066
FXUS63 KGRB 162354
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
654 PM CDT SAT AUG 16 2025
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
KEY MESSAGES
- MAINLY DRY WEATHER EXPECTED TONIGHT INTO SUNDAY EVENING.
- THE NEXT OPPORTUNITY FOR THUNDERSTORMS AND HEAVY RAIN IS MONDAY
AND MONDAY NIGHT AS A FRONT MOVES BACK NORTH AS A WARM FRONT.
SEVERE STORMS AND LOCALIZED FLOODING ARE POSSIBLE.
DISCUSSION
ISSUED AT 422 PM CDT SAT AUG 16 2025
THE ATMOSPHERE CONTINUES TO EVOLVE THIS AFTERNOON WITH REPEATED
ROUNDS OF CONVECTION, BUT SEEING SOME AGREEMENT THAT AFTER THIS
CURRENT ROUND OF RAIN AND THUNDERSTORMS DEPARTS, WE'LL ENTER A
MOSTLY DRY PERIOD THROUGH SUNDAY.
ONE ROUND OF RAIN AND STORM WENT THROUGH NEARLY THE ENTIRE AREA
FROM ABOUT 8AM-2PM TODAY, BRINGING ANYWHERE FROM 0.10-2.50 INCHES
OF RAIN, WITH THE HIGHER TOTALS OF 1.5"+ GENERALLY LOCATED IN A
LINE SOUTHWEST OF WAUSAU TO CLINTONVILLE. ONLY MINOR STREET
FLOODING WAS REPORTED. ISOLATED STRONG/DAMAGING WINDS OF ~60 MPH
WERE ALSO MEASURED AND REPORTED, BUT MOST PLACES SAW PEAK WIND
GUSTS CLOSER TO 30-40 MPH.
DESPITE THE MINIMAL RECOVERY TIME, JUST AS THE FIRST ROUND EXITED
TO THE EAST, A MID- LEVEL SHORTWAVE HELPED DEVELOP A SECONDARY
AREA OF CONVECTION IN WEST-CENTRAL WI, WHICH QUICKLY MOVED EAST
AND THROUGH CENTRAL WI. THIS LINE IS MOVING EAST, BUT THE
STRONGEST PORTION ON THE SOUTHERN END IS DIVING S/SE TOWARDS
SOUTHERN WI ALONG THE INSTABILITY GRADIENT. MUCAPE AT 21Z IN THE
SOUTHERN GRB FORECAST AREA RANGED FROM 400-600 J/KG, WITH 100-200
J/KG OF CIN. THEREFORE, THE LIKELIHOOD OF ANY SEVERE STORMS IS
LOW. COULD STILL SEE SOME WIND GUSTS OF 30-40 MPH ALONG THE
LEADING EDGE OF THESE STORMS, ALONG WITH BRIEF, HEAVY RAIN AND
LIGHTNING.
REST OF TODAY THROUGH SUNDAY...TRACKING THE BACK EDGE OF THE
LIGHTNING, MOST OF THIS SHOULD CLEAR THE AREA (MAINLY EAST-CENTRAL
WI) BY ABOUT 2230Z. SCATTERED, LIGHT RAIN SHOWERS WILL LINGER A
LITTLE LONGER AS THE SHORTWAVE MOVES ACROSS NORTHERN WI, AND A
SURFACE FRONT SAGS SOUTH ACROSS THE STATE. BUT, AT THIS POINT
THERE ISN'T MUCH INSTABILITY LEFT TO WORK WITH FOR ADDITIONAL
THUNDERSTORMS IN THE GRB FORECAST AREA.
THERE IS DECENT AGREEMENT THAT THIS COLD FRONT REACHES SOUTHERN
WI/NORTHERN IL TONIGHT, AND THEN HANGS OUT THERE FOR SUNDAY. THIS
WOULD ALLOW FOR MAINLY DRY CONDITIONS THROUGH LATE SUNDAY NIGHT.
MONDAY/MONDAY NIGHT...THIS FRONT AND THE ASSOCIATED SFC LOW MOVES
BACK NORTH AS A WARM FRONT ON MONDAY MORNING, BRINGING IN MORE
MOIST AND UNSTABLE AIR TO THE AREA. THERE IS VARIATION OF HOW FAR
NORTH THE FRONT GETS, BUT LOCATIONS ALONG AND SOUTH OF THIS FRONT
WILL BE PRIMED FOR MORE RAIN AND THUNDERSTORMS. CAPES OF
1000-2000+ J/KG, BULK SHEAR OF 30-40 KTS, SRH 200+ M2/S2, AND
PWATS OF 1.6-2.2" MAKE THIS SETUP CAPABLE OF PRODUCING SEVERE
STORMS WITH ALL HAZARDS, AND HEAVY RAIN/LOCALIZED FLOODING. THE
PROBABILITIES FOR AT LEAST 2" INCHES OF RAIN RANGE FROM ABOUT
5-25%, HIGHEST IN CENTRAL WI.
MID TO LATE WEEK...HIGH PRESSURE BUILDS IN ON TUESDAY BRINGING A
COUPLE DAYS OF DRY AND QUIET WEATHER. AN UPPER LOW APPROACHES THE
AREA LATE IN THE WEEK COULD BRING IN SOME PRECIP CHANGES AT TIMES.
AVIATION
FOR 00Z TAF ISSUANCE
ISSUED AT 645 PM CDT SAT AUG 16 2025
LOW CLOUDS AND PATCHY FOG OVERNIGHT INTO EARLY SUNDAY WILL BE
THE PRIMARY AVIATION CONCERNS.
SHOWERS WILL CONTINUE TO SHIFT EAST OF THE REGION THIS EVENING,
WITH MAINLY DRY CONDITIONS PREVAILING THROUGH THE TAF PERIOD.
DEVELOPING N-NE WINDS WILL PULL LOW CLOUDS SOUTH ACROSS THE
FORECAST AREA LATER THIS EVENING, AND PATCHY FOG MAY ALSO DEVELOP.
THE TOUGHEST PART OF THE FORECAST IS DETERMINING HOW QUICKLY THE
LOW CLOUDS WILL SCATTER OUT OR RISE TO VFR ON SUNDAY, AND THE MOST
LIKELY SCENARIO IS FOR THIS TO OCCUR DURING THE LATE MORNING OR
EARLY AFTERNOON. THE NE WINDS WILL BECOME GUSTY LATE TONIGHT INTO
SUNDAY, ESPECIALLY IN THE FOX VALLEY AND LAKESHORE AREAS.
GRB WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION.....KLJ
AVIATION.......KIECKBUSCH
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