163
FXUS63 KGRR 060509
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1209 AM EST SAT DEC 6 2025
KEY MESSAGES
- LIGHT SNOW AND FREEZING DRIZZLE TONIGHT INTO SATURDAY
- MULTIPLE QUICK ROUNDS OF SNOW SUNDAY INTO NEXT WEEK
DISCUSSION
ISSUED AT 242 PM EST FRI DEC 5 2025
- LIGHT SNOW AND FREEZING DRIZZLE TONIGHT INTO SATURDAY
THE SHORTWAVE TROUGH CURRENTLY MOVING THROUGH MINNESOTA AND
WESTERN WISCONSIN WILL CONTINUE TO SHIFT EAST TONIGHT BRINGING A
QUICK ROUNDS OF LIGHT SNOW AND FREEZING DRIZZLE. WITHIN THE WARM
AIR ADVECTION AHEAD OF THE TROUGH, LIGHT SNOW IS STARTING TO
DEVELOP ALONG AND NORTH OF M-20. SNOW WILL THEN GRADUALLY EXPAND
SOUTHWARD OVERNIGHT. AFTER 3AM WE START TO LOSE CLOUD ICE AS SEEN
IF MULTIPLE MODEL SOUNDINGS. THEREFORE WE'VE INCLUDED FREEZING
DRIZZLE INTO THE FORECAST WITH IT CONTINUING THROUGH SATURDAY
MORNING. THE BEST CHANCE (40 TO 60 PERCENT) FOR FREEZING DRIZZLE
WILL BE ALONG AND SOUTH OF I-96 PARTICULARLY IN PORTIONS OF VAN
BUREN, KALAMAZOO, ALLEGAN, BARRY, KENT, AND IONIA COUNTIES. THESE
HIGHER PROBABILITIES ARE TIED TO AN AREA OF SURFACE CONVERGENCE
ASSOCIATED WITH THE LOW TO THE NORTH. SNOWFALL AMOUNTS WEST OF
131 AND NORTH OF I-96 ARE EXPECTED TO BE IN THE 1 TO 2 INCH RANGE
WITH ISOLATED AMOUNTS TOWARD 3 INCHES IN MASON AND LAKE COUNTIES.
ELSEWHERE AMOUNTS WILL LIKELY BE AN INCH OR LESS WITH LITTLE TO NO
ACCUMULATION TOWARD 127. ANY FREEZING DRIZZLE THAT OCCURS WILL
CREATE A LIGHT GLAZE ON SURFACES.
DRY CONDITIONS RETURN SATURDAY AFTERNOON WITH TEMPERATURES IN THE
UPPER 20S TO LOW 30S.
- MULTIPLE QUICK ROUNDS OF SNOW SUNDAY INTO NEXT WEEK
A PARADE OF SNOW SYSTEMS IS EXPECTED TO START SATURDAY NIGHT AND
CONTINUE THROUGH NEXT WEEK. THIS IS DUE TO THE NORTHWEST FLOW AND
SERIES OF SHORTWAVES MOVING THROUGH RESULTING IN MULTIPLE CLIPPER
SYSTEMS.
THE NEXT ROUND OF SNOW MOVES IN LATE SATURDAY NIGHT INTO SUNDAY AS
A LOW MOVES SOUTHWEST OF THE REGION. THE BETTER POSITIVE VORTICITY
ADVECTION MOVES IN SUNDAY MORNING WITH THE BEST MOISTURE EXITING
SUNDAY AFTERNOON. THE PROBABILITY OF 1 INCH OR MORE OF SNOW IS
CURRENTLY AROUND 40 TO 70 PERCENT WITH THE BEST CHANCE ALONG AND
WEST OF 131 WITH LOWER CHANCES TOWARD 127. SOME LINGERING LAKE
EFFECT SHOWERS ARE POSSIBLE ALONG THE LAKESHORE INTO SUNDAY WITHIN
THE NORTHERLY FLOW.
DRY CONDITIONS MOVE IN SUNDAY NIGHT INTO MONDAY WITH HIGH PRESSURE
MOVING IN, BUT THIS WILL BE SHORT LIVED AS ANOTHER SHORTWAVE
TROUGH MOVES THROUGH MONDAY NIGHT INTO TUESDAY MORNING AND ANOTHER
DURING THE WEDNESDAY/THURSDAY TIMEFRAME. THERE IS A BIT OF
UNCERTAINTY WITH THE EXACT TRACK OF THESE SYSTEMS AND HOW DEEP
THEY ARE. THE DYNAMICS OF THIS SYSTEM HOWEVER WILL HAVE BETTER
LIFT AND DEEPER MOISTURE PROFILES LEADING TO HIGHER NBM
PROBABILITIES (40 TO 70 PERCENT) OF 2 INCHES OR MORE ALONG AND
WEST OF 131 FOR TUESDAY AND NORTH OF I-96 (30 TO 60 PERCENT) FOR
THE WEDNESDAY/THURSDAY SYSTEM. CHANCES ARE NOT AS HIGH WEDNESDAY
ACROSS THE AREA AS WE COULD SEE A MIX IF WARMER TEMPERATURES MOVE
INTO THE SOUTH. EITHER WAY, THERE IS STILL PLENTY OF TIME FOR
THESE TRACKS TO CHANGE AND THEREFORE IMPACT THE TIMING AND
AMOUNTS. KEEP UP TO DATE WITH THE FORECAST AND BE PREPARED FOR
MORE ROUNDS OF SNOW AND TEMPERATURES BELOW FREEZING.
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 1210 AM EST SAT DEC 6 2025
MVFR CONDITIONS WITH PATCHY IFR CAN BE EXPECTED THROUGH 12Z AS
SNOW MOVES THROUGH, WITH SOME FREEZING DRIZZLE EXPECTED BETWEEN
ROUGHLY 10Z AND 14Z. EXPECT SLOW IMPROVEMENT SATURDAY AFTERNOON TO
MVFR AND EVENTUALLY VFR. SOUTHWEST WINDS WILL GUST OVER 25 KNOTS
AT TIMES THROUGH SATURDAY MORNING WITH AREAS OF LLWS OVERNIGHT.
NO CHANGES FROM AFTERNOON BRIEFING FOR AIRPORT OPERATIONS.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR LMZ844>849.
DISCUSSION...RAH
AVIATION...OSTUNO
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