299
FXUS63 KGRR 090507
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1207 AM EST SUN NOV 9 2025
KEY MESSAGES
- SYNOPTIC SNOW SOUTHERN LOWER TONIGHT
- LAKE EFFECT SNOW MAINLY NORTHWEST TONIGHT/SUNDAY
- LAKE EFFECT SNOW EAST OF US-127 SUNDAY NIGHT
- COLD MONDAY MORNING, THEN A WARMING TREND NEXT WEEK
DISCUSSION
ISSUED AT 300 PM EST SAT NOV 8 2025
- SYNOPTIC SNOW SOUTHERN LOWER TONIGHT
REGIONAL RADAR SHOWS A BAND OF RAIN AND SNOW OVER IOWA MOVING
EAST TOWARD LOWER MI. THIS PRECIPITATION WILL MOVE ACROSS THE FAR
SOUTHWEST CWA AROUND 03...INITIALLY AS RAIN...AND THEN SPREAD
EASTWARD. FORECAST SOUNDINGS SHOW ABOVE FREEZING TEMPERATURES
BELOW 870 MB, BUT WET BULBING EFFECTS QUICKLY TAKE OVER AFTER
THAT RESULTING IN A QUICK TRANSITION TO WET SNOW AFTER THAT. ECMWF
ENSEMBLE MODEL TRACKS OF THE SURFACE LOW TAKE IT JUST NORTH OF THE
OHIO RIVER WHICH WILL KEEP MOST OF THE SYNOPTIC PRECIPITATION
ALONG/SOUTH OF I-96. THERE WILL BE SEVERAL HOURS OF LIGHT TO
OCCASIONALLY MODERATE SNOWFALL AFTER 05Z ACROSS THE
SOUTH/SOUTHEAST CWA. AN ADVISORY WAS CONSIDERED. HOWEVER, GROUND
TEMPERATURES ARE ABOVE FREEZING AND SURFACE TEMPERATURES ONLY COOL
TO 32-33 DEGREES BY SUNDAY MORNING. THIS WILL TEND TO MITIGATE
ACCUMULATIONS AND IMPACTS. SYNOPTIC SNOW SHOULD DIMINISH BY LATE
MORNING SUNDAY ACROSS THE SOUTHERN CWA.
- LAKE EFFECT SNOW MAINLY NORTHWEST TONIGHT/SUNDAY
FAVORABLE CONDITIONS FOR LAKE EFFECT SNOW WILL DEVELOP TONIGHT
ACROSS THE CWA. COLDER AIR WILL POUR SOUTH OVER THE LAKE TONIGHT
AS A COUPLE OF SHORT WAVES HELP TO CARVE OUT THE UPPER TROUGH OVER
THE GREAT LAKES AND THE CORE OF THE UPPER LOW DROPPING SOUTH
SUNDAY. ABUNDANT OVER-LAKE INSTABILITY WILL PRODUCE LAKE EFFECT
SNOW. THE QUESTION IS WHERE WILL THE MAIN LAKE BAND DEVELOP?
INITIALLY, BOUNDARY LAYER WINDS ARE NORTH TO NNE. CAMS SHOW A
DOMINANT LAKE BAND DEVELOPING NEAR MID LAKE AND SINKING SOUTH.
USING H85 OMEGA AS A PROXY FOR LAKE BAND PLACEMENT, SEVERAL MODELS
SHOW THE BAND CLIPPING THE POINTS IN MASON/OCEANA COUNTIES. A
LITTLE WIGGLE IN THIS BAND WILL MAKE ALL THE DIFFERENCE. AT THIS
POINT, IT LOOKS LIKE THE FAR WESTERN PORTIONS OF THE
AFOREMENTIONED COUNTIES WILL SEE SOME ACCUMULATION SNOW LATER
TONIGHT WITH MORE SNOW POSSIBLE SUNDAY. HREF ENSEMBLE
PROBABILITIES POINT TOWARD 50-60 PERCENT CHANCE AT GREATER THAN 6
INCHES OF SNOW IN THIS AREA THROUGH SUNDAY NIGHT. WE ISSUED A
WINTER WEATHER ADVISORY FOR MASON/OCEANA COUNTIES FROM THIS
EVENING THROUGH SUNDAY. IF THE LAKE BAND REALLY GETS GOING,
THOUGH, I COULD SEE THIS NEEDING A WARNING.
- LAKE EFFECT SNOW EAST OF US-127 SUNDAY NIGHT
NUANCES IN THE BOUNDARY LAYER FLOW MAY RESULT IN A SNEAKY LAKE
EFFECT SNOW EVENT ACROSS THE EASTERN CWA, MAINLY SOUTH OF ALMA
SUNDAY. AS THE LOW MOVES BY TO THE SOUTHEAST, A NORTHEAST WIND
FLOW DEVELOPS SUNDAY. WHEN COMBINED WITH H8 TEMPS NEAR -9C, LAKE
EFFECT SNOW WILL DEVELOP OVER LAKE HURON AND STREAM SOUTHWESTWARD.
INITIALLY, SURFACE TEMPERATURES WILL BE IN THE UPPER 30S, BUT COOL
BY LATE IN THE DAY. THIS BAND ALSO SHOWS UP IN MODEL H85 OMEGA
PROGS TOO, GIVING SOME CREDENCE THIS THIS SCENARIO. WASN'T
CONFIDENT ENOUGH TO ISSUE HEADLINE YET, BUT WE'LL KEEP AN EYE ON
IT.
- COLD MONDAY MORNING, THEN A WARMING TREND NEXT WEEK
TEMPERATURES MONDAY MORNING WILL BE 15 TO 20 DEGREES. SINCE GROUND
TEMPERATURES ARE STILL WARM, WE MAY SEE SOME HAZARDS DEVELOP WITH
LAKE EFFECT SNOW INITIALLY MELTING, THEN REFREEZING.
AFTER MONDAY, THE UPPER TROUGH AXIS WILL MOVE EAST AND A WARMING
TREND WILL DEVELOP. HIGHS WILL WARM THROUGH THE 40S MID WEEK AND
APPROACH 60 BY NEXT WEEKEND.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1206 AM EST SUN NOV 9 2025
IFR CONDITIONS IN SNOW WILL CONTINUE ACROSS SOUTHERN LOWER
MICHIGAN FROM AZO TO JXN OVERNIGHT THEN IMPROVE TO MVFR BY 12Z TO
15Z AS THE SNOW MOVES EAST. FURTHER NORTH, EXPECT MVFR WITH AREAS
IF IFR THROUGH ABOUT 10Z.MVFR CONDITIONS SHOULD PREVAIL MOST OF
SUNDAY WITH SNOW RETURNING IN THE EVENING ALONG WITH AREAS OF
IFR. WINDS WILL BE NORTHEAST AOB 10 KNOTS.
GRR AIRPORT DSS UPDATE
NO CHANGES TO THE DAY SHIFT BRIEFING.
GRR WATCHES/WARNINGS/ADVISORIES
MI...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ037-
043.
MARINE...SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 7 PM EST MONDAY
FOR LMZ844>849.
DISCUSSION...04
AVIATION...OSTUNO
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