734  
FXUS63 KGRB 161749  
AFDGRB  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREEN BAY WI  
1249 PM CDT FRI MAY 16 2025  
 
UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE  
   
KEY MESSAGES  
 
- GUSTY SOUTHWEST WINDS ARE EXPECTED TODAY WITH HIGHEST GUSTS UP  
TO 40 MPH, PRIMARILY BETWEEN FOX VALLEY AND LAKE MICHIGAN.  
 
- SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED THIS  
AFTERNOON. DAMAGING WIND GUSTS AND SMALL HAIL MAY BE POSSIBLE  
WITH ANY STRONGER STORMS.  
 
 
   
DISCUSSION  
 
ISSUED AT 1205 AM CDT FRI MAY 16 2025  
 
A WARM AND WINDY DAY IS IN STORE FOR TODAY. THE LOW WILL BE  
OVER NORTHWEST MN AT 7AM THIS MORNING AND SHOULD MAKE IT TO  
DULUTH AROUND 7PM. A LOBE OF VORTICITY IS EXPECTED TO SWING UP  
FROM IA THROUGH EASTERN WI DURING THE DAY. VORTICITY ADVECTION  
AND ALSO UPPER DIVERGENCE FROM THE LEFT EXIT REGION OF AN UPPER  
JET WILL PROVIDE SYNOPTIC FORCING TO ALLOW FOR SHOWERS AND  
STORMS.  
 
FORECAST SOUNDINGS SHOW VERY STEEP LOW AND MID LEVEL LAPSE  
RATES DURING THE AFTERNOON, WITH 500 TO 1000 J/KG CAPE. SOME  
MODELS SHOW A WEAK CAP WHILE OTHERS TRY TO MIX US ALL THE WAY UP  
TO 10KFT. THE WINDS THROUGH THE PROFILE ARE VERY STRONG WITH SW  
WINDS UP TO 43KT AT 5KFT AND 50 TO 60KT AT 10KFT. THERE WILL  
PROBABLY BE A WEAK CAP THAT WILL HELP KEEP OUR WIND GUSTS IN  
CHECK TODAY, BUT A FEW GUSTS OVER 39KT (WIND ADVISORY CRITERIA)  
ARE NOT OUT OF THE QUESTION. IF GUSTS BEGIN TO OVER-ACHIEVE BY  
NOON TODAY, WE WILL KNOW WE NEED A WIND ADVY FOR THE AFTERNOON.  
 
DESPITE THE WEAK CAP, THE OVERALL SYNOPTIC FORCING SHOULD BE  
ENOUGH FOR SCATTERED THUNDERSTORM DEVELOPMENT. THE CAPE VALUES  
AND LOW FREEZING LEVEL OF 9 OR 10KFT SUPPORT THE CHANCE FOR  
SMALL HAIL, WITH A REPORT OF TWO OF 1 INCH HAIL POSSIBLE. THERE  
IS STRONG SHEAR. THE MAIN THREAT FOR ANY STRONGER STORMS THAT  
DEVELOP IS THE DAMAGING WIND POTENTIAL, SINCE THE STRONG WINDS  
ALOFT WILL EFFICIENTLY MIX DOWN WITH MOMENTUM TRANSFER.  
 
AS THE UPPER LOW TRACKS ACROSS MN TODAY, ANOTHER FRONTAL  
BOUNDARY WILL PUSH INTO NORTH CENTRAL AND EASTERN WI. THIS WILL  
FEATURE COOLER TEMPERATURES, LOW CLOUDS, AND RAIN OR DRIZZLE.  
NORTHERN WI WILL BE FULLY ENGULFED IN THESE DAMP, BRISK  
CONDITIONS FRIDAY NIGHT.  
 
SATURDAY, EXPECT BREAKS IN THE CLOUDS AS THE UPPER LOW STARTS TO  
EXIT THE REGION. WITH STEEP LOW LEVEL LAPSE RATES AND LINGERING  
LOW LEVEL MOISTURE, SCATTERED SHOWERS ARE EXPECTED, ALTHOUGH  
COVERAGE IS STILL UNCERTAIN. IN ADDITION, EXPECT GUSTY WEST  
WINDS UP TO 30 MPH DURING PEAK DAYTIME HEATING/MIXING. SATURDAY  
HIGHS WILL RANGE FROM THE UPPER 50S NORTH CENTRAL TO THE MID 60S  
EAST.  
 
MRC  
 
SATURDAY NIGHT THROUGH NEXT THURSDAY  
 
UPPER TROUGH EXITS ACROSS THE EASTERN GREAT LAKES SATURDAY NIGHT WITH  
RIDGING ALOFT BEGINNING TO BUILD FROM THE PLAINS INTO THE WESTERN GREAT  
LAKES. SURFACE HIGH PRESSURE OVER MANITOBA AND NORTHERN ONTARIO WILL RIDGE  
INTO MN AND WI SATURDAY NIGHT WITH MORE INFLUENCE OF RIDGING BY SUNDAY NIGHT.  
THE RIDGE WILL BRING DRY WEATHER AND ALSO THE RISK OF FROST SATURDAY NIGHT  
AND/OR SUNDAY NIGHT. PWATS LOWER SUNDAY NIGHT, BUT WITH HIGH MORE OFF TO THE  
NORTH THAN THE EAST, THE AREA WILL KEEP SOME WIND IN LOWEST 1KFT WITH TIGHTER  
PRESSURE GRADIENT ON SOUTHERN EDGE OF HIGH. IT STILL APPEARS THAT TEMPS COULD  
DROP INTO THE MID 30S NORTH SATURDAY NIGHT AND/OR SUNDAY NIGHT. NBM PROBABILITIES  
OF MIN TEMPS LESS THAN 35 ARE 30 TO 40 PERCENT SATURDAY NIGHT OVER VILAS COUNTY,  
BUT INCREASE AND EXPAND TO 40-80 PERCENT SUNDAY NIGHT NORTH OF HIGHWAY 29. IF AND  
WHERE WINDS BECOME LIGHT, SOME FROST COULD OCCUR EITHER OF THESE NIGHTS, THOUGH  
SUNDAY NIGHT LOOKS MORE FAVORABLE AT THIS POINT.  
 
