829  
FXUS63 KGRR 052350  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
750 PM EDT SAT SEP 5 2026  
   
KEY MESSAGES  
 
- FAIR WEATHER THROUGH LABOR DAY  
 
- CHANCE FOR SHOWERS AND THUNDERSTORMS TUESDAY AND WEDNESDAY  
 
 
   
DISCUSSION  
 
ISSUED AT 157 PM EDT SAT SEP 5 2026  
 
- FAIR WEATHER THROUGH LABOR DAY  
 
AN OMEGA BLOCK DEVELOPS ACROSS THE CONUS THIS WEEKEND AS THE  
CENTRAL U.S. UPPER HIGH IS BOOKENDED BY CUT OFF LOWS ACROSS THE  
NE AND NW CONUS. THIS LOWERS HEIGHTS ACROSS THE CENTRAL GREAT  
LAKES AND ALLOWS SURFACE HIGH PRESSURE RIDGE TO BUILD IN FROM THE  
NORTHEAST WITH LOWER TEMPERATURES AND DEW POINTS. SHOWERS END THIS  
AFTERNOON AND CLEARING PUSHED SOUTH THIS EVENING WITH IT BECOMING  
NOTICEABLY COOLER OVERNIGHT. MORNING LOWS ON SUNDAY AND MONDAY  
EXPECTED TO BE IN THE UPPER 40S TO LOWER 50S ACROSS THE NORTHERN  
FORECAST AREA.  
 
- CHANCE FOR SHOWERS AND THUNDERSTORMS TUESDAY AND WEDNESDAY  
 
THE SURFACE HIGH RETREATS EAST EASTWARD BY TUESDAY. THE OMEGA  
BLOCK BREAKS DOWN AS A LOW ACROSS THE PACIFIC NW KICKS EAST AND  
FLATTENS THE UPPER HIGH, WITH SURFACE LOW PRESSURE TRACKING ACROSS  
SOUTHERN CANADA. RETURN FLOW OF MOISTURE AND A SURFACE WARM FRONT  
SHOULD KICK OFF SOME SHOWERS AND THUNDERSTORMS LATE TUESDAY INTO  
WEDNESDAY. ANOTHER ROUND OF STORMS WILL BE POSSIBLE AS A COLD  
FRONT MOVES THROUGH LATE WEDNESDAY AND SHEAR PROFILES SUGGEST  
STRONG STORMS ARE POSSIBLE IF INSTABILITY IS SUFFICIENT.  
 
 
   
AVIATION /00Z TAFS THROUGH 00Z MONDAY/  
 
ISSUED AT 750 PM EDT SAT SEP 5 2026  
 
SKIES ARE TRENDING MOSTLY CLEAR TONIGHT FOLLOWING A FAIRLY CLOUDY  
DAY WITH SOME RAIN SHOWERS IN SOUTHWEST MICHIGAN. DEW POINTS AT  
THE SURFACE ARE STILL FAIRLY HIGH COMPARED TO THE EXPECTED LOW  
TEMPERATURES TONIGHT. SOME OF THE HIGH RESOLUTION MODELS ARE  
DEVELOPING FOG OR LIFR CEILINGS FOR PRE-SUNRISE SUNDAY. THE ONE  
THING THAT MIGHT KEEP FOG IN CHECK IS 15-20 KNOT WINDS AT 500  
FEET. SEEMS REASONABLE TO PLAN ON THE POTENTIAL FOR IFR CEILINGS  
OR VISIBILITY BETWEEN 07 AND 13 Z, THOUGH IT IS MEDIUM CONFIDENCE.  
 
 
   
MARINE  
 
ISSUED AT 157 PM EDT SAT SEP 5 2026  
 
LIGHT OFFSHORE WINDS, GENERALLY LESS THAN 15 KNOTS, CAN BE  
EXPECTED THROUGH MONDAY. HIGH PRESSURE WILL MOVE EAST ON TUESDAY  
AND WINDS WILL BE ON THE INCREASE, WITH A SMALL CRAFT ADVISORY  
PROBABLY BEING NEEDED FOR TUESDAY AND WEDNESDAY.  
 
 
   
GRR WATCHES/WARNINGS/ADVISORIES  
 
MI...NONE.  
MARINE...NONE.  
 
 
 
 
 
DISCUSSION...OSTUNO  
AVIATION...CAS  
MARINE...OSTUNO  
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