Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 230439
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1139 PM CDT SUN MAR 22 2015

UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE

.UPDATE...
ISSUED AT 808 PM CDT SUN MAR 22 2015

RADARS THIS EVENING SHOW A STRONG FGEN BAND OF SNOW FROM CENTRAL
MINNESOTA TO SOUTHWEST WISCONSIN TO NORTHERN ILLINOIS. SHORT WAVE
OVER SOUTHEAST MINNESOTA ALONG THIS BAND WILL PRODUCE A SWATH OF
HEAVY SNOW WITH IT ALONG WITH THE BAND ITSELF. QUESTION FOR
CENTRAL WISCONSIN IS HOW MUCH SNOW ACCUMULATION WILL REACH THE
AREA. DRY FEED OF AIR CONTINUES TO ERODE OR HOLD OF WESTERN
ADVANCEMENT OF SNOW INTO CENTRAL WISCONSIN. HAVE ALREADY DELAYED
ARRIVAL A BIT THROUGH EARLY EVENING. BUT STILL OVERALL THEME OF A
MINOR ACCUMULATION FOR AREAS SOUTHWEST OF A LINE FROM MFI TO OSH
LOOKS REASONABLE FOR TONIGHT SO LITTLE CHANGES LIKELY NEEDED REST
OF TONIGHT.
&&

.SHORT TERM...TONIGHT AND MONDAY
ISSUED AT 244 PM CDT SUN MAR 22 2015

THE LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW LIGHT TO
MODERATE SNOW OCCURRING OVER SOUTHEAST MINNESOTA...SOUTHWEST
WISCONSIN...AND NORTHEAST IOWA EARLY THIS AFTERNOON ALONG THE
SOUTHWEST FLANK OF A POLAR AIRMASS.  ANOTHER AREA OF SNOW EXISTS
OVER THE EASTERN DAKOTAS AHEAD OF A COMPACT SHORTWAVE TROUGH.  DRY
AIR EMANATING FROM A CANADIAN HIGH CENTERED OVER THE GREAT LAKES HAS
PREVENTED THE SNOW FROM REACHING THE GROUND OVER CENTRAL WISCONSIN
DESPITE SOME RETURNS ON RADAR EARLIER.  AS THE SHORTWAVE OVER THE
DAKOTAS MOVES EAST...SNOW AND ACCUMULATION CHANCES ARE THE MAIN
FORECAST CONCERNS.

TONIGHT...800-700MB THERMAL GRADIENT WILL CONTINUE TO BE ACTIVE
EARLY THIS EVENING OVER SOUTHWEST WISCONSIN.  BUT THE MAIN PUSH OF
SNOW WILL BE EXITING MINNESOTA BY MID TO LATE EVENING AHEAD OF A
SHORTWAVE TROUGH...IN CONJUNCTION WITH MID-LEVEL FGEN ON THE NOSE OF
A 25KT LLJ AND A COUPLED JET STRUCTURE.  CENTRAL WISCONSIN WILL BE
ON THE NORTHERN FRINGE OF THE AREA OF SNOW WHERE LOW LEVEL EASTERLY
WINDS WILL BE FEEDING IN DRY AIR.  SOUNDINGS BECOME SATURATED ABOVE
750MB BY 06Z ACCORDING TO THE NAM...WHILE THE MESOMODELS AND SREF
ARE SLIGHTLY MORE AGGRESSIVE BRINGING IN PRECIP BY THIS TIME INTO
WOOD COUNTY.  AS A RESULT...WILL INCREASE PRECIP CHANCES IN THAT
CENTRAL WISCONSIN AREA IN THE 06-09Z PERIOD.  ACCUMULATIONS COULD
REACH UP TO AN INCH IN WOOD COUNTY BUT ONLY A TENTH OR TWO FROM
WAUSAU TO OSHKOSH.  THE REST OF THE AREA SHOULD SEE INCREASING
CLOUDS.  LOWS RANGING FROM THE UPPER TEENS NORTHEAST TO THE MIDDLE
20S SOUTH.

