330  
FXUS63 KGRR 011937  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
337 PM EDT MON SEP 1 2025  
   
KEY MESSAGES
 
 
- QUIET WEATHER CONTINUES THROUGH TUESDAY  
 
- COOLER AND MORE ACTIVE WEATHER WEDNESDAY INTO THE WEEKEND  
 

 
   
DISCUSSION
 
 
ISSUED AT 337 PM EDT MON SEP 1 2025  
 
- QUIET WEATHER CONTINUES THROUGH TUESDAY  
 
WE HAVE A FEW MORE FORECAST PERIODS OF QUIET WEATHER, TONIGHT  
THROUGH TUESDAY NIGHT. SURFACE RIDGING WILL CONTINUE TO HANG ON  
PROVIDING DRY WEATHER. HIGHS WILL PUSH TO AROUND 80 DEGREES ON  
TUESDAY PROVIDING ONE LAST DAY OF SUMMER LIKE WARMTH. LOWS TONIGHT  
AND TUESDAY NIGHT WILL MAINLY BE IN THE 50S WHICH IS CLOSE TO  
NORMALS FOR THIS TIME OF YEAR.  
 
- COOLER AND MORE ACTIVE WEATHER WEDNESDAY INTO THE WEEKEND  
 
A FAIRLY SIGNIFICANT PATTERN SHIFT WILL TAKE PLACE ON WEDNESDAY AS  
AN UPPER LOW DIVING SOUTHEAST OUT OF CANADA PLOWS INTO THE GREAT  
LAKES ALOFT. AT THE SURFACE A COLD FRONT WILL LEAD THE CHARGE,  
PASSING THROUGH OUR AREA IN THE AFTERNOON AND EVENING. THE FRONT  
WILL BE ACCOMPANIED BY SHOWERS AND THUNDERSTORMS. 850MB LIS DROP TO  
AROUND -2C, WITH MUCAPE VALUES LIKELY ECLIPSING 1,000 J/KG IN SPOTS.  
WE ARE IN THE DAY 3 (WED) GENERAL THUNDER OUTLOOK GIVEN THE  
INSTABILITY PARAMETERS AND THE FORCING FROM A STRONG COLD FRONT. THE  
STRONGER SHEAR WILL BE POST FRONTAL, BUT EVEN WITH THAT SAID, NOT  
OUT OF THE QUESTION TO SEE SOME HAIL GIVEN COOLING TEMPERATURES  
ALOFT AND A NOSE OF 60+ F DEW POINTS. PWAT VALUES WILL BE AROUND 1.4  
INCHES SO SOME BRIEF LOCALLY HEAVY RAIN IS LIKELY.  
 
BEYOND WEDNESDAY, UPPER TROUGHING SETTLES IN AS THE UPPER LOW HOLDS  
IN THE GREAT LAKES REGION. 850MB TEMPERATURES WILL BE VERY FALL LIKE  
IN THE SINGLE DIGITS C ABOVE ZERO. HIGHS WILL BE IN THE 60S FROM  
THURSDAY ONWARD FOR THE MOST PART WITH 50S ARE EVEN LIKELY ACROSS  
CENTRAL LOWER MICHIGAN.  
 
ANOTHER COLD FRONT WILL MOVE THROUGH ON FRIDAY INCREASING SHOWER  
CHANCES ONCE AGAIN. GIVEN THE COLD AIR ALOFT AND AN EARLY SEPTEMBER  
SUN ANGLE REALLY CAN'T RULE OUT SHOWERS ANY AFTERNOON BETWEEN  
THURSDAY AND SUNDAY.  
 

 
   
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
 
 
ISSUED AT 123 PM EDT MON SEP 1 2025  
 
SKIES ARE MOSTLY CLEAR MIXED WITH A FEW FLAT CUMULUS, WHICH WILL  
DISSIPATE WITH SUNSET. WINDS ARE GENERALLY LIGHT AND WILL BECOME  
VARIABLE OVERNIGHT.  
 

 
   
MARINE
 
 
ISSUED AT 123 PM EDT MON SEP 1 2025  
 
HIGH PRESSURE IS CREATING LIGHT WINDS AND LOW WAVE HEIGHTS ON THE  
LAKE, WHICH WILL CONTINUE INTO TUESDAY. A SMALL CRAFT ADVISORY MAY  
BE NEEDED WEDNESDAY AS THE HIGH MOVES EAST AND THE GRADIENT  
TIGHTENS AHEAD OF THE NEXT COLD FRONT RESULTING IN INCREASING  
WINDS AND WAVES.  
 

 
   
GRR WATCHES/WARNINGS/ADVISORIES
 
 
MI...NONE.  
MARINE...NONE.  
 

 
 

 
 
DISCUSSION...DUKE  
AVIATION...04  
MARINE...04  
 
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