270  
FXUS63 KGRR 070711  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
311 AM EDT SAT JUN 7 2025  
   
KEY MESSAGES  
 
- UPPER LOW BRINGS SOME RAIN EARLY NEXT WEEK  
 
 
   
DISCUSSION  
 
ISSUED AT 311 AM EDT SAT JUN 7 2025  
 
ONE MORE DAY OF FAIR WEATHER BEFORE RAIN CHANCES INCREASE ON  
SUNDAY IN ADVANCE OF A VIGOROUS UPPER LOW MOVING ACROSS THE GREAT  
LAKES REGION. BEFORE THEN...THERE IS A SLIGHT CHANCE OF RAIN  
ACROSS THE FAR SOUTHERN ZONES TONIGHT AS A SFC LOW TRACKS ACROSS  
THE OHIO VALLEY.  
 
THE UPPER LOW APPROACHES ON SUNDAY WITH AN AXIS OF POSITIVE  
VORTICITY ADVECTION AND UPPER LEVEL DIVERGENCE MOVING THROUGH IN  
THE AFTERNOON AND EVENING. THUNDER POTENTIAL IS LIMITED BY  
MARGINAL INSTABILITY WITH FORECAST SOUNDINGS SHOWING CONVECTIVE  
INHIBITION PERSISTING THROUGH THE AFTERNOON.  
 
A SECONDARY AREA OF DIFFERENTIAL POSITIVE VORTICITY ADVECTION  
ASSOCIATED WITH THE CORE REGION OF THE UPPER LOW MOVES IN BY  
MONDAY AFTERNOON AND COMBINES WITH DEEPER MOISTURE AND STEEPENING  
LAPSE RATES/INSTABILITY TO BRING A STRONGER DIURNAL ENHANCEMENT OF  
SHOWERS AND THUNDERSTORMS IN THE AFTERNOON AND EVENING. THE LOW  
MOVES OUT LATE TUESDAY WITH FAIR WEATHER RETURNING FOR WEDNESDAY.  
 
 
   
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/  
 
ISSUED AT 114 AM EDT SAT JUN 7 2025  
 
VFR CONDITIONS EXPECTED TO CONTINUE THROUGH SUNDAY. WINDS WILL BE  
LIGHT AND VARIABLE OVERNIGHT AND EAST TO NORTHEAST BLO 10 KNOTS  
TODAY.  
 
 
   
MARINE  
 
ISSUED AT 114 AM EDT SAT JUN 7 2025  
 
WINDS AND WAVES ARE EXPECTED TO BE RELATIVELY CALM THROUGH THE  
MIDDLE OF NEXT WEEK WITH WINDS LESS THAN 20 KNOTS AND WAVES 3 FEET  
OR LESS.  
 
 
   
GRR WATCHES/WARNINGS/ADVISORIES  
 
MI...NONE.  
MARINE...NONE.  
 
 
 
 
 
DISCUSSION...OSTUNO  
AVIATION...OSTUNO  
MARINE...OSTUNO  
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