Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 202349
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
649 PM CDT MON APR 20 2015

UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE

.SHORT TERM...TONIGHT AND TUESDAY
ISSUED AT 302 PM CDT MON APR 20 2015

AFTER PRECIPITATION PULLS AWAY THIS EVENING AS LOW PRESSURE IN
LOWER MICHIGAN IS KICKED EAST...MAIN FORECAST CONCERNS WILL BE
PRECIP CHANCES AND TYPE FOR LATER TONIGHT AND TUESDAY.

MODELS IN FAIRLY GOOD AGREEMENT THROUGH TUESDAY THAT LINGER LIGHT
PRECIP THAT HAS PLAGUED THE STATE TODAY WILL PULL AWAY THIS
EVENING AND THE SFC LOW SITTING IN LOWER MICHIGAN FINALLY EXITS
THE REGION. AFTER A BRIEF LULL IN THE PRECIP AND SOME THINNING OF
THE CLOUD COVER...CLOUDS AND POPS WILL INCREASE AGAIN LATE
TONIGHT AND TUESDAY AS THE MAIN UPPER LEVEL TROUGH SETTLES OVER
THE REGION. SHOWERY ACTIVITY SHOULD INCREASE IN COVERAGE AFTER
MIDNIGHT AS AN AREA OF BETTER LIFTS SWINGS INTO NORTHEAST
WISCONSIN AHEAD OF A WEAK SHORTWAVE MOVING THROUGH THE MEAN
CYCLONIC FLOW. CHANCE OF SHOWERS WILL CONTINUE ON
TUESDAY...THOUGH A DIMINISHING TREND IS POSSIBLE TUESDAY AFTERNOON
AS THE UPPER LEVEL CLOSED LOW SHIFTS OVERHEAD AND FORCING WILL BE
VERY WEAK. DIDNT MAKE TOO MANY CHANGES FROM THE PREVIOUS FORECAST TO
POPS OTHER THAN SLOWING THE ARRIVAL OF SHOWERS OVERNIGHT AS THE
SYSTEM TO OUR EAST WILL BE SLOW TO EXIT AND MODELS HAVE SLOWED THE
PROGRESSION OF SHOWERS EASTWARD.

THE BIGGER FCST CHALLENGE WILL BE PCPN TYPE. TODAY HAD MORE SNOW
THAN EXPECTED IN NORTHERN WISCONSIN...WITH FLAKES BEING REPORTED
AS FAR SOUTH AS WAUSAU AND MARSHFIELD THIS MORNING. GIVEN THE WARM
BIAS IN THE MODELS AND THAT TOMORROWS THERMAL SET UP WILL BE VERY
SIMILAR TO TODAYS. WITH THAT IN MIND...FAVORED THE COLDER MODELS
WHEN DECIDING A PCPN TYPE. THIS HAD SNOW EXPANDING FURTHER SOUTH
AND EAST FASTER...WITH RAIN SNOW MIX IN EASTERN WISCONSIN BY
TUESDAY MORNING. DIDNT MAKE SIGNIFICANT CHANGES TO THE SNOW
ACCUMULATIONS THOUGH EVEN THOUGH IT MAY SNOW A BIT LONGER THAN
PREVIOUS FORECASTS IN SOME PLACES. GROUND IS WARMER FROM THE PAST
WEEK OF SPRING LIKE WEATHER AND NO ACCUMULATION WAS REPORTED
THROUGH OUT MUCH OF CENTRAL WISCONSIN. NORTHERN WISCONSIN COULD
HAVE SOME ACCUMULATIONS...WITH MOST OF THE SNOW FALLING AND
STICKING IN THE FAR NORTH WHERE AROUND AN INCH IS POSSIBLE.

PRECIP SHOULD TRANSITION BACK TO RAIN SHOWERS TUESDAY AFTERNOON
THROUGH OUT ALL OF NORTHEAST WISCONSIN...EXCEPT IN NORTHERN
WISCONSIN NEAR VILAS WHERE SNOW OR A RAIN SNOW MIX SHOULD CONTINUE
THROUGH THE DAY (MUCH LIKE IT DAY TODAY).

.LONG TERM...TUESDAY NIGHT THROUGH MONDAY
ISSUED AT 302 PM CDT MON APR 20 2015

AN UPPER LOW MOVING SLOWLY FROM THE NORTHERN GREAT LAKES TOWARDS
QUEBEC WILL PRODUCE A NORTHWEST FLOW OF COOL AIR FOR THE REST OF
THE WEEK. COLD AIR ALOFT WILL MAKE FOR SCATTERED SNOW AND RAIN
SHOWERS TUESDAY NIGHT AND WEDNESDAY...ESPECIALLY IN THE FAR NORTH.
MAINLY DRY WEDNESDAY NIGHT THROUGH FRIDAY. SOME SNOW ACCUMULATION
POSSIBLE IN THE NORTH MAINLY ON THE GRASS. HIGH TEMPERATURES WILL
BE TEN OR MORE DEGREES BELOW NORMAL WITH LOWS 5 TO 10 DEGREES
BELOW USUAL.

MEDIUM RANGE MODELS THEN DIFFER ON WHETHER JET ENERGY ARRIVES FROM
THE CANADIAN PRAIRIES TOWARDS THE NORTHERN LAKES FRIDAY NIGHT AND
SATURDAY. THE ECMWF HAS THIS FEATURE WHILE THE GFS DOES NOT. MIGHT
NEED TO ADD SHOWERS TO THE FORECAST IF THE ECMWF IS RIGHT.
&&

.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 637 PM CDT MON APR 20 2015

LINGERING RAIN WILL EXIT NE WI EARLY THIS EVG...WITH CONDITIONS
RETURNING TO VFR AT MOST LOCATIONS THIS EVENING. AN UPPER LEVEL
LOW WILL ARRIVE LATER TONIGHT...BRINGING LIGHT SNOW SHOWERS OR
MIXED RAIN/SNOW SHOWERS AND ASSOCIATED MVFR CIGS TO THE REGION...
ESPECIALLY OVER NC/C WI. LIGHT PCPN WILL AFFECT THE ENTIRE
FORECAST AREA ON TUESDAY. PCPN TYPE WILL BE MAINLY SNOW OVER NC
WI...MIXED RAIN/SNOW IN C/FAR NE WI...AND MAINLY RAIN (POSSIBLE
LIGHT MIX EARLY) OVER THE FOX VALLEY/LAKESHORE AREAS. LOCAL IFR
VSBYS ARE POSSIBLE IN SNOW SHOWERS OVER NC WI.

GUSTY WEST WINDS WILL DIMINISH A BIT THIS EVG...WITH THEN INCREASE
AGAIN TUESDAY MORNING.
&&

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

$$

SHORT TERM.....ALLEN
LONG TERM......RDM
AVIATION.......KIECKBUSCH






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