLY MODELED STRATUS ACROSS THE AREA THIS AFTERNOON. RUC HAS
BEEN THE ONLY MODEL EVEN CLOSE TO INDICATE THIS LOW LEVEL
MOISTURE...HOWEVER IT ALSO HAS NOT HAD A REAL GOOD HANDLE ON IT.
VISIBILITY RESTRICTIONS CONTINUE ACROSS MUCH OF THE AREA
TODAY...HOWEVER FINALLY SEEING IMPROVEMENTS EARLY THIS AFTERNOON.
WINDS HAVE ALSO BEGUN TO PICK UP A BIT WITH TIGHTENING PRESSURE
GRADIENT THIS AFTERNOON WHICH SHOULD CONTINUE THROUGH TONIGHT.
ANOTHER AREA OF FOG/STRATUS CURRENTLY OVER EASTERN NEBRASKA/KANSAS
AND MISSOURI WILL PUSH NORTHEAST TOWARDS THE AREA FOR TONIGHT AND
SUNDAY MORNING. THIS SIGNAL HAS BEEN PRETTY CONSISTENT OVER THE PAST
FEW DAYS WITH BRINGING INCREASED MOISTURE INTO LOCATIONS MAINLY WEST
OF THE MISSISSIPPI RIVER. WITH CLOUDS INCREASING AND WINDS STAYING
UP...RATHER THAN RADIATION FOG DEVELOPMENT...THIS LOOKS TO BE AN
ADVECTION FOG EPISODE AFFECTING MORE OF THE HIGHER TERRAIN AREAS
WEST OF THE MISSISSIPPI RIVER...WITH STRATUS ELSEWHERE. STRATUS/FOG
LOOKS TO PUSH INTO THE KRST/KLSE AROUND 22.03-04Z. HELD OFF ON
SIGNIFICANTLY LOWERING VISIBILITIES OVER KRST UNTIL AFTER MIDNIGHT
WHEN T/TD SPREAD IS LOWEST. DID LOWER VISIBILITIES AT KLSE...HOWEVER
KEPT CEILINGS/VISIBILITIES IN MVFR CATEGORY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT/LONG TERM...AJ
AVIATION...JLB
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000
FXUS63 KGRB 212058
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
258 PM CST SAT NOV 21 2009
.SHORT TERM...TONIGHT AND TOMORROW.
LATEST RUC ANALYSIS AND VIS/IR/WV IMAGERY SHOW HIGH PRESSURE MOVING
TO THE EAST OVER THE CENTRAL GREAT LAKES AND RETURN FLOW ADVECTING A
1.5-2KFT STRATUS DECK INTO CENTRAL WISCONSIN. THE FOG WAS SLOW TO
BURN OFF TODAY...WHICH COMBINED WITH THE INCOMING STRATUS HAS
PREVENTED TEMPERATURES FROM CLIMBING OUT OF THE MIDDLE 40S OVER
CENTRAL WISCONSIN. STILL SEEING ALOT OF REDUCED VSBYS THIS
AFTERNOON...MOSTLY IN THE MVFR RANGE...BUT THERE ARE STILL SOME IFR
STRAGGLERS AT ARV AND AUW. FORECAST CONCERNS ARE PLENTIFUL FOR THIS
FORECAST PACKAGE...AND INCLUDE CLOUD AND FOG POTENTIAL TONIGHT...AND
PRECIP CHANCES TOMORROW.
TONIGHT...HIGH PRESSURE SHIFTS FARTHER TO THE EAST...ALLOWING THE
PRESSURE GRADIENT TO TIGHTEN ACROSS THE FORECAST AREA.
SOUTHWESTERLY WINDS WILL STRENGTHEN TO 25-35KTS AT 925MB...WHICH
SHOULD HELP KEEP THE BOUNDARY LAYER MORE CHURNED UP COMPARED TO LAST
NITE...AND LIMIT FOG POTENTIAL SOMEWHAT. THESE SOUTHWESTERLY WINDS
WILL ALSO CONTINUE TO ADVECT LOW LEVEL MOISTURE AND A STRATUS DECK
FROM THE GULF COAST INTO THE REGION. IT LOOKS TO BE MOST WIDESPREAD
ACROSS THE WESTERN FORECAST AREA...BUT NOT OUT OF THE QUESTION THAT
IT COULD EXPAND ACROSS THE FOX VALLEY AS WELL GIVEN THE ALREADY
MOIST BOUNDARY LAYER AND NOCTURNAL COOLING. CHECKING OUT THE UPS
FOG FORECASTING TECHNIQUE...BOUNDARY LAYER WIND SPEEDS BETWEEN
15-20KTS SUGGEST AN ELEVATED STRATUS DECK BUT WITH BUILD DOWN
POTENTIAL (ABSENT OF CLOUDS ALOFT). GIVEN THE IFR/MVFR VSBYS STILL OUT
THERE EARLY THIS AFTERNOON...WOULDNT TAKE MUCH COOLING FOR VSBYS
AND/OR CIGS TO CRASH AGAIN...ESPECIALLY IF THERE ARE BREAKS IN THE
CLOUDS LIKE THERE ARE IN IOWA AND NORTHERN MISSOURI. NOT CONFIDENT
THAT MANY BREAKS WILL OCCUR...AS NOCTURNAL COOLING SHOULD HELP ANY
BREAKS FILL BACK IN. AS A RESULT OF THE INCREASE UNCERTAINTY WITH
THE CLOUD COVER AND WINDS...WILL KEEP IN PATCHY FOG FOR THE ENTIRE
AREA AND LET THE EVENING CREW UPGRADE IF CONDITIONS WARRANT TONITE.
TOMORROW...SOUTHWESTERLY WINDS WILL CONTINUE TO ADVECT MOISTURE
BELOW 10KFT INTO THE AREA AS A COLD FRONT MOVES INTO MINNESOTA AND
FAR WESTERN LAKE SUPERIOR BY THE AFTERNOON. BEST FORCING WILL RESIDE OUT IN
THAT DIRECTION...WITH CONVERGENCE ALONG THE FRONT...AND UPPER
DIVERGENCE IN THE RIGHT ENTRANCE REGION OF A JET STREAK. MOISTURE
ABOVE 10KFT WILL BE SORELY LACKING IN OUR AREA...AND DO NOT SEE
ENOUGH LIFT OR SATURATION DEPTH FOR ANYTHING BUT SOME
SPRINKLES...MOSTLY IN THE AFTERNOON. SO...WE ARE LOOKING AT A
MOSTLY CLOUDY DAY WEST AND PARTLY SUNNY EAST WITH HIGHS IN THE UPPER
40S TO MIDDLE 50S.
.LONG TERM...SUNDAY NIGHT THROUGH NEXT SATURDAY. FOG POTENTIAL
AND PCPN CHCS THE MAIN CHALLENGE THROUGH THANKSGIVING AS RETURN
FLOW ON THE BACKSIDE OF THE DEPARTING RIDGE BEGINS TO AFFECT THE
AREA. MODELS CONTINUE TO WASH OUT THE INITIAL FRONTAL BOUNDARY
SUNDAY NIGHT INTO MONDAY OVER MN IN RESPONSE TO THE DIGGING
WESTERN TROF AND PERSISTENT RIDGE OVER THE GREAT LAKES REGION.
WILL MAINTAIN LIGHT NON MEASURABLE PCPN MENTION FOR SUNDAY NIGHT
AS RRQ REGION LIFTS NORTH...BUT DEPENDING ON CLOUD COVER...FOG
DEVELOPMENT WILL LIKELY BE THE MAIN FOCUS THROUGH MONDAY NIGHT FOR
THE LONG NIGHTS.
MEDIUM RANGE MODELS PROG THE DEVELOPING UPPER LOW WITH SURFACE
LOW TO BEGIN TO LIFT FROM THE CENTRAL PLAINS INTO THE GREAT LAKES
REGION LATER TUESDAY THROUGH THURSDAY. LATEST RUNS INDICATE MAIN
UPPER SUPPORT TO PASS OVER THE SOUTH HALF OF WI. WAFFLED BETWEEN
HIGH END CHC OR LIKELY POPS BUT TIMING AND LOCATION OF BEST UPPER
SUPPORT IN QUESTION WITH THIS SYSTEM. IN ADDITION...PCPN TYPE WILL
BE A PROBLEM. TEMP PROFILE SUGGESTS MAINLY RAIN INITIALLY BUT
CHANGING TO A MIX FIRST OVER THE NORTHERN AND WESTERN AREAS AS THE
COLUMN BEGINS TO COOL LATER WEDNESDAY INTO WED NIGHT. BUT COLD
CORE WITH THE UPPER LOW MAY ALSO BECOME COLD ENOUGH TO PRODUCE A
BAND OF SNOW AS WELL.
UPPER HEIGHTS CONTINUE TO FALL THROUGH WEDNESDAY NIGHT AS AN UPPER
JET WITH REINFORCING SHORTWAVE DROPS INTO INTO THE PLAINS TO
DEEPEN THE SYSTEM. LATEST ECMWF CONTINUES TO DEEPEN THE H8 LOW
OVER NORTHERN LOWER MICHIGAN THROUGH THURSDAY WHICH INDICATES SOME
ACCUM SNOW POTENTIAL OVER NE WI. THE GFS IS FASTER WITH THIS
SECONDARY H8 LOW AND FURTHER SOUTH. WOULD LIKE TO GET A FEW MORE
MODEL RUNS WITH THIS SYSTEM BEFORE GIVING A HEADS UP FOR THE
THANKSGIVING TRAVEL.
SYSTEM PROGGED TO DEPART LATE IN THE WEEK TO RETURN TO A DRIER
FORECAST WITH NEAR NORMAL TEMPERATURES FOR LATE NOVEMBER.
&&
.AVIATION...IFR/MVFR VSBYS IN MIST WILL CONTINUE TO PLAGUE THE TAF
SITES TONIGHT IN A RATHER STAGNANT AIRMASS. SATELLITE IMAGERY AND
MODEL DATA INDICATE A STEADY SUPPLY OF LOW LEVEL MOISTURE ADVECTING
FROM THE GULF COAST INTO THE REGION TONIGHT...CREATING A MVFR CLOUD
DECK AT AUW/CWA/RHI AND POSSIBLY EVEN GRB. NOT OUT OF THE QUESTION
THE STRATUS WILL BUILD DOWN INTO AN IFR DECK EITHER. MVFR CLOUD
COVER AND VSBYS WILL PERSIST INTO TOMORROW MORNING. SOME INDICATION
THAT CIGS WILL LIFT TO VFR STATUS AROUND MIDDAY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MPC/TDH
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000
FXUS63 KMKX 212041
AFDMKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
241 PM CST SAT NOV 21 2009
RATHER STABLE WEATHER PATTERN OVER US FOR THE NEXT FEW DAYS. UPPER
LEVEL RIDGING HOLDS OVER THE EASTERN HALF OF THE COUNTRY WHILE
TROFING OCCURS OVER THE MIDDLE OF THE U.S. THE RIDGE SHOULD PROTECT
THE SOUTHEAST THIRD OF THE STATE...INCLUDING OUR CWA...FROM ANY
INTRUSION OF PRECIP THROUGH MONDAY. SATELLITE DOES SHOW
MOISTURE/CLOUDS STREAMING NORTH THROUGH THE MISSISSIPPI
VALLEY...ON THE WEST SIDE OF THE RIDGE. LITTLE EXPANSION TO THE
EAST IS ANTICIPATED. INCREASING MID LEVEL SOUTHWEST FLOW WILL
STRETCH FROM THE OKLAHOMA PANHANDLE TO NORTHWEST WISCONSIN BY
SUNDAY AFTERNOON AS THE FIRST ROUND OF ENERGY DIGS A TROF INTO THE
CENTRAL PLAINS.
AS THIS FIRST SHORT WAVE ARRIVES AND PUSHES INTO THE RIDGE...
MORE CLOUDS WILL SPREAD INTO THE WESTERN CWA...BUT THE CHANCE FOR
PRECIPITATION SHOULD STAY WEST OF OUR AREA. OVERALL THROUGH
MONDAY...THE WEST WILL BE MOSTLY CLOUDY WHILE THE EAST STAYS
PARTLY CLOUDY. TEMPS WILL REMAIN UNSEASONABLY MILD.
A SECOND...MUCH STRONGER...PACIFIC NORTHWEST SHORT WAVE DIGS INTO
THE CENTRAL PLAINS MONDAY NIGHT. WOW...CAN THE PACIFIC NORTHWEST
CATCH A BREAK...THEY HAVE BEEN GETTING POUNDED. THIS SHORT WAVE
CLOSES OFF QUICKLY AND HEADS FOR NORTHERN ILLINOIS TUESDAY AND
TUESDAY NIGHT. THE FIRST MAIN BAND OF RAIN ASSOCIATED WITH THIS
STRONG LOW WILL LIFT NORTH INTO SOUTHERN WISCONSIN TUESDAY
AFTERNOON. THE MODEL GUIDANCE IS NOW IN FAIRLY GOOD AGREEMENT ON
THE TIMING. THIS HASN/T BEEN THE CASE OVER THE LAST WEEK OR SO.
TEMPS WILL BE WARM ENOUGH INITIALLY FOR THIS TO BE AN ALL RAIN
EVENT. THE LOW QUICKLY OCCLUDES AND SUCKS IN AND WRAPS AROUND DRY
AIR WHICH MAKES PCPN CHANCES FROM TUESDAY NIGHT INTO WEDNESDAY
RATHER MURKY. WOULD EXPECT SCATTERED LIGHT STUFF DURING THAT TIME.
THEN A THIRD SHORT WAVE DIVES INTO THE BACK SIDE OF THE DEPARTING
LOW ON WEDNESDAY...LOOKING MORE LIKE AN ALBERTA CLIPPER...THOUGH
ADMITTEDLY IT IS A LITTLE TOO FAR SOUTH FOR THAT. BUT...IT
ORIGINATES FARTHER NORTH AND PULLS DOWN A SURGE OF COLDER AIR INTO
THE BACK OF THE EXITING GREAT LAKES LOW. THE GFS BRINGS AN AREA OF
ASSOCIATED QPF ACROSS THE SOUTHERN CWA WED AFTERNOON AND WEDNESDAY
NIGHT...THAT WOULD BE ALL SNOW AND RESULTING IN A FEW INCHES OF
ACCUMULATION. THE ECMWF HAS A MUCH MORE NORTHERN PLACEMENT OF THE
QPF OVER CENTRAL WISCONSIN...KEEPING US IN THE MUCH LIGHTER
QPF/SNOWFALL REGIME. HOW THIS THIRD SHORT WAVE ENERGY INTERACTS
AND EVOLVES WITHIN THE LEAD GREAT LAKES LOW IS VERY COMPLICATED
AND PRONE TO SIGNIFICANT RUN TO RUN DEVIATIONS OVER THE NEXT FEW
DAYS. STAY TUNED.
&&
.AVIATION...LIMITED AVIATION CONCERNS OVER THE NEXT 24 HOURS. WINDS
WILL LIKELY STAY UP A BIT TONIGHT...LIMITING THE CHANCE FOR FOG.
COULD SEE SOME MVFR VISBYS IF WINDS ARE LIGHT ENOUGH...MAINLY AFTER
MIDNIGHT. OTHERWISE...VFR CONDITIONS WILL PREVAIL.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
SHORT/LONG TERM...DAVIS
AVIATION/MARINE...VANCLEVE
000
FXUS63 KARX 211638
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1038 AM CST SAT NOV 21 2009
.UPDATE...
FOG LIFTING AND DISSIPATING QUICKLY AFTER THE 10 AM HOUR THIS
MORNING. SOME DENSE FOG WAS STILL BEING OBSERVED ACROSS THE
NORTHERN PARTS OF THE FORECAST AREA YET LATE THIS MORNING...BUT
WITH THIS BEING MORE OF A LOCALIZED THREAT AND THAT THE MAJORITY
OF THE AREA HAS SEEN IMPROVEMENT...LET THE DENSE FOG ADVISORY
EXPIRE. A DIFFERENT CAVEAT OF THE FORECAST IS A STRATUS DECK WHICH
HAS PUSHED NORTH INTO THE FORECAST AREA FROM EASTERN IOWA THIS
MORNING. THE MAJORITY OF THE MODELS ARE NOT PICKING THIS MOISTURE
UP VERY WELL...WITH THE LATEST RUC BEING THE ONLY ONE TO HAVE ANY
INDICATION OF IT BEING THERE. ALTHOUGH THROUGH THE VISIBLE
IMAGERY PORTIONS OF IT MAY BE THINNING...DO THINK THESE CLOUDS
WILL AFFECT THE SOUTHEAST PARTS OF THE FORECAST AREA THROUGH AT
LEAST MID AFTERNOON.
