585
FXUS63 KGRB 031709
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1209 PM CDT THU SEP 3 2026
UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE
KEY MESSAGES
- FIRST ROUND OF THUNDERSTORMS WILL MOVE ACROSS THE AREA THIS
MORNING INTO EARLY THIS AFTERNOON. SOME OF THE STORMS COULD
BECOME SEVERE WITH DAMAGING WINDS AND LARGE HAIL ALONG AND
SOUTH OF HIGHWAY 29.
- THERE MAY BE A LULL OR A BREAK IN THE THUNDERSTORM ACTIVITY
DURING THE AFTERNOON, ANOTHER ROUND OF STRONG OR SEVERE
THUNDERSTORMS IS POSSIBLE AGAIN LATE THIS AFTERNOON AND
TONIGHT.
- ABOVE NORMAL TEMPERATURES AND PERIODIC RAIN/STORM CHANCES WILL
CONTINUE INTO THE WEEKEND.
DISCUSSION
ISSUED AT 215 AM CDT THU SEP 3 2026
ANOTHER WARM EARLY SEPTEMBER MORNING WITH TEMPERATURES IN THE 60S
TO LOWER 70S. PATCHY FOG DEVELOPED IN SOME SPOTS AND WILL MONITOR
THE LAKESHORE WHERE SOME PATCHY DENSE FOG MAY BE POSSIBLE ON LAKE
MICHIGAN WHERE RECENT UPWELLING HAS COOLED OFF WATER
TEMPERATURES.
COMPLEX FORECAST THIS MORNING DEALING WITH POTENTIAL FOR STRONG
OR SEVERE THUNDERSTORMS AT TIMES THROUGH LATE TONIGHT. FIRST
ROUND OF THUNDERSTORMS EXPECTED TO MOVE ACROSS THE AREA THIS
MORNING INTO EARLY THIS AFTERNOON. LOOKING AT TWO SIGNALS FOR
THIS TO HAPPEN. LATEST MODELS INDICATED SCATTERED THUNDERSTORMS
WILL DEVELOP BETWEEN 08Z AND 11Z ACROSS CENTRAL INTO EAST-CENTRAL
WI IN RESPONSE TO A 40 KNOT/850 WARM ADVECTION ON A LOW LEVEL JET.
ALSO WATCHING CONVECTION DEVELOPING ACROSS SOUTHERN MINNESOTA AND
NORTHERN IOWA THAT WILL MAKE ITS WAY EASTWARD INTO OUR AREA LATER
THIS MORNING. BUFKIT SOUNDINGS AT GREEN BAY INDICATED 40-50 KNOTS
OF 0-6 KM SHEAR, SURFACE BASE CAPE OF 1,000-1,500 J/KG WITH MOST
UNSTABLE CAPE VALUES AROUND 2,000 J/KG. SOME OF THE STORMS COULD
BECOME STRONG OR SEVERE WITH DAMAGING WINDS, LARGE HAIL AND
TORRENTIAL RAINFALL THIS MORNING.
THERE WILL LIKELY BE A LULL OR BREAK IN THE THUNDERSTORM ACTIVITY
THIS AFTERNOON. WITH THE BEST INSTABILITY TO OUR SOUTH, SCATTERED
THUNDERSTORMS MAY REDEVELOP DURING THE PEAK HEATING OF THE DAY
ACROSS CENTRAL INTO EAST-CENTRAL WI CLOSER TO THE BEST INSTABILITY.
SOME OF THESE STORMS COULD BECOME SEVERE AS WELL. THE PLOT
THICKENS TONIGHT WITH A COMPLEX OF THUNDERSTORMS DEVELOPING
ACROSS THE UPPER MIDWEST. THE LATEST CANADIAN/ECMWF/NAM/GFS MODEL
WOULD SUGGEST A COMPLEX OF THUNDERSTORMS WOULD WORK INTO THE AREA
DURING THE LATE EVENING AND OVERNIGHT HOURS. HOWEVER, THERE ARE A
FEW MESO MODELS WOULD SUGGEST DEVELOPMENT WOULD OCCUR DURING THE
EVENING CLOSER TO THE BETTER INSTABILITY AND THEN DROP SOUTH INTO
SOUTHERN WI.
THERE ARE PERIODIC CHANCES OF THUNDERSTORMS WHILE ABOVE NORMAL
TEMPERATURES WILL CONTINUE FRIDAY INTO EARLY NEXT WEEK AS THE
SUMMER TIME PATTERN CONTINUES.
AVIATION
FOR 18Z TAF ISSUANCE
ISSUED AT 1209 PM CDT THU SEP 3 2026
SCATTERED CLUSTERS OF SHOWERS WITH SOME EMBEDDED THUNDERSTORMS ARE
CREATING A MIX OF VFR, MVFR, AND IFR CONDITIONS ACROSS THE REGION
EARLY THIS AFTERNOON. SHOWER ACTIVITY IS EXPECTED TO DECREASE THIS
AFTERNOON, HOWEVER, ISOLATED SHOWERS/STORMS MAY CONTINUE TO DEVELOP,
MAINLY ACROSS PARTS OF CENTRAL WI THROUGH THE AFTERNOON. ANOTHER
CLUSTER OF STORMS IS EXPECTED TO TRACK OUT OF MN AND ACROSS THE
NORTHERN HALF OF WI OVERNIGHT. HAVE FRAMED OUT THE BEST TIMING FOR
THE ARRIVAL OF THESE STORMS WITH PROB30 GROUPS AT ALL TERMINALS,
OVERALL TIMING FOR THE FORECAST AREA IS ABOUT 04-11Z. AS STORMS MOVE
ACROSS EXPECT A MIX OF MVFR AND IFR CONDITIONS. BEHIND THIS CLUSTER
OF STORMS IFR CIGS ARE EXPECTED TO DEVELOP ALONG WITH PATCH AREAS OF
FOG THAT MAY LINGER THROUGH MUCH OF FRIDAY MORNING.
GRB WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION.....ECKBERG
AVIATION.......GK
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