300  
FXUS63 KGRR 301743  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
143 PM EDT SAT AUG 30 2025  
   
KEY MESSAGES  
 
- NEXT CHANCE FOR RAIN LATE WEDNESDAY  
 
 
   
DISCUSSION  
 
ISSUED AT 327 AM EDT SAT AUG 30 2025  
 
- NEXT CHANCE FOR RAIN LATE WEDNESDAY  
 
SURFACE HIGH DOMINATES THE GREAT LAKES THROUGH THE FIRST HALF OF  
NEXT WEEK WITH UPPER HEIGHT RISES BRINGING SLOWLY MODERATING  
TEMPERATURES. THE WARMING WILL BE BRIEF HOWEVER AS ANOTHER UPPER  
LOW DIVES SOUTHEAST FROM CANADA AND CARVES OUT A LONGWAVE TROUGH  
ACROSS THE CENTRAL AND EASTERN CONUS BY LATE IN THE WEEK. MOISTURE  
STREAMING UP FROM THE SOUTH WILL CONVERGE WITH THE TROUGH AXIS  
AND A SURFACE LOW TRAILING A COLD FRONT BY WEDNESDAY NIGHT WITH  
SHOWERS AND A FEW THUNDERSTORMS POSSIBLE.  
 
DIURNALLY DRIVEN SHOWERS WITH SOME LAKE ENHANCEMENT ARE POSSIBLE  
ON THURSDAY THROUGH THE END OF THE WEEK WITH SHORTWAVE TROUGHS AND  
VORTICITY MAXIMA ROTATING AROUND THE UPPER LOW IN BROAD CYCLONIC  
FLOW REGIME ALONG WITH STEEP MID LEVEL LAPSE RATES.  
 
 
   
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/  
 
ISSUED AT 142 PM EDT SAT AUG 30 2025  
 
VFR WILL DOMINATE FOR MOST TAF SITES OVER THE TAF PERIOD. THE SOLE  
EXCEPTION WILL BE JXN. WITH HIGH PRESSURE AND LIGHT WINDS  
DOMINATING THE PATTERN, LOW LEVEL MOISTURE AT JXN COULD ALLOW FOR  
ANOTHER ROUND OF SHALLOW FOG OVERNIGHT INTO SUNDAY MORNING. WHILE  
IT SHOULDN'T BE AS EXTENSIVE, THERE REMAINS THE POTENTIAL BETWEEN  
06Z TO 12Z OF REDUCING VSBYS. HAVE PUT IN A PERIOD OF IFR VSBYS  
FROM 09Z TO 11Z ACCORDINGLY.  
 
 
   
MARINE  
 
ISSUED AT 142 PM EDT SAT AUG 30 2025  
 
RELATIVELY CALM CONDITIONS EXPECTED FOR THE NEARSHORE WATERS  
THROUGH EARLY NEXT WEEK AS HIGH PRESSURE DOMINATES THE GREAT LAKES  
REGION. WATER AND AIR TEMPERATURES WILL REMAIN RATHER COOL FOR  
SWIMMING. WARMEST LAKE TEMPS REMAIN AROUND HOLLAND STATE PARK.  
 
 
   
GRR WATCHES/WARNINGS/ADVISORIES  
 
MI...NONE.  
MARINE...NONE.  
 
 
 
 
 
DISCUSSION...OSTUNO  
AVIATION...CERU  
MARINE...CERU/OSTUNO  
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