Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 301715
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1215 PM CDT MON MAR 30 2015

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND TUESDAY
ISSUED AT 418 AM CDT MON MAR 30 2015

NORTHWEST UPPER FLOW WILL PREVAIL THROUGH THE PERIOD WITH STRONG
JET STREAKS PRODUCING VERTICAL MOTION LATER TODAY THROUGH TONIGHT.
THE MODELS ARE NOT IN GREAT AGREEMENT GIVEN THE FACT THAT WHATEVER
PRECIPITATION WE GET WILL ARRIVE THIS AFTERNOON AND EVENING.
BELIEVE THE DIFFERENCES ARE CHIEFLY DUE TO THE INITIALIZATION OF
A STRONG JET STREAK THAT WAS COMING ASHORE OVER BRITISH COLUMBIA
AT 00Z. IT LOOKS TO BE BETTER INITIALIZED BY THE ECMWF THAN THE
OTHER MODELS AND ALSO LOOKS BETTER BASED ON AIRCRAFT WIND
OBSERVATIONS AT 06Z. NOT SURE THAT THIS MAKES THE FURTHER SOUTH
TRACK OF THE ECMWF CORRECT BUT HEDGED A BIT THAT WAY AND BROUGHT
HIGHER PROBABILITIES OF PRECIPITATION FURTHER SOUTH.

PRECIPITATION TYPE IS ALSO AN ISSUE AS 925MB TEMPERATURES ARE INITIALLY
WELL ABOVE FREEZING THOUGH THEY COOL DURING THE LATE EVENING AND
OVERNIGHT DUE TO EVAPORATION AND VERTICAL MOTIONS. THINK THERE COULD
BE A HALF INCH OR INCH OF SLUSH ON GRASSY SURFACES ROUGHLY NORTH OF
HIGHWAY 29. THE JET STREAK EXITS THE AREA BY EARLY TUESDAY MORNING
WITH GENERALLY DRY WEATHER TUESDAY.

TEMPERATURES TODAY AND LOWS TONIGHT SHOULD BE ABOUT 5 DEGREES ABOVE
NORMAL WITH SLIGHTLY BELOW NORMAL TEMPERATURES TUESDAY.

.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY
ISSUED AT 418 AM CDT MON MAR 30 2015

AFTER THE SHORT TERM SYSTEM DEPARTS THERE SHOULD BE A PERIOD OF
DRY WEATHER WITH A SURFACE RIDGE PASSING ACROSS WISCONSIN AND THE
ARRIVAL OF A MID LEVEL RIDGE.

STRONG WARM ADVECTION AHEAD OF A MIDWEEK SYSTEM WILL BRING ENOUGH
WARM AIR INTO THE AREA TO KEEP ANY PRECIPITATION IN LIQUID FORM.
THE 00Z ECMWF HAD MOST OF THE QPF ON WEDNESDAY REMAINING NORTH OF
WISCONSIN WHILE THE 00Z GFS...AND 12Z GEM-NH...HAD QPF ACROSS
ALMOST THE ENTIRE FORECAST AREA. CHANCE POPS ACROSS NORTHERN...AND
PART OF CENTRAL...WISCONSIN WEDNESDAY AFTERNOON SEEMED A
REASONABLE COMPROMISE AND FIT WELL WITH SURROUNDING FORECAST
GRIDS. LOOKS LIKE A PRETTY GOOD BET THAT THERE WILL BE SHOWERS
ACROSS THE AREA WEDNESDAY NIGHT AND MID LEVEL LAPSE RATES ARE
EXPECTED TO BE QUITE STEEP...SO HAVE ALSO MENTIONED SOME THUNDER
WEDNESDAY NIGHT. KEPT A CHANCE FOR SHOWERS LINGERING INTO THURSDAY
MORNING BUT NOT TOO CONFIDENT IN THIS SINCE THE GFS LOOKS LIKE IT
ENDS THE RAIN ABOUT 6 HOURS FASTER THAN THE EC. EXPECT MUCH ABOVE
NORMAL HIGH TEMPERATURES UNTIL AFTER THE SYSTEM PASSES...THEN
HIGHS ARE EXPECTED TO BE CLOSE TO OR BELOW NORMAL FOR THE REST OF
THE PERIOD. POPS REMAIN SLIGHT CHANCE AT HIGHEST THROUGH THE
UPCOMING WEEKEND.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1209 PM CDT MON MAR 30 2015

CLOUDS WILL INCREASE ACROSS THE AREA THIS AFTERNOON AS A WEAK
DISTURBANCE MOVES INTO THE STATE...HOWEVER CIGS SHOULD STAY IN THE
VFR CATEGORY FOR MUCH OF THE AFTERNOON. THERE IS A CHANCE FOR
LIGHT RAIN THIS AFTERNOON IN CENTRAL TAF SITES...BUT THE REST OF
THE AREA SHOULD REMAIN DRY UNTIL THIS EVENING. THIS SYSTEM WILL
THEN OVERSPREAD LIGHT RAIN AND SNOW TO THE AREA TONIGHT WITH
CEILINGS AND VISIBILITY LOWERING TO IFR CONDITIONS. NORTHERN
WISCONSIN SHOULD SEE THE LONGEST PERIOD OF SNOW...WITH AROUND AN
INCH OF ACCUMULATION POSSIBLE. FURTHER SOUTH AND EAST...RAIN WILL
MIX WITH SNOW AND ACCUMULATIONS WILL BE LESS THAN A HALF INCH.

PRECIP WILL MOVE OUT TUESDAY MORNING...HOWEVER CONTINUED MVFR TO
IFR CIGS ARE EXPECTED THROUGH THE MORNING.


&&

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

$$

SHORT TERM.....RDM
LONG TERM......MG
AVIATION.......ALLEN





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