904  
FXUS63 KGRB 190023  
AFDGRB  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREEN BAY WI  
723 PM CDT THU SEP 18 2025  
 
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE  
   
KEY MESSAGES
 
 
- ISOLATED SHOWERS AND STORMS THIS EVENING, MAINLY CENTRAL WI.  
 
- PERIODIC CHANCES FOR SHOWERS AND THUNDERSTORMS ARE EXPECTED  
FRIDAY INTO EARLY NEXT WEEK. THE SEVERE WEATHER THREAT REMAINS  
LOW.  
 
- CONDITIONS HAZARDOUS TO SMALL CRAFT WILL BE POSSIBLE ON LAKE  
MICHIGAN WATERS SOUTH OF TWO RIVERS FRIDAY NIGHT INTO SATURDAY  
MORNING. THERE WILL LIKEWISE BE INCREASED POTENTIAL FOR RIP  
CURRENTS ON LAKE MICHIGAN BEACHES ALONG THIS SECTION OF  
SHORELINE.  
 

 
   
DISCUSSION
 
 
ISSUED AT 157 PM CDT THU SEP 18 2025  
 
SHORT TERM...TONIGHT AND FRIDAY  
 
THIS AFTERNOON... RADAR CONTINUES TO SHOW RETURNS POPPING OVER  
NORTHERN AND EAST-CENTRAL WISCONSIN THIS AFTERNOON WHERE  
INSTABILITY HAS BEEN ALLOWED TO BUILD IN THE VICINITY OF A COLD  
FRONT. ANY RUMBLES OF THUNDER WERE CONFINED TO THE SOUTHERN FOX  
VALLEY. LOW-LEVEL MOISTURE LIKEWISE CONTINUES TO STREAM NORTH OF  
THE FRONTAL BOUNDARY AS A DEFORMATION ZONE ASSOCIATED WITH LOW  
PRESSURE OVER SOUTH DAKOTA TAKES RESIDENCE OVER WESTERN  
WISCONSIN. BROKEN STRATUS/STRATOCU DECK HAS PERSISTED OVER MUCH OF  
NORTHEAST WISCONSIN AS A RESULT.  
 
FORECAST OVER THE COURSE OF THE NEXT 24 HOURS REMAINS VOLATILE,  
WITH SEVERAL CHANCES FOR LOW IMPACT RAIN/STORMS EXISTING ACROSS  
THE FORECAST AREA. THUNDER POTENTIAL WILL BE ON THE RISE MAINLY OVER  
NORTHERN WISCONSIN LATER THIS AFTERNOON AND EVENING AS MUCAPES  
APPROACH 1,000 J/KG, THOUGH COVERAGE WILL REMAIN SCATTERED AT BEST  
AS STABILITY INCREASES FROM THE EAST. BETTER CHANCES FOR  
RAIN/STORMS THEN ARRIVE FRIDAY AFTERNOON AS AN UPPER TROUGH  
INTERACTS WITH A MOISTURE CORRIDOR OF PWATS AROUND 175 TO 200% OF  
NORMAL. BRIEF PERIODS OF MODERATE TO HEAVY RAIN WILL THUS BE  
POSSIBLE FRIDAY AFTERNOON AND EVENING AS THE COLD FRONT SINKS  
SOUTH, ESPECIALLY IF/WHERE SHOWERS TRAIN OVER THE SAME AREA. POST-  
FRONTAL TEMPERATURES THEN DROP INTO THE MID 60S ACROSS THE  
NORTHWOODS FRIDAY AFTERNOON, WHILE REMAINING IN THE MID TO UPPER  
70S IN/AROUND THE FOX VALLEY.  
 
FOG... PATCHY FOG WILL BE POSSIBLE LATE TONIGHT INTO EARLY FRIDAY  
MORNING ALONG/NORTH OF HIGHWAY 29 AS A LOW-LEVEL INVERSION TRAPS  
REMNANT MOISTURE FROM RECENT RAINFALL NEAR THE SURFACE. ANY FOG  
SHOULD THEN QUICKLY SCATTER OUT BY DAYBREAK AS WINDS PICK UP OUT  
OF THE EAST. ANOTHER POSSIBILITY IS THAT THIS MOISTURE COULD  
MANIFEST AS LOW STRATUS INSTEAD.  
 
LONG TERM...FRIDAY NIGHT THROUGH THURSDAY  
 
A SLOW MOVING UPPER TROUGH WILL BE THE MAIN DRIVER FOR THE  
ACTIVE WEATHER OVER MUCH OF THE EXTENDED, BRINGING ANOTHER PUSH OF  
WARMER, MORE MOIST AIR INTO THE REGION.  
 
