Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 031703
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1203 PM CDT THU SEP 3 2015

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND FRIDAY
ISSUED AT 324 AM CDT THU SEP 3 2015

MAIN FORECAST CONCERN IS PRECIPITATION CHANCES AS AN AREA OF HEAVY
RAIN TRACKS SOUTHWARD THROUGH THE CWA WITH THE POSSIBILITY OF
ADDITIONAL ACTIVITY OUT TO THE WEST THIS AFTERNOON AND TONIGHT
WITH A LINGERING BOUNDARY.

A PERUSAL OF THE HI-RES MODELS DOES NOT YIELD TOO MUCH IN THE WAY
OF HELP IN THE SHORT TERM AS THE NAM SEEMS TO BE THE ONLY USEFUL
MODEL IN THE INITIAL PLACEMENT OF THE CURRENT AREA OF SHOWERS AND
THUNDERSTORMS ACROSS NORTHEAST WISCONSIN. THIS ACTIVITY IS
ASSOCIATED WITH A SHORTWAVE TROUGH SEEN ON WATER VAPOR IMAGERY
OVER NORTHEAST WISCONSIN. THIS SHORTWAVE IS EXPECTED TO TRACK EAST
OF THE AREA DURING THE MORNING HOURS...TAKING THE SHOWERS AND
THUNDERSTORMS WITH IT. SOME PATCHY DENSE FOG IS POSSIBLE THIS
MORNING AS THE COMPLEX HEADS EAST...MAINLY ACROSS CENTRAL AND
NORTH CENTRAL WISCONSIN WHERE SOME CLEARING IS EXPECTED BEFORE
SUNRISE. WILL HANDLE ANY FOG WITH SPECIAL WEATHER STATEMENTS.

THIS COMPLEX HAS LAID OUT A WEAK SURFACE BOUNDARY ACROSS CENTRAL
WISCONSIN...WHICH WILL REMAIN OVER THE WESTERN CWA DURING THE
AFTERNOON HOURS WHILE INSTABILITY BUILDS TO THE WEST OF THE
BOUNDARY AS MUCAPES RISE TO 2000 TO 3000 J/KG DURING THE AFTERNOON
HOURS. TWO SEPARATE SHORTWAVES ARE ON TRACK TO TRAVEL THROUGH THE
WESTERN GREAT LAKES THIS AFTERNOON AND THIS EVENING IN THE
VICINITY OF THE AFOREMENTIONED SURFACE BOUNDARY. ALTHOUGH THE NAM
DOES NOT LIGHT THIS BOUNDARY UP UNTIL THE SECOND SHORTWAVE TRACKS
THROUGH THIS EVENING...THE PRESENCE OF THE SURFACE BOUNDARY AND
INSTABILITY DESERVE A MENTION OF LOW CHANCY POPS ACROSS THE
WESTERN CWA THIS AFTERNOON. WITH A VERY WEAK WIND FIELD IN PLACE
THESE STORMS ARE EXPECTED TO BE SUB SEVERE THIS AFTERNOON AND THIS
EVENING. FOG IS AGAIN EXPECTED DURING THE OVERNIGHT HOURS GIVEN
THE RECENT RAINS...LIGHT WINDS AND BREAKS IN THE CLOUD COVER.

YET ANOTHER SHORTWAVE WILL TRACK THROUGH THE WESTERN GREAT LAKES
FRIDAY AFTERNOON AS MUCAPES RISE TO 1000 TO 2000 J/KG. HOWEVER A
LAYER OF WARM AIR AROUND 800 MB WILL MAKE CONVECTION LESS LIKELY
THAN TODAY...THEREFORE WILL STAY WITH A SLIGHT CHANCE POP GIVEN
THE CAP IN PLACE.

CLOUDS CURRENTLY IN PLACE ACROSS THE WESTERN GREAT LAKES WILL
EVENTUALLY ERODE FROM WEST TO EAST...ALLOWING DAYTIME HIGHS TO GET
INTO THE LOWER TO MIDDLE 80S DURING THE AFTERNOON HOURS. A VERY
WARM AIRMASS WILL REMAIN OVER THE REGION TONIGHT...WITH LOWS
STAYING IN THE LOWER TO MIDDLE 60S. DAYTIME HIGHS ON FRIDAY WILL
AGAIN BE SIMILAR TO TODAY...WITH HIGHS IN THE LOWER TO MIDDLE 80S
EXPECTED AWAY FROM THE GREAT LAKES.

