Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 210338
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1038 PM CDT MON APR 20 2015

UPDATED AVIATION PORTION FOR 06Z 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 06Z TAF ISSUANCE
ISSUED AT 1029 PM CDT MON APR 20 2015

VFR AND LOCAL MVFR CONDITIONS WERE FOUND ACROSS THE REGION LATE
THIS EVG...ALONG WITH WIDELY SCATTERED LIGHT SPRINKLES OR FLURRIES.
AN UPPER LEVEL LOW WILL MOVE INTO THE REGION OVERNIGHT...BRINGING
LIGHT SNOW OR MIXED RAIN/SNOW AND ASSOCIATED MVFR CIGS TO THE
REGION...ESPECIALLY OVER NC/C WI. LIGHT PCPN WILL AFFECT THE
ENTIRE FORECAST AREA ON TUESDAY AS THE UPPER LOW SLOWLY TRACKS EAST.
PCPN TYPE WILL BE MAINLY SNOW OVER NC WI...MIXED RAIN/SNOW IN
CENTRAL/FAR NE WI...AND MAINLY RAIN (WITH A LIGHT MIX EARLY) OVER
THE FOX VALLEY/LAKESHORE AREAS. OCNL IFR VSBYS ARE POSSIBLE WITH
THE SNOW OVER NC WI. DURING THE EVENING...THE PCPN SHOULD TAPER
OFF...EXCEPT OVER NC/FAR NE WI...WHERE SOME SNOW SHOWERS WILL
CONTINUE.

GUSTY WEST WINDS WILL INCREASE AGAIN TUESDAY MORNING AND LINGER
UNTIL AROUND SUNSET.
&&

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

$$

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






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