432
FXUS63 KGRB 041103
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
603 AM CDT MON MAY 4 2026
UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE
KEY MESSAGES
- WARM AND BREEZY TODAY WITH LOWER RH VALUES. 60-90% CHANCE OF
WIND GUSTS 35 TO 40 MPH CENTRAL TO EASTERN WI. ELEVATED FIRE
WEATHER CONDITIONS WHERE FINE FUELS HAVE DRIED OUT AND GREEN UP
IS NOT AS ADVANCED.
- BAND OF SHOWERS AND STORMS (20-40% CHANCE) DEVELOPS MID TO LATE
AFTERNOON, ESPECIALLY SOUTHERN FOX VALLEY TO THE LAKESHORE.
STRONGER STORMS COULD PRODUCE WIND GUSTS 40-50 MPH.
- TEMPERATURES FALL BELOW NORMAL FOR THE REST OF THE WEEK. RISK
FOR FROST/FREEZE HEADLINES RAMPS UP BEGINNING TUESDAY NIGHT.
DISCUSSION
ISSUED AT 204 AM CDT MON MAY 4 2026
BREEZY AND WARM TODAY WITH ELEVATED FIRE WEATHER CONDITIONS. ALSO,
STILL A SMALL CHANCE OF SOME SHOWERS AND STORMS, ESPECIALLY LATER
IN THE AFTERNOON. COOLER FOR THE REST OF THE WEEK, WITH FROST/FREEZE
HEADLINES LIKELY NEEDED MULTIPLE NIGHTS.
ELEVATED FIRE WEATHER CONDITIONS TODAY: COLD FRONT OVER NORTHERN
MN ARRIVES LATE TODAY. AHEAD OF THE FRONT, ANOTHER WARM AND BREEZY
DAY IS EXPECTED TODAY. HIGHS WILL REACH THE LOWER TO MIDDLE 70S
WHERE CLOUDS WILL NOT BE AS PREVALENT EARLY ON (NORTH-CENTRAL).
THAT WILL HAVE TO BE MONITORED THOUGH AS IT WILL BE GUSTY THERE AS
WELL WITH LOW RH VALUES. BASED ON DEEP MIXING, WIND GUSTS SHOULD
REACH 35 TO 40 MPH, WITH EVEN ISOLATED HIGHER GUSTS LATE MORNING
THROUGH MID AFTERNOON. STRONGEST WINDS WILL BE FROM CENTRAL TO
EASTERN WI (60-90% CHANCE OF GUSTS OVER 35 MPH). CONDITIONS WILL
BE MOST FAVORABLE FOR FIRE SPREAD WHERE GREEN UP IS NOT QUITE AS
ADVANCED, BUT WITH THE GUSTY WINDS AND WARM TEMPS (10-15 ABOVE
CLIMO), HAVE ISSUED AN SPS FOR ALL AREAS EXCEPT NORTH-CENTRAL.
SHOWER AND STORM POTENTIAL THIS AFTERNOON: DRY AIRMASS WILL IMPACT
POTENTIAL FOR SHOWERS AND STORMS MID TO LATE AFTERNOON. UPSTREAM
SOUNDINGS AT OMAHA, DAVENPORT ARE QUITE DRY, SO EVEN WITH THE
FRONT MOVING IN DURING PEAK HEATING, DRY AIR AND SOME EVIDENCE OF
CAPPING UP TO H7 LOOKS TO LIMIT CONVECTIVE POTENTIAL. USED GRADIENT
OF MLCAPE (UP TO 400J/KG) AS GUIDE AND PLACED NARROW RIBBON OF
CHANCE POPS FROM SOUTHERN FOX VALLEY TO THE LAKESHORE. A FEW
SHOWERS COULD OCCUR NORTHWEST OF THIS AREA, BUT THIS IS WHERE
THUNDER IS MOST FAVORED. GIVEN WINDS ALOFT AND INVERTED-V LOOK TO
SOUNDINGS, IF A STORM DEVELOPS, GUSTY WINDS 40-50 MPH WOULD BE IN
PLAY. HONESTLY, GIVEN THE WINDS ALOFT, EVEN A MORE DEVELOPED
SHOWER COULD PULL DOWN SIMILAR WIND GUSTS THIS AFTERNOON. WILL BE
A NEAR TERM FORECAST ITEM FOR DAYSHIFT TO KEEP TABS ON. ANY
SHOWERS QUICKLY END EARLY THIS EVENING AND IT WILL BE A BIT
BREEZY BEHIND THE FRONT AS WELL AS COOLER AIR BEGINS TO ARRIVE.
