042
FXUS63 KGRB 311734
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1234 PM CDT MON AUG 31 2026
UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE
KEY MESSAGES
- SMALL CHANCE (20-30%) FOR SHOWERS AND STORMS THIS AFTERNOON AND
EVENING. IF STORMS DEVELOP, THEY MAY BECOME STRONG OR SEVERE,
CAPABLE OF PRODUCING HAIL, DAMAGING WINDS, AND TORRENTIAL
DOWNPOURS.
- WARM, HUMID CONDITIONS CONTINUE INTO TUESDAY. HEAT INDICES IN
THE 90S EXPECTED THIS AFTERNOON, AND AGAIN FOR SOME LOCATIONS
ON TUESDAY.
- CONDITIONAL THREAT FOR HAZARDOUS BOATING AND SWIMMING CONDITIONS
ON LAKE MICHIGAN THIS AFTERNOON. DENSE FOG POSSIBLE AT TIMES ON
LAKE MICHIGAN THROUGH TUESDAY.
DISCUSSION
ISSUED AT 248 AM CDT MON AUG 31 2026
PRECIPITATION/STORM TRENDS...ISOLATED SHOWERS PREVAILED ACROSS
PORTIONS OF CENTRAL AND EAST-CENTRAL WI EARLY THIS MORNING WHERE AN
850MB JET WAS INCREASING WITHIN AN AREA OF WAA, WHILE A NARROW LINE
OF ELEVATED THUNDERSTORMS DEVELOPED OVER THE WI/UPPER MI BORDER AND
EXITED THE REGION TO THE NORTHEAST WHERE AN AREA OF STEEPER MID-
LEVEL LAPSE RATES, 850MB F-GEN, AND ANOTHER AREA OF 850MB WAA
PREVAILED. AS THE 850MB JET CONTINUES TO INCREASE WITHIN THE AREA OF
WAA OVER CENTRAL AND EAST-CENTRAL WI THIS MORNING, ANTICIPATE THE
SHOWER ACTIVITY INCREASING INTO NORTHEAST WI BEFORE EXITING EAST BY
9 AM. DESPITE UP TO 1000 J/KG OF MUCAPE AND EFFECTIVE SHEAR AROUND
30 KTS, EXPECTING ONLY A FEW ELEVATED, NON-SEVERE STORMS WITHIN THE
SHOWER ACTIVITY. IF ANYTHING, THE SHOWERS WILL PRODUCE BRIEF HEAVY
DOWNPOURS WITH PWATS NEAR 2.00 INCHES.
ONCE THE MORNING SHOWER ACTIVITY ENDS, MUCH OF TODAY WILL BE DRY AS
A WEAK CAPPING INVERSION WILL BE IN PLACE. HOWEVER, SOME CAMS/SHORT-
RANGE MODELS INDICATING A BRIEF PERIOD WHEN THE CAP MAY BREAK DURING
THE AFTERNOON/EVENING PRODUCING ISOLATED SHOWERS/STORMS AS A WEAK
LOW-PRESSURE SYSTEM AND ASSOCIATED WEAK COLD FRONT MOVE OVER THE
REGION. IF THIS CAP CAN BREAK, CONVECTION WILL DEVELOP IN A RATHER
UNSTABLE AND MOIST ATMOSPHERE WITH MUCAPE OF 2000-3000 J/KG, DEEP-
LAYER SHEAR OF 35-45 KTS, AND DEW POINTS IN THE UPPER 60S TO LOW
70S. IF ANY STORMS CAN DEVELOP, THERE WILL BE A MARGINAL THREAT FOR
STRONG/SEVERE STORMS CAPABLE OF PRODUCING HAIL AROUND 1 INCH AND
DAMAGING WINDS, IN ADDITION TO TORRENTIAL DOWNPOURS. SPC HAS A
MARGINAL RISK FOR SEVERE STORMS OVER MUCH OF THE FORECAST AREA,
EXCEPT NORTH-CENTRAL WI. A FEW ELEVATED STORMS MAY LINGER INTO THE
EVENING, BUT COVERAGE LOOKS LIMITED.
THE AFOREMENTIONED WEAK COLD FRONT/BOUNDARY WILL SAG SOUTH INTO
TUESDAY AND HOVER JUST TO THE SOUTH OF THE FORECAST AREA FOR
TUESDAY, LEAVING DRY CONDITIONS IN PLACE FOR MOST OF THE DAY.
CHANCES FOR SHOWERS AND STORMS THEN RETURN TUESDAY EVENING/NIGHT AS
THE FRONTAL BOUNDARY LIFTS NORTH AIDED BY MID-LEVEL FORCING FROM AN
APPROACHING MID-LEVEL SHORTWAVE. SHOWER/STORM CHANCES WILL CONTINUE
INTO WEDNESDAY AS THE SHORTWAVE MOVES OVER THE REGION. A COUPLE
SHORTWAVES THEN LOOK TO MOVE OVER THE REGION THROUGH THE REMAINDER
OF THE WORK WEEK AND INTO THE START OF THE WEEKEND, BRINGING
INTERMITTENT CHANCES FOR SHOWERS AND STORMS AT TIMES.
