766
FXUS63 KGRR 051745
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1245 PM EST FRI DEC 5 2025
KEY MESSAGES
- LIGHT SNOW ACCUMULATIONS AT TIMES THROUGH SUNDAY
- GOOD POTENTIAL FOR SNOW ACCUMULATIONS NEXT TUESDAY AND WEDNESDAY
DISCUSSION
ISSUED AT 332 AM EST FRI DEC 5 2025
- LIGHT SNOW ACCUMULATIONS AT TIMES THROUGH SUNDAY
AFTER A GOOD DEAL OF SUNSHINE ON THURSDAY FOR MOST LOCATIONS UNDER
HIGH PRESSURE, CLOUDS ARE REDEVELOPING OVER THE NW SECTION OF THE
AREA THIS MORNING. THIS IS OCCURRING AS THE RIDGE HAS MOVED EAST,
AND THE FLOW FROM THE SW IS BRINGING CLOUDS AND FLURRIES TO THAT
PART OF THE AREA.
THE POTENTIAL FOR SNOW SHOWERS WILL CONTINUE TO BE POSSIBLE ACROSS
THE NW PORTION OF THE AREA THIS MORNING WITH SOME LAKE EFFECT, AND
THEN INCREASE LATER FOR ALL AREAS. THIS OCCURS AS WE SEE THE NEXT
SHORT WAVE/CLIPPER SYSTEM IN THE SERIES APPROACH THIS AFTERNOON. THE
EXPECTATION REMAINS THAT SOME LIGHT ACCUMULATIONS OF 1 TO 3 INCHES
OF SNOW ARE LIKELY FOR THE NW QUARTER OF THE AREA. THIS SYSTEM IS
MOISTURE STARVED TO START WITH, AND DOESN'T HAVE MUCH COLD AIR TO
WORK WITH FOR GOOD OVER-LAKE INSTABILITY, EXCEPT RIGHT AT THE SFC.
THE BEST ACCUMULATIONS ARE LIKELY A RESULT OF SOME OVER-LAKE
INSTABILITY, AND MORE SO MOISTURE FLUX OFF OF THE LAKE.
ELSEWHERE, SNOW AMOUNTS WILL GENERALLY BE LESS THAN AN INCH. THERE
IS A BIT OF A CONCERN FOR SOME LIGHT FREEZING DRIZZLE THAT HAS
DEVELOPED. THIS POTENTIAL IS THE RESULT OF THE LACK OF MOISTURE, AND
MORE SO WHEN WE LOSE THE MID LEVEL MOISTURE AT THE END OF THE EVENT
DOWN SOUTH. THIS DOESN'T LOOK LIKE A LONG DURATION EVENT, BUT COULD
BE JUST ENOUGH TO CAUSE SOME MINOR IMPACTS AROUND DAYBREAK SATURDAY
MORNING. COLDER AIR COMES IN BY MID SATURDAY MORNING, AND HELPS TO
SATURATE THE DGZ ONCE AGAIN WITH SOME LINGERING LAKE EFFECT SNOW
SHOWERS BEHIND THE FRONT AS 850 MB TEMPS DROP DOWN INTO THE NEGATIVE
MID TEENS ONCE AGAIN.
THE SCATTERED LAKE EFFECT SNOW SHOWERS EARLIER SATURDAY WILL TAPER
OFF LATE SATURDAY AS A WEAK SFC RIDGE TRAVERSES THE AREA IN THE WAKE
OF THE COLD FRONT. THIS BREAK IN THE SNOW SHOWERS WILL BE SHORT IN
DURATION, AND THEY WILL THEN INCREASE IN COVERAGE LATER SATURDAY
NIGHT AS THE NEXT SHORT WAVE DIVES SW OF THE AREA OUT OF THE PLAINS.
IT WILL BE CLOSE ENOUGH, AND COMBINED WITH THE LAKE AGGREGATE
TROUGHING WILL PRODUCE SOME LIGHT SNOW THROUGH SUNDAY MORNING. THE
SNOW ACCUMULATIONS WITH THIS EVENT ARE EXPECTED TO BE LIGHTER WITH
THE BEST FORCING STAYING SOUTH, AND NOT A GOOD LOW LEVEL FLOW FOR
ANY KIND OF ORGANIZED LAKE EFFECT.
A BETTER AREA OF RIDGING WILL BUILD OVER THE AREA LATER SUNDAY, AND
LINGER THROUGH THE DAYLIGHT HOURS ON MONDAY.
- GOOD POTENTIAL FOR SNOW ACCUMULATIONS NEXT TUESDAY AND WEDNESDAY
THE MODELS AND THEIR ENSEMBLES CONTINUE TO ADVERTISE A COUPLE OF
MORE POTENT SYSTEMS THAT ARE BECOMING MORE LIKELY TO BRING MORE
IMPACTS TO THE AREA THAN THE SYSTEMS THROUGH SUNDAY.
