583
FXUS63 KGRB 011737
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1237 PM CDT TUE JUL 1 2025
UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE
KEY MESSAGES
- DRY WEATHER EXPECTED THROUGH WEDNESDAY MORNING.
- TEMPERATURES WILL BE ABOVE NORMAL THROUGH THE WEEK, WITH VERY
WARM AND HUMID CONDITIONS ARRIVING FOR THE 4TH OF JULY.
- SHOWERS AND THUNDERSTORMS EXPECTED AT TIMES FROM WEDNESDAY
AFTERNOON THROUGH MUCH OF THE HOLIDAY WEEKEND. THE GREATEST
RAIN CHANCES OCCUR ON SATURDAY.
DISCUSSION
ISSUED AT 355 AM CDT TUE JUL 1 2025
THE SHORT-WAVE AND ASSOCIATED WEAK SURFACE TROUGH THAT PRODUCED
SCATTERED THUNDERSTORMS YESTERDAY AFTERNOON/EVENING HAVE SHIFTED
EAST OF THE REGION, LEAVING MOSTLY CLEAR SKIES ACROSS GRB CWA
EARLY THIS MORNING. HAVE BEEN WATCHING FOR FOG DEVELOPMENT, AS
SEVERAL SITES IN NORTHERN WI HAVE SURFACE RHS AT OR NEAR 100
PERCENT, BUT BOUNDARY LAYER WINDS OF 20 TO 25 KNOTS AND WESTERLY
SURFACE WINDS AROUND 5 KNOTS WERE APPARENTLY PROVIDING JUST ENOUGH
MIXING TO PREVENT DEVELOPMENT.
SUBSIDENCE/DRYING IN THE WAKE OF THE SHORT-WAVE AND THE ARRIVAL
OF A WEAK RIDGE OF HIGH PRESSURE WILL KEEP THE REGION DRY TODAY
AND TONIGHT, AND LIKELY THROUGH MUCH OF WEDNESDAY MORNING.
THUNDERSTORM CHANCES MID-WEEK THROUGH NEXT WEEKEND: ZONAL FLOW
WILL PERSIST THROUGH WEDNESDAY, WITH A WEAK SHORT-WAVE EXPECTED TO
BRUSH THROUGH NORTHERN WI DURING THE AFTERNOON. A WEAK CONVERGENCE
ZONE IS ALSO EVIDENT OVER MENOMINEE COUNTY MI AND FAR NE WI DURING
THE AFTERNOON. SBCAPE IS EXPECTED TO INCREASE TO 1-2K J/KG DURING
THE AFTERNOON, ALONG WITH DEEP LAYER SHEAR OF 25-40 KNOTS,
STRONGEST IN NORTHERN WI. SPC HAS OUTLOOKED MUCH OF WISCONSIN
FOR A MARGINAL RISK OF SEVERE, BUT FEEL THAT THE MAIN THREAT
WOULD BE ACROSS NORTHERN WI, WHERE THE BETTER FORCING AND SHEAR
ARE EVIDENT. EVEN SO, THINK THE SEVERE THREAT WILL BE ISOLATED.
ANY CONVECTION THAT DEVELOPS SHOULD WEAKEN AS INSTABILITY WANES
WEDNESDAY EVENING.
A WARM FRONT IS EXPECTED TO LIFT NORTHEAST INTO SW WI ON THURSDAY,
THEN MOVE INTO THE FORECAST AREA THURSDAY NIGHT. THIS FRONT
SHOULD BRING A CHANCE OF STORMS. A WARM, MUGGY AND UNSTABLE AIR
MASS WILL RESIDE OVER THE FORECAST AREA BY THE 4TH OF JULY, BUT
A BUILDING UPPER LEVEL RIDGE MAY RESULT IN LESS OVERALL COVERAGE
OF CONVECTION DURING THE DAY AND EVENING. SOUTHWEST FLOW, A
STRONGER SHORT-WAVE TROUGH AND ASSOCIATED COLD FRONTAL PASSAGE
WILL LIKELY BRING A MORE WIDESPREAD PERIOD OF SHOWERS AND STORMS
CENTERED AROUND THE SATURDAY TIME FRAME. IF THE TIMING OF THE WAVE
COINCIDES WITH PEAK HEATING, STRONG TO MARGINALLY SEVERE STORMS
COULD DEVELOP, THOUGH WEAKER DEEP LAYER SHEAR OF 20 TO 25 KTS
COULD BE A MITIGATING FACTOR. PRECIPITATION CHANCES SHOULD TAPER
OFF SUNDAY AND MONDAY, AFTER THE FRONT SHIFTS EAST AND DRIER AIR
ARRIVES.
TEMPERATURES: ABOVE NORMAL TEMPERATURES ARE EXPECTED THROUGH
SATURDAY, FOLLOWED BY NEAR-NORMAL CONDITIONS EARLY NEXT WEEK.
VERY WARM AND MUGGY CONDITIONS ARRIVE FOR THE 4TH OF JULY, WITH
HEAT INDICES RISING INTO THE UPPER 80S TO MIDDLE 90S DURING THE
AFTERNOON.
AVIATION
FOR 18Z TAF ISSUANCE
ISSUED AT 1237 PM CDT TUE JUL 1 2025
GENERALLY, GOOD FLYING CONDITIONS ARE EXPECTED FOR THE TAF PERIOD.
SCATTERED CLOUD COVER WILL BE AROUND IN THE AFTERNOON, BUT BASES
SHOULD LARGELY REMAIN VFR THROUGH THE AFTERNOON. WINDS COULD SEE A
FEW GUSTS UP TO 15 KNOTS IN THE AFTERNOON AS WELL. SKIES ARE
EXPECTED TO CLEAR AGAIN OVERNIGHT AS WINDS DROP. WEDNESDAY,
SKIES WILL BE CLEAR INITIALLY BUT SOME SCATTERED CLOUD COVER WILL
BE POSSIBLE BY THE EARLY AFTERNOON. SCATTERED SHOWERS AND SOME
ISOLATED THUNDER WILL ALSO BE POSSIBLE WEDNESDAY AFTERNOON, BEYOND
THE CURRENT TAF PERIOD.
GRB WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION.....KIECKBUSCH
AVIATION.......UHLMANN
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