Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 251952
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
252 PM CDT TUE AUG 25 2015

FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SHORT TERM...TONIGHT AND WEDNESDAY
ISSUED AT 251 PM CDT TUE AUG 25 2015

AN UPPER LEVEL CYCLONE THAT WAS SOUTH OF JAMES BAY IS NOT EXPECTED
TO MOVE MUCH OVERNIGHT BUT SHOULD WEAKEN AS IT STARTS TO MAKE ITS
WAY ACROSS QUEBEC ON WEDNESDAY. LOW CLOUDS IN CYCLONIC FLOW AROUND
THE LOW SHOULD REMAIN ACROSS THE AREA DURING THE NIGHT AND BEGIN
TO EXIT DURING THE DAY ON WEDNESDAY. THERE COULD STILL BE SOME
LIGHT SHOWERS OR SPRINKLES IN FAR NORTHERN WISCONSIN THIS
EVENING.

WINDS WILL BE LIGHTER TONIGHT...MAKING CLOUD COVER THE ONLY THING
REALLY KEEPING TEMPERATURES FROM TANKING AFTER SUNSET...ESPECIALLY
SINCE THEY NEVER WARMED UP VERY MUCH IN THE FIRST PLACE. MODELS
GENERALLY SHOWED NEUTRAL OR WARM ADVECTION AT 850MB TONIGHT SO
HAVE OVERNIGHT LOWS SIMILAR TO WHAT THEY WERE THIS MORNING.

DECREASING CLOUDS ON WEDNESDAY SHOULD ALLOW TEMPERATURES TO GET SEVERAL
DEGREES WARMER THAN THEY WERE TODAY. HAVE MOSTLY MID 60S TO LOWER
70S FOR HIGHS...WHICH MIGHT BE TOO COOL IF THERE ARE FEWER CLOUDS
THAN EXPECTED.

.LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY
ISSUED AT 251 PM CDT TUE AUG 25 2015

UPPER LOW OVER SE CANADA CONTINUES TO LOSE INFLUENCE OVER AREA
WEATHER AS UPPER RIDGING OVER THE WEST MOVES EAST. DURING THIS
TRANSITION...AT LEAST ONE WAVE (LATE THIS WEEK) WILL MOVE ACROSS
MID/UPPER MISS VALLEY AND BRING WITH IT WIDESPREAD PRECIP. HOW
FAR NORTH THE HEAVIEST PRECIP GETS IS MAIN QUESTION.

TEMPS THIS PERIOD WL START AT OR BELOW NORMAL...BUT WARM TO ABOVE
NORMAL LEVELS BY THE LATTER PART OF THE WEEKEND.

BEFORE RAIN SYSTEM MOVES IN...SURFACE HI PRESSURE WILL PROVIDE
CLEAR SKIES...LITTLE WIND AND NEARLY IDEAL RADIATIONAL COOLING
CONDITIONS WED NIGHT. MIN TEMPS COULD DIP INTO THE UPR 30S OVER
THE COLDER LOCATIONS OF THE NORTHWOODS. OTHERWISE...THE REST OF
NRN WI TO SEE READINGS IN THE 40-45 DEG RANGE...WITH UPR 40S TO
LWR 50S CNTRL/E-CNTRL WI.

MID-LEVEL SHORTWAVE TROF THEN UNDERCUTS WESTERN UPR RDG AND IS
FORECAST TO MOVE ACROSS THE PLAINS INTO THE MIDWEST THU NIGHT
THROUGH FRI NIGHT. 25/12Z MODELS ARE SHOWING GENERAL AGREEMENT ON
TIMING...BUT DIFFERENCES REMAIN ON EXACT PLACEMENT OF HEAVIEST
RAIN...WITH 25/12Z ECMWF FARTHEST SOUTH WITH HEAVY RAIN AREA. AND
NOT TO MENTION POSSIBLE CONVECTIVE FEEDBACK ISSUES WITH NAM. WILL
LEAN MOST ON 25/12Z GFS FOR THIS SYSTEM...BUT KEEP HEAVIEST PRECIP
NEAR OR JUST S OF A WISC RAPIDS TO SHEBOYGAN LINE....WHICH IS
CLOSE TO PREVIOUS FCST.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1257 PM CDT TUE AUG 25 2015

THE CLOUD SHIELD...WITH MVFR CIGS...AROUND A DEPARTING UPPER
CYCLONE AND SURFACE LOW WILL LIKELY STAY IN PLACE THROUGHOUT THE
NIGHT AND INTO THE MORNING HOURS. THERE MAY ALSO BE SOME AREAS OF
MVFR VSBY IN FOG TONIGHT...MAINLY ACROSS NORTHERN WISCONSIN. ENDED
UP MORE CLOSELY FOLLOWING THE 12Z GFS THAN THE 12Z NAM AND HAVE
CLOUDS DEPARTING DURING THE MORNING ON WEDNESDAY. SHOULD JUST BE
CLR TO SCT CLOUDS AFTER THAT WITH WINDS LESS THAN 10 KNOTS.
&&

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

$$

SHORT TERM.....MG
LONG TERM......JKL
AVIATION.......MG



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