Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 210244
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
944 PM CDT MON OCT 20 2014

UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE

.UPDATE...
ISSUED AT 930 PM CDT MON OCT 20 2014

OBSERVATIONS OVER THE NORTH CONTINUE TO REPORT SHOWERS THIS
EVENING. WILL EXPAND THE TIME PERIOD OF SHOWERS AND SPRINKLES
ACROSS THE AREA THIS EVENING AND OVERNIGHT AS AREA RADARS CONTINUE
TO SHOW WEAK RETURNS DRIFTING SOUTHWARD.  IN ADDITION CLOUD
TRENDS ALSO SUGGEST A LESS CHANCE OF A CLEARING TREND OVERNIGHT.
&&

.SHORT TERM...TONIGHT AND TUESDAY
ISSUED AT 314 PM CDT MON OCT 20 2014

CLOUD TRENDS AND THEIR IMPACT ON TEMPERATURES ARE THE PRIMARY
CONCERNS THROUGH TUESDAY.

CYCLONIC FLOW OF COLDER AIR BROUGHT PLENTY OF CLOUDS INTO THE
FORECAST AREA TODAY...AND THERE WAS SOME LIGHT RAIN AND DRIZZLE
ACROSS PARTS OF NORTH CENTRAL WISCONSIN. THE PRECIPITATION IS IN
THE AREA WHERE SOME OF THE 12Z MODELS FROM SUNDAY WERE SHOWING QPF.
A LOOK AT THE 925MB TEMPERATURES FROM 12Z SOUNDINGS AT
KINL...4C...AND CWPL...-2C...AND SURFACE TEMPERATURES OF LAKE
SUPERIOR...AROUND 9C...SHOWED LAKE SURFACE TO 925MB DELTA T VALUES
OF 5 TO 11C. SO LAPSE RATES WERE STEEP ENOUGH FOR LAKE EFFECT
PRECIPITATION...BUT INVERSION HEIGHTS WERE TOO LOW FOR ANYTHING
SIGNIFICANT. 12Z MODEL RUNS HAD QPF NEAR THE UPPER MICHIGAN
BORDER TODAY...BUT NOTHING AFTER 00Z TUESDAY SO NO POPS IN THE
FORECAST TONIGHT.

BUFKIT TIME/HEIGHT PLOTS FROM THE 12Z NAM/12Z GFS/09Z SREF HAD
PLENTY OF MOISTURE BELOW ABOUT 5000FT FOR MUCH THE PERIOD. IT
APPEARS THAT CLOUDS SHOULD CLEAR OUT TUESDAY AFTERNOON IN MOST
LOCATIONS AS THE SURFACE HIGH AND AN APPROACHING MID LEVEL RIDGE
BECOME THE MAIN INFLUENCE ON OUR WEATHER. THE CANADIAN CLOUD FORECAST
FROM THE GEM-REG HAD CLOUDS STARTING TO CLEAR OUT OF MOST OF THE
FORECAST AREA...STARTING IN CENTRAL WISCONSIN THIS EVENING. WINDS
AT 925MB ARE FORECAST TO BECOME MORE NORTHEAST OVERNIGHT INTO
TUESDAY...SO THE CLOUDS THAT THE CANADIAN HAS MOVING IN FROM THE
EAST MAKE SENSE.

HAVE THE CLEARING MAINLY AFTER 06Z TUESDAY BUT THINK THERE WILL
BE ENOUGH WIND TO KEEP TEMPERATURES FROM TANKING. CLOUDS EXPECTED
TO BE MAINLY IN THE EAST ON TUESDAY DURING THE MORNING OTHERWISE
THERE SHOULD BE PLENTY OF SUNSHINE. AM A LITTLE CONCERNED THAT
THERE COULD BE SOME LAKE EFFECT RAIN OR DRIZZLE IN THE EAST ALONG
WITH THE CLOUDS BUT HAVE LEFT THAT OUT FOR NOW. THE COLDER AIR
MASS WILL RESULT IN LOWER HIGH TEMPERATURES THAN TODAY.

.LONG TERM...TUESDAY NIGHT THROUGH MONDAY
ISSUED AT 314 PM CDT MON OCT 20 2014

PCPN CHANCES FROM LATE WEDS NGT THROUGH THU EVG...AND WARMER
TEMPERATURES FOR THE REST OF THE EXTENDED PERIOD...ARE THE MAIN
FCST CONCERNS.

