Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 011131
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
631 AM CDT MON SEP 1 2014

UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND TUESDAY
ISSUED AT 318 AM CDT MON SEP 1 2014

LINE OF CONVECTION WHICH DEVELOPED OVER MINNESOTA AND IOWA SUNDAY
EVENING ALONG AND AHEAD OF A COLD FRONT HAS DIMINISHED MOVING
INTO WISCONSIN EARLIER THIS MORNING. RADAR TRENDS SUGGEST THE
FOCUS OF THE CONVECTION THIS MORNING WILL FIRST BE OVER THE
NORTHWEST HALF OF THE STATE AS THE SHORT WAVE TROUGH AND INITIALLY
AN UPPER JET COUPLET THEN LFQ REGION OF THE UPPER JET LIFTS OVER
NORTHWEST WISCONSIN INCLUDING NORTH CENTRAL WISCONSIN. FOCUS OF
HEAVY RAINFALL WILL LIKELY BE OVER FAR NORTHWEST WISCONSIN THIS
MORNING. WILL NEED TO DIMINISH POPS ELSEWHERE FOR A PORTION OF
THE EARLY MORNING HOURS AS PER RADAR TRENDS BUT CANNOT COMPLETELY
REMOVE DUE TO AVAILABLE INSTABILITY IN THE WARM SECTOR AND LIKELY
SOME SHEAR AVAILABLE. OTHERWISE WILL FOCUS ON CONVECTION POTENTIAL
AS THE FRONT PASSES OVER FOR THE SECOND ROUND AS MU CAPES APPROACH
1200 LATE MORNING INTO THE AFTERNOON OVER CENTRAL AND NORTHEAST
WISCONSIN. AT 08Z STORMS WERE ALREADY REDEVELOPING NEAR THE FROPA
OVER MINNESOTA AND CENTRAL IOWA EARLY THIS MORNING AND PROGRESSING
EASTWARD WITH THE FRONT REACHING WESTERN WISCONSIN TOWARD
DAYBREAK. SPC SLIGHT REMAINS MAINLY SOUTH OF THE AREA TODAY SO
WILL CONTINUE TO LEAVE OUT SEVERE WORDING IN THE MORNING HWO.

WILL CONTINUE TO LINGER A SMALL MENTION OF PCPN OVER FAR EASTERN
AREAS THIS EVENING UNTIL THE FRONTAL PCPN CLEARS OUT. WITH PARTIAL
CLEARING POSSIBLE TONIGHT...THREAT OF FOG LATE TONIGHT. SOME
MODELS KEEPING SOME MID LEVEL MOISTURE AROUND SO CLOUDS MAY AID
WITH PREVENTING WIDESPREAD DENSE FOG FOR THE TUESDAY MORNING
HOURS FOR THE START OF MOST SCHOOLS TUESDAY.

EVEN THOUGH THE SURFACE FRONT IS WELL SOUTH ON TUESDAY AND WEAK
HIGH PRESSURE SETTLING...STILL SOME SUPPORT THIS MORNING TO KEEP A
SMALL CHANCE OF SHOWERS. BROAD UPPER TROUGH REMAINS WITH COLDER
AIR ALOFT TO THE NORTH. WV LOOPS ALSO SUGGEST A SUBTLE SHORT WAVE
CURRENTLY OVER NORTHWEST WYOMING AND SOUTHERN MONTANA AND TRACKING
EASTWARD. FORECAST SOUNDINGS STILL INDICATE SOME MID LEVEL
MOISTURE AND INSTABILITY IN THE WESTERLY FLOW AND A UPPER JET
SLIDING NORTH AS THE UPPER HEIGHTS GRADUALLY BUILDING LATE IN THE
DAY. WILL ADD A DIURNAL TREND TO THE SHOWERS AND MAY CONSIDER
ADDING A SMALL MENTION OF TSRA FOR THE AFTERNOON HOURS.

.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY
ISSUED AT 318 AM CDT MON SEP 1 2014

MDLS ARE IN GENERAL AGREEMENT THAT A SUBTROPICAL RDG WL DOMINATE
THE SRN CONUS THRU THE FCST PERIOD. A POSITIVE-TILTED UPR TROF
INITIALLY FROM HUDSON BAY TO THE PACIFIC NW IS EXPECTED TO BREAK
OFF WITH THE NRN PART OF THE TROF MOVING FROM THE NRN PLAINS THU
TO ONTARIO ON FRI. A FRONTAL BOUNDARY PRECEDING THIS UPR TROF WL
BRING THE NEXT CHC OF PCPN TO NE WI DURING THE LATE WED THRU FRI
TIME FRAME. HI PRES IS THEN FCST TO BUILD INTO THE REGION FOR NEXT
WEEKEND WITH TEMPS FALLING BELOW NORMAL.

WEAK SFC HI TO DRIFT EAST TOWARD THE ERN GREAT LAKES/OHIO RIVE
VALLEY TUE NGT BRINGING A RETURN FLOW TO WI. WHILE A STRAY SHWR
CANNOT BE COMPLETELY RULED OUT TUE EVENING ASSOCIATED WITH THE
DEPARTED SHORTWAVE TROF...NOT CONFIDENT ENUF TO ADD TO THE FCST AS
FORCING/LIFT/INSTABILITY PRACTICALLY NON-EXISTENT. THUS...HAVE
KEPT TUE NGT DRY WITH SKY CONDITIONS BECOMING AT LEAST PARTLY
CLOUDY. MIN TEMPS TO RANGE FROM THE LWR TO MID 50S NORTH...MID TO
UPR 50S SOUTH.

