835  
FXUS63 KGRR 210459  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
1159 PM EST FRI DEC 20 2024  
   
KEY MESSAGES  
 
- A FEW LIGHT LAKE EFFECT SNOW BANDS INTO SATURDAY  
 
- PRECIPITATION EXPECTED FOR MONDAY INTO MONDAY NIGHT  
 
- MODERATING TEMPERATURES FOR THE MID TO END OF NEXT WEEK  
 
 
   
UPDATE  
 
ISSUED AT 948 PM EST FRI DEC 20 2024  
 
A WEDGE OF CLEARING HAS DEVELOPED IN THE WAKE OF THE DEPARTING  
SYSTEM BUT LAKE CLOUDS HAVE BEEN MOVING BACK IN FROM THE NORTH.  
VARIABLE CLOUDINESS EXPECTED FOR THE OVERNIGHT WITH MOSTLY CLOUDY  
GENERALLY PREVAILING IN THE WEST AND PARTLY CLOUDY IN THE EAST.  
NORTHERLY FLOW LAKE EFFECT SNOW SHOWERS WILL CONTINUE TO CLIP THE  
COAST WITH SOME LOCALIZED ACCUMULATIONS UP TO 1 INCH NOT OUT OF  
THE QUESTION, MAINLY OVER FAR WRN MASON AND OCEANA COUNTIES AND  
NEAR/SOUTH OF SOUTH HAVEN. COLD WITH LOWS TEMPS DIPPING INTO THE  
TEENS (ALREADY THERE AROUND MOP/AMN).  
 
 
   
DISCUSSION  
 
ISSUED AT 155 PM EST FRI DEC 20 2024  
 
- A FEW LIGHT LAKE EFFECT SNOW BANDS INTO SATURDAY  
 
A NORTHEAST FLOW BACKS TO THE NORTH THIS EVENING, RESULTING IN  
STRENGTHENING COLD AIR ADVECTION. ALREADY SEVERAL BANDS OF LIGHT  
SNOW HAVE BEEN TRACKING SOUTHWESTWARD THROUGH OUR CWA. MOST  
LOCATIONS WILL SEE UP TO A DUSTING OF SNOW FROM THE SNOW  
SHOWERS/FLURRIES. THE MOISTURE TONIGHT IS NOT FORECAST TO BE VERY  
DEEP, REMAINING UNDER 5K FT WITH THE DGZ ABOVE THE MOISTURE.  
UNLESS THAT CHANGES, ANY SNOWFALL THAT WE SEE SHOULD REMAIN VERY  
LIGHT/FLURRIES. FOR NOW WE WILL KEEP POPS MOSTLY IN THE LOW CHANCE  
RANGE FOR FAVORED AREAS TO SEE ANY SNOW SHOWERS. WITH NORTHERLY  
FLOW, THIS TYPICALLY FAVORS THE LAKESHORE COUNTIES FOR INCREASED  
LOW LEVEL CONVERGENCE.  
 
- PRECIPITATION EXPECTED FOR MONDAY INTO MONDAY NIGHT  
 
WARM AND MOIST AIR ADVECTION STRENGTHENS MONDAY INTO MONDAY NIGHT.  
THE MOISTURE DEEPENS UP AS A WAVE OF LOW PRESSURE TRACKS  
NORTHEASTWARD THROUGH THE NORTHWEST GREAT LAKES REGION DURING THIS  
TIME. FROM A DGZ SATURATION PERSPECTIVE, THIS SYSTEM LOOKS  
DISORGANIZED OVER OUR CWA. THE LOW AND MID LEVEL MOISTURE NEVER  
REALLY LINE UP WHICH COMMONLY LEADS TO RATHER LIGHT AMOUNTS OF  
QPF. WE DON'T RISE ABOVE FREEZING ON MONDAY UNTIL THE AFTERNOON,  
SO IF ANY OF THE PRECIPITATION ENDS UP BEING LIQUID(UNSATURATED  
DGZ) THEN A RISK FOR A SHORT PERIOD OF FREEZING RAIN COULD OCCUR.  
 
- MODERATING TEMPERATURES FOR THE MID TO END OF NEXT WEEK  
 
BASED ON THE TRACK OF THE MONDAY-TUESDAY SYSTEM, ANY COLD AIR  
ADVECTION ON THE BACKSIDE OF IT WILL BE WEAK AND NOT VERY DEEP.  
WARM AIR ADVECTION RETURNS WEDNESDAY AND MORE SO THURSDAY. TEMPS  
AT 850 MB CLIMB TO 5 OR 6 DEG C, BUT ITS SHOWN TO BE MOIST AT  
THAT LEVEL. THE 925 MB TEMPS ARE A LITTLE LOWER, SO ITS SOMEWHAT  
OF A STABLE MIXING SITUATION. WE WILL FEATURE ABOVE NORMAL  
TEMPERATURES WITH VALUES REACH THE 40'S BY THE END OF THE WEEK,  
WHICH IS IN LINE WITH THE ENSEMBLE VALUES.  
 
 
   
AVIATION /00Z TAFS THROUGH 00Z SUNDAY/  
 
ISSUED AT 1159 PM EST FRI DEC 20 2024  
 
VFR WEATHER CONTINUING TONIGHT AND SATURDAY WITH SCATTERED TO  
BROKEN CLOUDS AROUND 5000 FT. HOWEVER CAN'T RULE OUT SOME BRIEF  
MVFR OR EVEN IFR VSBYS IN SNOW AT MKG THROUGH MIDDAY SATURDAY AS  
LAKE EFFECT SNOW SHOWERS CONTINUE TO HUG THE COASTLINE. NORTHERLY  
WINDS 5 TO 10 KTS.  
 
 
   
GRR WATCHES/WARNINGS/ADVISORIES  
 
MI...NONE.  
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST SATURDAY FOR LMZ844-845-848-  
849.  
 
 
 
 
 
UPDATE...MEADE  
DISCUSSION...MJS  
AVIATION...MEADE  
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