THE UPPER AIR PATTERN CONTINUES TO LOOK LIKE IT WILL TRANSITION FROM
THIS MORE BROAD LONG WAVE TROUGH WITH THE FLOW FROM THE WNW, TO MORE
AMPLIFIED AND FLOW MORE FROM THE NW. THIS CHANGE OCCURS AS THE RIDGE
OUT WEST AND OVER THE EASTERN PACIFIC BUILDS. THIS CHANGE WILL HELP
TO SPIN THE NEXT COUPLE SHORT WAVES A BIT BETTER, AND PACK MORE OF A
PUNCH FOR THE AREA.
THE FIRST ONE ARRIVES EARLY TUESDAY MORNING BEFORE DAYBREAK. THE
ASSOCIATED SFC LOW WILL BE NORTH OF THE AREA AND A SOLID LOW LEVEL
FLOW FROM THE SW. THE AIR AHEAD OF THIS SYSTEM WILL BE A BIT COLDER,
AND PROVIDE FOR BETTER LAKE ENHANCEMENT. PLENTY OF DEEP LAYER
FORCING WILL BE COMING THROUGH THE HEART OF THE FORECAST AREA WITH A
DIRECT HIT BY THE SHORT WAVE. THE NW SECTION OF THE AREA WILL SEE
THE BEST ACCUMULATIONS WITH THE BOOST FROM THE LAKE, AND AMOUNTS
TAPERING OFF MOVING AWAY FROM THAT AREA.
THE LAST SHORT WAVE IN THE SERIES THROUGH NEXT THURSDAY WILL COME
LATER TUESDAY NIGHT AND INTO WEDNESDAY. THIS WAVE WILL BE DIVING A
LITTLE FURTHER SOUTH THAN THE MON NIGHT WAVE. HOWEVER, THE THERMAL
PATTERN IS A BIT WARMER EVEN WITH THE LOW FURTHER SOUTH. DEPENDING
ON WHERE THE LOW TRACKS, THERE WILL BE A BAND OF SNOW ACCUMULATIONS
JUST NORTH OF IT. NEAR AND JUST SOUTH OF THE LOW, AREAS ARE LIKELY
TO SEE A MIXTURE OF RAIN AND SNOW WITH THE LOWER LEVELS SUFFICIENTLY
WARM ENOUGH TO MELT SOME OF THE PRECIPITATION BEFORE IT REACHES THE
GROUND. PLENTY OF TIME TO MONITOR THE EXACT LOW TRACK AND SNOW AND
MIXED PRECIPITATION TYPES.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 1245 PM EST FRI DEC 5 2025
SATELLITE AND SURFACE OBSERVATIONS SUGGEST CLOUD BASES AROUND
4-5KFT THROUGH THE AFTERNOON. CONDITIONS DETERIORATE TO LOW MVFR
TO HIGH IFR OVERNIGHT AS SNOW MOVES ACROSS THE AREA. AHEAD OF THE
SNOW A PERIOD OF LLWS LOOKS LIKELY WITH A 30 KNOT WIND SPEED
CHANGE AND 30 DEGREE DIRECTIONAL CHANGE IN THE LOWEST 2KFT. THE
EXCEPTION IS MKG WHO LOOKS TO REMAIN JUST BELOW CRITERIA. THE
OTHER CONCERN IS FOR FZDZ TO DEVELOP FOR A FEW HOURS AFTER 09Z
SATURDAY AS MID-LEVEL MOISTURE DECREASES BEHIND THE SNOW.HAVE KEPT
THE PROB30S FOR NOW BUT MAY NEED TO BUMP AT LEAST AZO AND BTL TO
PREVAILING WITH THE 00Z PACKAGE. MVFR CIGS PERSIST THROUGH
SATURDAY MORNING THROUGH THE END OF THE TAF PERIOD.
MARINE
ISSUED AT 332 AM EST FRI DEC 5 2025
NO CHANGES NEEDED AT THIS TIME TO THE CURRENT SET OF MARINE
HEADLINES. BIG SABLE OBSERVATION HAS BEEN AT GALES FOR THE LAST HOUR
OR SO, VERIFYING THE GALE WARNING. IT CONTINUES TO LOOK LIKE THE
OTHER MARINE ZONES WILL STAY JUST BELOW GALES, BUT CAN NOT RULE OUT
A FEW GUSTS DOWN TO WHITEHALL.
AFTER THIS CURRENT GALE EVENT UP NORTH, IT LOOKS LIKE WE MAY AVOID
GALES UNTIL AROUND TUESDAY.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EST SATURDAY FOR LMZ844>849.
DISCUSSION...NJJ
AVIATION...THOMAS
MARINE...NJJ
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