TROUGHING OVER THE WESTERN CONUS LATE THIS WEEKEND SHIFTS EAST EARLY NEXT  
WEEK, BRINGING THE NEXT CHANCE OF SHOWERS AND STORMS TO THE AREA MONDAY NIGHT  
INTO TUESDAY. ONE TREND THAT SEEMS TO BE EMERGING THOUGH IS THE DRY EAST FLOW  
OUT OF THE HIGH TO THE NORTH MAY RESTRICT CHANCES OF RAIN ONLY TO THE SOUTHERN  
PART OF THE FORECAST AREA ON INTO SOUTHERN WI. RISK OF ANY STRONGER STORMS ALSO  
IS WELL TO THE SOUTH OF THE AREA. GIVEN THESE TRENDS, ITS FEASIBLE THAT MUCH OF  
NORTHERN WI COULD STAY DRY EARLY THIS WEEK. WHATEVER CHANCES OF RAIN OCCUR WILL  
SHIFT SOUTH AND EAST OF THE WESTERN GREAT LAKES WED INTO THU AS BROAD 850-700MB  
LOW SHIFTS ACROSS LOWER GREAT LAKES. COOL FLOW IN WAKE OF THE LOW FLOWING ACROSS  
THE REGION COULD LEAD TO MORE CLOUDS AND A SMALL CHANCE OF SPOTTY SHOWERS BY  
THURSDAY. OVERALL A COOLER THAN NORMAL STRETCH IS EXPECTED FOR THE COMING WEEK  
WITH HIGHS IN THE UPPER 50S TO MID 60S.  
 
JLA.  
 
 
   
AVIATION  
FOR 18Z TAF ISSUANCE  
ISSUED AT 1249 PM CDT FRI MAY 16 2025  
 
MOSTLY CLEAR SKIES AND VFR CONDITIONS WERE OBSERVED FOR MOST  
EARLY THIS AFTERNOON; HOWEVER, SATELLITE IMAGERY SHOWS MID-CLOUDS  
STARTING TO ENTER CENTRAL WI. THE MAIN FEATURE WAS THE WINDS WITH  
SSW GUSTS TO AROUND 30 KTS.  
 
SCATTERED SHOWERS AND THUNDERSTORMS ARE LIKELY TO DEVELOP THIS  
AFTERNOON, BUT EXACT LOCATION IS DIFFICULT TO PINPOINT. COVERAGE  
WILL NOT BE AS WIDESPREAD AS YESTERDAY, BUT THE CHANCE (30-45%)  
EXISTS EVERYWHERE. MAIN TIME WINDOW IS 20Z-24Z. INCLUDED TEMPO  
GROUPS TO ACCOUNT FOR THIS. PRECIP CHANCES WILL BE MINIMAL THE  
REST OF THE EVENING INTO SATURDAY MORNING. A FEW SPOTTY SHOWERS  
ARE POSSIBLE, BUT COVERAGE/CONFIDENCE WAS TOO LOW TO INCLUDE IN  
TAFS THIS ISSUANCE.  
 
CLOUD BASES WILL LOWER LATE THIS EVENING WITH A MIX OF MVFR/IFR  
CIGS TONIGHT (APPROX. 06Z) THROUGH SATURDAY MORNING. WINDS WILL  
ALSO INCREASE AGAIN AND PEAK LATE SATURDAY MORNING THROUGH THE  
AFTERNOON WITH GUSTS UP TO 30 KTS.  
 
 
   
MARINE  
 
ISSUED AT 1205 AM CDT FRI MAY 16 2025  
 
GUSTY SOUTH-SOUTHWEST WINDS ARE EXPECTED TODAY, HIGHEST OVER  
LAND. COOLER LAKE WATER SHOULD KEEP WIND GUSTS BELOW GALE  
FORCE, SO A SMALL CRAFT ADVISORY GOES INTO EFFECT MID MORNING.  
WE INITIALLY SET THE END TIME OF 7PM THIS EVENING, BUT AFTER A  
BRIEF LULL IN THE WINDS TONIGHT, GUSTY WESTERLY WINDS WILL  
DEVELOP. THEREFORE, WE EXTENDED THE END TIME ALL THE WAY UNTIL  
7PM SATURDAY.  
 
MRC.  
 
 
   
GRB WATCHES/WARNINGS/ADVISORIES  
 
NONE.  
 
 
 
 
 
DISCUSSION.....  
AVIATION.......KLJ  
MARINE.........  
CLICK HERE TO GO TO PREVIOUS BULLETINS.
The Nexlab WI Page
Main Text Page