Area Forecast Discussion
Issued by NWS Green Bay, WI

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998
FXUS63 KGRB 020420
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1120 PM CDT SUN MAY 1 2016

UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE

.SHORT TERM...TONIGHT AND MONDAY
ISSUED AT 308 PM CDT SUN MAY 1 2016

LOW TEMPERATURES AND POTENTIAL FOR FROST ARE THE MAIN CONCERNS
DURING THIS PART OF THE FORECAST.

CLOUDS AND A SLIGHT CHANCE FOR SHOWERS WILL EVENTUALLY DEPART THE
SOUTHERN PART OF THE FORECAST AREA DURING THE EVENING AS LOW
PRESSURE TO THE SOUTH OF WISCONSIN CONTINUES TO MOVE EAST. AS
CLOUDS DEPART AND THE SURFACE PRESSURE GRADIENT WEAKENS...WINDS
WILL DIMINISH. TEMPERATURES SHOULD DROP INTO THE 30S ACROSS THE
AREA SO FROST LOOKS LIKELY ACROSS THE NORTHERN PART OF THE STATE.
FARTHER TO THE SOUTH AND EAST LOWS SHOULD BE MAINLY IN THE UPPER
HALF OF THE 30S...SO A FROST ADVISORY DOES NOT APPEAR TO BE
NECESSARY. PATCHY FROST OR AREAS OF FROST WORDING SHOULD COVER
THE SITUATION. THE 12Z NAM MOS AT GRB WAS 4F COLDER THAN THE 00Z
VERSION AND TOOK THE TEMPERATURE DOWN TO 35 TONIGHT...BUT THE
CURRENT TEMPERATURE IS CLOSER TO THE 3 HOURLY TEMPERATURES ON THE
12Z GFS MOS...WHICH WAS 1F WARMER THAN THE 00Z VERSION AND GAVE A
LOW OF 39. THUS...HAVE GONE CLOSER TO THE WARMER GFS MOS FORECAST
LOWS TONIGHT.

LOOKS LIKE PLENTY OF SUNSHINE FOR MONDAY...AND DRY THROUGH AT
LEAST THE MORNING. THE 12Z GFS AND 12Z ECMWF BOTH SPREAD SOME QPF
INTO THE AREA DURING THE AFTERNOON BUT NOT EXACTLY IN THE SAME
LOCATION AND THE 12Z NAM AND 12Z CANADIAN DIDN`T SHOW IT SO HAVE
KEPT THE AFTERNOON DRY AS WELL. HIGHS SHOULD BE NEAR NORMAL FOR
EARLY MAY.

.LONG TERM...MONDAY NIGHT THROUGH SUNDAY
ISSUED AT 308 PM CDT SUN MAY 1 2016

MAIN FCST CONCERNS INCLUDE PCPN CHANCES AND THUNDERSTORM POTENTIAL
WITH A STRONG COLD FRONTAL PASSAGE ON TUESDAY AND TUESDAY NIGHT...
AND ANOTHER COLD FRONT ON SATURDAY AND SATURDAY NIGHT.

HAVE MAINTAINED A DRY FCST ON MONDAY NIGHT...AS A WEAK RIDGE OF
HIGH PRESSURE SAGS SOUTH OF THE REGION. LIGHT WINDS AND MOSTLY
CLEAR SKIES DURING THE EVG SHOULD ALLOW TEMPS TO DROP INTO THE
30S AND LOWER 40S...BUT INCREASING WINDS OVERNIGHT MAY RESULT IN
A SLIGHT RISE IN TEMPS LATE.

MODELS HAVE COME INTO BETTER AGREEMENT WITH THE TIMING OF A STRONG
COLD FRONT TUESDAY AND TUESDAY NIGHT. WITH THE CURRENT TIMING...
LIKELY POPS LOOK LIKE A GOOD BET OVER THE NORTHERN THIRD OF THE
FORECAST AREA TUESDAY AFTERNOON...AND THE SOUTHERN TWO-THIRDS
TUESDAY EVENING. MODELS CONTINUE TO SHOW SOME MODEST INSTABILITY
(CAPES 200-500 J/KG...LI`S ZERO TO -3 AND 700-500 MB LAPSE RATES
AROUND 7 C/KM)...SO WILL CONTINUE WITH A CHANCE OF THUNDERSTORMS.
MOSTLY CLOUDY AND COOLER WEATHER...AND A SMALL CHANCE OF SHOWERS...
CAN BE EXPECTED ON WEDNESDAY...WITH A THERMAL TROUGH IN PLACE
AND AN UPPER LOW SITUATED TO OUR EAST. HIGH TEMPERATURES WILL
ONLY BE IN THE UPPER 40S AND 50S.

THE REST OF THE WORK WEEK LOOKS MAINLY DRY...WITH A SIGNIFICANT
MODERATION IN TEMPERATURES. STRONG WAA IS POISED TO OCCUR ON
THURSDAY AND THURSDAY NIGHT...WITH HIGH TEMPS EXPECTED TO WARM
INTO THE LOWER TO MIDDLE 70S ON FRIDAY AND SATURDAY.

ANOTHER COLD FRONT IS NOW EXPECTED TO MOVE THROUGH THE AREA
ON SATURDAY AFTERNOON AND NIGHT. HAVE BUMPED UP MODEL BLENDED
POPS A BIT...AND SUSPECT THAT FURTHER INCREASES WILL BE NEEDED
WITH SUBSEQUEBT FCSTS. THE FRONT SHOULD CLEAR THE AREA BY
SUNDAY...ALLOWING FOR A DRY END TO THE WEEKEND.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1119 PM CDT SUN MAY 1 2016

SURFACE HIGH PRESSURE RIDGE BUILDING INTO THE WESTERN GREAT LAKES
OVERNIGHT INTO MONDAY WILL PRODUCE VFR CONDITIONS. WEAK UPPER LOW
PRESSURE ALOFT THROUGH MONDAY...ALONG WITH STEEP LAPSE RATES DUE
TO COLD H7 TEMPERATURES WILL PRODUCE SCT-BKN MID LEVEL CLOUDS.
BOUNDARY LAYER DRY BUT VIRGA POSSIBLE MONDAY AFTERNOON.
&&

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

$$

SHORT TERM.....MG
LONG TERM......KURIMSKI
AVIATION.......TDH



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