Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 122037
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
337 PM CDT SAT JUL 12 2014

FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SHORT TERM...TONIGHT AND SUNDAY
ISSUED AT 337 PM CDT SAT JUL 12 2014

SHOWERS AND THUNDERSTORMS ARE THE MAIN CONCERN DURING THIS PART OF
THE FORECAST.

A WEAK COLD FRONT ACROSS NORTH CENTRAL WISCONSIN HAS MOVED LITTLE
DURING THE DAY. THIS FRONT WAS FORECAST TO MAKE IT ABOUT HALF WAY
THROUGH THE AREA BEFORE WEAKENING AND DYING. DEW POINTS ACROSS THE
AREA WERE MOSTLY IN THE MIDDLE 60S TO AROUND 70 DEGREES. MUCAPE
VALUES WERE IN EXCESS OF 1000J/KG ACROSS PARTS OF NORTH CENTRAL
WISCONSIN BY MIDDAY...WITH LITTLE TO NO CIN...AND THERE WAS SOME
UPPER LEVEL DIVERGENCE ASSOCIATED WITH A 300MB JET MAX. BUT IT
TOOK UNTIL EARLY THIS AFTERNOON BEFORE SOME SHORT WAVE ENERGY
PUSHED EASTWARD AND CONVECTION REACHED THE WESTERN PART OF THE
FORECAST AREA. EXPECT SHOWERS AND THUNDERSTORMS TO CONTINUE TO
PUSH EASTWARD DURING THE LATE AFTERNOON AND EVENING WITH THE
PASSING SHORT WAVE...AS DEPICTED BY HRRR. 12Z GRB SOUNDING HAD PW
OF 1.51 INCHES SO HEAVY RAINFALL IS POSSIBLE WITH STORMS. MODELS
WERE GENERALLY DRY OVERNIGHT AND ON SUNDAY. A COLD FRONT...THAT
WAS MOVING INTO NORTH DAKOTA THIS AFTERNOON...WILL PUSH THROUGH
THE AREA ON SUNDAY AND BRING DRIER AND MUCH COOLER AIR INTO WISCONSIN.

.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY
ISSUED AT 337 PM CDT SAT JUL 12 2014

THE MUCH PUBLICIZED COLD UPPER LOW WILL APPROACH
NORTHERN WISCONSIN LATE SUNDAY NIGHT. SHOWERS ARE POSSIBLE IN
THE NORTH TOWARDS DAYBREAK. THE UPPER LOW THEN IS FORECAST TO MOVE
SLOWLY ACROSS THE NORTHERN GREAT LAKES MONDAY AND TUESDAY. THE GFS
IS FASTER IN MOVING THE SYSTEM THROUGH THE REGION THAN THE ECMWF.
COLD TEMPERATURES ALOFT AND CYCLONIC FLOW SHOULD MAKE FOR CONSIDERABLE
SHOWER ACTIVITY MONDAY AND TO A LESSER DEGREE TUESDAY. 850MB TEMPERATURES
ARE FORECAST TO DROP TO AROUND 4 TO 6 C BY MONDAY AFTERNOON AND CONTINUE
THROUGH TUESDAY. THIS SHOULD RESULT IN HIGH TEMPERATURES IN THE UPPER
50S TO MIDDLE 60S MONDAY AND TUESDAY AND BREAK A FEW LOW MAXIMUM
TEMPERATURE RECORDS. LOW TEMPERATURES WILL NOT GET THAN COOL DUE
TO CLOUD COVER AND AT LEAST SOME WIND. HIGH PRESSURE BUILDS IN
WEDNESDAY AND THURSDAY WITH PLEASANT SUMMER WEATHER. THERE IS A
SMALL CHANCE OF SHOWERS FRIDAY OR SATURDAY AS SOUTHERLY FLOW
BRINGS MOISTURE NORTHWARD FROM THE SOUTHERN PLAINS. THINK THE AIR
WILL BE SUFFICIENTLY DRY IN THE LOW LEVELS TO KEEP PRECIPITATION
AWAY UNTIL SATURDAY NIGHT OR SUNDAY.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 106 PM CDT SAT JUL 12 2014

CIGS WERE MAINLY MVFR ACROSS NORTH CENTRAL AND
NORTHEAST WISCONSIN...IN THE VICINITY OF A COLD FRONT THAT WAS
SLOWLY PUSHING SOUTHEAST. CIGS ACROSS THE REST OF THE AREA WERE
VFR. LEFT OUT MENTION OF THUNDER IN THE RHI TAF AND ONLY HAVE
SHOWERS IN THE VICINITY...THOUGH THE ENTIRE AREA IS IN SPC DAY 1
GENERAL THUNDER. MUCAPE AT RHI WAS IN EXCESS OF 1000J/KG WITH NO
CIN AS OF 17Z...BUT THUNDER HAS BEEB CONFINED TO WESTERN
WISCONSIN AND MINNESOTA. THINK THE POTENTIAL FOR THUNDER SHOULD
DECREASE ONCE THE COLD FRONT PASSES.

HAVE LOWER CLOUDS MOVING INTO CENTRAL AND EAST CENTRAL WISCONSIN
TAF SITES DURING THE LATE AFTERNOON AND EARLY EVENING WITH
SHOWERS IN THE VICINITY...AND TEMPO THUNDER WITH MVFR CIGS AS AN
UPPER LEVEL SHORT WAVE PASSES ACROSS WISCONSIN. GRB AND ARX RADARS
HAD ECHOES OVER CENTRAL WISCONSIN AT 1745Z...AROUND 8-9KFT AGL
BUT SURFACE OBSERVATIONS IN THAT AREA HAD YET TO INDICATE ANY
RAIN.

EXPECT CLOUDS TO DECREASE OVERNIGHT AS THE SHORT WAVE DEPARTS AND
THE FRONT SLOWLY DIES OFF AS IT SLOWLY MOVES SOUTHEAST.
&&

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

$$

SHORT TERM.....MG
LONG TERM......RDM
AVIATION.......MG






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