&&
.PREV DISCUSSION... /ISSUED 342 AM CST SAT NOV 21 2009/
SHORT TERM...TODAY THROUGH MONDAY
AT 3 AM...HIGH PRESSURE...CENTERED OVER THE OHIO VALLEY...WAS IN
CONTROL OF THE WEATHER IN THE UPPER MISSISSIPPI RIVER VALLEY. THE
COMBINATION OF LIGHT WINDS AND A MOIST BOUNDARY LAYER HAS RESULTED
IN THE DEVELOPMENT OF DENSE FOG EARLY THIS MORNING. THIS FOG
SHOULD PERSIST ACROSS THE FORECAST AREA THROUGH 10 AM THIS
MORNING. AS A RESULT...NO CHANGES WILL BE NEEDED TO DENSE FOG
ADVISORY THAT WAS ISSUED ON FRIDAY EVENING.
THE BUFKIT SOUNDINGS CONTINUE TO SHOW A VERY DRY AIR MASS LOCATED
ABOVE THE INITIALLY MOIST BOUNDARY LAYER TODAY. AS DIURNAL HEATING
OCCURS...WE SHOULD EASILY MIX UP TO 900 MB. THIS IN TURN WILL
BRING THIS DRY AIR TO THE SURFACE. AS TYPICAL IN THESE
SITUATIONS...THE MOS DEW POINT GUIDANCE ARE TOO HIGH AND THE GFE
DEW POINT TOO WAS USED TO LOWER THESE DEW POINTS TO AROUND
30 DEGREES THIS AFTERNOON.
FROM TONIGHT INTO SUNDAY MORNING...THE MODELS CONTINUE TO SHOW THAT
THE MOISTURE BELOW 800 MB DRAMATICALLY INCREASES AHEAD OF AN
APPROACHING LONG WAVE TROUGH IN THE NORTHERN AND CENTRAL PLAINS.
THIS MOISTURE IS CURRENTLY PRODUCING LIFR/IFR CEILINGS AND
VISIBILITIES ACROSS OKLAHOMA THIS MORNING. THERE WAS ENOUGH
CONFIDENCE TO INCLUDE AREAS OF DENSE FOG IN THE GRIDS INTO THE
HIGHER ELEVATIONS OF NORTHEAST IOWA AND SOUTHEAST MINNESOTA AFTER
MIDNIGHT TONIGHT. THIS FOG WILL LIKELY PERSIST THROUGH MID TO LATE
MORNING. THE DRIZZLE IS STILL IN QUESTION FOR LATE TONIGHT...
BECAUSE THERE IS VERY LITTLE LIFT /IF ANY/ IN THE DEEP MOISTURE
LAYER.
IN ADDITION TO THE INCREASING MOISTURE...THE WARM AIR ADVECTION
SHOULD RESULT IN STEADY TO SLOWLY RISING TEMPERATURES ACROSS THE
FORECAST AREA TONIGHT. AS A RESULT...A NON DIURNAL TEMPERATURE
CURVE WAS USED ACCOUNT FOR THIS FROM LATE TONIGHT INTO SUNDAY
MORNING.
FROM SUNDAY NIGHT INTO MONDAY...IT WAS THE CONSENSUS THAT THE
SLOWER OPERATIONAL NAM/WRF...GEM...AND ECMWF SOLUTIONS WERE
PREFERRED OVER THE FASTER OPERATIONAL GFS. DUE TO THIS...THE
TEMPERATURES WERE RAISED SOME AND THE PRECIPITATION CHANCES WERE
LOWERED.
LONG TERM...MONDAY NIGHT THROUGH FRIDAY
MUCH OF THE TIME THIS MORNING WAS SPENT WORKING ON THE FORECAST
GRIDS FROM MONDAY NIGHT INTO WEDNESDAY NIGHT.
THE 21.00Z MODELS CONTINUE TO STRUGGLE WITH THE EVOLUTION AND
TIMING OF A LOW PRESSURE SYSTEM MOVING THROUGH THE UPPER
MISSISSIPPI RIVER VALLEY SOMEWHERE FROM MONDAY NIGHT THROUGH
THANKSGIVING. MUCH OF THIS HAS TO DEAL WITH HOW THIS SYSTEM
INTERACTS WITH ANOTHER SYSTEM DROPPING INTO THE MEAN TROUGH BEHIND
THE INITIAL STRONG WAVE. WHILE THE OPERATIONAL GFS HAS SLOWED ITS
MOVEMENT OF THIS SYSTEM FROM 24 HOURS AGO...IT CONTINUES TO BE
MUCH FASTER THAN THE ECMWF AND GEM. ABOUT TWO THIRDS /8 OUT OF 12/
OF ITS FAMILY MEMBERS SUPPORT THIS FASTER SOLUTION. MEANWHILE THE
REMAINING GFS MEMBERS ARE CLUSTERED WITH THE SLOWER ECMWF WHICH
MOVES THE SYSTEM THROUGH OUR AREA BETWEEN TUESDAY THROUGH
THANKSGIVING. THIS ADDS TO QUITE A BIT OF UNCERTAINTY TO THIS TIME
PERIOD...BUT THE OVERALL CONSENSUS OF OUR OFFICE AND THE
SURROUNDING WFOS WAS TO CONTINUE TO TREND OUR FORECAST GRIDS
TOWARD THE SLOWER ECMWF AND GEM SOLUTIONS. THIS ULTIMATELY
RESULTED IN SOME CHANGES TO TEMPERATURES /RAISED TEMPERATURES FROM
MONDAY NIGHT INTO TUESDAY NIGHT/...PRECIPITATION CHANCES /LOWERED
CHANCES ON MONDAY NIGHT AND THEN INCREASED THEM SOME FROM TUESDAY
INTO WEDNESDAY NIGHT/...AND WEATHER /DELAYED CHANGE OVER TO SNOW/
GRIDS FROM MONDAY NIGHT THROUGH WEDNESDAY NIGHT.
THE ECMWF ACTUALLY GENERATES QUITE A BIT OF SNOW /4 TO 8 INCHES/
ACROSS THE NORTHERN IOWA AND SOUTHERN MINNESOTA...AND THEN
NORTHEAST INTO UPPER MICHIGAN FROM LATE WEDNESDAY INTO
THANKSGIVING. THE OPERATIONAL GFS ACTUALLY SHOW A SIMILAR
TOTALS...BUT IT IS FURTHER NORTHWEST AND SLIGHTLY EARLIER. WHILE
THESE MODELS ARE SHOWING THIS...THE COBB DATA ONLY SHOWS MINOR
SNOW ACCUMULATIONS IN THE GFS. WITH SUCH DIFFERENCES...WE DECIDED
NOT TO HIGHLIGHT THIS SYSTEM IN OUR HAZARDOUS WEATHER OUTLOOK.
HOPEFULLY THIS WILL BECOME A BIT CLEARER IN THE UPCOMING DAYS.
AVIATION...TODAY AND TONIGHT
PRIMARY CONCERNS WERE FOCUSED ON IFR CONDITIONS IN LOW CLOUDS AND
FOG DURING THE VALID TAF PERIOD.
RADIATIONAL COOLING AND A MOIST BOUNDARY LAYER HAS ALLOWED FOR
WIDESPREAD IFR CONDITIONS IN FOG EARLY THIS MORNING. AS SOUTH WINDS
INCREASE TODAY AND MIXING COMMENCES...IMPROVEMENT IS EXPECTED.
HOWEVER...HAZE SHOULD LINGER THROUGH THE DAY WITH PERSISTENT
SOUTHERLY FLOW. THIS SAME SOUTHERLY FLOW CONTINUES DRAWING HIGHER
RELATIVE HUMIDITY NORTHWARD TONIGHT. VARIOUS DATA SETS WERE STRONGLY
SUGGESTIVE OF IFR AND/OR MVFR IN LOW CLOUDS/FOG AGAIN TONIGHT.
POOREST CONDITIONS ANTICIPATED ACROSS HIGHER ELEVATION AIRPORTS
MAINLY WEST OF THE MISSISSIPPI RIVER...SUCH AS KRST TAF SITE...WHERE
CONFIDENCE WAS HIGH ENOUGH TO FORECAST CONDITIONS AT INSTRUMENT
APPROACH MINIMUMS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
UPDATE...BROOKS
SHORT/LONG TERM...BOYNE
AVIATION...THOMPSON/AJ
000
FXUS63 KGRB 211220 CCA
AFDGRB
AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE GREEN BAY WI
618 AM CST SAT NOV 21 2009
.SHORT TERM...TODAY THROUGH SUNDAY.
MAIN FORECAST CONCERN WILL BE FOG/FREEZING FOG THIS MORNING.
WEAK AREA OF HIGH PRESSURE WORKING ITS WAY ACROSS THE FORECAST
AREA THIS MORNING. RESIDUAL LOW-LEVEL MOISTURE...CLEARING SKIES
AND LIGHT WINDS HAVE ALLOWED DENSE FOG TO FORM ACROSS MUCH OF CENTRAL
AND NORTHERN WISCONSIN...WITH SEVERAL LOCATIONS REPORTING A QUARTER
MILE OR LESS. DECIDED TO GO WITH A DENSE FOG ADVISORY GENERALLY
WEST A LINE FROM IRON MOUNTAIN TO WAUPACA UNTIL ABOUT 15Z.
SURFACE TEMPERATURES ACROSS NORTHCENTRAL WISCONSIN HAVE ALSO
FALLEN TO WELL BELOW FREEZING...THUS SOME SLIPPERY ROAD
CONDITIONS ARE POSSIBLE ESPECIALLY ON BRIDGES AND OVERPASSES. IR
IMAGERY ALSO SHOWS LINGERING MID-LEVEL CLOUDS ACROSS PARTS OF
EASTCENTRAL WISCONSIN WHICH IS HOLDING TEMPERATURES UP CLOSER TO
40F IN SOME LOCATIONS. VISIBILITIES IN THE FOX VALLEY CURRENTLY
IN 2 TO 5 MILE RANGE...BUT EXPECT PATCHY AREAS OF DENSE FOG TO
DEVELOP HERE AS WELL...ESPECIALLY WEST OF HIGHWAY 41 BEFORE
SUNRISE.
AFTER FOG BURNS OFF LATER THIS MORNING...EXPECT MOSTLY SUNNY
SKIES WITH UNSEASONABLY MILD TEMPERATURES...APPROACHING MID 50S
TODAY. NORMAL HIGHS THIS TIME OF YEAR AROUND 40F.
EXPECT SOME AREAS OF FOG TO DEVELOP AGAIN TONIGHT OVER MUCH OF THE
FORECAST AREA AS WEAK HIGH PRESSURE SLOWLY DRIFTS OFF TO THE EAST
AND SOME LOW-LEVEL MOISTURE WORKS NORTHWARD AHEAD OF APPROACHING
SHORTWAVE TROUGH. INCREASING CLOUDS AHEAD OF THE APPROACHING
SHORTWAVE AND SOMEWHAT MORE WIND IN THE BOUNDARY LAYER SHOULD
PREVENT WIDESPREAD DENSE FOG SATURDAY NIGHT...HOWEVER WILL LET
DAY SHIFT REASSESS THIS POSSIBILITY. FOX VALLEY AREA MAY STAND THE
BEST CHANCE FOR SEEING PATCHY DENSE FOG EARLY SUNDAY MORNING.
MILD CONDITIONS TO CONTINUE ON SUNDAY AS SOUTHERLY FLOW INCREASES
AHEAD OF SHORTWAVE TROUGH. KEPT LOW CHANCE POPS ACROSS WESTERN
SECTIONS AS BEST LIFT (ALBEIT WEAK) SHOULD BE APPROACHING THAT
AREA IN ASSOCIATION WITH RRQ OF UPPER JET. ANY PRECIPITATION THAT
DOES FORM LATER IN THE DAY IS EXPECTED TO SCATTERED AND RATHER
LIGHT.
.LONG TERM...SATURDAY NIGHT THROUGH NEXT FRIDAY.
MEDIUM RANGE MODEL SOLUTIONS ONCE AGAIN STARTED DOING THEIR OWN
THING BY EARLY NEXT WEEK. THIS ONCE AGAIN LED TO HPC GUIDANCE
BEING FOLLOWED MORE CLOSELY THAN ANY OF THE 12Z MODEL RUNS. RAIN
CHANCES WERE CONFINED TO THE WESTERN PART OF THE FORECAST AREA
SUNDAY NIGHT...AHEAD OF AN APPROACHING COLD FRONT. PRECIPITATION
CHANCES CONTINUED INTO WEDNESDAY AS THE HPC MANUAL SURFACE PROG
BROUGHT A LOW THROUGH WISCONSIN. COLDER AIR IN THE WAKE OF THE
SYSTEM MADE PRECIPITATION TYPE AN ISSUE FOR TUESDAY NIGHT AND
WEDNESDAY SO BOTH RAIN AND SNOW WERE MENTIONED FOR THOSE PERIODS.
LAKE EFFECT APPEARED TO BE A POSSIBILITY ACROSS THE EXTREME NORTH
AND NORTHEAST STARTING THURSDAY...AS DELTA TS...LAKE SURFACE TO
850MB...INCREASE. OTHERWISE ONLY WENT WITH SOME SLIGHT CHANCE POPS
ACROSS THE AREA. MADE A GOOD FAITH EFFORT TO BLEND WELL WITH
SURROUNDING FORECAST GRIDS.
DID NOT MAKE MAJOR CHANGES TO HIGH OR LOW TEMPERATURES.
&&
.AVIATION...AREAS OF DENSE FOG EXPECTED AT RHI...CWA AND AUW THROUGH
ABOUT 15Z SATURDAY MORNING. CONDITIONS TO GRADUALLY IMPROVE TO VFR
THEREAFTER. SOME PATCHY FOG POSSIBLE AGAIN AFTER 06Z SUNDAY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR WIZ005-
010>012-018-019-030-035-036.
&&
$$
ESB/ECKBERG
000
FXUS63 KGRB 211053 CCA
AFDGRB
AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE GREEN BAY WI
452 AM CST SAT NOV 21 2009
.SHORT TERM...TODAY THROUGH SUNDAY.
MAIN FORECAST CONCERN WILL BE FOG/FREEZING FOG THIS MORNING.
WEAK AREA OF HIGH PRESSURE WORKING ITS WAY ACROSS THE FORECAST
AREA THIS MORNING. RESIDUAL LOW-LEVEL MOISTURE...CLEARING SKIES
AND LIGHT WINDS HAVE ALLOWED DENSE FOG TO FORM ACROSS MUCH OF CENTRAL
AND NORTHERN WISCONSIN...WITH SEVERAL LOCATIONS REPORTING A QUARTER
MILE OR LESS. DECIDED TO GO WITH A DENSE FOG ADVISORY GENERALLY
WEST A LINE FROM IRON MOUNTAIN TO WAUPACA UNTIL ABOUT 15Z.
SURFACE TEMPERATURES ACROSS NORTHCENTRAL WISCONSIN HAVE ALSO
FALLEN TO WELL BELOW FREEZING...THUS SOME SLIPPERY ROAD
CONDITIONS ARE POSSIBLE ESPECIALLY ON BRIDGES AND OVERPASSES. IR
IMAGERY ALSO SHOWS LINGERING MID-LEVEL CLOUDS ACROSS PARTS OF
EASTCENTRAL WISCONSIN WHICH IS HOLDING TEMPERATURES UP CLOSER TO
40F IN SOME LOCATIONS. VISIBILITIES IN THE FOX VALLEY CURRENTLY
IN 2 TO 5 MILE RANGE...BUT EXPECT PATCHY AREAS OF DENSE FOG TO
DEVELOP HERE AS WELL...ESPECIALLY WEST OF HIGHWAY 41 BEFORE
SUNRISE.
AFTER FOG BURNS OFF LATER THIS MORNING...EXPECT MOSTLY SUNNY
SKIES WITH UNSEASONABLY MILD TEMPERATURES...APPROACHING MID 50S
TODAY. NORMAL HIGHS THIS TIME OF YEAR AROUND 40F.
EXPECT SOME AREAS OF FOG TO DEVELOP AGAIN TONIGHT OVER MUCH OF THE
FORECAST AREA AS WEAK HIGH PRESSURE SLOWLY DRIFTS OFF TO THE EAST
AND SOME LOW-LEVEL MOISTURE WORKS NORTHWARD AHEAD OF APPROACHING
SHORTWAVE TROUGH. INCREASING CLOUDS AHEAD OF THE APPROACHING
SHORTWAVE AND SOMEWHAT MORE WIND IN THE BOUNDARY LAYER SHOULD
PREVENT WIDESPREAD DENSE FOG SATURDAY NIGHT...HOWEVER WILL LET
DAY SHIFT REASSESS THIS POSSIBILITY. FOX VALLEY AREA MAY STAND THE
BEST CHANCE FOR SEEING PATCHY DENSE FOG EARLY SUNDAY MORNING.
MILD CONDITIONS TO CONTINUE ON SUNDAY AS SOUTHERLY FLOW INCREASES
AHEAD OF SHORTWAVE TROUGH. KEPT LOW CHANCE POPS ACROSS WESTERN
SECTIONS AS BEST LIFT (ALBEIT WEAK) SHOULD BE APPROACHING THAT
AREA IN ASSOCIATION WITH RRQ OF UPPER JET. ANY PRECIPITATION THAT
DOES FORM LATER IN THE DAY IS EXPECTED TO SCATTERED AND RATHER
LIGHT.
