116
FXUS63 KGRB 022358
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
658 PM CDT WED SEP 2 2026
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
KEY MESSAGES
- MULTIPLE ROUNDS OF THUNDERSTORMS ARE POSSIBLE LATE TONIGHT
THROUGH THURSDAY. A FEW STRONG TO SEVERE THUNDERSTORMS ARE
POSSIBLE WITH DAMAGING WINDS AND LARGE HAIL BEING THE MAIN
THREATS.
- ABOVE NORMAL TEMPERATURES AND PERIODIC RAIN/STORM CHANCES WILL
CONTINUE THROUGH THE WEEKEND.
DISCUSSION
ISSUED AT 213 PM CDT WED SEP 2 2026
DRY CONDITIONS WILL PREVAIL FOR THE REMAINDER OF THE DAY AS A WEAK
RIDGE BUILDS OVER THE REGION. TONIGHT AREAS OF PATCHY FOG WILL AGAIN
BE POSSIBLE WITH LIGHT WINDS AND A MOIST BOUNDARY LAYER. A ROUND OF
SHOWERS/THUNDERSTORMS IS EXPECTED TO DEVELOP OVERNIGHT/EARLY
THURSDAY MORNING ACROSS IA AND SOUTHWEST WI ALONG THE NOISE OF A
STRENGTHENING LLJ. THERE IS STILL A LOT OF SPREAD AMOUNTS THE LATEST
CAMS AS TO HOW MORNING CONVECTION WILL PLAY OUT EXACTLY, BUT A
PARAMETER SPACE OF ~1500 J/KG AND 40-45KT 0-6KM SHEAR ALONG AND JUST
NORTH OF I-90 DOES POINT TO AT LEAST A LOW (10-20% CHANCE) FOR
STRONG TO SEVERE STORMS WITH UP TO 1 INCH HAIL AND 40-60 MPH WIND
GUSTS AS THESE STORMS MOVE NORTHEASTWARD THROUGH CENTRAL AND EAST-
CENTRAL WI. A SECOND ROUND OF THUNDERSTORMS IS POSSIBLE THURSDAY
AFTERNOON/EVENING AS A COMPACT MID-LEVEL SHORTWAVE MOVES ACROSS THE
REGION. CAMS SUGGEST INITIALLY DISCRETE CELLS DEVELOP OVER ND/MN WITH
THE POTENTIAL TO GROW UPSCALE INTO AN EASTWARD PROPAGATING MCS
DURING THE AFTERNOON. IF AN ORGANIZED MCS IS ABLE TO DEVELOP WOULD
EXPECT IT TO TRACK ALONG THE INSTABILITY GRADIENT FROM EAST CENTRAL
WI TOWARD NORTHERN IL. THIS WOULD PUT PARTS OF THE FORECAST AREA,
SOUTH OF A MERRILL TO GREEN BAY LINE IN PLAY, HOWEVER, THERE IS STILL
A LOT OF UNCERTAINTY WITH HOW CONVECTION WILL EVOLVE THROUGH THE
AFTERNOON AND EVENING.
THE WARM AND HUMID AIRMASS WILL CONTINUE TO LINGER OVER THE AREA
FRIDAY THROUGH THIS WEEKEND KEEPING ON AND OFF CHANCES FOR SHOWERS
AND STORMS EACH DAY. HOWEVER, CONFIDENCE IN THE TIMING OF ANY
PRECIPITATION IS LOW AS FORCING REMAINS RATHER NEBULOUS DUE TO THE
LACK OF STRONGER SYNOPTIC FEATURES.
AVIATION
FOR 00Z TAF ISSUANCE
ISSUED AT 657 PM CDT WED SEP 2 2026
A RATHER COMPLEX TAF PERIOD WITH UNCERTAINTY REGARDING FOG, LOW
CLOUDS AND SHOWER/STORM CHANCES OVERNIGHT INTO THURSDAY. THE
SIMPLE PART IS THIS EVENING WHERE VFR CONDITIONS WILL PREVAIL AS A
FEW CUMULUS CLOUDS AND MID/HIGH CLOUDS DRIFT ACROSS THE REGION.
THE LIGHT WINDS, CLEAR SKIES WILL ALLOW FOR SOME FOG TO FORM, BUT
GUIDANCE NOT VERY BULLISH ON ANYTHING WIDESPREAD OR DENSE, WITH
THE HIGHER CHANCES (UNDER 30% FOR UNDER 3 MILE VSBY) OVER EASTERN
WI. HAVE INCLUDED MAINLY MVFR BR FOR NOW AND WILL MONITOR FOG
TRENDS. LOW CLOUDS ARE ALSO POSSIBLE EARLY THURSDAY MORNING, WITH
SOME GUIDANCE SHOWING A 700-2000 FT DECK, BUT AGAIN, NOT MUCH
AGREEMENT TO HAVE MUCH CONFIDENCE THIS WILL OCCUR. FINALLY, THE
SHOWER/STORM THREAT IS QUITE MUDDLED, WITH ELEVATED CONVECTION
POSSIBLE AS EARLY AS 07-09Z ACROSS EAST-CENTRAL WI, WITH A LARGER
AREA POSSIBLE AFTER 12-13Z THURSDAY. DEPENDING ON WHAT OCCURS WITH
THOSE AREA, ANOTHER ROUND OF SHOWERS AND STORMS MAY OR MAY NOT
OCCUR THURSDAY EVENING. THE END RESULT WILL BE PLENTY OF TEMPO
AND PROB30 GROUPS TO ACCOUNT FOR THE MORE LIKELY SCENARIOS, BUT
CONFIDENCE IN ONE OVER THE OTHER IS VERY LOW AT THIS TIME. A LOW-
END ~20% CHANCE THAT A STORM BECOMES STRONG TO SEVERE WITH STRONG
WIND GUSTS AND HAIL BEING THE MAIN IMPACTS ALONG WITH HEAVY
DOWNPOURS. WIND WILL REMAIN FAIRLY LIGHT AWAY FROM ANY STORM.
GRB WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION.....GK
AVIATION.......BERSCH
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