TEMPERATURES/HUMIDITY...SUMMER CONTINUES! A RATHER HOT AND HUMID DAY
IS EXPECTED WITH DEW POINTS IN THE UPPER 60S TO LOW 70S AS HIGH
TEMPERATURES CLIMB INTO THE MID 80S TO LOW 90S. THIS WILL RESULT IN
AFTERNOON HEAT INDICES IN THE LOW TO MID 90S. SOME SPOTS MAY EVEN
SEE HEAT INDICES IN THE UPPER 90S IF TEMPS OR DEWPOINTS SLIGHTLY
OVER PERFORM. DESPITE THE COLD FRONT MOVING OVER THE REGION THIS
EVENING, TEMPERATURES ON TUESDAY WILL BE ONLY A FEW DEGREES LOWER
THAN TODAY. IT WILL ALSO STILL BE HUMID ON TUESDAY, AS DEW POINTS
REMAIN IN THE 60S TO LOW 70S, BUT LOCATIONS IN NORTH-CENTRAL WI MAY
SEE A LITTLE RELIEF WITH DEW POINTS FORECAST IN THE LOW 60S.
AVIATION
FOR 18Z TAF ISSUANCE
ISSUED AT 1234 PM CDT MON AUG 31 2026
PESKY AREA OF LIFR/IFR CEILINGS WILL CONTINUE TO SLOWLY LIFT AND
ERODE ACROSS CENTRAL AND NORTHERN WI LATE THIS MORNING, WITH OTHER
MVFR CLOUDS SPREADING INTO NORTHERN WI IN FROM NORTHWEST. SOME
SPOTS OVER THE FAR NORTH MAY NEVER ACTUALLY CLEAR OUT FROM THE
LOWER CLOUDS. VFR CONDITIONS EXPECTED FURTHER SOUTH THIS
AFTERNOON.
ISOLATED TO SCATTERED SHOWERS AND STORMS ARE EXPECTED LATER THIS
AFTERNOON AND EVENING, MAINLY BETWEEN 4-11PM, INITIATING BETWEEN
RHI AND AIG, THEN TRACKING EAST/SOUTHEAST. CONFIDENCE IS NOT HIGH
IN THESE SHOWERS OR STORMS MOVING DIRECTLY OVER ANY ONE TERMINAL,
AND IF THEY WILL FORM OVER OR JUST EAST OF AUW/CWA/RHI, SO WILL
CONTINUE WITH PROB30 GROUPS FOR NOW AND ADD TEMPO GROUPS IF THE
STORMS DO FORM NEAR THE TAF SITES. IF ONE OF THESE SHOWERS OR
STORMS MOVE OVER A TAF SITE, A BRIEF REDUCTION IN VISIBILITY TO
MVFR/IFR IS EXPECTED WITH THE POTENTIAL FOR STRONG WIND GUSTS AND
HAIL.
SOME QUESTION IF WE CAN GET MORE LOW CLOUDS OVER NORTHERN WI
TONIGHT (MVFR/IFR) AS FLOW IS NOT AS FAVORABLE AS LAST NIGHT. BUT
WITH SOME RECENT RAIN, LIGHT WINDS, AND SOME CLEARING SKIES,
GROUND FOG WILL BE POSSIBLE AS WELL. CONTINUED TO USE TEMPO
GROUPS AT ALL TAF SITES FOR THE LOWER CLOUD/FOG POTENTIAL.
WEST TO SOUTHWEST WINDS WILL CONTINUE THIS AFTERNOON GUSTING TO
AROUND 10 KTS, THEN WINDS WILL BECOME LIGHT AND VARIABLE TONIGHT
AS THE COLD FRONT EXITS TO THE EAST. WINDS TURN TO THE SOUTHWEST
TUESDAY MORNING, WITH GUSTS TO 15-20 KTS BY AROUND NOON.
MARINE
ISSUED AT 248 AM CDT MON AUG 31 2026
SOUTHERLY WINDS ARE EXPECTED TO INCREASE AGAIN TODAY, GUSTING TO
AROUND 20 KTS, BUILDING WAVES TO AROUND 3-4 FT WITH A FEW WAVES TO
5 FT WITHIN THE NEARSHORE WATERS ALONG LAKE MICHIGAN. THIS WILL
BRING A CONDITIONAL THREAT FOR HAZARDOUS CONDITIONS TO SMALL CRAFT
AND A MODERATE RISK OF RIP CURRENTS ALONG LAKE MICHIGAN BEACHES.
BASED ON HOW SUNDAY'S MARGINAL WINDS/WAVES PERFORMED IN A SIMILAR
PATTERN, DECIDED NOT TO ISSUE ANY HEADLINES. THERE WILL ALSO BE A
SLIGHT OFFSHORE COMPONENT TO THE WIND TODAY, WHICH MAY KEEP THE
HIGHER WAVES JUST OFFSHORE. WITH DEW POINTS IN THE UPPER 60S TO
LOW 70S THROUGH TUESDAY AND WATER TEMPS IN THE UPPER 50S AND 60S,
SOME DENSE FOG WILL BE POSSIBLE AT TIMES. ANY FOG THREAT SHOULD
END AS WINDS TURN OFFSHORE TUESDAY NIGHT.
GRB WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION.....KRUK
AVIATION.......BERSCH
MARINE.........KRUK
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