.LONG TERM...SATURDAY NIGHT THROUGH NEXT FRIDAY.
MEDIUM RANGE MODEL SOLUTIONS ONCE AGAIN STARTED DOING THEIR OWN
THING BY EARLY NEXT WEEK. THIS ONCE AGAIN LED TO HPC GUIDANCE
BEING FOLLOWED MORE CLOSELY THAN ANY OF THE 12Z MODEL RUNS. RAIN
CHANCES WERE CONFINED TO THE WESTERN PART OF THE FORECAST AREA
SUNDAY NIGHT...AHEAD OF AN APPROACHING COLD FRONT. PRECIPITATION
CHANCES CONTINUED INTO WEDNESDAY AS THE HPC MANUAL SURFACE PROG
BROUGHT A LOW THROUGH WISCONSIN. COLDER AIR IN THE WAKE OF THE
SYSTEM MADE PRECIPITATION TYPE AN ISSUE FOR TUESDAY NIGHT AND
WEDNESDAY SO BOTH RAIN AND SNOW WERE MENTIONED FOR THOSE PERIODS.
LAKE EFFECT APPEARED TO BE A POSSIBILITY ACROSS THE EXTREME NORTH
AND NORTHEAST STARTING THURSDAY...AS DELTA TS...LAKE SURFACE TO
850MB...INCREASE. OTHERWISE ONLY WENT WITH SOME SLIGHT CHANCE POPS
ACROSS THE AREA. MADE A GOOD FAITH EFFORT TO BLEND WELL WITH
SURROUNDING FORECAST GRIDS.
DID NOT MAKE MAJOR CHANGES TO HIGH OR LOW TEMPERATURES.
&&
.AVIATION...AREAS OF DENSE FOG EXPECTED AT RHI...CWA AND AUW THROUGH
ABOUT 15Z SATURDAY MORNING. CONDITIONS TO GRADUALLY IMPROVING TO
IFR THEREAFTER. SOME PATCHY FOG POSSIBLE AGAIN AFTER 06Z SUNDAY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR WIZ005-
010>012-018-019-030-035-036.
&&
$$
ESB/ECKBERG
000
FXUS63 KGRB 211003
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
403 AM CST SAT NOV 21 2009
.SHORT TERM...TODAY THROUGH SUNDAY.
MAIN FORECAST CONCERN WILL BE FOG/FREEZING FOG THIS MORNING.
WEAK AREA OF HIGH PRESSURE WORKING ITS WAY ACROSS THE FORECAST
AREA THIS MORNING. RESIDUAL LOW-LEVEL MOISTURE...CLEARING SKIES
AND LIGHT WINDS HAVE ALLOWED DENSE FOG TO FORM ACROSS MUCH OF CENTRAL
AND NORTHERN WISCONSIN...WITH SEVERAL LOCATIONS REPORTING A QUARTER
MILE OR LESS. DECIDED TO GO WITH A DENSE FOG ADVISORY GENERALLY
WEST A LINE FROM IRON MOUNTAIN TO WAUPACA UNTIL ABOUT 15Z.
SURFACE TEMPERATURES ACROSS NORTHCENTRAL WISCONSIN HAVE ALSO
FALLEN TO WELL BELOW FREEZING...THUS SOME SLIPPERY ROAD
CONDITIONS ARE POSSIBLE ESPECIALLY ON BRIDGES AND OVERPASSES. IR
IMAGERY ALSO SHOWS LINGERING MID-LEVEL CLOUDS ACROSS PARTS OF
EASTCENTRAL WISCONSIN WHICH IS HOLDING TEMPERATURES UP CLOSER TO
40F IN SOME LOCATIONS. VISIBILITIES IN THE FOX VALLEY CURRENTLY
IN 2 TO 5 MILE RANGE...BUT EXPECT PATCHY AREAS OF DENSE FOG TO
DEVELOP HERE AS WELL...ESPECIALLY WEST OF HIGHWAY 41 BEFORE
SUNRISE.
AFTER FOG BURNS OFF LATER THIS MORNING...EXPECT MOSTLY SUNNY
SKIES WITH UNSEASONABLY MILD TEMPERATURES...APPROACHING MID 50S
TODAY. NORMAL HIGHS THIS TIME OF YEAR AROUND 40F.
EXPECT SOME AREAS OF FOG TO DEVELOP AGAIN TONIGHT OVER MUCH OF THE
FORECAST AREA AS WEAK HIGH PRESSURE SLOWLY DRIFTS OFF TO THE EAST
AND SOME LOW-LEVEL MOISTURE WORKS NORTHWARD AHEAD OF APPROACHING
SHORTWAVE TROUGH. INCREASING CLOUDS AHEAD OF THE APPROACHING
SHORTWAVE AND SOMEWHAT MORE WIND IN THE BOUNDARY LAYER SHOULD
PREVENT WIDESPREAD DENSE FOG SATURDAY NIGHT...HOWEVER WILL LET
DAY SHIFT REASSESS THIS POSSIBILITY. FOX VALLEY AREA MAY STAND THE
BEST CHANCE FOR SEEING PATCHY DENSE FOG EARLY SATURDAY MORNING.
MILD CONDITIONS TO CONTINUE ON SUNDAY AS SOUTHERLY FLOW INCREASES
AHEAD OF SHORTWAVE TROUGH. KEPT LOW CHANCE POPS ACROSS WESTERN
SECTIONS AS BEST LIFT (ALBEIT WEAK) SHOULD BE APPROACHING THAT
AREA IN ASSOCIATION WITH RRQ OF UPPER JET. ANY PRECIPITATION THAT
DOES FORM LATER IN THE DAY IS EXPECTED TO SCATTERED AND RATHER
LIGHT.
.LONG TERM...SATURDAY NIGHT THROUGH NEXT FRIDAY.
MEDIUM RANGE MODEL SOLUTIONS ONCE AGAIN STARTED DOING THEIR OWN
THING BY EARLY NEXT WEEK. THIS ONCE AGAIN LED TO HPC GUIDANCE
BEING FOLLOWED MORE CLOSELY THAN ANY OF THE 12Z MODEL RUNS. RAIN
CHANCES WERE CONFINED TO THE WESTERN PART OF THE FORECAST AREA
SUNDAY NIGHT...AHEAD OF AN APPROACHING COLD FRONT. PRECIPITATION
CHANCES CONTINUED INTO WEDNESDAY AS THE HPC MANUAL SURFACE PROG
BROUGHT A LOW THROUGH WISCONSIN. COLDER AIR IN THE WAKE OF THE
SYSTEM MADE PRECIPITATION TYPE AN ISSUE FOR TUESDAY NIGHT AND
WEDNESDAY SO BOTH RAIN AND SNOW WERE MENTIONED FOR THOSE PERIODS.
LAKE EFFECT APPEARED TO BE A POSSIBILITY ACROSS THE EXTREME NORTH
AND NORTHEAST STARTING THURSDAY...AS DELTA TS...LAKE SURFACE TO
850MB...INCREASE. OTHERWISE ONLY WENT WITH SOME SLIGHT CHANCE POPS
ACROSS THE AREA. MADE A GOOD FAITH EFFORT TO BLEND WELL WITH
SURROUNDING FORECAST GRIDS.
DID NOT MAKE MAJOR CHANGES TO HIGH OR LOW TEMPERATURES.
&&
.AVIATION...AREAS OF DENSE FOG EXPECTED AT RHI...CWA AND AUW THROUGH
ABOUT 15Z SATURDAY MORNING. CONDITIONS TO GRADUALLY IMPROVING TO
IFR THEREAFTER. SOME PATCHY FOG POSSIBLE AGAIN AFTER 06Z SUNDAY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR WIZ005-
010>012-018-019-030-035-036.
&&
$$
ESB/ECKBERG
000
FXUS63 KARX 210942
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
342 AM CST SAT NOV 21 2009
.SHORT TERM...TODAY THROUGH MONDAY
AT 3 AM...HIGH PRESSURE...CENTERED OVER THE OHIO VALLEY...WAS IN
CONTROL OF THE WEATHER IN THE UPPER MISSISSIPPI RIVER VALLEY. THE
COMBINATION OF LIGHT WINDS AND A MOIST BOUNDARY LAYER HAS RESULTED
IN THE DEVELOPMENT OF DENSE FOG EARLY THIS MORNING. THIS FOG
SHOULD PERSIST ACROSS THE FORECAST AREA THROUGH 10 AM THIS
MORNING. AS A RESULT...NO CHANGES WILL BE NEEDED TO DENSE FOG
ADVISORY THAT WAS ISSUED ON FRIDAY EVENING.
THE BUFKIT SOUNDINGS CONTINUE TO SHOW A VERY DRY AIR MASS LOCATED
ABOVE THE INITIALLY MOIST BOUNDARY LAYER TODAY. AS DIURNAL HEATING
OCCURS...WE SHOULD EASILY MIX UP TO 900 MB. THIS IN TURN WILL
BRING THIS DRY AIR TO THE SURFACE. AS TYPICAL IN THESE
SITUATIONS...THE MOS DEW POINT GUIDANCE ARE TOO HIGH AND THE GFE
DEW POINT TOO WAS USED TO LOWER THESE DEW POINTS TO AROUND
30 DEGREES THIS AFTERNOON.
FROM TONIGHT INTO SUNDAY MORNING...THE MODELS CONTINUE TO SHOW THAT
THE MOISTURE BELOW 800 MB DRAMATICALLY INCREASES AHEAD OF AN
APPROACHING LONG WAVE TROUGH IN THE NORTHERN AND CENTRAL PLAINS.
THIS MOISTURE IS CURRENTLY PRODUCING LIFR/IFR CEILINGS AND
VISIBILITIES ACROSS OKLAHOMA THIS MORNING. THERE WAS ENOUGH
CONFIDENCE TO INCLUDE AREAS OF DENSE FOG IN THE GRIDS INTO THE
HIGHER ELEVATIONS OF NORTHEAST IOWA AND SOUTHEAST MINNESOTA AFTER
MIDNIGHT TONIGHT. THIS FOG WILL LIKELY PERSIST THROUGH MID TO LATE
MORNING. THE DRIZZLE IS STILL IN QUESTION FOR LATE TONIGHT...
BECAUSE THERE IS VERY LITTLE LIFT /IF ANY/ IN THE DEEP MOISTURE
LAYER.
IN ADDITION TO THE INCREASING MOISTURE...THE WARM AIR ADVECTION
SHOULD RESULT IN STEADY TO SLOWLY RISING TEMPERATURES ACROSS THE
FORECAST AREA TONIGHT. AS A RESULT...A NON DIURNAL TEMPERATURE
CURVE WAS USED ACCOUNT FOR THIS FROM LATE TONIGHT INTO SUNDAY
MORNING.
FROM SUNDAY NIGHT INTO MONDAY...IT WAS THE CONSENSUS THAT THE
SLOWER OPERATIONAL NAM/WRF...GEM...AND ECMWF SOLUTIONS WERE
PREFERRED OVER THE FASTER OPERATIONAL GFS. DUE TO THIS...THE
TEMPERATURES WERE RAISED SOME AND THE PRECIPITATION CHANCES WERE
LOWERED.
.LONG TERM...MONDAY NIGHT THROUGH FRIDAY
MUCH OF THE TIME THIS MORNING WAS SPENT WORKING ON THE FORECAST
GRIDS FROM MONDAY NIGHT INTO WEDNESDAY NIGHT.
THE 21.00Z MODELS CONTINUE TO STRUGGLE WITH THE EVOLUTION AND
TIMING OF A LOW PRESSURE SYSTEM MOVING THROUGH THE UPPER
MISSISSIPPI RIVER VALLEY SOMEWHERE FROM MONDAY NIGHT THROUGH
THANKSGIVING. MUCH OF THIS HAS TO DEAL WITH HOW THIS SYSTEM
INTERACTS WITH ANOTHER SYSTEM DROPPING INTO THE MEAN TROUGH BEHIND
THE INITIAL STRONG WAVE. WHILE THE OPERATIONAL GFS HAS SLOWED ITS
MOVEMENT OF THIS SYSTEM FROM 24 HOURS AGO...IT CONTINUES TO BE
MUCH FASTER THAN THE ECMWF AND GEM. ABOUT TWO THIRDS /8 OUT OF 12/
OF ITS FAMILY MEMBERS SUPPORT THIS FASTER SOLUTION. MEANWHILE THE
REMAINING GFS MEMBERS ARE CLUSTERED WITH THE SLOWER ECMWF WHICH
MOVES THE SYSTEM THROUGH OUR AREA BETWEEN TUESDAY THROUGH
THANKSGIVING. THIS ADDS TO QUITE A BIT OF UNCERTAINTY TO THIS TIME
PERIOD...BUT THE OVERALL CONSENSUS OF OUR OFFICE AND THE
SURROUNDING WFOS WAS TO CONTINUE TO TREND OUR FORECAST GRIDS
TOWARD THE SLOWER ECMWF AND GEM SOLUTIONS. THIS ULTIMATELY
RESULTED IN SOME CHANGES TO TEMPERATURES /RAISED TEMPERATURES FROM
MONDAY NIGHT INTO TUESDAY NIGHT/...PRECIPITATION CHANCES /LOWERED
CHANCES ON MONDAY NIGHT AND THEN INCREASED THEM SOME FROM TUESDAY
INTO WEDNESDAY NIGHT/...AND WEATHER /DELAYED CHANGE OVER TO SNOW/
GRIDS FROM MONDAY NIGHT THROUGH WEDNESDAY NIGHT.
THE ECMWF ACTUALLY GENERATES QUITE A BIT OF SNOW /4 TO 8 INCHES/
ACROSS THE NORTHERN IOWA AND SOUTHERN MINNESOTA...AND THEN
NORTHEAST INTO UPPER MICHIGAN FROM LATE WEDNESDAY INTO
THANKSGIVING. THE OPERATIONAL GFS ACTUALLY SHOW A SIMILAR
TOTALS...BUT IT IS FURTHER NORTHWEST AND SLIGHTLY EARLIER. WHILE
THESE MODELS ARE SHOWING THIS...THE COBB DATA ONLY SHOWS MINOR
SNOW ACCUMULATIONS IN THE GFS. WITH SUCH DIFFERENCES...WE DECIDED
NOT TO HIGHLIGHT THIS SYSTEM IN OUR HAZARDOUS WEATHER OUTLOOK.
HOPEFULLY THIS WILL BECOME A BIT CLEARER IN THE UPCOMING DAYS.
&&
.AVIATION...TODAY AND TONIGHT
PRIMARY CONCERNS WERE FOCUSED ON IFR CONDITIONS IN LOW CLOUDS AND
FOG DURING THE VALID TAF PERIOD.
RADIATIONAL COOLING AND A MOIST BOUNDARY LAYER HAS ALLOWED FOR
WIDESPREAD IFR CONDITIONS IN FOG EARLY THIS MORNING. AS SOUTH WINDS
INCREASE TODAY AND MIXING COMMENCES...IMPROVEMENT IS EXPECTED.
HOWEVER...HAZE SHOULD LINGER THROUGH THE DAY WITH PERSISTENT
SOUTHERLY FLOW. THIS SAME SOUTHERLY FLOW CONTINUES DRAWING HIGHER
RELATIVE HUMIDITY NORTHWARD TONIGHT. VARIOUS DATA SETS WERE STRONGLY
SUGGESTIVE OF IFR AND/OR MVFR IN LOW CLOUDS/FOG AGAIN TONIGHT.
POOREST CONDITIONS ANTICIPATED ACROSS HIGHER ELEVATION AIRPORTS
MAINLY WEST OF THE MISSISSIPPI RIVER...SUCH AS KRST TAF SITE...WHERE
CONFIDENCE WAS HIGH ENOUGH TO FORECAST CONDITIONS AT INSTRUMENT
APPROACH MINIMUMS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR WIZ017-
WIZ029-WIZ032-WIZ033-WIZ034-WIZ041-WIZ042-WIZ043-WIZ044-
WIZ053-WIZ054-WIZ055-WIZ061.
MN...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR MNZ079-
MNZ086-MNZ087-MNZ088-MNZ094-MNZ095-MNZ096.
IA...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR IAZ008-
IAZ009-IAZ010-IAZ011-IAZ018-IAZ019-IAZ029-IAZ030.
&&
$$
SHORT/LONG TERM...BOYNE
AVIATION...THOMPSON/AJ
000
FXUS63 KMKX 210922
AFDMKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
322 AM CST SAT NOV 21 2009
FORECAST FOCUS ON DENSE FOG THIS MORNING...QUIET WEATHER INTO
MONDAY NIGHT...PRECIPITATION CHANCES TUESDAY THROUGH THANKSGIVING
DAY.
LATEST WATER VAPOR IMAGERY INDICATED AN UPPER TROUGH SHIFTING INTO
THE WESTERN USA...WITH A DOWNSTREAM UPPER RIDGE OVER THE UPPER
MIDWEST...AND A SHORTWAVE TROUGH OVER NORTHERN INDIANA. AT THE
SURFACE...HIGH PRESSURE WAS CENTERED OVER SOUTHERN OHIO.
