Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 010349
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1049 PM CDT TUE SEP 30 2014

UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE

.SHORT TERM...TONIGHT AND WEDNESDAY
ISSUED AT 255 PM CDT TUE SEP 30 2014

STUBBORN LOW CLOUDS TRAPPED UNDER A STRONG INVERSION FINALLY
DISSIPATED THIS AFTERNOON ACROSS NRN AND PARTS OF CNTRL WI. NE
WINDS OFF OF LAKE MI KEPT MOISTURE FILTERING INTO E-CNTRL WI...
MAKING IT HARDER FOR THE LOW CLOUDS TO DISPERSE. APART FROM THE
LOW CLOUD ISSUE...THE MAIN FCST CONCERN WL BE TIMING OF PCPN AHEAD
OF A CDFNT ON WED.

THE 19Z MSAS SFC ANALYSIS SHOWED HI PRES OVER SRN SECTIONS OF
ONTARIO AND QUEBEC WITH A SWD EXTENSION INTO NRN WI. A STRONG AREA
OF LOW PRES WAS SITUATED OVER W-CNTRL SD WITH A CDFNT OVER THE
CNTRL HI PLAINS. VSBL SATL IMAGERY INDICATED THE BACK EDGE OF THE
LOW CLOUDS FROM ROUGHLY MFI-AIG-SOUTH OF IMT. FARTHER WEST...A MIX
OF CLOUDS WERE OVER THE PLAINS/UPR MIDWEST AS LOW-LEVEL MOISTURE
STREAMED NWD FROM THE GULF.

ANY BREAKS IN THE CLOUD COVER SHOULD NOT LAST LONG AS LOW-LEVEL
MOISTURE LINGERS OVER THE REGION AND INCREASING MID/HI CLOUDS
AHEAD OF OUR NEXT WEATHER SYSTEM OVERSPREADS WI. THESE CLOUDS WL
HELP PREVENT TEMPS FROM REALLY DROPPING OFF TNGT WITH MINS TO
RANGE FROM THE UPR 30S N-CNTRL...TO THE MID 40S ALONG LAKE MI.

A STRONG SHORTWAVE TROF IS FCST TO PUSH ACROSS THE ROCKIES ON WED
AND HELP TO SHOVE A CDFNT EWD INTO THE UPR MS VALLEY BY 00Z THU.
PRECEDING THIS FNT...A 30 KT SW LOW-LEVEL JET WL BRING BOTH A
STEADY INCREASE IN ISEN LIFT AND GULF MOISTURE BACK INTO WI AND
HELP TO SET OFF SHWRS. THIS EXPECTED BAND OF PCPN IS PROGGED TO
REACH CNTRL WI AROUND MIDDAY AND ERN WI BY MID TO LATE AFTERNOON.
NOT QUITE SURE ABOUT THE THUNDER THREAT ACROSS CNTRL WI...BUT
KEPT AN ISOLATED POTENTIAL IN FCST AS THERE ARE SIGNS OF A LATE
DAY INCREASE IN INSTABILITY PARAMETERS. MAX TEMPS TO RANGE FROM
AROUND 60 DEGS N-CNTRL...TO THE MID 60S E-CNTRL WI.

.LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY
ISSUED AT 255 PM CDT TUE SEP 30 2014

THE MAIN CONCERNS DURING THIS PART OF THE FORECAST CONTINUE TO BE
PRECIPITATION CHANCES WEDNESDAY NIGHT THROUGH FRIDAY NIGHT. THERE
IS EVEN SOME CONCERN REGARDING PRECIPITATION TYPE IN NORTH CENTRAL
WISCONSIN ON FRIDAY NIGHT.

CHANCES FOR SHOWERS INCREASE FROM WEST TO EAST ACROSS THE AREA ON
WEDNESDAY NIGHT WITH THE APPROACH OF AN UPPER LEVEL SHORT WAVE AND
SURFACE FRONT. BUFKIT TIME/HEIGHT SECTION OF 12Z NAM AND 12Z GFS
INDICATED SOME ELEVATED CAPE SO HAVE A MENTION OF THUNDER AS
WELL. TEMPERATURES SHOULD BE WELL ABOVE NORMAL ON THURSDAY IN
SOUTHERLY FLOW AHEAD OF THE APPROACHING SYSTEMS BUT THE CHANCE FOR
SHOWERS INCREASES AS A SURFACE LOW...MOVING ALONG THE
FRONT...APPROACHES WISCONSIN. THE CHANCE FOR SHOWERS...AND
POSSIBLY SOME THUNDER...REMAINS HIGH ON THURSDAY EVENING BUT THERE
ARE NOTICEABLE DIFFERENCES AMONG THE MODELS AFTER 06Z FRIDAY. BOTH
THE 12Z ECMWF AND THE 12Z GEM-NH HAD A DRY SLOT MAKING ITS WAY INTO
CENTRAL WISCONSIN 06Z-12Z WHILE THE 12Z NAM...12Z GFS AND 15Z SREF
KEEP A SOLID AREA OF PRECIPITATION OVER THE AREA. SURFACE BASED
CAPE WAS STARTING TO SHOWING UP ON THURSDAY NIGHT ON 12Z NAM AND
12Z GFS IN BUFKIT...SO WOULD EXPECT A BETTER CHANCE FOR SOME
THUNDER. HAVE OPTED FOR THE WETTER FORECAST AND THIS AGREES WITH
THE FORECAST FOR SURROUNDING OFFICES.

THE SURFACE LOW WILL BE MOVING AWAY FROM THE STATE ON FRIDAY BUT
COLD CYCLONIC FLOW IS FORECAST TO CONTINUE BOTH AT THE SURFACE AND
ALOFT SO CHANCE POPS CONTINUE INTO FRIDAY NIGHT. TEMPERATURES IN
NORTH CENTRAL WISCONSIN GET COLD ENOUGH FOR THE POSSIBILITY OF
SOME LIGHT SNOW OR FLURRIES ON FRIDAY NIGHT. STILL A SLIGHT
CHANCE FOR SHOWERS IN SOME PART...OR PARTS...OF THE AREA PRETTY
MUCH THROUGH THE END OF THE FORECAST.

THOUGH HIGHS ON THURSDAY SHOULD BE WELL ABOVE NORMAL...THE SWITCH
TO NORTHWEST FLOW ALOFT AND NORTHERN SURFACE FLOW WILL RESULT IN
COLDER THAN NORMAL HIGH TEMPERATURES FROM FRIDAY INTO EARLY NEXT
WEEK.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1048 PM CDT TUE SEP 30 2014

IFR CEILINGS EXPECTED ACROSS MUCH OF THE AREA OVERNIGHT
WITH INCREASING CEILING HEIGHTS AFTER 15Z WEDNESDAY. RAIN MAY
ARRIVE DURING THE AFTERNOON HOURS IN CENTRAL AND NORTHCENTRAL
WISCONSIN. RAIN SHOWERS AND IFR CEILINGS AND VISIBILITIES LIKELY
WEDNESDAY NIGHT.

&&

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

$$

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






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