Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 241134
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
634 AM CDT MON AUG 24 2015

UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND TUESDAY
ISSUED AT 338 AM CDT MON AUG 24 2015

MINOR PCPN CHANCES...TEMPERATURES AND WINDS WILL BE THE MAIN FCST
CONCERNS.

THE UPPER LOW OVER SW ONTARIO WILL DRIFT EAST ACROSS SOUTHERN
ONTARIO AND NORTHERN LAKE SUPERIOR OVER THE NEXT TWO DAYS. S/W
TROFS WILL ROTATE AROUND THE UPPER LOW...AND IMPACT FAR NORTHERN
WI ROUGHLY EVERY 12 HOURS. THIS WILL KEEP SCT LIGHT SHOWERS AND
CLOUD COVER IN THE FCST...ESPECIALLY OVER NORTH CENTRAL AND FAR
NE WI...THOUGH A GRADUAL DECREASE IN SHOWERS IS EXPECTED BY
TUESDAY AFTERNOON.

CAA WILL CAUSE H8 TEMPS TO DROP TO +2 TO +4 C THIS AFTERNOON...
SO HIGH TEMPS WILL BE WELL BLO NORMAL...IN THE LOWER TO MID 50S
NW TO THE LOWER TO MIDDLE 60S SOUTHEAST. DAYTIME MIXING WILL
CAUSE STG WINDS (25-35 KTS) ALOFT TO REACH THE SFC...RESULTING
IN GUSTS TO 30 MPH OR A LITTLE HIGHER. EXPECT A DIURNAL INCREASE
IN CLOUD COVER.

USED A BLEND OF THE BETTER PERFORMING GUIDANCE SETS FOR TEMPS
TONIGHT AND TUESDAY...WITH LOWS IN THE UPPER 40S AND LOWER 50S
ANTICIPATED TONIGHT...AND HIGHS IN THE UPPER 50S AND 60S EXPECTED
ON TUESDAY.

.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY
ISSUED AT 338 AM CDT MON AUG 24 2015

THE MEAN FLOW BECOMES RATHER STAGNANT (BLOCKY) INTO NEXT WEEKEND
WITH UPR RIDGING OVER THE ERN PACIFIC...A NEARLY CLOSED UPR LOW
OFF THE WEST COAST AND A WEAK UPR RDG OVER THE ROCKIES. EVEN TO
THE EAST...SYTEMS WL BE SLOW MOVERS WITH A LONGWAVE TROF
IMPACTING ERN NOAM AND AN UPR RDG OVER GREENLAND. FOR NE WI...THIS
WL TRANSLATE TO A DRY MID-WEEK BEFORE A SHORTWAVE TROF AND MODEST
SFC REFLECTION MOVE INTO THE GREAT LAKES FRI NGT INTO SAT. TEMPS
ARE FCST TO START NEAR NORMAL AND THEN WARM TO ABOVE NORMAL LEVELS
FROM FRI ONWARD.

THE STUBBORN...SLOW-MOVING...NEARLY VERTICALLY-STACKED SYSTEM
FINALLY BEGINS TO PULL FAR ENUF AWAY TO ALLOW AN AREA OF HI PRES
TO BEGIN BUILDING TOWARD THE WRN GREAT LAKES. CLOUDS SHOULD
GRADUALLY DISSIPATE ACROSS CNTRL WI DURING THE NGT...WHEREAS ERN
WI MAY STILL BE DEALING WITH CLOUDS THRU THE NGT. NW WINDS TO ALSO
DIMINISH TO AROUND 5 MPH (EXCEPT DOOR CNTY)...THUS TEMPS SHOULD BE
ABLE TO DROP OFF ACROSS CNTRL WI. LOOK FOR MIN TEMPS TO RANGE FROM
THE MID TO UPR 40S NORTH...MAINLY IN THE 50-55 DEG RANGE SOUTH.

THIS SFC HI TO DRIFT ACROSS WI ON WED AND WL BE ABLE TO PROVIDE
FOR MOSTLY SUNNY SKIES...LIGHT WINDS AND A NOTICEABLE UPTICK IN
TEMPS. READINGS ARE EXPECTED TO BE IN THE MID TO UPR 60S NORTH/
LAKESHORE (AS WINDS TURN ONSHORE)...TO AROUND 70 DEGS CNTRL/
E-CNTRL WI.