.TODAY...LIGHT WINDS AND CLEARING SKIES HELPING FOG FORM ACROSS
SOUTH CENTRAL AND PORTIONS OF SOUTHEAST WISCONSIN EARLY THIS
MORNING. SOME MID LEVEL CLOUDS LINGERING IN THE NORTHEAST COUNTIES
MAY LIMIT THE FOG SOMEWHAT EARLY...BUT THESE CLOUDS SHOULD
DISSIPATE WITHIN A FEW HOURS. RUC FORECAST SOUNDINGS ACROSS THE
AREA THROUGH 15Z THIS MORNING SHOW A DECENT TEMPERATURE INVERSION
JUST ABOVE THE SURFACE.
HOWEVER...MOISTURE PROFILE IN THE LOW LEVELS NOT SATURATED...SO
SOME QUESTION AS TO IF DENSE FOG WILL OCCUR OTHER THAN IN THE
WISCONSIN RIVER VALLEY. LOWEST VISIBILITIES NOT EXPECTED UNTIL THE
11Z TO 14Z TIME FRAME...SO WILL GIVE CURRENT DENSE FOG ADVISORY FOR
THE FAR WESTERN COUNTIES AND GREEN COUNTY MORE TIME.
AFTER FOG DISSIPATES LATER THIS MORNING...EXPECT A PLEASANT DAY
UNDER THE INFLUENCE OF THE HIGH TO THE SOUTHEAST. MOSTLY SUNNY
SKIES AND MILD TEMPERATURES ARE EXPECTED...WITH HIGHS IN THE
LOWER TO MID 50S.
.TONIGHT THROUGH MONDAY NIGHT...FOLLOWED THE CONSISTENTLY DRIER
NAM/ECMWF MODELS FOR THIS PERIOD. THE HIGH SLOWLY MOVES FURTHER
EAST OF THE REGION...WITH A CONFLUENT ZONE SETTING UP FROM
NORTHWEST WISCONSIN SOUTHWEST TO IOWA AND NEBRASKA. ANY LIGHT
PRECIPITATION FROM THIS AREA WILL STAY WEST OF THE FORECAST
AREA...AS DRY AIRMASS IN PLACE HOLDS STEADY.
MENTIONED PATCHY FOG TONIGHT AND SUNDAY NIGHT...WITH SOLID LOW
LEVEL TEMPERATURE INVERSION OVER THE AREA. MILD TEMPERATURES TO
CONTINUE THROUGH THE PERIOD...WITH A GRADUAL INCREASE IN CLOUDS
MONDAY AND MONDAY NIGHT AHEAD OF NEXT SYSTEM.
.TUESDAY THROUGH FRIDAY...CONTINUED TO FOLLOW THE ECWMF MODEL FOR
THIS PERIOD...PREFERRED BY HPC. THIS CONTINUES TO SHOW
CYCLOGENESIS OVER SOUTHEAST NEBRASKA MONDAY NIGHT...THEN MOVES THE
LOW SLOWLY EAST NORTHEAST TO NORTHERN ILLINOIS BY 12Z
WEDNESDAY...THEN TO THE EASTERN UPPER PENINSULA OF MICHIGAN BY
12Z THANKSGIVING DAY. STRONG UPPER LOW ACCOMPANIES THE SURFACE
LOW.
BEST LOW LEVEL FRONTOGENESIS AND QPF COMES ACROSS THE AREA TUESDAY
AND TUESDAY NIGHT...WITH WEAKER UPWARD MOTION AND QPF WEDNESDAY
THROUGH THANKSGIVING DAY. ADJUSTED POPS ACCORDINGLY FOR THIS
PERIOD. LOOKS WARM ENOUGH FOR ALL RAIN TUESDAY THROUGH WEDNESDAY.
925MB TEMPERATURES GET COLD ENOUGH FOR A MIXTURE OF RAIN AND
SNOW WEDNESDAY NIGHT INTO THANKSGIVING DAY...BUT AM NOT EXPECTING
MUCH IN THE WAY OF ACCUMULATING SNOW AT THIS TIME.
&&
.AVIATION...A HIGH PRESSURE RIDGE WILL MOVE EWD ACROSS SRN WI
TODAY WITH SLY WINDS DEVELOPING TNT AND SUN AS THE HIGH MOVES EAST
OF THE REGION. RADIATIONAL FOG WILL PREVAIL THROUGH 15Z THIS AM
WITH IFR TO MVFR VSBYS EXPECTED AT THE TAF SITES OVER SOUTH
CENTRAL AND SE WI. LGT RADIATIONAL FOG WILL DEVELOP ONCE AGAIN
LATE TNT AROUND 09Z SUN BUT MAINLY REMAIN MVFR VSBYS. ISOLD IFR
VSBYS MAY OCCUR ESPECIALLY AT KENW.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR WIZ056-062-
067-068.
LM...NONE.
&&
$$
SHORT/LONG TERM...08/WOOD
AVIATION/MARINE...20/GEHRING
000
FXUS63 KARX 210418 AAA
AFDARX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LA CROSSE WI
1017 PM CST FRI NOV 20 2009
UPDATED AVIATION DISCUSSION AND TO INCLUDE UPDATE SECTION
.UPDATE...
AFTER MUCH COORDINATION WITH SURROUNDING OFFICES AND WATCHING TRENDS
WITH SURFACE OBSERVATIONS...HAVE ISSUED A DENSE FOG ADVISORY ACROSS
ALL OF THE FORECAST AREA.
SKIES HAVE MOSTLY CLEARED OUT ACROSS THE AREA AS DRIER AIR SEEN ON
THE 00Z MPX SOUNDING MOVED IN. MOST OF THIS DRIER AIR APPEARS TO BE
COMING IN ALOFT...AS DEWPOINTS HAVE MOSTLY BEEN FALLING AS A RESULT
OF FALLING TEMPERATURES. WINDS ALSO REMAIN LIGHT...WITH A SURFACE
RIDGE IN PLACE...AIDING IN THE FALLING TEMPERATURES. THEREFORE...THE
REGIME IS NOT FAVORABLE FOR MUCH IN THE WAY OF LOW LEVEL DRY AIR
ADVECTION. THIS ALLOWS THE USE OF THE CROSS-OVER TECHNIQUE. LOOKING
BACK AT LATE AFTERNOON DEWPOINTS...READINGS WERE IN THE UPPER 30S TO
LOW 40S F. WITH READINGS DROPPING TO AT OR BELOW THESE DEWPOINTS...
VISIBILITIES OF 2-4 MILES IN MIST HAVE BECOME WIDESPREAD. A FEW
LOCALIZED AREAS ARE SEEING VISIBILITIES APPROACH ONE HALF OF A MILE
SUCH AS OELWEIN AND BOSCOBEL. WITH CONTINUED COOLING OVERNIGHT...
DROPPING FURTHER PAST THE LATE AFTERNOON DEWPOINTS...BELIEVE
VISIBILITIES SHOULD DROP TO ONE QUARTER OF A MILE OR LESS AT MANY
LOCATIONS. BEST BET WOULD BE IN THE RIVER VALLEYS GIVEN WATER
TEMPERATURES IN THE LOW TO MID 40S. COMBINATION OF SOUTH WINDS
PICKING UP AND DAYTIME HEATING SHOULD ALLOW THE FOG TO DISSIPATE BY
16Z SATURDAY.
&&
.SHORT TERM...TONIGHT THROUGH MONDAY NIGHT
BIGGEST FORECAST CONCERN IS ON DEGREE OF SATURATION LATE SATURDAY
NIGHT AND CORRESPONDING RAIN/DRIZZLE CHANCES...WITH RAIN CHANCES
SUNDAY THROUGH MONDAY NIGHT.
DATA ANALYSIS AT 19Z SHOWS HIGH PRESSURE LOCATED OVER KANSAS...WITH
CLEAR SKIES EXTENDING FROM THE SOUTHERN PLAINS INTO SOUTHERN CANADA.
LINGERING MID LEVEL CLOUDS PERSIST OVER MUCH OF THE FORECAST AREA...
WITH THE SLOW MOVING BACK EDGE OVER SOUTHEAST MINNESOTA.
BIGGEST DIFFERENCE IN THE 20.12Z MODELS ARE SATURDAY NIGHT AS GFS
CONTINUES TO GENERATE QPF ACROSS IOWA INTO MINNESOTA...WHILE NAM
REMAINS DRY. OTHERWISE MODELS APPEAR IN REASONABLE AGREEMENT.
IN THE NEAR TERM...UPPER LEVEL RIDGE AND SURFACE HIGH PRESSURE WILL
DOMINATE THE WEATHER INTO SATURDAY. MODELS CONSISTENT IN CLEARING
CLOUDS OUT OF THE AREA THIS EVENING. THUS EXPECTING A MOSTLY CLEAR
NIGHT WITH LIGHT WINDS. SURFACE OBSERVATIONS AND MODEL SOUNDINGS
INDICATING RESIDUAL LOW LEVEL MOISTURE OVER THE AREA. WITH THE
LIGHT WINDS AND CLEAR SKIES WILL LIKELY SEE SOME FOG FORMATION LATE
TONIGHT AN THUS HAVE ADDED THIS TO THE GRIDDED DATABASE. QUIET/SUNNY
AND MILD WEATHER ON TAP FOR SATURDAY AS HIGH PUSHES EAST AND
SOUTHERLY WINDS RETURN TO THE AREA.
WITH THE SOUTHERLY FLOW INCREASING SATURDAY NIGHT...MODELS
INDICATING LOW LEVEL SATURATION BEGINNING TO OCCUR AFTER MIDNIGHT.
BOTH THE NAM AND GFS INDICATING SOME WEAK LIFT THROUGH THE SATURATED
LAYER AND THUS HAVE CONTINUED THE MENTION OF DRIZZLE AFTER 09Z.
OTHERWISE COLUMN CONTINUES TO SATURATE SUNDAY/SUNDAY NIGHT IN MOIST
SOUTHERLY FLOW WITH WEAK WARM ADVECTION/ISENTROPIC LIFT AHEAD OF AN
APPROACHING TROUGH. ENOUGH LIFT GENERATED FOR LOWER END RAIN
PROBABILITIES AREA-WIDE...WITH SLIGHTLY BETTER CHANCES ACROSS THE
WESTERN COUNTIES.
ON MONDAY/MONDAY NIGHT...TROUGH DIGS OVER THE ROCKIES WITH WEAK
SHORTWAVE BEING EJECTED NORTHWARD TOWARD THE AREA. WITH CONTINUED
MOIST SOUTHERLY FLOW AND WEAK LIFT AHEAD OF THE DEEPENING TROUGH
WILL CONTINUE MID-LOW CHANCE RAIN PROBABILITIES.
TEMPERATURES LOOK TO REMAIN MILD THROUGH THE PERIOD AVERAGING SOME
10 TO 15 DEGREES ABOVE NORMAL THROUGH MONDAY. GUIDANCE VALUES LOOK
REASONABLE AD NOT MUCH DEVIATION FROM THEM OR PREVIOUS FORECAST.
.LONG TERM...TUESDAY THROUGH FRIDAY
MEDIUM RANGE MODELS IN BETTER AGREEMENT WITH THEIR LATEST
RUNS. 20.06Z GFS IS THE OUTLIER WITH THE WEAKER AND FASTER SOLUTION
IN HANDLING THE TROUGH/SURFACE AND MID LEVEL FEATURES...WHILE THE GEM
HAS COME AROUND TO THE ECMWF SOLUTION. HOWEVER...WITH THE
20.12Z GFS RUN IT IS COMING MORE IN-LINE WITH THE ECMWF/GEM
SOLUTIONS. PREFERENCE WAS THE BETTER CLUSTERING OF THE ECMWF/GEM.
PATTERN WILL BE DOMINATED BY LONGWAVE TROUGH ACROSS THE CENTRAL CONUS
AT THE BEGINNING OF THE PERIOD...WITH CLOSED MID LEVEL LOW OVER IOWA.
THIS FEATURE WILL THEN LIFT NORTHEAST THROUGH THE UPPER MISSISSIPPI
RIVER VALLEY REGION TUESDAY AND TUESDAY NIGHT...WITH A SECONDARY WAVE
DROPPING ACROSS THE AREA WEDNESDAY AND WEDNESDAY NIGHT...KEEPING
TROUGH FIRMLY ENTRENCHED ACROSS THE AREA. SOUNDINGS FROM THE ECMWF
SHOWING 5000 FOOT SURFACE WARM LAYER TUESDAY ACROSS MUCH OF THE AREA
AND THUS EXPECT MAINLY RAIN. AS COLUMN COOLS TUESDAY NIGHT AND
WEDNESDAY WILL CONTINUE TO MENTION RAIN/SNOW POSSIBILITIES. WRAP
AROUND MOISTURE WITH CYCLONIC FLOW WILL KEEP LOWER END PRECIPITATION
CHANCES WEDNESDAY NIGHT...WITH ENOUGH COLDER AIR TO RESULT IN ALL
SNOW.
TROUGH TRANSLATES INTO THE EASTERN CONUS THURSDAY AND FRIDAY AS
RIDGE BUILDS ACROSS THE CENTRAL CONUS. THUS EXPECT RISING HEIGHTS
AND QUIET WEATHER.
ABOVE NORMAL TEMPERATURES AT THE BEGINNING OF THE PERIOD WILL FALL
BACK TO NEAR OR SLIGHTLY BELOW FROM WEDNESDAY THROUGH FRIDAY.
ALL IN ALL THE SYSTEM TUESDAY/TUESDAY NIGHT BEARS WATCHING. IF
MORE COLDER AIR GETS WRAPPED INTO THE SYSTEM ACCUMULATING SNOW IS NOT
OUT OF THE QUESTION FOR PARTS OF THE AREA.
&&
.AVIATION...TONIGHT AND SATURDAY
SKIES HAVE CLEARED ACROSS BOTH TAF SITES...ALLOWING FOR MVFR
VISIBILITIES IN BR TO DEVELOP. THESE VISIBILITIES SHOULD CONTINUE TO
FALL THROUGH THE NIGHT AS TEMPERATURES COOL FURTHER...AIDED BY LIGHT
WINDS AND DRY AIR ALOFT. RIGHT NOW HAVE FORECAST VISIBILITIES
BOTTOMING OUT AT IFR AT KRST AND LIFR AT KLSE LATE TONIGHT...BUT
THESE WILL NEED MONITORING...ESPECIALLY AT KLSE WITH THE WARMER
MISSISSIPPI RIVER NEARBY ADDING EXTRA MOISTURE. IN ADDITION...WOULD
NOT BE SURPRISED IF A LIFR CEILING DEVELOPS AT KLSE LATE TONIGHT IF
INDEED A STRATUS DECK DEVELOPS WITHIN THE RIVER VALLEY. SOUTH WINDS
SHOULD PICK UP DURING THE DAY SATURDAY AS A SURFACE RIDGE OVER THE
TAF SITES MOVES OFF TO THE EAST. THE COMBINATION OF THESE WINDS AND
DAYTIME HEATING WILL ALLOW MOST FOG TO MIX OUT AROUND 15Z. VFR
CONDITIONS ARE EXPECTED TO PREVAIL FOR THE REST OF THE DAY WITH A
DRY AIRMASS IN PLACE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...DENSE FOG ADVISORY UNTIL 10 AM CST SATURDAY FOR WIZ017-WIZ029-
WIZ032-WIZ033-WIZ034-WIZ041-WIZ042-WIZ043-WIZ044-WIZ053-
WIZ054-WIZ055-WIZ061.
MN...DENSE FOG ADVISORY UNTIL 10 AM CST SATURDAY FOR MNZ079-MNZ086-
MNZ087-MNZ088-MNZ094-MNZ095-MNZ096.
IA...DENSE FOG ADVISORY UNTIL 10 AM CST SATURDAY FOR IAZ008-IAZ009-
IAZ010-IAZ011-IAZ018-IAZ019-IAZ029-IAZ030.
&&
$$
UPDATE...AJ
SHORT/LONG TERM...RABERDING
AVIATION...AJ
000
FXUS63 KMKX 210351
AFDMKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
951 PM CST FRI NOV 20 2009
.UPDATE...
WILL ADD DENSE FOG ADVISORY FOR COUNTIES WEST AND SW OF MADISON
TONIGHT AND SATURDAY MORNING.
&&
.PREV DISCUSSION... /ISSUED 224 PM CST FRI NOV 20 2009/
TONIGHT...GOOD LOOKING MID LEVEL SHORT WAVE TRACKS SLOWLY THROUGH
THE CWA OVERNIGHT. THE COLUMN IS DRY OVERALL WITH ASSOCIATED CLOUD
BASES RELATIVELY HIGH THIS AFTERNOON. RADAR IS SHOWING SOME
ELEVATED RETURNS AND SATELLITE SHOWS A RATHER BUMPY MID AND HIGH
LEVEL CLOUD FIELD. COULD HAVE SOME SHALLOW VIRGA OUT THERE BUT
NOTHING IS EXPECTED TO REACH THE GROUND. CLEARING SHOULD BE SLOW.
