398  
FXUS63 KGRR 141728  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
128 PM EDT MON JUL 14 2025  
   
KEY MESSAGES  
 
- CHANCES FOR RAIN WED/THU AND NEXT WEEKEND  
 
 
   
DISCUSSION  
 
ISSUED AT 339 AM EDT MON JUL 14 2025  
 
- CHANCES FOR RAIN WED/THU AND NEXT WEEKEND  
 
ZONAL FLOW WITH WEAK SFC RIDGING BRINGS FAIR WEATHER THROUGH  
TUESDAY THEN RAIN CHANCES RETURN FOR MID-WEEK WITH THE APPROACH  
OF A WEAK SHORTWAVE TROUGH. SHOWERS AND STORMS ARRIVE WEDNESDAY  
AND PERSIST INTO THURSDAY AS A COLD FRONT MOVES THROUGH. THE GFS  
HAS BACKED OFF THE SEVERE WEATHER THREAT, NOW SHOWING RATHER WEAK  
SHEAR OF 20 KNOTS ON WEDNESDAY AND THURSDAY. THIS LOOKS LIKE  
ANOTHER PULSE THUNDERSTORM ENVIRONMENT AND ONLY ISOLATED WIND  
GUSTS AS A THREAT. STORM TOTAL QPF IS ONLY AROUND 0.15  
INCHES AVERAGE OVER THE FORECAST AREA.  
 
UPPER RIDGING ACROSS THE SE CONUS LATE IN THE WEEK WITH ZONAL FLOW  
ACROSS NORTHERN PERIPHERY COULD RESULT IN MCS ACTIVITY MAKING IT  
INTO LOWER MICHIGAN OVER THE WEEKEND BUT CONFIDENCE IS LOW AT THIS  
POINT WITH LOCATION AND TIMING.  
 
 
   
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/  
 
ISSUED AT 128 PM EDT MON JUL 14 2025  
 
CANADIAN WILDFIRE SMOKE IS REDUCING VISIBILITY TO 5 OR 6 MILES IN  
PORTIONS OF SOUTHERN AND MID LOWER MICHIGAN THIS AFTERNOON.  
IMPROVEMENT IS POSSIBLE TONIGHT, ALTHOUGH CONSENSUS OF SHORT-TERM  
MODEL GUIDANCE LEANS TOWARD SHALLOW FOG DEVELOPMENT AT LAN AND  
JXN BETWEEN 08 AND 12 Z. DAYTIME CUMULUS CLOUDS THIS AFTERNOON AND  
TOMORROW WILL HAVE BASES AROUND 4,000 FEET. WINDS MOSTLY BELOW 10  
KNOTS.  
 
 
   
MARINE  
 
ISSUED AT 128 PM EDT MON JUL 14 2025  
 
LOW WAVES AND SWIM RISK THROUGH TUESDAY WITH A LIGHT SOUTHERLY  
BREEZE. THUNDERSTORMS ARE POSSIBLE BETWEEN WEDNESDAY AND  
THURSDAY. WINDS BECOMING NORTH ON THURSDAY MAY INCREASE THE WAVES  
AND SWIM RISK.  
 
 
   
GRR WATCHES/WARNINGS/ADVISORIES  
 
MI...AIR QUALITY ALERT UNTIL MIDNIGHT EDT TONIGHT FOR MIZ037>040-  
043>046-050>052-056>059-064>067-071>074.  
MARINE...NONE.  
 
 
 
 
 
DISCUSSION...OSTUNO  
AVIATION...CAS  
MARINE...CAS  
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