ACTIVE WEATHER...  
 
AS THE UPPER TROUGH MOVES EASTWARDS, A PUSH OF WARMTH AND MOISTURE  
WILL MOVE INTO THE REGION FRIDAY NIGHT, BRINGING WITH IT A CHANCE  
FOR SCATTERED RAINFALL. ELEVATED INSTABILITY DURING THIS PERIOD  
RANGES AROUND 200-500 J/KG, WHICH WOULD SUPPORT SOME RUMBLES OF  
THUNDER AT TIMES, BUT ANY STRONGER STORMS SEEM UNLIKELY AT THIS  
TIME. SOME ISOLATED TO SCATTERED SHOWER ACTIVITY MAY THEN STICK  
AROUND ON SATURDAY BEFORE THE NEXT SURGE OF INSTABILITY ARRIVES ON  
SUNDAY, BRINGING ANOTHER ROUND OF MORE WIDESPREAD PRECIPITATION TO  
THE REGION. INSTABILITY PARAMETERS FOR SUNDAY ARE A LITTLE BETTER  
THAN THE DAY PRIOR, BUT DO LARGELY DEPEND UPON CLEARING FOR SOME  
SURFACE HEATING EARLIER IN THE DAY. IF THIS OCCURS, THUNDER WILL  
BE MORE LIKELY ONCE AGAIN, BUT GIVEN THE LONG SKINNY SOUNDINGS AND  
RELATIVELY WEAK SHEAR, THE THREAT OF SEVERE WEATHER REMAINS LOW.  
 
FINALLY, A STACKED LOW PRESSURE SYSTEM IS EXPECTED TO DEVELOP OVER  
THE CENTRAL PLAINS NEXT WEEK, BUT THE PATH OF THIS LOW CONTINUES  
TO CHANGE. CURRENT TRENDS WOULD TAKE THE ACTIVE WEATHER SOUTH OF  
OUR AREA, WHICH WOULD REDUCE ANY ACTIVE WEATHER IMPACTS.  
 
TEMPERATURES...  
 
HIGH TEMPERATURES WILL HOLD FAIRLY STEADY OVER THE WEEKEND INTO  
NEXT WEEK, WITH HIGH TEMPERATURES REMAINING FAIRLY SOLIDLY IN THE  
UPPER 60S TO LOWER 70S.  
 
MARINE...  
 
THE INCOMING ACTIVE WEATHER FOR FRIDAY NIGHT WILL LIKELY ALSO  
BRING SOME INCREASING WINDS AND WAVES FOR THE FRIDAY NIGHT PERIOD,  
WHICH MAY POSE A CONCERN FOR MARINERS AND BEACH GOERS.  
 

 
   
AVIATION
 
FOR 00Z TAF ISSUANCE  
ISSUED AT 722 PM CDT THU SEP 18 2025  
 
SHOWERS AND STORMS AT CWA AND AUW TO START. ALSO HAVE SOME IFR  
STRATUS OFF LAKE MICHIGAN AT MTW. AFTER THE STORMS AND LOW CLOUDS  
DIMINISH EARLY, CONDITIONS SHOULD REMAIN VFR THROUGH MIDNIGHT.  
EVENTUALLY, STILL EXPECT MVFR/IFR CIGS TO DEVELOP AT MOST SITES  
EARLY FRIDAY MORNING AS LOW-LEVEL MOISTURE PERSISTS ALONG WITH  
LIGHT EAST-NORTHEAST WINDS. WHETHER OR NOT THESE LOWER CIGS MANIFEST  
AS PATCHY FOG OR LOW STRATUS IS UNCERTAIN, THOUGH LOCALIZED REDUCTIONS  
IN VSBYS TO MVFR WILL BE POSSIBLE REGARDLESS, ESPECIALLY WHERE SOME  
RAIN OCCURRED THIS EVENING. ANY PATCHY FOG SHOULD SCATTER OUT BY  
DAYBREAK FRIDAY THOUGH AS WINDS INCREASE OUT OF THE EAST. GREATEST  
RISK FOR ADDITIONAL SHOWERS AND STORMS ON FRIDAY WILL BE OVER CENTRAL  
AND NORTH-CENTRAL WI ESPECIALLY IN THE AFTERNOON. MAY INCLUDE SOME  
MENTIONS FOR THESE SITES VIA PROB30 WITH 06Z TAFS.  
 

 
   
GRB WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  
 

 
 

 
 
DISCUSSION.....GOODIN/UHLMANN  
AVIATION.......JLA  
 
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