BUT ONCE IT DOES CLEAR...THE FLOW WILL BE WEAK THROUGH A DEEP
LAYER. LATE TONIGHT WINDS UP THROUGH H6 DON/T GET ABOVE 10KTS AND
THE BNDRY LAYER SHOULD DECOUPLE TO CALM. DWPNTS STILL A BIT
ELEVATED AND WITH GOOD RADITIONAL COOLING AFTER CLOUDS MOVE
OUT...WOULD EXPECT AREAS OF FOG TO DEVELOP. THE EAST AND FAR NORTH
MAY STAY PATCHY IN COVERAGE DUE TO MORE CLOUDS LINGERING LATER.
THIS WEEKEND...ONCE THE S/W EXITS...MID LEVEL RIDGING TAKES OVER
AND KEEPS THE AREA DRY AND MILD. ABOVE NORMAL HIGHS IN THE LOWER TO
MID 50S WITH SUNSHINE EXPECTED FROM TIME TO TIME...ESPECIALLY
EAST.
EARLY NEXT WEEK...BY LATE IN THE WEEKEND INTO EARLY NEXT WEEK...A
LARGE SCALE TROUGH BEGINS TO DIG INTO THE MIDDLE OF THE COUNTRY.
THE NAM AND GFS SHOW AN AREA OF WAA IN THE RETURN FLOW THAT COULD
GENERATE SOME LIGHT QPF JUST WEST OF THE CWA SUNDAY AFTERNOON AND
SUNDAY NIGHT. ON MONDAY...THERE IS DISAGREEMENT BETWEEN THE NAM
AND THE GFS/ECMWF. THE NAM KICKS OUT A LEADING S/W AND KEEPS IT
BACK TO THE WEST...AS AN EXTENSION OF THE LARGER PLAINS TROF. THIS
ALLOWS THE MOISTURE/PCPN TO SPREAD UP INTO THE AREA ON MONDAY. THE
ECMWF AND THE GFS...KICK THIS SHORT WAVE QUICKLY TO THE EAST AND
KEEP IT MORE OF A SEPARATE ENTITY. THEREFORE THE MOISTURE/PCPN
STAY EAST OF OUR AREA. I/LL STICK WITH THE MORE TRUSTWORTHY
GFS/ECMWF ON THIS ONE.
THE BIGGER STRUGGLE TODAY WAS DEALING WITH THE DISPARITY BETWEEN
THE GFS AND ECMWF FOR THE MIDDLE OF THE WEEK. EVENTUALLY A RATHER
STRONG LOW EJECTS OUT OF THE SOUTHERN PLAINS...OUT OF THE BASE OF
THE TROF AND TRACKS INTO THE GREAT LAKES. THE ECMWF HAS BEEN
SLOWER THAN THE GFS OVER THE LAST FEW RUNS AND IS THE MODEL OF
CHOICE BY THE HPC. THE GFS IS...AND HAS BEEN...FAST AND IS MORE
AGGRESSIVE IN PULLING DOWN COLD AIR INTO THE UPPER MIDWEST ON THE
BACK SIDE OF THE LOW. MY MONEY IS ON THE ECMWF...THIS SYSTEM WILL
BRING IN PRECIP TUESDAY THROUGH WEDNESDAY NIGHT. INITIALLY...
CONDITIONS WILL BE WARM ENOUGH TO KEEP IT ALL RAIN. COLD AIR WILL
EVENTUALLY WRAP INTO THIS LOW CHANGING THE PCPN OVER TO RAIN/SNOW
AND EVENTUALLY SNOW. BY THE TIME THIS HAPPENS...AS USUAL...THE
BULK OF THE PCPN WILL BE PULLING OUT. SO FOR NOW...NOT SEEING ANY
TYPE OF SIGNIFICANT WINTER SITUATION SETTING UP.
AVIATION...UPPER WAVE MOVING THROUGH THE STATE WILL BRING CONTINUED
VFR CLOUDS THROUGH TONIGHT...WITH DECREASING CLOUDS WEST TO EAST
EARLY TONIGHT INTO TOMORROW MORNING. LIGHT WINDS FROM WEAK PRESSURE
GRADIENT UNDER HIGH PRESSURE WILL LIKELY LEAD TO SOME FOG
DEVELOPMENT LATER TONIGHT. EXPECT MVFR VISBYS BY MIDNIGHT...WITH IFR
POSSIBLE LATER IN THE NIGHT. MOST OF THE FOG POTENTIAL WILL DEPEND
ON WHEN CLOUDS SCATTER OUT. COULD HOLD ON TO VFR VISBYS LONGER IF
CLOUDS LINGER. WILL HAVE TO KEEP AN EYE ON CLOUD TRENDS THIS
EVENING. OTHERWISE...VISBYS WILL RETURN TO VFR TOMORROW
MORNING...WITH A QUIET DAY ON SATURDAY.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...DENSE FOG ADVISORY FROM 1 AM TO 10 AM CST SATURDAY FOR WIZ056-
062-067-068.
LM...NONE.
&&
$$
SHORT/LONG TERM...06
AVIATION/MARINE...06
000
FXUS63 KGRB 210347 AAB
AFDGRB
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GREEN BAY WI
947 PM CST FRI NOV 20 2009
.UPDATE...GOING TO HOLD OFF ON DENSE FOG ADVISORY AT THIS POINT.
WL CERTAINLY WILL SEE PATCHES OF DENSE FOG...BUT JUST NOT SURE
IT/S GOING TO BE WIDESPREAD ENOUGH TO WARRANT AN ADVISORY. WILL
ISSUE SPS DETAILING THE IMPACT ON HUNTERS AND OTHER MOVING AROUND
EARLY SATURDAY MORNING. CONCERNED ABOUT THE POSSIBILITY ROADS
COULD BECOME SLIPPERY AS A THICK LAYER OF FROST DEVELOPS ON THE
ROADWAY BY MORNING. WILL ALSO MENTION THAT IN THE SPS.
ALREADY UPDATED ZONES AND GRIDS A COUPLE HOURS AGO TO HAVE
MENTION OF PATCHY DENSE FOG. WL TWEAK MINS DOWN A BIT...AND HAVE
UPDATE OUT SHORTLY.
SKOWRONSKI
&&
.PREV DISCUSSION...ISSUED AT 923 PM CST FRI NOV 20 2009...
UPDATE...VSBYS DROPPING ACRS THE N WHERE SKIES HAVE CLEARED.
OBVIOUSLY GOING TO HAVE PATCHY DENSE FOG...QUESTION IS WHETHER OR
NOT IT BECOMES DENSE ENOUGH TO WARRANT AND ADVISORY. REALIZING
THERE WILL BE A LOT OF MOVEMENT EARLY TOMORROW AS HUNTERS HEAD OUT
FOR THE START OF THE DEER SEASON...AM A LITTLE MORE WILLING THAN
NORMAL TO GO WITH AN ADVISORY FOR MARGINAL CONDITIONS. WL CONTINUE
TO MONITOR OBS FOR A BIT LONGER...BUT INTEND TO HAVE DECISION
BEFORE 1000 PM.
SKOWRONSKI
DISCUSSION ISSUED AT 310 PM CST FRI NOV 20 2009...
SHORT TERM....LATEST RUC ANALYSIS AND VIS/IR/WV/RADAR IMAGERY SHOW
A SHORTWAVE PROGRESSING TO THE EAST ACROSS THE WESTERN GREAT LAKES
THIS AFTERNOON WITH BROAD CYCLONIC FLOW AT THE SURFACE. ALTHOUGH
CLOUDY SKIES PREVAIL AHEAD OF THE WAVE IN A FAIRLY SOUPY LOW LEVEL
AIRMASS...FORCING AND MOISTURE DEPTH HAVE NOT BEEN SUFFICIENT ENOUGH
FOR ANY PRECIP. SKIES HAVE CLEARED ACROSS ALL OF MINNESOTA AND FAR
NORTHWEST WISCONSIN BEHIND THE SHORTWAVE THIS AFTERNOON AS RIDGING
BUILDS INTO THE REGION. FORECAST CONCERNS OVER THE NEXT 24 HOURS
INCLUDE CLOUD TRENDS AND FOG POTENTIAL TONIGHT.
TONIGHT...THE SHORTWAVE TROUGH WILL CONTINUE TO SLOWLY PASS ACROSS
THE AREA DURING THE EVENING BEFORE EXITING AFTER MIDNIGHT. WILL SEE
DECREASING CLOUD COVER AS THIS OCCURS...WHILE BROAD LOW LEVEL
CYCLONIC FLOW GETS REPLACED BY AN INCOMING WEAK RIDGE AXIS. A DRIER
LOW LEVEL AIRMASS WILL FILTER INTO THE STATE FROM THE WEST AND
WILL EAT AWAY AT THE JUICY AIR IN PLACE CURRENTLY. WITH CLEARING
SKIES...LIGHT WINDS...AND A REASONABLY MOIST BOUNDARY LAYER...EXPECT
TO SEE SOME RADIATIONAL FOG TOMORROW MORNING. BEST CHANCES WILL
APPEAR TO BE ACROSS THE HIGHER TERRAIN OF N-C WISCONSIN...WHERE
CLEARING WILL ARRIVE FIRST. LOOKING UPSTREAM LAST NIGHT...THERE WAS
SOME PATCHY DENSE FOG ACROSS NORTHERN MINNESOTA...ESPECIALLY WITHIN
LOW LYING VALLEYS. CROSS-OVER TEMPS UPSTREAM APPEAR TO BE AROUND
30F OR IN THE LOWER 30S...SO THOSE AREAS WHERE MIN TEMPS FALL BELOW
THIS THRESHOLD WILL BE MORE SUSCEPTIBLE TO FOG. AS A RESULT...WILL
BEEF UP FOG WORDING ACROSS N-C WISCONSIN TO AREAS...BUT KEEP PATCHY
ELSEWHERE WHERE TEMPS WILL ONLY FALL INTO THE THE LOW TO MID 30S.
TOMORROW...A QUIET DAY TOMORROW ONCE THE FOG BURNS OFF BY
MID-MORNING DUE TO THE PRESENCE OF RIDGING THROUGH THE COLUMN. A
LACK OF CLOUD COVER UPSTREAM SUGGESTS A MOSTLY SUNNY DAY. 925MB
TEMPS AROUND 6C WILL YIELD HIGHS IN THE LOW TO MID 50S.
LONG TERM...SATURDAY NIGHT THROUGH NEXT FRIDAY.
MEDIUM RANGE MODEL SOLUTIONS ONCE AGAIN STARTED DOING THEIR OWN
THING BY EARLY NEXT WEEK. THIS ONCE AGAIN LED TO HPC GUIDANCE
BEING FOLLOWED MORE CLOSELY THAN ANY OF THE 12Z MODEL RUNS. RAIN
CHANCES WERE CONFINED TO THE WESTERN PART OF THE FORECAST AREA
SUNDAY NIGHT...AHEAD OF AN APPROACHING COLD FRONT. PRECIPITATION
CHANCES CONTINUED INTO WEDNESDAY AS THE HPC MANUAL SURFACE PROG
BROUGHT A LOW THROUGH WISCONSIN. COLDER AIR IN THE WAKE OF THE
SYSTEM MADE PRECIPITATION TYPE AN ISSUE FOR TUESDAY NIGHT AND
WEDNESDAY SO BOTH RAIN AND SNOW WERE MENTIONED FOR THOSE PERIODS.
LAKE EFFECT APPEARED TO BE A POSSIBILITY ACROSS THE EXTREME NORTH
AND NORTHEAST STARTING THURSDAY...AS DELTA TS...LAKE SURFACE TO
850MB...INCREASE. OTHERWISE ONLY WENT WITH SOME SLIGHT CHANCE POPS
ACROSS THE AREA. MADE A GOOD FAITH EFFORT TO BLEND WELL WITH
SURROUNDING FORECAST GRIDS.
DID NOT MAKE MAJOR CHANGES TO HIGH OR LOW TEMPERATURES.
AVIATION...MVFR VSBYS WILL IMPROVE TO VFR THIS AFTERNOON AND EARLY
THIS EVENING AS SKIES WILL SEE A GRADUAL CLEARING TREND. WILL SEE
RADIATIONAL FOG DEVELOP TONIGHT WITH THE BIGGEST IMPACT EXPECTED AT
RHI TOMORROW MORNING WHERE LIFR VSBYS (OR POSSIBLY LOWER) ARE
POSSIBLE. A LITTLE MORE UNCERTAINTY EXISTS AT AUW/CWA/GRB AS ITS
TOUGH TO GAUGE HOW MUCH DRY AIR IN THE LOW LEVELS WILL ARRIVE
TONITE. THINK THAT AT LEAST IFR VSBYS ARE POSSIBLE AT AUW/CWA AND
MVFR AT GRB. WILL LET THE EVENING CREW MONITOR TRENDS AND ADJUST.
ONCE ANY FOG BURNS OFF BY MID-MORNING TOMORROW...VFR CONDITIONS WILL
PREVAIL THROUGH THE REST OF THE DAY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
000
FXUS63 KGRB 210323 AAA
AFDGRB
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GREEN BAY WI
923 PM CST FRI NOV 20 2009
.UPDATE...VSBYS DROPPING ACRS THE N WHERE SKIES HAVE CLEARED.
OBVIOUSLY GOING TO HAVE PATCHY DENSE FOG...QUESTION IS WHETHER OR
NOT IT BECOMES DENSE ENOUGH TO WARRANT AND ADVISORY. REALIZING
THERE WILL BE A LOT OF MOVEMENT EARLY TOMORROW AS HUNTERS HEAD OUT
FOR THE START OF THE DEER SEASON...AM A LITTLE MORE WILLING THAN
NORMAL TO GO WITH AN ADVISORY FOR MARGINAL CONDITIONS. WL CONTINUE
TO MONITOR OBS FOR A BIT LONGER...BUT INTEND TO HAVE DECISION
BEFORE 1000 PM.
SKOWRONSKI
&&
.PREV DISCUSSION...ISSUED AT 310 PM CST FRI NOV 20 2009...
SHORT TERM....LATEST RUC ANALYSIS AND VIS/IR/WV/RADAR IMAGERY SHOW
A SHORTWAVE PROGRESSING TO THE EAST ACROSS THE WESTERN GREAT LAKES
THIS AFTERNOON WITH BROAD CYCLONIC FLOW AT THE SURFACE. ALTHOUGH
CLOUDY SKIES PREVAIL AHEAD OF THE WAVE IN A FAIRLY SOUPY LOW LEVEL
AIRMASS...FORCING AND MOISTURE DEPTH HAVE NOT BEEN SUFFICIENT ENOUGH
FOR ANY PRECIP. SKIES HAVE CLEARED ACROSS ALL OF MINNESOTA AND FAR
NORTHWEST WISCONSIN BEHIND THE SHORTWAVE THIS AFTERNOON AS RIDGING
BUILDS INTO THE REGION. FORECAST CONCERNS OVER THE NEXT 24 HOURS
INCLUDE CLOUD TRENDS AND FOG POTENTIAL TONIGHT.
TONIGHT...THE SHORTWAVE TROUGH WILL CONTINUE TO SLOWLY PASS ACROSS
THE AREA DURING THE EVENING BEFORE EXITING AFTER MIDNIGHT. WILL SEE
DECREASING CLOUD COVER AS THIS OCCURS...WHILE BROAD LOW LEVEL
CYCLONIC FLOW GETS REPLACED BY AN INCOMING WEAK RIDGE AXIS. A DRIER
LOW LEVEL AIRMASS WILL FILTER INTO THE STATE FROM THE WEST AND
WILL EAT AWAY AT THE JUICY AIR IN PLACE CURRENTLY. WITH CLEARING
SKIES...LIGHT WINDS...AND A REASONABLY MOIST BOUNDARY LAYER...EXPECT
TO SEE SOME RADIATIONAL FOG TOMORROW MORNING. BEST CHANCES WILL
APPEAR TO BE ACROSS THE HIGHER TERRAIN OF N-C WISCONSIN...WHERE
CLEARING WILL ARRIVE FIRST. LOOKING UPSTREAM LAST NIGHT...THERE WAS
SOME PATCHY DENSE FOG ACROSS NORTHERN MINNESOTA...ESPECIALLY WITHIN
LOW LYING VALLEYS. CROSS-OVER TEMPS UPSTREAM APPEAR TO BE AROUND
30F OR IN THE LOWER 30S...SO THOSE AREAS WHERE MIN TEMPS FALL BELOW
THIS THRESHOLD WILL BE MORE SUSCEPTIBLE TO FOG. AS A RESULT...WILL
BEEF UP FOG WORDING ACROSS N-C WISCONSIN TO AREAS...BUT KEEP PATCHY
ELSEWHERE WHERE TEMPS WILL ONLY FALL INTO THE THE LOW TO MID 30S.