MODELS TAKE THE SFC HI EWD TOWARD THE CENTER OF THE GREAT LAKES
REGION WED NGT AND WL CONT TO BE THE MAIN FOCAL POINT FOR QUIET
WEATHER CONDITIONS ACROSS THE REGION. MOSTLY CLEAR SKIES AND LIGHT
WINDS SHOULD PROVIDE FOR FAVORABLE RADIATIONAL COOLING TO TAKE
PLACE AND THIS WL ALLOW FOR TEMPS TO LIKELY FALL TO THE COOLEST OF
THE EXTENDED PERIOD. MIN TEMPS TO RANGE FROM THE LWR TO MID 40S
NORTH...UPR 40S TO LWR 50S CNTRL/E-CNTRL WI AND MID 50S NEAR LAKE
MI (DOOR CNTY). AS THE SFC HI SLIPS FARTHER EAST TOWARD THE ERN
GREAT LAKES ON THU...RETURN FLOW SETS UP OVER WI AS WINDS VEER
AROUND TO THE S-SW OVER CNTRL WI AND S-SE OVER ERN WI. PLENTIFUL
SUNSHINE COMBINED WITH WEAK WAA...WL ALLOW FOR ANOTHER BUMP UP IN
TEMPS AS READINGS TOP OUT IN THE LWR 70S NORTH AND LAKESHORE...MID
70S OVER CNTRL/E-CNTRL WI.

ATTENTION THEN SHIFTS TO THE WEST WHERE THE MODELS INDICATE A
SHORTWARE TROF TO AROUND THE TOP OF THE ROCKIES UPR RDG AND HEAD
TOWARD THE UPR MS VALLEY THU NGT. AFTER A MOSTLY CLEAR EVENING...
ANTICIPATE AT LEAST AN INCREASE IN MID OR HI CLOUDS INTO CNTRL WI
DURING THE OVRNGT HOURS. THIS SHORTWAVE TROF IS PROGGED TO MOVE
INTO THE WRN GREAT LAKES ON FRI...ACCOMPANIED BY A WEAK AREA OF
LOW PRES OVER THE MIDWEST AND SOME SEMBLANCE OF AN INVERTED SFC
TROF INTO AT LEAST SW WI. INSTABILITY IS PRACTICALLY NON-EXISTENT
AND MID-LEVEL FORCING IS AVERAGE AT BEST...THUS HARD TO GET TOO
EXCITED ABOUT THUNDER PROSPECTS. HAVE KEPT POPS FAIRLY LOW ON FRI
AND TRIED TO MINIMIZE THE THUNDER POTENTIAL. MAX TEMPS ON FRI WL
BE AT OR ABOVE NORMAL FOR LATE AUGUST.

THE CHCS FOR PCPN WL CONT THRU FRI NGT INTO SAT MORNING AS THE
SYSTEM SLOWLY TRACKS TO THE EAST. MODELS SHOW THE UPR TROFFING OFF
THE WEST COAST TO MOVE CLOSER TO THE WRN CONUS ON SAT WHICH ALLOWS
THE DOWNSTREAM UPR RDG AXIS TO SHIFT FROM THE ROCKIES INTO THE
CNTRL CONUS. RISING UPR HEIGHTS WL PUSH TOWARD WI WHICH WOULD HELP
TO END THE PCPN THREAT BY SAT AFTERNOON. TIMING IS NOT A SURE
THING AT THIS RANGE...THUS HAVE KEPT GENERIC LOW POPS IN THE FCST
FOR SAT.

THERE IS SOME MODEL DISAGREEMENT HEADED TOWARD THE END OF THE
UPCOMING WEEKEND WITH REGARDS TO THE STAYING POWER OF THIS UPR
RDG. THE GFS WEAKENS THE RDG ON SUNDAY AS A MODEST SHORTWAVE TROF
MOVES ACROSS THE NRN TIER OF STATES. THE ECMWF IS STRONGER WITH
THE UPR RDG AND KEEPS ANY SHORTWAVE TROFS WELL TO OUR WEST. PREFER
TO KEEP THE FCST DRY FOR NOW UNTIL THIS PICTURE BECOMES MORE
CLEAR. TEMPS THIS WEEKEND SHOULD BE ABOVE NORMAL WITH SOME
LOCATIONS SURPASSING THE 80 DEG MARK.
&&

.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 628 AM CDT MON AUG 24 2015

HAVE ADDED A FEW HOURS OF LLWS TO THE GRB/ATW/MTW TAFS EARLY
THIS MORNING...AS WEST WINDS QUICKLY INCREASE TO 35 KTS JUST
ABOVE THE SFC.

AN UPPER LEVEL DISTURBANCE WILL CONTINUE TO BRING SCATTERED
SHOWERS AND MVFR CONDITIONS TO NORTH CENTRAL AND FAR NORTHEAST
WI THROUGH THE TAF PERIOD. VFR CONDITIONS SHOULD PREVAIL AT
GRB/ATW/MTW. WEST WINDS WILL GUST TO 25 TO 30 KTS AGAIN LATER
THIS MORNING AND AFTERNOON.

CIGS MAY LOWER TO IFR IN THE FAR NORTH...INCLUDING THE RHI
TAF SITE...LATE TONIGHT.
&&

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

$$

SHORT TERM.....KIECKBUSCH
LONG TERM......KALLAS
AVIATION.......KIECKBUSCH



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