323  
FXUS63 KGRR 240802  
AFDGRR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
402 AM EDT FRI MAR 24 2023  
 
LATEST UPDATE...  
DISCUSSION/MARINE  
   
DISCUSSION  
(TODAY THROUGH NEXT THURSDAY)  
ISSUED AT 329 AM EDT FRI MAR 24 2023  
 
-- WINTER WEATHER TONIGHT INTO SATURDAY --  
 
BOTTOM LINE UP FRONT...WE ARE ADDING A FEW COUNTIES INTO A WINTER  
STORM WATCH UP AGAINST APX'S AREA. MASON, OCEANA AND LAKE COUNTIES  
WILL BE NOW BE IN A WINTER STORM WATCH FOR LATE TONIGHT AND MUCH  
OF SATURDAY.  
 
UPPER WAVE THAT BRINGS A MIX OF PRECIPITATION INTO THE AREA  
TONIGHT IS CURRENTLY IN NM/TX. THE UPPER WAVE RACES OUR DIRECTION  
TODAY ON A 100-120 KNOT UPPER JET. THE SURFACE LOW DEEPENS FROM  
ABOUT 1000MB THIS AFTERNOON/EVENING TO BELOW 990MB BY 12Z ON  
SATURDAY. THE TRACK OF THE LOW THROUGH LOWER MICHIGAN IS STILL A  
BIT UNCERTAIN, BUT THE ECMWF AND GFS OPERATIONAL RUNS HAVE TRENDED  
A BIT TOWARDS EACH OTHER. LEANING ON THE GEFS MSLP OUTPUT WE FEEL  
THE LOW WILL TRACK FROM NORTH CENTRAL/NORTHEAST IN INTO SOUTH  
CENTRAL LOWER MICHIGAN AND FURTHER NORTHEAST INTO LAKE HURON. WE  
FEEL THE AREA THAT STANDS THE BEST CHANCE AT ACCUMULATIONS  
REACHING WARNING CRITERIA POSSIBLY WILL BE OUR FAR NORTHWEST CWA  
TOWARDS LUDINGTON, HART AND BALDWIN. THERE IS A CHANCE ESPECIALLY  
IF A BIT FURTHER EAST TRACK VERIFIES THAT WARNING SNOWS MAY BE  
POSSIBLE AS WELL ACROSS THE REST OF THE U.S. 10 CORRIDOR TOWARDS  
EVART AND CLARE AS WELL. NOT AS CONFIDENT IN THAT OCCURRING SO  
HELD OFF ON THOSE AREAS. A WINTRY MIX OF PRECIPITATION IS POSSIBLE  
BETWEEN I-96 AND U.S. 10 AS A NOSE OF WARMER AIR ALOFT OVERSPREAD  
NEAR TO POSSIBLY JUST BELOW FREEZING SURFACE TEMPERATURES AND  
DYNAMIC COOLING OF THE PROFILE AND WET BULB AFFECTS BRING FREEZING  
RAIN INTO THE PICTURE. WE WILL LIKELY BE ISSUING WINTER WEATHER  
ADVISORIES AND POSSIBLY WARNINGS ON THE DAY SHIFT TODAY IN  
COORDINATION WITH NEIGHBORING OFFICES. SNOWFALL TOTALS IN THE  
NORTHWEST CWA MAY APPROACH OR EXCEED 8 INCHES. 6+ INCH TOTALS  
SEEM POSSIBLE ACROSS THE REMAINDER OF THE U.S. 10 CORRIDOR. CANNOT  
RULE OUT A TENTH OF SO OF ICE ACCUMULATION BEFORE WARM AIR  
ADVECTION CHANGES IT OVER TO RAIN.  
 
-- ADDITIONAL CHANCES FOR PRECIPITATION THROUGH THE PERIOD --  
 
A WEAK WAVE SLIDING THROUGH THE AREA EARLY IN THE WEEK MONDAY INTO  
MONDAY NIGHT WILL BE A LIGHT MIX OF PRECIPITATION. THE  
PRECIPITATION IS NOT VERY SUBSTANTIAL AND WE THEREFORE ONLY HAVE  
20 PCT POPS IN THE FORECAST AT THIS POINT.  
 
LATER IN THE WEEK FROM WEDNESDAY INTO FRIDAY, BETTER CHANCES FOR  
PRECIPITATION EXISTS AS FIRST A LEAD WAVE MOVES THROUGH MID WEEK  
FOLLOWED BY A STRONGER SYSTEM FOR WEEKS END.  
 
 
   
AVIATION  
(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)  
ISSUED AT 149 AM EDT FRI MAR 24 2023  
 
CONDITONS WILL CONTINUE TO BE QUIET EARLY THIS MORNING, BUT SOME  
MVFR/IFR CIGS MAY ADVECT INTO SOUTHERN LOWER MI IMPACTING AZO,  
BTL, AND JXN FOR A BRIEF PERIOD. THESE CLOUDS WILL ADVECT FROM  
EAST TO WEST AND SHOULD CLEAR AZO BY MID-DAY.  
 
 
   
MARINE  
 
ISSUED AT 329 AM EDT FRI MAR 24 2023  
 
WE HAVE DECIDED TO HOLD OFF ON MARINE HEADLINES AT THIS POINT. THE  
TIME FRAME OF CONCERN IS LATER TONIGHT AND MORE SO INTO SATURDAY.  
AS A DEEPENING LOW PRESSURE CENTER APPROACHES THE AREA FROM THE  
SOUTH STRONGER OFF SHORE WINDS WILL DEVELOP ON THE ORDER OF 15 TO  
25 KNOTS TONIGHT. WE MAY NEED TO ISSUE A SMALL CRAFT ADVISORY FOR  
TONIGHT. GIVEN THE OFFSHORE FLOW TONIGHT WAVES WILL BE ON THE  
LOWER SIDE. SO WITH WIND BEING THE ONLY COMPONENT, IT COMING AT  
NIGHT AND IT BEING EARLY IN THE BOATING SEASON WE HAVE HELD OFF.  
THE BIGGER CONCERN IS SATURDAY IN THE NORTHWEST COLD AIR ADVECTION  
PORTION OF THE SYSTEM. 35-40 KNOT NORTHWEST GALES LOOK TO DEVELOP  
ON SATURDAY. THIS IS CONTINGENT ON THE TRACK OF THE LOW. GIVEN A  
BIT OF UNCERTAINTY DECIDED TO HOLD OFF. CERTAINLY POSSIBLE THOUGH  
THAT WE MAY NEED A SCA TONIGHT TRANSITIONING INTO A GALE ON  
SATURDAY.  
 
 
   
GRR WATCHES/WARNINGS/ADVISORIES  
 
MI...WINTER STORM WATCH FROM LATE TONIGHT THROUGH SATURDAY AFTERNOON  
FOR MIZ037-038-043.  
 
LM...NONE.  
 
 
 
 
DISCUSSION...DUKE  
AVIATION...THIELKE  
MARINE...DUKE  
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