TOMORROW...A QUIET DAY TOMORROW ONCE THE FOG BURNS OFF BY
MID-MORNING DUE TO THE PRESENCE OF RIDGING THROUGH THE COLUMN. A
LACK OF CLOUD COVER UPSTREAM SUGGESTS A MOSTLY SUNNY DAY. 925MB
TEMPS AROUND 6C WILL YIELD HIGHS IN THE LOW TO MID 50S.
LONG TERM...SATURDAY NIGHT THROUGH NEXT FRIDAY.
MEDIUM RANGE MODEL SOLUTIONS ONCE AGAIN STARTED DOING THEIR OWN
THING BY EARLY NEXT WEEK. THIS ONCE AGAIN LED TO HPC GUIDANCE
BEING FOLLOWED MORE CLOSELY THAN ANY OF THE 12Z MODEL RUNS. RAIN
CHANCES WERE CONFINED TO THE WESTERN PART OF THE FORECAST AREA
SUNDAY NIGHT...AHEAD OF AN APPROACHING COLD FRONT. PRECIPITATION
CHANCES CONTINUED INTO WEDNESDAY AS THE HPC MANUAL SURFACE PROG
BROUGHT A LOW THROUGH WISCONSIN. COLDER AIR IN THE WAKE OF THE
SYSTEM MADE PRECIPITATION TYPE AN ISSUE FOR TUESDAY NIGHT AND
WEDNESDAY SO BOTH RAIN AND SNOW WERE MENTIONED FOR THOSE PERIODS.
LAKE EFFECT APPEARED TO BE A POSSIBILITY ACROSS THE EXTREME NORTH
AND NORTHEAST STARTING THURSDAY...AS DELTA TS...LAKE SURFACE TO
850MB...INCREASE. OTHERWISE ONLY WENT WITH SOME SLIGHT CHANCE POPS
ACROSS THE AREA. MADE A GOOD FAITH EFFORT TO BLEND WELL WITH
SURROUNDING FORECAST GRIDS.
DID NOT MAKE MAJOR CHANGES TO HIGH OR LOW TEMPERATURES.
AVIATION...MVFR VSBYS WILL IMPROVE TO VFR THIS AFTERNOON AND EARLY
THIS EVENING AS SKIES WILL SEE A GRADUAL CLEARING TREND. WILL SEE
RADIATIONAL FOG DEVELOP TONIGHT WITH THE BIGGEST IMPACT EXPECTED AT
RHI TOMORROW MORNING WHERE LIFR VSBYS (OR POSSIBLY LOWER) ARE
POSSIBLE. A LITTLE MORE UNCERTAINTY EXISTS AT AUW/CWA/GRB AS ITS
TOUGH TO GAUGE HOW MUCH DRY AIR IN THE LOW LEVELS WILL ARRIVE
TONITE. THINK THAT AT LEAST IFR VSBYS ARE POSSIBLE AT AUW/CWA AND
MVFR AT GRB. WILL LET THE EVENING CREW MONITOR TRENDS AND ADJUST.
ONCE ANY FOG BURNS OFF BY MID-MORNING TOMORROW...VFR CONDITIONS WILL
PREVAIL THROUGH THE REST OF THE DAY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
000
FXUS63 KGRB 202110
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
310 PM CST FRI NOV 20 2009
.SHORT TERM....LATEST RUC ANALYSIS AND VIS/IR/WV/RADAR IMAGERY SHOW
A SHORTWAVE PROGRESSING TO THE EAST ACROSS THE WESTERN GREAT LAKES
THIS AFTERNOON WITH BROAD CYCLONIC FLOW AT THE SURFACE. ALTHOUGH
CLOUDY SKIES PREVAIL AHEAD OF THE WAVE IN A FAIRLY SOUPY LOW LEVEL
AIRMASS...FORCING AND MOISTURE DEPTH HAVE NOT BEEN SUFFICIENT ENOUGH
FOR ANY PRECIP. SKIES HAVE CLEARED ACROSS ALL OF MINNESOTA AND FAR
NORTHWEST WISCONSIN BEHIND THE SHORTWAVE THIS AFTERNOON AS RIDGING
BUILDS INTO THE REGION. FORECAST CONCERNS OVER THE NEXT 24 HOURS
INCLUDE CLOUD TRENDS AND FOG POTENTIAL TONIGHT.
TONIGHT...THE SHORTWAVE TROUGH WILL CONTINUE TO SLOWLY PASS ACROSS
THE AREA DURING THE EVENING BEFORE EXITING AFTER MIDNIGHT. WILL SEE
DECREASING CLOUD COVER AS THIS OCCURS...WHILE BROAD LOW LEVEL
CYCLONIC FLOW GETS REPLACED BY AN INCOMING WEAK RIDGE AXIS. A DRIER
LOW LEVEL AIRMASS WILL FILTER INTO THE STATE FROM THE WEST AND
WILL EAT AWAY AT THE JUICY AIR IN PLACE CURRENTLY. WITH CLEARING
SKIES...LIGHT WINDS...AND A REASONABLY MOIST BOUNDARY LAYER...EXPECT
TO SEE SOME RADIATIONAL FOG TOMORROW MORNING. BEST CHANCES WILL
APPEAR TO BE ACROSS THE HIGHER TERRAIN OF N-C WISCONSIN...WHERE
CLEARING WILL ARRIVE FIRST. LOOKING UPSTREAM LAST NIGHT...THERE WAS
SOME PATCHY DENSE FOG ACROSS NORTHERN MINNESOTA...ESPECIALLY WITHIN
LOW LYING VALLEYS. CROSS-OVER TEMPS UPSTREAM APPEAR TO BE AROUND
30F OR IN THE LOWER 30S...SO THOSE AREAS WHERE MIN TEMPS FALL BELOW
THIS THRESHOLD WILL BE MORE SUSCEPTIBLE TO FOG. AS A RESULT...WILL
BEEF UP FOG WORDING ACROSS N-C WISCONSIN TO AREAS...BUT KEEP PATCHY
ELSEWHERE WHERE TEMPS WILL ONLY FALL INTO THE THE LOW TO MID 30S.
TOMORROW...A QUIET DAY TOMORROW ONCE THE FOG BURNS OFF BY
MID-MORNING DUE TO THE PRESENCE OF RIDGING THROUGH THE COLUMN. A
LACK OF CLOUD COVER UPSTREAM SUGGESTS A MOSTLY SUNNY DAY. 925MB
TEMPS AROUND 6C WILL YIELD HIGHS IN THE LOW TO MID 50S.
.LONG TERM...SATURDAY NIGHT THROUGH NEXT FRIDAY.
MEDIUM RANGE MODEL SOLUTIONS ONCE AGAIN STARTED DOING THEIR OWN
THING BY EARLY NEXT WEEK. THIS ONCE AGAIN LED TO HPC GUIDANCE
BEING FOLLOWED MORE CLOSELY THAN ANY OF THE 12Z MODEL RUNS. RAIN
CHANCES WERE CONFINED TO THE WESTERN PART OF THE FORECAST AREA
SUNDAY NIGHT...AHEAD OF AN APPROACHING COLD FRONT. PRECIPITATION
CHANCES CONTINUED INTO WEDNESDAY AS THE HPC MANUAL SURFACE PROG
BROUGHT A LOW THROUGH WISCONSIN. COLDER AIR IN THE WAKE OF THE
SYSTEM MADE PRECIPITATION TYPE AN ISSUE FOR TUESDAY NIGHT AND
WEDNESDAY SO BOTH RAIN AND SNOW WERE MENTIONED FOR THOSE PERIODS.
LAKE EFFECT APPEARED TO BE A POSSIBILITY ACROSS THE EXTREME NORTH
AND NORTHEAST STARTING THURSDAY...AS DELTA TS...LAKE SURFACE TO
850MB...INCREASE. OTHERWISE ONLY WENT WITH SOME SLIGHT CHANCE POPS
ACROSS THE AREA. MADE A GOOD FAITH EFFORT TO BLEND WELL WITH
SURROUNDING FORECAST GRIDS.
DID NOT MAKE MAJOR CHANGES TO HIGH OR LOW TEMPERATURES.
&&
.AVIATION...MVFR VSBYS WILL IMPROVE TO VFR THIS AFTERNOON AND EARLY
THIS EVENING AS SKIES WILL SEE A GRADUAL CLEARING TREND. WILL SEE
RADIATIONAL FOG DEVELOP TONIGHT WITH THE BIGGEST IMPACT EXPECTED AT
RHI TOMORROW MORNING WHERE LIFR VSBYS (OR POSSIBLY LOWER) ARE
POSSIBLE. A LITTLE MORE UNCERTAINTY EXISTS AT AUW/CWA/GRB AS ITS
TOUGH TO GAUGE HOW MUCH DRY AIR IN THE LOW LEVELS WILL ARRIVE
TONITE. THINK THAT AT LEAST IFR VSBYS ARE POSSIBLE AT AUW/CWA AND
MVFR AT GRB. WILL LET THE EVENING CREW MONITOR TRENDS AND ADJUST.
ONCE ANY FOG BURNS OFF BY MID-MORNING TOMORROW...VFR CONDITIONS WILL
PREVAIL THROUGH THE REST OF THE DAY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MPC/MG
000
FXUS63 KARX 202058
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
258 PM CST FRI NOV 20 2009
.SHORT TERM...TONIGHT THROUGH MONDAY NIGHT
BIGGEST FORECAST CONCERN IS ON DEGREE OF SATURATION LATE SATURDAY
NIGHT AND CORRESPONDING RAIN/DRIZZLE CHANCES...WITH RAIN CHANCES
SUNDAY THROUGH MONDAY NIGHT.
DATA ANALYSIS AT 19Z SHOWS HIGH PRESSURE LOCATED OVER KANSAS...WITH
CLEAR SKIES EXTENDING FROM THE SOUTHERN PLAINS INTO SOUTHERN CANADA.
LINGERING MID LEVEL CLOUDS PERSIST OVER MUCH OF THE FORECAST AREA...
WITH THE SLOW MOVING BACK EDGE OVER SOUTHEAST MINNESOTA.
BIGGEST DIFFERENCE IN THE 20.12Z MODELS ARE SATURDAY NIGHT AS GFS
CONTINUES TO GENERATE QPF ACROSS IOWA INTO MINNESOTA...WHILE NAM
REMAINS DRY. OTHERWISE MODELS APPEAR IN REASONABLE AGREEMENT.
IN THE NEAR TERM...UPPER LEVEL RIDGE AND SURFACE HIGH PRESSURE WILL
DOMINATE THE WEATHER INTO SATURDAY. MODELS CONSISTENT IN CLEARING
CLOUDS OUT OF THE AREA THIS EVENING. THUS EXPECTING A MOSTLY CLEAR
NIGHT WITH LIGHT WINDS. SURFACE OBSERVATIONS AND MODEL SOUNDINGS
INDICATING RESIDUAL LOW LEVEL MOISTURE OVER THE AREA. WITH THE
LIGHT WINDS AND CLEAR SKIES WILL LIKELY SEE SOME FOG FORMATION LATE
TONIGHT AN THUS HAVE ADDED THIS TO THE GRIDDED DATABASE. QUIET/SUNNY
AND MILD WEATHER ON TAP FOR SATURDAY AS HIGH PUSHES EAST AND
SOUTHERLY WINDS RETURN TO THE AREA.
WITH THE SOUTHERLY FLOW INCREASING SATURDAY NIGHT...MODELS
INDICATING LOW LEVEL SATURATION BEGINNING TO OCCUR AFTER MIDNIGHT.
BOTH THE NAM AND GFS INDICATING SOME WEAK LIFT THROUGH THE SATURATED
LAYER AND THUS HAVE CONTINUED THE MENTION OF DRIZZLE AFTER 09Z.
OTHERWISE COLUMN CONTINUES TO SATURATE SUNDAY/SUNDAY NIGHT IN MOIST
SOUTHERLY FLOW WITH WEAK WARM ADVECTION/ISENTROPIC LIFT AHEAD OF AN
APPROACHING TROUGH. ENOUGH LIFT GENERATED FOR LOWER END RAIN
PROBABILITIES AREA-WIDE...WITH SLIGHTLY BETTER CHANCES ACROSS THE
WESTERN COUNTIES.
ON MONDAY/MONDAY NIGHT...TROUGH DIGS OVER THE ROCKIES WITH WEAK
SHORTWAVE BEING EJECTED NORTHWARD TOWARD THE AREA. WITH CONTINUED
MOIST SOUTHERLY FLOW AND WEAK LIFT AHEAD OF THE DEEPENING TROUGH
WILL CONTINUE MID-LOW CHANCE RAIN PROBABILITIES.
TEMPERATURES LOOK TO REMAIN MILD THROUGH THE PERIOD AVERAGING SOME
10 TO 15 DEGREES ABOVE NORMAL THROUGH MONDAY. GUIDANCE VALUES LOOK
REASONABLE AD NOT MUCH DEVIATION FROM THEM OR PREVIOUS FORECAST.
.LONG TERM...TUESDAY THROUGH FRIDAY
MEDIUM RANGE MODELS IN BETTER AGREEMENT WITH THEIR LATEST
RUNS. 20.06Z GFS IS THE OUTLIER WITH THE WEAKER AND FASTER SOLUTION
IN HANDLING THE TROUGH/SURFACE AND MID LEVEL FEATURES...WHILE THE GEM
HAS COME AROUND TO THE ECMWF SOLUTION. HOWEVER...WITH THE
20.12Z GFS RUN IT IS COMING MORE IN-LINE WITH THE ECMWF/GEM
SOLUTIONS. PREFERENCE WAS THE BETTER CLUSTERING OF THE ECMWF/GEM.
PATTERN WILL BE DOMINATED BY LONGWAVE TROUGH ACROSS THE CENTRAL CONUS
AT THE BEGINNING OF THE PERIOD...WITH CLOSED MID LEVEL LOW OVER IOWA.
THIS FEATURE WILL THEN LIFT NORTHEAST THROUGH THE UPPER MISSISSIPPI
RIVER VALLEY REGION TUESDAY AND TUESDAY NIGHT...WITH A SECONDARY WAVE
DROPPING ACROSS THE AREA WEDNESDAY AND WEDNESDAY NIGHT...KEEPING
TROUGH FIRMLY ENTRENCHED ACROSS THE AREA. SOUNDINGS FROM THE ECMWF
SHOWING 5000 FOOT SURFACE WARM LAYER TUESDAY ACROSS MUCH OF THE AREA
AND THUS EXPECT MAINLY RAIN. AS COLUMN COOLS TUESDAY NIGHT AND
WEDNESDAY WILL CONTINUE TO MENTION RAIN/SNOW POSSIBILITIES. WRAP
AROUND MOISTURE WITH CYCLONIC FLOW WILL KEEP LOWER END PRECIPITATION
CHANCES WEDNESDAY NIGHT...WITH ENOUGH COLDER AIR TO RESULT IN ALL
SNOW.
TROUGH TRANSLATES INTO THE EASTERN CONUS THURSDAY AND FRIDAY AS
RIDGE BUILDS ACROSS THE CENTRAL CONUS. THUS EXPECT RISING HEIGHTS
AND QUIET WEATHER.
ABOVE NORMAL TEMPERATURES AT THE BEGINNING OF THE PERIOD WILL FALL
BACK TO NEAR OR SLIGHTLY BELOW FROM WEDNESDAY THROUGH FRIDAY.
ALL IN ALL THE SYSTEM TUESDAY/TUESDAY NIGHT BEARS WATCHING. IF
MORE COLDER AIR GETS WRAPPED INTO THE SYSTEM ACCUMULATING SNOW IS NOT
OUT OF THE QUESTION FOR PARTS OF THE AREA.
&&
.AVIATION...
A MID-LEVEL SHORTWAVE TROUGH PUSHED ACROSS THE REGION DURING THE DAY
FRIDAY WHICH HAD A BROKEN VFR CLOUD DECK SITUATED ACROSS THE AREA.
THE CLOUDS WILL PUSH EASTWARD AS RIDGING BUILDS IN THROUGH THE
REMAINDER OF THE DAY. BEHIND THESE CLOUDS...THE AIRMASS IS QUITE DRY
THEREFORE...EXPECTING CLEAR SKIES INTO SATURDAY AFTERNOON. SOUNDINGS
AND TIME/HEIGHT CROSS-SECTIONS FROM THE NAM ARE INDICATING
SATURATION IN THE BOUNDARY LAYER WITH GOOD RADIATIONAL COOLING AND
LIGHT WINDS SO FOG FORMATION IS OF CONCERN LATE TONIGHT AND EARLY
SATURDAY MORNING. RETURN FLOW ON THE BACK-SIDE OF THE HIGH MAY START
TO BECOME MORE APPARENT ACROSS MINNESOTA/IOWA OVERNIGHT BUT DON/T
THINK WINDS WILL COME UP ENOUGH AT KRST TO COMPLETELY KEEP FROM
HAVING ANY VISIBILITY RESTRICTIONS. CONTINUED THE TREND FROM THE
PREVIOUS FORECAST OF LOWERING VISIBILITIES...HOWEVER IF CONFIDENCE
INCREASES...IFR VISIBILITIES DON/T LOOK TO BE OUT OF THE REALM OF
POSSIBILITY FOR THE MORNING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT/LONG TERM...RABERDING
AVIATION...JLB
000
FXUS63 KMKX 202024
AFDMKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
224 PM CST FRI NOV 20 2009
.TONIGHT...GOOD LOOKING MID LEVEL SHORT WAVE TRACKS SLOWLY THROUGH
THE CWA OVERNIGHT. THE COLUMN IS DRY OVERALL WITH ASSOCIATED CLOUD
BASES RELATIVELY HIGH THIS AFTERNOON. RADAR IS SHOWING SOME
ELEVATED RETURNS AND SATELLITE SHOWS A RATHER BUMPY MID AND HIGH
LEVEL CLOUD FIELD. COULD HAVE SOME SHALLOW VIRGA OUT THERE BUT
NOTHING IS EXPECTED TO REACH THE GROUND. CLEARING SHOULD BE SLOW.