HIGH PRESSURE...LIGHT WINDS...CLEAR SKIES AND A VERY DRY AIR
MASS (PWATS AT OR BLO 0.25 INCH) WILL LEAD TO COOL CONDITIONS
ON TUESDAY NIGHT. HAVE LOWERED MIN TEMPS SEVERAL DEGREES...WITH
MOST PLACES EXPECTED TO DROP INTO THE 20S AND LOWER 30S. 1000-850
MB AVERAGE MIXING RATIOS OF 2-2.5 G/KG SUGGEST THAT A FEW OF THE
TYPICAL COLD SPOTS COULD GET INTO THE UPPER TEENS...BUT DIDN`T
GO QUITE THAT COLD. ON WEDNESDAY...SUNNY CONDITIONS SHOULD
ALLOW AFTERNOON HIGHS TO REACH NORMAL READINGS IN THE LOWER TO
MIDDLE 50S.

AS THE SFC HIGH SHIFTS EAST ON WEDS NGT AND THURSDAY...SOUTHERLY
WINDS WILL GRADUALLY BRING A MORE MOIST AIR MASS INTO WI...WITH
PWATS RISING TO 0.75 TO 1.00 INCH ON THU/THU NGT. AN UPPER LEVEL
TROF WILL MOVE INTO WSTRN MN LATE WED NGT...THEN ACROSS GRB CWA
LATE THURSDAY AFTERNOON AND EVG. WILL KEEP MOST OF THE PCPN WEST
OF THE FORECAST WED NGT...THEN SPREAD CHC POPS FROM WEST TO EAST
THURSDAY AND THURSDAY EVG. SUSPECT THAT MOST LOCATIONS WILL
RECEIVE LESS THAN A TENTH OF AN INCH OF RAIN FROM THIS SYSTEM.

ZONAL FLOW ALOFT IS EXPECT FROM FRIDAY THROUGH SUNDAY...WITH
DRY AND MILD CONDITIONS ANTICIPATED THROUGH THE PERIOD. ABOVE
TO MUCH ABOVE NORMAL TEMPERATURES LOOK LIKE A GOOD BET...SO
HAVE RAISED MAX TEMPS 2-3 DEGREES ABOVE THE PREVIOUS FCST AND
THE EXTENDED MODEL BLEND. ADDITIONAL UPWARD ADJUSTMENTS MAY
BE NEEDED...WITH POTENTIAL FOR OUR WARM SPOTS IN C WI GETTING
TO AROUND 70 DEGREES ON SUN/MON.

AN UPPER TROF WILL MOVE INTO THE PLAINS SUNDAY NIGHT AND
MONDAY...CAUSING A SFC LOW TO DEVELOP AND TRACK NE TOWARD
LAKE SUPERIOR. THIS SYSTEM MAY BRING A CHANCE OF SHOWERS AND
ISOLD TSTMS TO OUR NW COUNTIES SUNDAY NIGHT...AND TO THE ENTIRE
FORECAST AREA ON MONDAY/MONDAY NIGHT. CONTINUED MILD CONDITIONS
ARE EXPECTED AHEAD OF THE APPROACHING COLD FRONT.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 944 PM CDT MON OCT 20 2014

BKN-OVC CLOUDS LATE THIS EVENING RANGED FROM MVFR LEVELS OVER
NORTH CENTRAL WISCONSIN TO A LOWER END VFR CIG OVER CENTRAL AND
EAST CENTRAL WISCONSIN. WHILE POCKETS OF CLEAR SKIES WILL DEVELOP
TONIGHT...IMPROVEMENT EXPECTED TO BE LATE TONIGHT FROM NORTH TO
SOUTH AS DRIER AIR WORKS INTO THE AREA FROM THE NORTH. SAT IMAGERY
SHOWS A DECREASING CLOUD AREA WORKING OVER LAKE SUPERIOR AND MY
BEGIN TO REACH FAR NORTH CENTRAL WISCONSIN STARTING AROUND 07Z.
ISOLATED SPRINKLES OR LIGHT SHOWERS WILL LINGER THIS EVENING AND
OVERNIGHT AS WELL. CONTINUED FEED OF DRIER AIR WITH A HIGH PRESSURE
RIDGE BUILDING INTO THE STATE FROM THE WEST WILL PRODUCE VFR
CONDITIONS TUESDAY...WITH THE EXCEPTION OF LINGERING MVFR OR LOW
VFR CIGS TOWARD LAKE MICHIGAN OR EASTERN WISCONSIN.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE.........TDH
SHORT TERM.....MG
LONG TERM......KIECKBUSCH
AVIATION.......TDH





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