MONDAY...ANY PRECIP WILL HAVE EXITED CENTRAL WISCONSIN BY THE START
OF THE MORNING BUT CLOUDS WILL TAKE MUCH LONGER TO THIN AS CENTRAL
WISCONSIN WILL BE ON THE NORTHEAST EDGE OF THE BAROCLINIC ZONE.
NORTHEAST WISCONSIN WILL HAVE A MUCH GREATER CHANCE OF CLEARING
DURING THE AFTERNOON.  THE COMBINATION OF CLOUDS AND AN EAST WIND
WILL KEEP MAX TEMPS COOL.  HIGHS WILL BE RANGING THROUGH THE 30S.

.LONG TERM...MONDAY NIGHT THROUGH SUNDAY
ISSUED AT 244 PM CDT SUN MAR 22 2015

MAIN CONCERN FOR THIS PACKAGE WILL BE THE SYSTEM TUESDAY NIGHT
AND WEDNESDAY...THEN BELOW NORMAL TEMPERATURES FOR THE END OF
THE WORK WEEK INTO NEXT WEEKEND.

12Z MODELS CONTINUE TO SHOW SIGNIFICANT SYSTEM MOVING ACROSS THE
REGION TUESDAY NIGHT INTO WEDNESDAY. MANY ISSUES TO CONTEND WITH
PRECIPITATION TYPE DUE TO DRY AND COLD EASTERLY FLOW WITH LOW
DEW POINTS TUESDAY AFTERNOON...THEN WARM LAYER ALOFT TUESDAY NIGHT
INTO WEDNESDAY. ONE THING IS FOR SURE...PLENTY OF DRY AIR IN THE
LOW LEVELS TO OVERCOME AS NUMERICAL GUIDANCE INDICATING DEW POINTS
IN THE TEENS TO LOWER 20S. ALOFT...MODELS DIFFER ON HOW FAR NORTH
WARM LAYER WILL GET ON INCREASING SOUTHEAST TO SOUTH WINDS. ALSO...
ANOTHER FACTOR THAT MAY IMPACT PRECIPITATION TYPES WILL BE THE
STEEP MID LEVEL LAPSE RATES (700-500MB) AROUND 6.5 C/KM. EVEN THE
WARM LOCATIONS ACROSS EAST CENTRAL WISCONSIN COULD SEE A MIX OR
START AS SNOW UNTIL WARMER AND MORE MOIST AIR ARRIVES. THESE
ISSUES WILL HAVE AN IMPACT ON SNOW TOTALS...BUT FEEL CONFIDENT THAT
AN ACCUMULATING SNOW WILL OCCUR ACROSS THE NORTH.

PRECIPITATION WILL LINGER INTO WEDNESDAY AS SYSTEM DEPARTS THE REGION.
AN UPPER TROUGH MOVING ACROSS THE REGION WILL BRING A CHANCE OF
RAIN OR SNOW WEDNESDAY NIGHT AND THURSDAY. MAINLY DRY CONDITIONS ARE
EXPECTED INTO SATURDAY THE NEXT CHANCE OF RAIN AND SNOW IS EXPECTED
SATURDAY NIGHT AND SUNDAY.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1139 PM CDT SUN MAR 22 2015

AN UPPER DISTURBANCE WILL TRACK SOUTHWEST OF THE AREA OVERNIGHT.
A NORTHWEST TO SOUTHEAST BAND OF SNOW WILL EXTEND FROM CENTRAL
MINNESOTA TO FAR SOUTHWEST WISCONSIN TO NORTHERN ILLINOIS. SOME
MVFR CIGS WITH LIGHT SNOW MAY WORK INTO PARTS OF CENTRAL WISCONSIN
OR SOUTH OF LINE FROM MFI TO Y50 FOR AT TIME TONIGHT...OTHERWISE
VFR CONDITIONS EXPECTED TONIGHT INTO MONDAY.
&&

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

$$

UPDATE.........TDH
SHORT TERM.....MPC
LONG TERM......ECKBERG
AVIATION.......TDH






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