BUT ONCE IT DOES CLEAR...THE FLOW WILL BE WEAK THROUGH A DEEP
LAYER. LATE TONIGHT WINDS UP THROUGH H6 DON/T GET ABOVE 10KTS AND
THE BNDRY LAYER SHOULD DECOUPLE TO CALM. DWPNTS STILL A BIT
ELEVATED AND WITH GOOD RADITIONAL COOLING AFTER CLOUDS MOVE
OUT...WOULD EXPECT AREAS OF FOG TO DEVELOP. THE EAST AND FAR NORTH
MAY STAY PATCHY IN COVERAGE DUE TO MORE CLOUDS LINGERING LATER.
.THIS WEEKEND...ONCE THE S/W EXITS...MID LEVEL RIDGING TAKES OVER
AND KEEPS THE AREA DRY AND MILD. ABOVE NORMAL HIGHS IN THE LOWER TO
MID 50S WITH SUNSHINE EXPECTED FROM TIME TO TIME...ESPECIALLY
EAST.
.EARLY NEXT WEEK...BY LATE IN THE WEEKEND INTO EARLY NEXT WEEK...A
LARGE SCALE TROUGH BEGINS TO DIG INTO THE MIDDLE OF THE COUNTRY.
THE NAM AND GFS SHOW AN AREA OF WAA IN THE RETURN FLOW THAT COULD
GENERATE SOME LIGHT QPF JUST WEST OF THE CWA SUNDAY AFTERNOON AND
SUNDAY NIGHT. ON MONDAY...THERE IS DISAGREEMENT BETWEEN THE NAM
AND THE GFS/ECMWF. THE NAM KICKS OUT A LEADING S/W AND KEEPS IT
BACK TO THE WEST...AS AN EXTENSION OF THE LARGER PLAINS TROF. THIS
ALLOWS THE MOISTURE/PCPN TO SPREAD UP INTO THE AREA ON MONDAY. THE
ECMWF AND THE GFS...KICK THIS SHORT WAVE QUICKLY TO THE EAST AND
KEEP IT MORE OF A SEPARATE ENTITY. THEREFORE THE MOISTURE/PCPN
STAY EAST OF OUR AREA. I/LL STICK WITH THE MORE TRUSTWORTHY
GFS/ECMWF ON THIS ONE.
THE BIGGER STRUGGLE TODAY WAS DEALING WITH THE DISPARITY BETWEEN
THE GFS AND ECMWF FOR THE MIDDLE OF THE WEEK. EVENTUALLY A RATHER
STRONG LOW EJECTS OUT OF THE SOUTHERN PLAINS...OUT OF THE BASE OF
THE TROF AND TRACKS INTO THE GREAT LAKES. THE ECMWF HAS BEEN
SLOWER THAN THE GFS OVER THE LAST FEW RUNS AND IS THE MODEL OF
CHOICE BY THE HPC. THE GFS IS...AND HAS BEEN...FAST AND IS MORE
AGGRESSIVE IN PULLING DOWN COLD AIR INTO THE UPPER MIDWEST ON THE
BACK SIDE OF THE LOW. MY MONEY IS ON THE ECMWF...THIS SYSTEM WILL
BRING IN PRECIP TUESDAY THROUGH WEDNESDAY NIGHT. INITIALLY...
CONDITIONS WILL BE WARM ENOUGH TO KEEP IT ALL RAIN. COLD AIR WILL
EVENTUALLY WRAP INTO THIS LOW CHANGING THE PCPN OVER TO RAIN/SNOW
AND EVENTUALLY SNOW. BY THE TIME THIS HAPPENS...AS USUAL...THE
BULK OF THE PCPN WILL BE PULLING OUT. SO FOR NOW...NOT SEEING ANY
TYPE OF SIGNIFICANT WINTER SITUATION SETTING UP.
&&
.AVIATION...UPPER WAVE MOVING THROUGH THE STATE WILL BRING CONTINUED
VFR CLOUDS THROUGH TONIGHT...WITH DECREASING CLOUDS WEST TO EAST
EARLY TONIGHT INTO TOMORROW MORNING. LIGHT WINDS FROM WEAK PRESSURE
GRADIENT UNDER HIGH PRESSURE WILL LIKELY LEAD TO SOME FOG
DEVELOPMENT LATER TONIGHT. EXPECT MVFR VISBYS BY MIDNIGHT...WITH IFR
POSSIBLE LATER IN THE NIGHT. MOST OF THE FOG POTENTIAL WILL DEPEND
ON WHEN CLOUDS SCATTER OUT. COULD HOLD ON TO VFR VISBYS LONGER IF
CLOUDS LINGER. WILL HAVE TO KEEP AN EYE ON CLOUD TRENDS THIS
EVENING. OTHERWISE...VISBYS WILL RETURN TO VFR TOMORROW
MORNING...WITH A QUIET DAY ON SATURDAY.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
SHORT/LONG TERM...DAVIS
AVIATION/MARINE...VANCLEVE
000
FXUS63 KARX 200944
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
344 AM CST FRI NOV 20 2009
.SHORT TERM...TODAY THROUGH SUNDAY
AT 3 AM...HIGH PRESSURE STRETCHED FROM THE NORTHERN AND CENTRAL
PLAINS SOUTHEAST INTO MISSOURI. THIS HIGH CAUSED THE SKIES TO
BRIEFLY CLEAR IN MANY OF THESE AREAS AND THEN FOG DEVELOPED. A LOW
PRESSURE AREA WAS SITUATED ACROSS THE EASTERN GREAT LAKES. FURTHER
UPSTREAM...A TROUGH WAS MOVING EAST ACROSS MINNESOTA. THE
COMBINATION OF THE LOW PRESSURE SYSTEM AND THE TROUGH KEPT SKIES
GENERALLY CLOUDY ACROSS MUCH OF THE UPPER MISSISSIPPI RIVER
VALLEY.
THE 20.00Z MODELS ARE IN EXCELLENT AGREEMENT THAT THE RIDGE AXIS
WILL SLIDE ACROSS MINNESOTA AND IOWA TODAY. AS THIS OCCURS...SKIES
SHOULD CLEAR FROM WEST TO EAST ACROSS THESE AREAS LATE THIS
MORNING AND AFTERNOON. MEANWHILE THE TROUGH WILL LIKELY HELP TO
KEEP CYCLONIC FLOW ACROSS WISCONSIN THROUGH MUCH OF THE DAY. THIS
WILL LIKELY PREVENT OUR WISCONSIN COUNTIES FROM CLEARING OUT UNTIL
LATE THIS AFTERNOON OR EVENING...AND THIS MAY LEAD EVENTUALLY TO
THE DEVELOPMENT OF FOG. IN ADDITION...THE LACK OF SUNSHINE WILL
LIKELY KEEP THE TEMPERATURES ACROSS MUCH OF WISCONSIN FROM GETTING
OUT OF THE 40S TODAY. MEANWHILE LOW AND MID 50S WILL BE POSSIBLE
WEST OF THE MISSISSIPPI RIVER.
ON SATURDAY NIGHT...THE BUFKIT SOUNDINGS SHOW THAT THE OMEGA IS
SITUATED ABOVE THE MOISTURE LAYER. IN ADDITION...THE BEST
ISENTROPIC 280 TO 290K LIFT AND MOISTURE TRANSPORT REMAINS TO OUR
WEST AND NORTH. AS A RESULT...IT WAS THE CONSENSUS THIS MORNING THAT
THE RAIN CHANCES IN THE 20.00Z GFS AND ECMWF WERE OVERDONE...AND THE
RAIN CHANCES WERE EITHER TAKEN OUT OF THE GRIDS...OR REPLACED WITH
DRIZZLE /I.E. SOUTHEAST MINNESOTA AND NORTHEAST IOWA/.
ON SUNDAY...THE BUFKIT SOUNDINGS IN THE 20.00Z GFS AND NAM/WRF
SUGGEST ANYWHERE FROM 5 TO 10 MICROBARS/SECOND OF OMEGA IN THE
MOISTURE LAYER WHICH EXTENDS UP TO 10K FEET DURING THE AFTERNOON.
AS A RESULT...THE 20 TO 30 PERCENT PRECIPITATION CHANCES STILL
LOOK GOOD /ESPECIALLY WEST OF A BLACK RIVER FALLS WISCONSIN TO AN
OELWEIN IOWA LINE/.
.LONG TERM...SUNDAY NIGHT THROUGH THANKSGIVING
THE 20.00Z MODELS CONTINUE TO SHOW THAT A LOW PRESSURE SYSTEM WILL
LIKELY AFFECT THE AREA SOMEWHERE BETWEEN MONDAY NIGHT INTO
WEDNESDAY. THE GFS IS CURRENTLY ABOUT 12 HOURS SLOWER THAN THE
ECMWF AND GEM. IN ADDITION TO PRECIPITATION TIMING...THERE ARE
ALSO CONCERNS ABOUT THE POSSIBILITY THAT PARTS OF THE UPPER
MISSISSIPPI RIVER VALLEY MAY SEE SOME ACCUMULATING SNOW. DUE TO
THESE DIFFERENCES NOT MANY CHANGES WERE DONE TO THIS TIME PERIOD.
&&
.AVIATION...TODAY THROUGH TONIGHT
LOW PRESSURE THAT BROUGHT RAIN/DRIZZLE/LOW CLOUDS TO THE AREA
THURSDAY NOW OVER WESTERN LAKE HURON EARLY THIS MORNING. LINGERING
CYCLONIC FLOW ACROSS THE AREA ON THE BACKSIDE OF THE LOW THIS
MORNING WAS CONTINUING TO PRODUCE VFR STRATOCUMULUS WITH SOME LIGHT
FOG REDUCING VISIBILITIES INTO THE 3-5SM RANGE.
WITH BREAKS IN THE CLOUDS WEST OF THE MISSISSIPPI RIVER...VIS COULD
BRIEFLY DIP INTO IFR RANGE IN SPOTS...INCLUDING KRST TAF SITE.
PREVIOUS FORECASTER WAS CARRYING 1/2SM FG AT THE KRST TAF SITE FROM
12-16Z. WILL CONTINUE TO MONITOR THIS DENSER FOG POTENTIAL THROUGH
THIS MORNING.
OTHERWISE...A SURFACE RIDGE OF HIGH PRESSURE WILL BE WORKING
EASTWARD INTO THE AREA THROUGH THE REST OF THE DAY FROM THE NORTHERN
PLAINS. SUBSIDENCE/DRYING UNDER THE RIDGE IS EXPECTED TO DISPERSE
VFR STRATOCUMULUS CLOUD COVER MAINLY WEST OF THE RIVER BY 18Z TODAY.
VFR CLOUD COVER WILL BE A BIT SLOWER TO CLEAR EAST OF THE RIVER DUE
TO LINGERING CYCLONIC FLOW ALOFT. MAY HAVE TO ADJUST TAFS FOR A
SLIGHTLY SLOWER CLEARING TREND BASED ON THIS SCENARIO. WILL DIG
FURTHER INTO THE MODEL DATA AND TRY TO DISCERN FOR THE 20.12Z TAF
ISSUANCE. HIGH PRESSURE WILL DRIFT ACROSS THE AREA TONIGHT FOR
FURTHER CLEARING. WILL HAVE TO WATCH THE KLSE TAF AFTER 21.06Z FOR
FOG POTENTIAL GIVEN CLEAR SKIES/DECOUPLING WINDS IN THE RIVER
VALLEY/RATHER MOIST LOWER BOUNDARY LAYER.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT/LONG TERM...BOYNE
AVIATION...DAS
000
FXUS63 KMKX 200919
AFDMKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
319 AM CST FRI NOV 20 2009
FORECAST FOCUS ON CLOUDS/FOG/TEMPERATURES THROUGH THE
WEEKEND...PRECIPITATION CHANCES EARLY TO THE MIDDLE OF NEXT
WEEK.
LATEST WATER VAPOR IMAGERY INDICATED AN UPPER LEVEL LOW CENTERED
OVER EASTERN LOWER MICHIGAN...WITH ITS CYCLONIC CIRCULATION
EXTENDING WEST INTO EASTERN WISCONSIN. AN UPSTREAM SHORTWAVE
TROUGH/VORTICITY MAXIMUM WAS LOCATED FROM NORTHWEST MINNESOTA TO
CENTRAL SOUTH DAKOTA. AN UPPER LEVEL TROUGH WAS MOVING TOWARD THE
PACIFIC NORTHWEST COAST. AT THE SURFACE...A WEAK SURFACE LOW WAS
MOVING EAST INTO NORTHERN LAKE MICHIGAN. HIGH PRESSURE WAS LOCATED
OVER THE OHIO RIVER VALLEY.
.TODAY AND TONIGHT...LINGERING ISOLATED RAIN SHOWERS WITH THE
CYCLONIC UPPER LEVEL FLOW SHOULD DIMINISH BY SUNRISE ACROSS THE
EASTERN COUNTIES. PATCHY FOG SEEN ACROSS THE FORECAST AREA...AND
THIS SHOULD PERSIST INTO THE EARLY MORNING HOURS WITH LOW LEVEL
MOISTURE LINGERING.
SOME BREAKS IN THE LOW CLOUD SHIELD SEEN ACROSS PORTIONS OF THE
AREA AT THIS TIME. AREA FORECAST SOUNDINGS FROM THE NAM/GFS/RUC
SHOW SOME DRYING OF THE AIR COLUMN AT TIMES TODAY. WOULD EXPECT
MORE CLOUDS THAN SUNSHINE TODAY GIVEN WHAT IS OUT THERE...WITH A
GRADUAL RISE IN CEILINGS. HIGHS TODAY SHOULD ONCE AGAIN BE
MILD...WITH MAINLY LOWER 50S ACROSS THE AREA.
CLOUDS SHOULD GRADUALLY THIN OUT TONIGHT WITH DRIER AIR MOVING
INTO THE AREA. SOME MIDDLE TO HIGH CLOUDS WITH PASSING SHORTWAVE
TROUGH ARE POSSIBLE. MODELS DO SHOW LIGHT WINDS ALLOWING FOR SOME
RADIATIONAL COOLING AND A MODERATE TO STRONG TEMPERATURE INVERSION
FORMING AFTER MIDNIGHT. THIS SHOULD LEAD TO PATCHY FOG AT LEAST
ACROSS THE AREA...WITH MORE WIDESPREAD FOG POSSIBLE IN LOW LYING
AREAS.
.SATURDAY THROUGH SUNDAY...QUIET WEATHER EXPECTED SATURDAY AND
SATURDAY NIGHT ACROSS THE AREA...WITH INFLUENCE OF HIGH PRESSURE
TO THE EAST OF THE REGION. DO EXPECT ANOTHER ROUND OF PATCHY FOG
SATURDAY NIGHT INTO EARLY SUNDAY MORNING...WITH LIGHT WINDS AND
SOME CLEARING. MILD TEMPERATURES SHOULD CONTINUE...WITH HIGHS IN
THE LOWER TO MID 50S ON SATURDAY.
ECMWF AND GFS HAVE BOTH BACKED OFF ON PRECIPITATION ON SUNDAY.
THEY KEEP THE MAIN RAIN AREA TO THE WEST AND NORTHWEST OF THE
FORECAST AREA. AREA FORECAST SOUNDINGS ARE QUITE DRY FOR THIS
PERIOD. HAVE TRIMMED POPS BACK TO JUST THE FAR WESTERN COUNTIES.
TEMPERATURES WILL CONTINUE TO BE ON THE MILD SIDE.
.SUNDAY NIGHT THROUGH THURSDAY...FOLLOWED THE ECMWF/CANADIAN
MODELS FOR THIS FORECAST PERIOD. THEY BOTH SHOW STRONG CYCLOGENESIS
OVER THE CENTRAL PLAINS ON MONDAY NIGHT...THEN MOVE THE SURFACE
AND UPPER LOW NORTHEAST THROUGH THE REGION THROUGH WEDNESDAY
NIGHT. GOOD UPWARD VERTICAL MOTION FIELDS SEEN WITH THIS SYSTEM.