PREVAILING S-SW WINDS TO BRING INCREASING LOW-LEVEL MOISTURE INTO
WI ON WED WITH DEW POINTS CLIMBING INTO THE LWR TO MID 60S AND PW
VALUES SURPASSING 1.5" BY 00Z THU. AS THIS OCCURS...A WRMFNT IS
EXPECTED TO LIFT NEWD INTO AT LEAST SRN WI AND ACT AS A FOCUS FOR
SHWR/TSTM ACTIVITY. STRONGER WAA/THETA-E ADVECTION TO TAKE PLACE
OVER THE WRN HALF OF WI...THUS CHC POPS PLACED OVER N-CNTRL WI...
SCALING DOWN TO NIL POPS FOR ERN WI. DESPITE THE INCREASE IN
CLOUDS...MAX TEMPS SHOULD BE ABLE TO REACH THE 75-80 DEG RANGE
OVER THE NORTH AND LAKESHORE...LOWER 80S ACROSS THE SOUTH.

BETTER CHCS FOR SHWRS/TSTMS ARRIVE WED NGT AS THE WRMFNT LIFTS
NORTH THRU THE REST OF WI. INSTABILITY STEADILY INCREASES THRU THE
NGT WITH MDLS SHOWING MODERATE TO STRONG SHEAR AND A FAVORABLE JET
STRUCTURE ADDITIONAL LIFT. MAY NEED TO RAISE POPS INTO THE LIKELY
CATEGORY BASED ON THE ABOVE-MENTIONED FACTORS PLUS THE STRENGTH OF
THE WAA. A MILD AND MUGGY NGT CAN BE EXPECTED WITH MIN TEMPS IN
THE LWR TO MID 60S NORTH...MID TO UPR 60S SOUTH. MDLS ARE IN FAIR
AGREEMENT IN MOVING THE SHORTWAVE TROF ACROSS S-CNTRL CANADA/NRN
PLAINS ON THU WITH A CDFNT DRIVING TOWARD THE WRN GREAT LAKES.
WHILE BETTER MID-LEVEL FORCING TO BE LOCATED TO OUR NORTH...BETTER
INSTABILITY TO BE SITUATED OVER WI WITH CAPES RISING TO > 2K J/KG
AND LI`S DOWN TO AT LEAST -6. HAVE KEPT MODERATE TO HI CHC POPS IN
THE FCST FOR NOW AND WL WAIT TO NAIL THE TIMING OF THE CDFNT
BEFORE RAISING POPS HIGHER. THU COULD CONCEIVABLY BE THE WARMEST/
MOST HUMID DAY OF THE EXTENDED FCST WITH MAX TEMPS IN THE UPR 70S
TO LWR 80S NORTH...MID 80S OVER CNTRL WI AND DEW POINTS EITHER IN
THE UPR 60S OR LWR 70S.

THE CDFNT IS PROGGED TO SWEEP THRU NE WI THU NGT...THEREFORE A
CONTINUATION OF POPS ARE NECESSARY. TOO EARLY TO DETERMINE THE
STRENGTH OF THESE TSTMS THU INTO THU NGT...BUT GIVE THE
INSTABILITY AND SHEAR FCST TO BE IN PLACE...WE WL HAVE TO MONITOR
THE SITUATION IN THE COMING DAYS. IMPROVING CONDITIONS EXPECTED ON
FRI AS THE CDFNT EXITS TO THE SE AND HI PRES BUILDS EWD FROM THE
UPR MS VALLEY. HAVE KEPT A TOKEN POP IN THE FCST OVER E-CNTRL WI
INTO THU NGT...BUT BELIEVE A GRADUAL DECREASE IN CLOUDS WL TAKE
PLACE AS COOLER/DRIER AIR MOVES INTO WI.

THIS AREA OF HI PRES TO SETTLE OVER THE GREAT LAKES FOR NEXT
WEEKEND AND BRING A SOMEWHAT COOL...BUT PLEASANT STRETCH OF
WEATHER TO THE REGION. TEMPS TO BE A BIT BELOW NORMAL FOR BOTH SAT
AND SUNDAY.
&&

.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 631 AM CDT MON SEP 1 2014

MAINLY A BAND OF MVFR CIGS WITH SHOWERS WILL SWEEP FROM WEST TO
EAST OVER THE STATE ALONG AND NEAR A COLD FRONT. SCATTERED IFR
CIGS ALONG WITH ISOLATED STORMS CAN ALSO BE EXPECTED WITH THIS
BAND OF SHOWERS DURING THE COLD FRONT PASSAGE. A PERIOD OF LLWS
CONDITIONS WILL CONTINUE UNTIL FROPA.

SHOWERS AND STORMS WILL END FROM WEST TO EAST THIS AFTERNOON
FOLLOWED WITH VFR CONDITIONS LATER THIS AFTERNOON AND INTO
TONIGHT. PARTIAL CLEARING SKIES AND AREAS OF CALMING WINDS MAY
PRODUCE POCKETS OF MVFR/IFR FOG LATE TONIGHT.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
BEACH HAZARDS STATEMENT THROUGH THIS EVENING FOR WIZ022-040-050.
&&

$$

SHORT TERM.....TDH
LONG TERM......KALLAS
AVIATION.......TDH






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