.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 324 AM CDT THU SEP 3 2015

500MB RIDGE OVER THE CENTRAL UNITED STATES WILL FLATTEN BY EARLY
NEXT WEEK...THEN A SHIFT IN THE PATTERN IS EXPECTED AS 500MB
RIDGE BUILDS ACROSS THE EASTERN PACIFIC OCEAN/WEST COAST
OF NORTH AMERICA WITH 500MB TROUGHING ACROSS THE CENTRAL
PORTIONS OF THE UNITED STATES AND SOUTHERN CANADA.
ABOVE NORMAL TEMPERATURES SHOULD RETURN CLOSER TO NORMAL BY
THE MIDDLE OF NEXT WEEK.

MAIN CONCERN TONIGHT IS THE SMALL CHANCES OF THUNDERSTORMS FRIDAY
NIGHT AND SATURDAY. FOR FRIDAY NIGHT...WEAK WARM FRONT LIFTS
NORTHWARD WITH A FEW MODELS DEPICTING SOME LIGHT QPF AMOUNTS.
VERY WARM AND HUMID CONDITIONS SHOULD PREVAIL ON SATURDAY.
BUFKIT SOUNDINGS INDICATED 1500 TO 2500 J/KG OF CAPE WITH LITTLE
CIN. HAVE SMALL CHANCES OF THUNDERSTORMS ON SATURDAY. ANY STORM
COULD PRODUCE GUSTY WINDS AND LOCALLY HEAVY RAINFALL. LATER SHIFTS
MAY NEED TO INCREASE RAIN CHANCES.

THE BEST CHANCE OF THUNDERSTORMS WILL LATE SUNDAY AFTERNOON INTO
MONDAY MORNING AS COLD FRONT MOVES SLOWLY THROUGH THE REGION.
WIDESPREAD SEVERE WEATHER IS NOT EXPECTED AT THIS TIME. THE LATEST
ECMWF WOULD SUGGEST ENOUGH LINGERING MOISTURE FOR A SMALL CHANCE
OF STORMS ACROSS EAST-CENTRAL WISCONSIN MONDAY AFTERNOON. HIGH
PRESSURE WILL THEN DOMINATE THE WEATHER PATTERN MONDAY NIGHT INTO
TUESDAY MORNING. SOME TIMING DIFFERENCES NOTED OF THE ARRIVAL OF
THE NEXT SYSTEM TUESDAY AFTERNOON INTO TUESDAY NIGHT. LATER SHIFTS
CAN FINE TUNE THE DETAILS ON THE TIMING OF THIS SYSTEM.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1059 AM CDT THU SEP 3 2015

CLOUDS TODAY HAVE BEEN SLOW TO DISSIPATE IN THIS VERY MOIST
AIRMASS. EXPECT THE CURRENT IFR TO MVFR CLOUD COVER TO GRADUALLY LIFT
THIS AFTERNOON...WITH THE BEST IMPROVEMENT IN CENTRAL AND NORTHERN
WISCONSIN TODAY. THERE IS ALSO A SLIGHT CHANCE FOR SHOWERS AND
THUNDERSTORMS THIS AFTERNOON AND THIS EVENING OVER THE EASTERN TAF
SITES...HOWEVER COVERAGE WILL BE ISOLATED.

FOG WILL AGAIN BE POSSIBLE TONIGHT AS PARTLY CLOUDY SKIES WILL
COMBINE WITH LIGHT WINDS. MUCH LIKE THE PAST FEW DAYS...IFR
CONDITIONS CAN BE EXPECTED LATE TONIGHT INTO FRIDAY MORNING BEFORE
CONDITIONS IMPROVE INTO THE DAY FRIDAY.

&&

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

$$

SHORT TERM.....KURIMSKI
LONG TERM......ECKBERG
AVIATION.......ALLEN


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