Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 212336
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
636 PM CDT TUE APR 21 2015

UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE

.SHORT TERM...TONIGHT AND WEDNESDAY
ISSUED AT 252 PM CDT TUE APR 21 2015

A SLOW MOVING UPPER LEVEL LOW WILL CONTINUE TO DOMINATE THE
WEATHER FOR TONIGHT AND WEDNESDAY...WITH THE MAIN FOCUS BEING ON
THE CHANCES FOR SCATTERED PRECIPITATION AND PRECIP TYPE.

NUMEROUS SHOWERS DEVELOPED THIS AFTERNOON AS A DEEP UPPER LEVEL
TROUGH SAT OVER THE GREAT LAKES REGION. THIS TROUGH IS FORECASTED
TO MEANDER SIGHTLY EAST BY WEDNESDAY AFTERNOON...HOWEVER NOT MUCH
CHANGE IS EXPECTED IN THE NEXT 24 HOURS TO THE WEATHER PATTERN.
FOLLOWED TODAYS OVERALL TREND WHEN PUTTING TOGETHER THE FORECAST
PACKAGE FOR TONIGHT AND WEDNESDAY...AS IT SHOULD BE MORE OF THE
SAME.

TONIGHT...SHOWERS SHOULD DIMINISH IN COVERAGE THIS EVENING AS
MIDLEVEL INSTABILITY AND LIFT WEAKENS. FORCING OVER THE REGION WILL
BE WEAK AS WELL SO WITHOUT THIS AFTERNOON INSTABILITY NOTED ON THE
RAP MESOANALYSIS IT WILL BE HARD TO GET SHOWERS TO HANG ON
TONIGHT. THE EXCEPTION OF COURSE BEING NORTHERN WISCONSIN WHERE
WNW FLOW ALOFT AND LAKE INSTABILITY WILL ALLOW FOR LAKE EFFECT SNOW
SHOULD TO CONTINUE MUCH OF THE NIGHT. PRECIPITATION TODAY HAS
BEEN MAINLY SNOW...SO MADE TRENDED COLDER AND MADE SNOW THE
PREDOMINANT WEATHER TYPE ACROSS NE WI...WITH RAIN SHOWERS MIXING
IN ACROSS EAST CENTRAL WISCONSIN EARLY.

WEDNESDAY...ONLY MINOR CHANGES MADE TO THE FORECAST FOR WEDNESDAY.
CYCLONIC FLOW ALOFT WILL ALLOW FOR ANOTHER DAY WITH MOSTLY CLOUDY
SKIES. SHOWERS ARE EXPECTED AGAIN WEDNESDAY AFTERNOON BUT SHOULD
NOT BE AS NUMEROUS AS WHAT WE SAW TODAY AS MID LEVEL INSTABILITY
WILL BE WEAKER WITH THE MAIN UL TROUGH DRIFTING EAST. LAKE EFFECT
SNOW SHOWERS IN NORTHERN WISCONSIN WILL BE NUMEROUS IN THE MORNING
BEFORE DIMINISHING TO MORE SCATTERED-LIKE WEDNESDAY AFTERNOON AS
FLOW ALOFT BECOMES LESS FAVORABLE OUT OF THE WEST. TEMPERATURES
WILL BE CHILLY AGAIN WITH ANOTHER BLUSTERY DAY EXPECTED.

.LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY
ISSUED AT 252 PM CDT TUE APR 21 2015

THE UPPER LEVEL LOW WILL MOVE SLOWLY FROM SOUTHERN ONTARIO TO
NORTHERN NEW ENGLAND BY THE END OF THE WEEK. AS IT DOES HEIGHTS
WILL SLOWLY RISE AND TEMPERATURES WILL CLIMB SLOWLY AS WELL. SOME
SCATTERED SNOW OR RAIN SHOWERS ARE STILL POSSIBLE WEDNESDAY NIGHT
AND THURSDAY IN THE REMAINING CYCLONIC FLOW BUT THEN IT SHOULD BE
DRY THROUGH AT LEAST FRIDAY NIGHT AS A WEAK UPPER RIDGE APPROACHES.
MODELS NOW SEEM TO KEEP AN UPPER LEVEL TROUGH FROM THE CENTRAL
PLAINS SOUTH OF OUR AREA SATURDAY WHICH WOULD KEEP US DRY THROUGH
SUNDAY.

TEMPERATURES WILL BE 10 TO 15 DEGREES BELOW NORMAL WEDNESDAY NIGHT
THROUGH THURSDAY NIGHT AND THEN JUST 5 TO 10 DEGREES BELOW NORMAL
AFTER THAT.
&&

.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 624 PM CDT TUE APR 21 2015

AN UPPER LEVEL LOW OVER NORTHERN LAKE SUPERIOR WAS PRODUCING
NUMEROUS SNOW OR MIXED RAIN/SNOW SHOWERS ACROSS THE FORECAST
AREA EARLY THIS EVENING. ALTHOUGH THE SHOWERS MAY TAPER OFF A
BIT AFTER SUNSET...A SHORT-WAVE TROF WILL PASS THROUGH THE REGION
AND KEEP AT LEAST SCT SNOW SHOWERS GOING INTO THE OVERNIGHT HOURS.
CONDITIONS WILL ALSO BECOME MORE FAVORABLE FOR LAKE-EFFECT SNOW
SHOWERS IN FAR NC WI TOWARD MIDNIGHT. LOW-END VFR AND MVFR
CONDITIONS WILL PREVAIL OVER MOST OF THE REGION...THOUGH BRIEF
IFR VSBYS ARE POSSIBLE...ESPECIALLY OVER NC WI.

ALTHOUGH THE UPPER LOW WILL BE SHIFTING NE OF THE REGION AS THE
DAY WEARS ON...CLOUDY SKIES AND SCATTERED SNOW OR MIXED RAIN/SNOW
SHOWERS WILL CONTINUE ON WEDNESDAY. THE SHOWER ACTIVITY SHOULD BE
LESS WIDESPREAD THAN TODAY...EXCEPT IN NORTHERN WISCONSIN WHERE
OCNL SNOW SHOWERS WILL CONTINUE FOR MOST OF THE DAY.

GUSTY WNW WINDS WILL DIMINISH A BIT THIS EVG BEFORE INCREASING
AGAIN LATE WEDNESDAY MORNING.
&&

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

$$

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






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