148  
FXUS63 KGRR 152023  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
323 PM EST SUN DEC 15 2024  
   
KEY MESSAGES  
 
- FOG TONIGHT, RAIN MONDAY  
 
- COLDER WITH SNOW CHANCES WEDNESDAY THROUGH SATURDAY  
 
 
   
DISCUSSION  
 
ISSUED AT 323 PM EST SUN DEC 15 2024  
 
- FOG TONIGHT, RAIN MONDAY  
 
PATCHY DENSE FOG WILL CONTINUE THROUGH TONIGHT WITH LIGHT WINDS  
AND SATURATED LOW LEVELS. THERE WILL BE SLOW IMPROVEMENT MONDAY  
MORNING AS LIGHT RAIN HELPS TO SLOWLY DISPERSE THE FOG. WEST  
WINDS PICK UP IN THE AFTERNOON AND EVENING WHICH WILL DISPERSE ANY  
REMAINING FOG. LOW LEVEL MOISTURE REMAINS ALTHOUGH RH PROFILES  
SHOW A PARTIALLY UNSATURATED DGZ, RESULTING IN ONLY LIGHT SHOWERS  
AND DRIZZLE PERHAPS MIXING WITH SNOW FLAKES BEFORE ENDING MONDAY  
NIGHT.  
 
- COLDER WITH SNOW CHANCES WEDNESDAY THROUGH SATURDAY  
 
COOLER AIR ADVECTS IN ON TUESDAY AND THIS COULD SET THE STAGE FOR  
SOME SNOW LATE TUESDAY NIGHT INTO WEDNESDAY MORNING IN AN AREA OF  
MID LEVEL FRONTOGENESIS TO THE NORTH OF A SFC LOW TRACKING EAST  
NORTHEAST ACROSS THE OHIO VALLEY. THIS IS FOLLOWED BY A THERMAL  
TROUGH AND CYCLONIC FLOW RESULTING IN LIGHT LAKE EFFECT SNOW  
SHOWERS INTO WEDNESDAY EVENING.  
 
THERE HAS BEEN A SIGNAL IN THE MODEL GUIDANCE FOR A CLIPPER TO  
MOVES ACROSS THE GREAT LAKES WITH SNOW BY LATE IN THE WEEK. THE  
UNCERTAINTY IN TIMING AND TRACK IS DECREASING AS TODAY THERE  
APPEARS TO BE A CONVERGENCE OF MODEL TIMING ON THURSDAY NIGHT TO  
FRIDAY FOR SOME SYNOPTIC SNOW FOLLOWED BY A VERY COLD SHOT OF AIR  
AND LAKE EFFECT SNOWS FOR THE WEEKEND.  
 
 
   
AVIATION /18Z TAFS THROUGH 18Z MONDAY/  
 
ISSUED AT 1133 AM EST SUN DEC 15 2024  
 
IFR/LIFR CONDITIONS ARE FORECAST TO CONTINUE AT ALL THE TERMINALS  
THIS AFTERNOON DUE TO PATCHY FOG LOW CIGS AND LINGERING LIGHT RAIN  
SHOWERS. THE MIX OF IFR/LIFR WILL CONTINUE TONIGHT DUE TO AREAS  
OF FOG AND LOW CIGS. SOME RAIN SHOWERS WILL REDEVELOP MONDAY  
MORNING AND EARLY AFTERNOON WITH A CONTINUED MIX OF LIFR/IFR  
EXPECTED DUE TO VERY LOW CIGS AND SOME PATCHY LINGERING FOG.  
 
 
   
GRR WATCHES/WARNINGS/ADVISORIES  
 
MI...NONE.  
MARINE...NONE.  
 
 
 
 
 
DISCUSSION...OSTUNO  
AVIATION...LAURENS  
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