IF THIS SCENARIO PLAYS OUT...SUNDAY NIGHT THROUGH MONDAY NIGHT
COULD END UP DRY...AS BEST UPWARD VERTICAL MOTION REMAINS TO THE
SOUTHWEST. FOR NOW...TRIMMED BACK POPS A BIT FOR THESE PERIODS.
THE BEST CHANCES FOR RAIN WOULD BE TUESDAY THROUGH WEDNESDAY
ACROSS THE AREA. ENOUGH COLD AIR IS BROUGHT WITH THIS SYSTEM TO
PERHAPS MIX IN SOME LIGHT SNOW WITH THE LIGHT RAIN TUESDAY NIGHT
AND WEDNESDAY. IT IS STILL TOO EARLY TO SAY IF THERE WILL BE
ACCUMULATIONS WITH ANY LIGHT SNOW THAT FALLS...BUT IT BEARS
WATCHING GIVEN ITS TIMING THE DAY BEFORE THANKSGIVING DAY.
TEMPERATURES REMAIN MILD UNTIL THE COLDER AIR WORKS IN FOR
WEDNESDAY AND BEYOND.
&&
.AVIATION...BLUE RIVER WIND PROFILER SHOWING MIXY CONDITIONS WITH
20 KT WNDS UNDER 1KM AND LATEST TAMDAR SOUNDINGS FROM KRFD CONFIRM
MIXINESS ABV 500FT. WITH LACK OF DRY AIR SURGE IN THE LOW
LEVELS...FAVOR MORE ST DEVELOPMENT THIS MRNG...HWVR ENUF LINGERING
LOW LEVEL MOISTURE TO ALLOW MOSTLY LIGHT FOG TO PERSIST INTO THE
MRNG.
CIGS SHOULD RISE IN ERN AREAS EARLY THIS MRNG AS ISENTROPIC
FORCING FURTHER WEAKENS...WITH MOST AREAS CIGS RETURNING TO VFR
LTR TODAY. LIGHT BOUNDARY LAYER WINDS WILL ALLOW MORE FOG TO
DEVELOP TNGT. POTENTIAL FOR DENSE FOG DEVELOPMENT IN THOSE AREAS
THAT CLR...ESPECIALLY IN WEST.
&&
.MARINE...EXPECT PATCHY FOG TO CONTINUE THIS MORNING AND
REDEVELOP AGAIN TONIGHT WITH LACK OF ANY SIGNIFICANT LOW LEVEL
DRYING. BOUNDARY LAYER WINDS LESS TONIGHT BELOW INVERSION ALLOWING
MORE PATCHY FOG DEVELOPMENT.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
SHORT/LONG TERM...08/WOOD
AVIATION/MARINE...11/MBK
000
FXUS63 KGRB 200911
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
311 AM CST FRI NOV 20 2009
.SHORT TERM...UPPER LOW OVER LAKE HURON WILL MOVE EAST TODAY AND
SCATTERED SHOWERS SHOULD END BY AROUND DAYBREAK. THERE IS STILL A
DECENT AMOUNT OF MOISTURE AROUND...SO DO NOT EXPECT MUCH CLEARING
UNTIL WEAK UPPER TROUGH NOW OVER MINNESOTA MOVES THROUGH THIS
EVENING. IT WILL BE MILD ONCE AGAIN DESPITE THE LACK OF MUCH
SUNSHINE...AS 925MB TEMPERATURES OF 6-8C FORECAST THIS AFTERNOON.
UPPER RIDGE AXIS APPROACHES TONIGHT...SO WINDS WILL BECOME NEARLY
CALM. THE LIGHT WINDS AND WET GROUND SHOULD PRODUCE AREAS OF FOG
LATE TONIGHT AND EARLY SATURDAY. NICE WEATHER EXPECTED SATURDAY
WITH SUNNY SKIES AND LIGHT WINDS. 925MB TEMPERATURES OF 5-6C
SHOULD MAKE FOR HIGHS AROUND 50F ONCE AGAIN.
.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY
QUIET WEATHER PATTERN EXPECTED SATURDAY NIGHT. MODELS CONTINUE
TO DEPICT LOW STRATUS DECK DEVELOPING ACROSS THE WEST LATE SATURDAY
NIGHT INTO SUNDAY MORNING. LOW TEMPERATURES TRICKY DEPENDING
ON THE GRADIENT. LATEST 00Z MEX GUIDANCE A DEGREE OR TWO COOLER
THAN THE 12Z RUN. HAVE TRENDED TEMPERATURES DOWN A DEGREE OR
TWO...ESPECIALLY OVER THE EAST. SOUTHERLY FLOW CONTINUES ON
SUNDAY. LATEST MODEL RUNS SUGGEST THE REALLY LOW CLOUDS STAY TO
THE WEST OF GREEN BAY. WILL CONTINUE THE SMALL CHANCE OF RAIN OVER
THE FAR WEST WITH TROUGH MOVING INTO THE AREA. STILL THINK THERE
IS SOME POTENTIAL FOR DRIZZLE SINCE MID LEVEL MOISTURE DOES
NOT ARRIVE UNTIL LATER IN THE DAY...BUT WILL NOT INCLUDE FOR THE
TIME BEING.
WEAK TROUGH WASHES OUT SUNDAY NIGHT INTO MONDAY AS THE LATEST
ECMWF AND CANADIAN MODELS INDICATING RIDGING ACROSS EASTERN
WISCONSIN. HAVE LOWERED PRECIPITATION CHANCES...ESPECIALLY ACROSS
THE EAST. IF THE ECMWF/CANADIAN MODELS ARE CORRECT...LATER SHIFTS
MAY BE ABLE TO REMOVE THE MENTION OF PRECIPITATION ACROSS MUCH OF
THE AREA SUNDAY NIGHT AND MONDAY AND POSSIBLY MONDAY NIGHT AS
WELL.
SIGNIFICANT DIFFERENCES BEGIN IN EARNEST WITH THE MODELS ON MONDAY.
UPPER TROUGH MOVING ACROSS THE CENTRAL UNITED STATES WILL DEVELOP
A SIGNIFICANT LOW PRESSURE SYSTEM ACROSS THE CENTRAL UNITED STATES
EARLY IN THE WEEK...THEN GRADUALLY PUSH IT EAST BY THE END OF
THE WEEK. THE GFS IS MUCH QUICKER WITH THIS SYSTEM COMPARED TO
THE ECMWF AND CANADIAN MODELS. PAST EXPERIENCE WOULD INDICATE THAT
WHEN THE ECMWF/CANADIAN AGREE THAT FAR OUT...THIS WOULD BE THE
MODEL OF CHOICE AND WOULD IGNORE THE GFS SOLUTION. SYSTEM SHOULD
START AS RAIN AND THEN BECOME MIXED WITH SNOW OR CHANGE TO SNOW
WEDNESDAY INTO THANKSGIVING DAY. THE ECMWF IS MORE BULLISH WITH
PRECIPITATION ON THANKSGIVING DAY...SO LATER SHIFTS WILL NEED TO
MONITOR THE FORECAST AND MAY NEED TO INCREASE PRECIPITATION CHANCES
FROM WHAT WE CURRENTLY ARE ADVERTISING. DECIDED NOT TO MENTION IN
THE HAZARDOUS WEATHER OUTLOOK SINCE TIMING AND DETAILS ARE STILL
VERY SKETCHY. IF THE ECMWF AND CANADIAN AGREE AGAIN ON THE 00Z RUN
TONIGHT...CONFIDENCE WILL BE HIGH ENOUGH TO MENTION A SYSTEM THAT
COULD IMPACT THANKSGIVING TRAVEL. WILL NOT GET TO SPECIFIC UNTIL
THE MODELS SORT OF THE DETAILS ONCE WE GET CLOSER TO THE EVENT.
&&
.AVIATION...MVFR CIGS/VSBYS SHOULD IMPROVE TO VFR BY AFTERNOON AS
UPPER LOW MOVES AWAY AND SLIGHTLY DRIER AIR ARRIVES FROM THE WEST.
PARTIAL CLEARING TONIGHT SHOULD ALLOW FOR AREAS OF DENSE FOG LATE
TONIGHT. IFR/LIFR POSSIBLE AWAY FROM THE LAKE AND BAY BETWEEN 08Z-
13Z. ANY FOG SHOULD DISSIPATE BY 15Z SATURDAY WITH VFR AFTERWARDS.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
RDM/ECKBERG
000
FXUS63 KARX 200028 AAA
AFDARX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LA CROSSE WI
627 PM CST THU NOV 19 2009
UPDATED AVIATION DISCUSSION
.SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT
FORECAST CONCERNS THIS PERIOD DEAL WITH EXITING LOW PRESSURE
SYSTEM...RAIN TONIGHT THEN CLOUD COVER INTO THE WEEKEND.
RADAR LOOP AT 20Z SHOWED ENHANCED AREA OF RAIN ACROSS CENTRAL
WISCONSIN SPINNING AROUND THE SURFACE LOW PRESSURE SYSTEM...LOCATED
OVER NORTHEAST WISCONSIN/UPPER MICHIGAN. WATER VAPOR IMAGERY
SHOWED THE UPPER LOW A BIT DISPLACED FROM THE SURFACE
FEATURES...CENTERED OVER EASTERN WISCONSIN/LAKE MICHIGAN.
THE RAIN SEEN OVER WISCONSIN THIS AFTERNOON WAS IN AN AREA OF
WEAK ISENTROPIC UPGLIDE ON THE 290K SURFACE/WEAK FRONTOGENESIS IN THE
800-700MB LAYER SPINNING AROUND THE LOW. THE UPPER LOW WILL PICK
UP SPEED AND SHIFT EAST TONIGHT ACROSS MICHIGAN WHILE THE SURFACE
LOW WEAKENS. THE ISENTROPIC UPGLIDE/FRONTOGENESIS WEAKENS AS THE
WHOLE SYSTEM PUSHES EAST SO EXPECTING THE RAIN TO ALSO SHIFT EAST
INTO THE EVENING HOURS AND COMPLETELY EXIT THE FORECAST AREA BY
MIDNIGHT. CLOUDS MAY BE A BIT TROUBLESOME AS SOME LARGE BREAKS
HAVE BEEN SEEN THROUGH THURSDAY AFTERNOON...MAINLY ON THE WESTERN
SIDE OF THE CLOUD SHIELD. AT LEAST SOME OF THIS SHOULD FILL IN
WITH LOSS OF DAYTIME HEATING SO STILL EXPECTING A CLOUDY NIGHT.
ALSO...DID ADD PATCHY FOG INTO THE OVERNIGHT AND EARLY MORNING
HOURS FRIDAY WITH WEAK RIDGING IN PLACE/LIGHT WINDS AND PLENTY OF
BOUNDARY LAYER MOISTURE.
A WEAK MID-LEVEL SHORTWAVE WILL PUSH ACROSS THE FORECAST AREA ON
FRIDAY...BUT FROM LOOKING AT SOUNDINGS/TIME-HEIGHT CROSS-SECTIONS
AND FROM CURRENT DATA FROM UPSTREAM...THINKING THAT WEATHER
EFFECTS WILL ONLY BE SOME INCREASED CLOUD COVER WITH THIS PASSING
WAVE. THERE SHOULD BE PEAKS OF SUNSHINE THROUGH THE DAY...AND WITH
925MB TEMPERATURES APPROACHING 7C...TEMPERATURES RISING INTO THE
50S LOOKS GOOD FOR FRIDAY.
THEN MID AND UPPER LEVEL RIDGING WILL BUILD IN FOR FRIDAY NIGHT
AND SATURDAY...WITH A CLEARING TREND IN SKY COVER EXPECTED. WILL
ALSO BE SEEING WARM AIR ADVECTION THROUGH THIS TIME FRAME WITH
UPPER LEVEL TROUGH MOVING ACROSS THE ROCKIES WITH ASSOCIATED SURFACE
LOW PRESSURE SYSTEM DEVELOPING OVER THE PLAINS ON SATURDAY. THUS
WILL KEEP THE ABOVE NORMAL TEMPERATURES THROUGH SATURDAY NIGHT.
.LONG TERM...SUNDAY THROUGH WEDNESDAY
RAIN CHANCES FOR SUNDAY BEGIN THIS PERIOD OF THE FORECAST WITH A
SHORTWAVE TROUGH MOVING ACROSS THE PLAINS AND INTO THE UPPER
MISSISSIPPI RIVER VALLEY REGION. 19.00Z DETERMINISTIC MODELS
SHOWING SOME WEAK TO MODERATE CONVERGENCE/UPWARD MOTION AHEAD OF
THIS WAVE. ALSO DECENT MOISTURE IN THE LOWER LEVELS AND SOME WEAK
ISENTROPIC LIFT ASSOCIATED WITH IT. PRECIPITATION CHANCES STILL
LOOK GOOD FOR THIS TIME FRAME...ALTHOUGH FORCING FIELDS LOOK TO BE
WEAKENING A BIT THROUGH THIS PERIOD. BEYOND SUNDAY THOUGH MODEL
DIVERGENCE BECOMES VERY APPARENT WITH ANOTHER STRONGER SHORTWAVE
TROUGH MOVING ACROSS THE ROCKIES AND INTO THE CENTRAL CONUS FOR
MONDAY THROUGH WEDNESDAY. GFS/GFE ENSEMBLE MEAN COME IN WITH
FASTER SOLUTIONS...BRINGING THE TROUGH/SURFACE LOW THROUGH MUCH OF
THE REGION BY TUESDAY NIGHT. ECMWF SITTING THE MIDDLE OF THE ROAD
WHILE THE CANADIAN IS SLOWEST...KEEPING THE SYSTEM SOUTH OF THE
REGION THROUGH TUESDAY NIGHT/WEDNESDAY. ALTHOUGH PRECIPITATION
CHANCES LOOK TO GOOD WITH THE SYSTEM COMING THROUGH AT SOME POINT
DURING THIS TIME PERIOD...SPEED DIFFERENCES IN THIS SYSTEM BRING
ABOUT QUESTIONS OF PRECIPITATION TYPE. FASTER SOLUTIONS BRING IN THE
COLDER AIR AND THEREFORE MIXED RAIN/SNOW EARLIER ON. MORAL IS...HAVE
DECENT CONFIDENCE ON A SYSTEM MOVING THROUGH THE AREA SOMETIME FROM
MONDAY THROUGH WEDNESDAY...HOWEVER CONFIDENCE ON WHEN IT WILL HAPPEN
AND DETAILS OF THE FORECAST IN THIS PERIOD ARE QUITE LOW AND WILL
STICK CLOSE TO HPC GUIDANCE/KEEPING CONSISTENCY WITH PREVIOUS
FORECAST.
&&
.AVIATION...TONIGHT AND FRIDAY
TRICKY FORECAST FOR BOTH TAF SITES BEFORE 18Z FRIDAY. ABUNDANT
STRATUS EXISTS ACROSS MUCH OF WISCONSIN AND MINNESOTA...IN THE WAKE
OF A SURFACE LOW IN UPPER MICHIGAN. THIS STRATUS HAS CEILINGS OF
EITHER MVFR OR VFR. AT KRST...CEILINGS HAVE BEEN VFR FOR THE PAST
FEW HOURS WHILE KLSE HAS SOLIDLY STAYED AT MVFR. SOME MVFR BR EXISTS
AS WELL...MAINLY AT KLSE. THIS EVENING...WESTERLY WINDS ARE PROGGED
BY MODELS TO INCREASE TO 15 TO 20 KT JUST OFF THE SURFACE...WHICH
ONE WOULD THINK WOULD BE ENOUGH TO KEEP CEILINGS AT OR ABOVE MVFR.
IF IT WERE NOT FOR THE WIND ABOVE THE SURFACE...THE RECENT -RA/-DZ
AND RELATIVELY HIGH DEWPOINTS ALONG WITH NIGHTTIME COOLING COULD
RESULT IN VERY LOW STRATUS. HAVE ADJUSTED THE PREVIOUS FORECAST TO
GO WITH MUCH HIGHER CEILINGS AT KRST. KLSE OVERALL STILL LOOKED
GOOD. AS FOR VISIBILITIES...THEY SHOULD STAY AT OR ABOVE MVFR AT
BOTH TAF SITES THROUGH THE NIGHT. AROUND 12Z...SUGGESTIONS ARE THAT
THE WINDS ABOVE THE SURFACE WILL DIMINISH...SO HAVE FORECAST IFR BR
TO DEVELOP AT KRST. MODEL STATISTICAL GUIDANCE SUGGESTS EVEN VLIFR
FOG AT KRST...SOMETHING DEFINITELY TO WATCH. OTHERWISE...DAYTIME
HEATING AND AN INFLUX OF LOW LEVEL DRY AIR LATER FRIDAY MORNING
SHOULD HELP CONDITIONS GO TO VFR. A LOW PRESSURE TROUGH APPROACHING
THE TAF SITES IN THE AFTERNOON IS ONLY EXPECTED TO BRING SOME
ALTOSTRATUS WITH IT.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT/LONG TERM...BROOKS
AVIATION...AJ
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