COOLER WITH FROST/FREEZE POTENTIAL REST OF THE WEEK: SMALL CHANCES
FOR A FEW SHOWERS OR SPRINKLES CANNOT BE RULED OUT TUE OR WED OVER
NORTHERN WI. BETTER CHANCES STILL IN FORECAST FOR THURSDAY ALL
AREAS AS STRONGER WAVE CROSSES THE REGION. MAY BE JUST COLD ENOUGH
FOR SOME GRAUPEL OR SNOWFLAKES TO MIX WITH THE SHOWERS THAT DAY,
AT LEAST DURING THE MORNING. FROST/FREEZE POTENTIAL HIGHEST TUESDAY
NIGHT THROUGH THURSDAY NIGHT, AND MAYBE ON FRIDAY NIGHT AS WELL.
RIGHT NOW, APPEARS THAT GREATER FROST POTENTIAL IS SETTING UP
MORE WEST OF THE FOX VALLEY AND LAKESHORE. DAYTIME TEMPERATURES
WILL MAINLY BE IN THE 50S, THOUGH HIGHS LIKELY STAY IN THE 40S
OVER THE FAR NORTH. TEMPERATURES WILL BEGIN TO REBOUND TO AROUND
CLIMO STARTING NEXT WEEKEND.
AVIATION
FOR 12Z TAF ISSUANCE
ISSUED AT 602 AM CDT MON MAY 4 2026
MAIN CONCERN THROUGH THIS AFTERNOON ARE THE SFC WINDS. LLWS STARTS
THE TAF PERIOD AT ALL SITES WITH 45-50KT LOW-LEVEL JET 1-3K AGL.
INCREASING MIXING BY MID MORNING WILL THEN RESULT IN GUSTS 25-35
KTS MAKING IT TO THE SFC AND THE CEASING OF THE LLWS. CONDITIONS
WILL REMAIN VFR WITH SCATTERED MID CLOUDS DRIFTING ACROSS. REGIONAL
RADAR DOES SHOW A FEW ENHANCED ECHOES OVER NORTHWEST WI, SO A BRIEF
LIGHT SHOWER OR SPRINKLE COULD OCCUR AT RHI EARLY THIS MORNING
(12-14Z) BUT CHANCE IS LESS THAN 20% AND THUS FAR NOTHING IS
REACHING THE GROUND DUE TO DRY AIR IN LOW-LEVELS.
LATE THIS AFTERNOON AS A COLD FRONT APPROACHES, SCATTERED SHOWERS
(20-40% CHANCE) AND PERHAPS A THUNDERSTORM WILL DEVELOP
ESPECIALLY FROM THE SOUTHERN FOX VALLEY TO THE LAKESHORE
(INCLUDING MTW) AND POINTS SOUTH. IF A STRONGER STORM OCCURS, WIND
GUSTS OVER 40 KTS WOULD BE POSSIBLE GIVEN STRONG WINDS ALOFT AND
AN INVERTED-V TYPE SOUNDING PROFILE.
FOR TONIGHT, AS WINDS SHIFT TO THE WEST-NORTHWEST EXPECT GUSTY
WINDS TO PERSIST IN THE THIS EVENING. WINDS WILL GRADUALLY SUBSIDE
OVERNIGHT. CONDITIONS WILL REMAIN VFR.
GRB WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION.....JLA
AVIATION.......JLA
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