Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 121746
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1246 PM CDT FRI SEP 12 2014

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND SATURDAY
ISSUED AT 319 AM CDT FRI SEP 12 2014

PCPN TRENDS FOR TODAY AND POTENTIAL FOR ANOTHER ROUND OF FROST
TNGT REMAIN THE BIGGEST FCST HURDLES OVER THE NEXT 36 HOURS.

THE 07Z MSAS SFC ANALYSIS INDICATED A LARGE AREA OF HI PRES OVER
THE LEE-SIDE OF THE ROCKIES FROM WRN NEBRASKA NWD INTO
SASKATCHWAN. AN EWD EXTENSION OF THIS HI POKED INTO NRN WI AND IT
WAS THIS FEATURE THAT ALLOWED SKIES TO CLEAR OVRNGT AND TEMPS TO
TANK ACROSS NRN WI. SATL IMAGERY DID SHOW CLOUDS BEGINNING TO
OVERSPREAD WI AHEAD OF AN IMPRESSIVE SHORTWAVE TROF OVER THE NRN
PLAINS. RADAR MOSAIC DID PICK UP ON SOME LIGHT RAIN MOVING ACROSS
NRN SECTIONS OF IA.

AFTER A FROSTY START TO THE DAY OVER NRN SECTIONS OF THE FCST
AREA...CLOUDS WL QUICKLY OVERSPREAD THE REST OF WI THIS MORNING IN
ADVANCE OF THE VIGOROUS SHORTWAVE TROF SWEEPING ACROSS THE UPR MS
VALLEY/MIDWEST. THE LEADING EDGE OF LIGHT RAIN TO ALREADY BE
PUSHING INTO CNTRL/E-CNTRL WI LATER THIS MORNING WITH THE PCPN
BECOMING MORE WIDESPREAD IN COVERAGE THIS AFTERNOON AS THE TROF
PUSHES INTO THE WRN GREAT LAKES. DESPITE NOT HAVING MUCH LOW-LEVEL
MOISTURE AT ITS DISPOSAL...THIS SYSTEM IS DYNAMIC ENUF IN THE MID-
LEVELS WITH STRONG PV ADVECTION...Q-G FORCING AND FRONTOGENETICAL
FORCING TO WRING OUT ANY AVAILABLE MOISTURE. HAVE RAISED POPS FOR
THIS AFTERNOON INTO CATEGORICAL OVER E-CNTRL WI AND LIKELY FROM
CNTRL WI TO FAR NE WI. ALL THE CLOUDS AND PCPN WL AGAIN PUT A LID
ON DIURNAL WARMING WITH MAX TEMPS GENERALLY IN THE 50-55 DEG
RANGE...AGAIN AROUND RECORD MIN HI TEMP RECORDS.

THE SHORTWAVE TROF TO MOVE OVER NE WI THIS EVENING AND REACH THE
ERN GREAT LAKES BY 12Z SAT. LIGHT RAIN WL CONT THIS EVENING AND
BEGIN TO DIMINISH FROM WEST TO EAST DURING THE OVRNGT HOURS.
EXACTLY HOW FAST THIS SYSTEM DEPARTS WL BE KEY TO FROST/FREEZE
POTENTIAL LATE TNGT AS HI PRES TO RE-ESTABLISH ITSELF OVER WI WITH
CLEARING SKIES AND LIGHT WINDS. IF THE FASTER GFS/GEM ARE CORRECT...
TEMPS OVER N-CNTRL AND CNTRL WI WOULD HEAD TOWARD OR SURPASS THE
FREEZING MARK ONCE AGAIN. HAVE KEPT FROST WORDING IN THE FCST...
BUT TOO AVOID CONFUSION WITH THE CURRENT FROST/FREEZE HEADLINES...
WL NOT ISSUE ANOTHER ONE FOR TNGT AND ALLOW THE DAYSHIFT TO FINE
TUNE THE DETAILS WITH SURROUNDING OFFICES.

HI PRES TO DOMINATE NE WI WEATHER ON SAT WITH MOSTLY SUNNY SKIES...
LIGHT WINDS AND WARMER TEMPS. LOOK FOR MAX TEMPS TO BE ABOUT FIVE
DEGS WARMER THAN TODAY WITH MOST LOCATIONS IN THE 55-60 DEG RANGE.

.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY
ISSUED AT 319 AM CDT FRI SEP 12 2014

SATURDAY NIGHT LOOKS TO BE DRY WITH HIGH PRESSURE THE MAIN SURFACE
FEATURE. TEMPERATURES ACROSS NORTHERN WISCONSIN WILL BE LOW ENOUGH
FOR PATCHY FROST TO DEVELOP...BUT DO NOT THINK FROST WILL BE
WIDESPREAD. AN APPROACHING MID LEVEL SHORT WAVE...LEFT EXIT
REGION OF AN UPPER JET MAX...AND A SURFACE FRONT ARE EXPECTED TO
BRING RAIN CHANCES TO NORTH CENTRAL WISCONSIN SUNDAY AFTERNOON AND
THE REST OF THE AREA ON SUNDAY NIGHT. THE RAIN SHOULD END FROM
NORTH TO SOUTH ON MONDAY. A LARGE SURFACE HIGH PRESSURE SYSTEM
SHOULD KEEP THE FORECAST AREA DRY THROUGH THE END OF THE PERIOD.
THERE WILL BE SOME SHORT WAVE ENERGY MOVING SOUTHEAST OUT OF
CANADA BUT IT IS EXPECTED TO BE MAINLY NORTHEAST OF WISCONSIN.

AFTER A CHILLY START TO THE WEEK TEMPERATURES SHOULD WARM UP A
BIT BY MIDWEEK...BUT HIGHS ARE STILL FORECAST TO BE BELOW NORMAL
FOR MID SEPTEMBER.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1246 PM CDT FRI SEP 12 2014

AN UPPER LEVEL DISTURBANCE WILL PRODUCE SOME LIGHT
RAIN AND AREAS OF MVFR CEILINGS THIS AFTERNOON AND EVENING. IT
SHOULD END FROM WEST TO EAST LATER TONIGHT WITH CLEARING SKIES.
WHERE SKIES CLEAR THERE IS A GOOD CHANCE OF FROST AND FOG. ANY FOG
OR FROST THAT DOES OCCUR SHOULD END BY 14Z SATURDAY WITH GOOD
FLYING WEATHER EXPECTED SATURDAY AND SUNDAY.
&&

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

$$

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





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