467
FXUS63 KGRR 151204
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
704 AM EST MON DEC 15 2025
KEY MESSAGES
- A LITTLE BIT OF LIGHT SNOW POSSIBLE ACROSS CENTRAL LOWER TODAY
- QUIET WEATHER WITH SLOW WARMING INTO MID WEEK
- RAIN TO MOVE THROUGH ON THURSDAY
- COLDER WITH LAKE EFFECT SNOW ON FRIDAY
DISCUSSION
ISSUED AT 356 AM EST MON DEC 15 2025
- A LITTLE BIT OF LIGHT SNOW POSSIBLE ACROSS CENTRAL LOWER TODAY
NORTHWEST UPPER FLOW PERSISTS TODAY ON THE BACKSIDE OF A DEPARTING
TROUGH ACROSS THE GREAT LAKES REGION. A SHORTWAVE DIVING SOUTHEAST
THROUGH THE NORTHERN GREAT LAKES WILL BRUSH BY CENTRAL LOWER
MICHIGAN. A PERIOD OF LIGHT SNOW IS POSSIBLE THIS MORNING,
ESPECIALLY UP TOWARDS U.S. 10 AS A ZONE OF ISENTROPIC LIFT MOVES
THROUGH. WHILE LIFT LOOKS FAIRLY STRONG, CONDENSATION PRESSURE
DEFICITS ARE STILL FAIRLY HIGH LEADING TO A LOWER CONFIDENCE IN
MUCH OCCURRING UP THERE. BUFKIT OVERVIEWS BEAR THIS OUT AS WELL,
WITH A BREAK IN THE MOISTURE BETWEEN MID LEVEL ISENTROPIC LIFT
MOISTURE AND THE LOW CLOUDS STILL IN PLACE. BEST CHANCE FOR ANY
ACCUMULATION WOULD BE TOWARDS CLARE AND HARRISON ONE THE ORDER OF
A DUSTING TO A HALF INCH IF WE SEE THAT.
- QUIET WEATHER WITH SLOW WARMING INTO MID WEEK
A PERIOD OF DRY WEATHER LOOKS TO OCCUR FROM LATE THIS AFTERNOON
THROUGH WEDNESDAY NIGHT. A COLD FRONT DOES MOVE THROUGH THE AREA
TUESDAY NIGHT INTO WEDNESDAY MORNING, BUT IT LOOKS TO MOVE THROUGH
DRY. THE MAIN WEATHER ITEM OF NOTE IN THIS PERIOD IS A GRADUAL
WARMING OF TEMPERATURES. 850MB TEMPERATURES RISE FROM AROUND -10C
THIS MORNING OVERHEAD TO +7C TUESDAY NIGHT AND AGAIN WEDNESDAY
NIGHT. WE WILL BE IN THE 30S FOR HIGHS BOTH TUESDAY AND WEDNESDAY
SO WE SHOULD SEE THE SNOWPACK RIPEN UP A BIT AND WE WILL BEGIN TO
MELT SOME SNOW AND ICE OFF OF SECONDARY/NEIGHBORHOOD ROADS.
- RAIN TO MOVE THROUGH ON THURSDAY
THE BIGGEST SURGE IN WARMTH AND MOISTURE WILL COME ON THURSDAY
AHEAD OF A FRONTAL PASSAGE. THE SURFACE FRONT IS ASSOCIATED WITH
AND BEING DRIVEN BY AN AMPLIFYING WAVE THAT MOVES OUT OF THE
ROCKIES AND INTO THE PLAINS WEDNESDAY NIGHT TAKING AIM ON THE
GREAT LAKES FOR THURSDAY. AS THE SURFACE LOW DEEPENS INTO THE 980S
MB ON THURSDAY THE SOUTHERLY INFLOW INTO OUR AREA INCREASES. SO
MUCH SO THAT THE 850MB LLJ RAMPS UP TO 55-60 KNOTS IN THE GFS,
ECMWF AND CANADIAN MODELS. SOUTHWEST WIND GUSTS IN THE STRONGER
ECWMF INCREASE TO 40-50MPH ON THURSDAY.
THE SOUTHERLY SURGE WILL ALSO BRING MOISTURE WITH PWAT VALUES
INCREASING TO AROUND 0.90 INCHES WHICH IS ABOVE THE 90TH
PERCENTILE IN SOUNDING CLIMATOLOGY FOR DTX AND NEAR THE DAILY MAX
FOR THE DAY. SURFACE DEW POINTS WILL CLIMB INTO THE 40S.
THANKFULLY, RAINFALL AMOUNTS DO NOT LOOK TO BE EXCESSIVE (TOWARDS
A HALF INCH IN MOST AREAS) AND THE WARMER AIR WILL NOT BE IN THE
AREA THAT LONG AS ITS QUICKLY SWEPT TO THE EAST BY THE COLD FRONT
IN THE AFTERNOON. AS WE TALKED ABOUT YESTERDAY, NOT EXPECTING BIG
IMPACTS FROM THE RAIN AND BRIEF WARM UP. THE SNOWPACK WILL RIPEN,
WE WILL LOSE SOME DEPTH AND THERE WILL BE SOME PONDING OF WATER IN
AREAS WHERE STORM DRAINS ARE PACKED BY ICE AND SNOW. WIDESPREAD
FLOODING ISSUES ARE NOT ANTICIPATED AND THAT IS BACKED UP BY OUR
HYDROLOGIC ENSEMBLE FORECAST SIMULATIONS. THE SITES THAT COULD SEE
A QUICK RUN TO NEAR BANKFULL WOULD BE OUR MORE QUICK RESPONSE
SITES LIKE SYCAMORE CREEK AT HOLT, THE PORTAGE RIVER AT VICKSBURG
AND THE GRAND AT JACKSON.
- COLDER WITH LAKE EFFECT SNOW ON FRIDAY
A QUICK BURST OF LAKE EFFECT SNOW IS EXPECTED THURSDAY NIGHT INTO
FRIDAY MORNING, BUT THE MOISTURE AVAILABILITY WILL BE SHORT LIVED
AND ANY LAKE EFFECT LIKELY GETS SHUT DOWN BY FRIDAY AFTERNOON. A
QUICK 1-3 OR 2-4 INCHES LOOKS LIKE THE BEST BET AT THIS POINT, BUT
WE HAVE TIME TO ZERO IN ON THIS SNOW CHANCE AS IT GETS CLOSER.
AVIATION /12Z TAFS THROUGH 12Z TUESDAY/
ISSUED AT 703 AM EST MON DEC 15 2025
THE TWO MAIN AVIATION CONCERNS TODAY ARE MVFR CEILINGS AND THE
WIND. WITH REGARD TO CEILINGS, THERE WILL BE ENOUGH INSTABILITY
OVER LAKE MICHIGAN FOR THE PRODUCTION OF LAKE STRATOCUMULUS BOTH
TODAY AND TONIGHT. THE CLOUDS WILL LIKELY VARY BETWEEN 1500 AND
2500 FEET AND BE DICTATED BY WIND DIRECTION. SO, AS THE WINDS HAVE
BACKED TO THE SOUTHWEST OVERNIGHT FROM THE WEST THE LOWER CEILINGS
HAVE MOVED NORTHWARD WITH THE MEAN WIND DIRECTION. LAN FOR
INSTANCE HAS CLEARED OUT THE LOW CLOUDS. MKG IN FACT IS THE ONLY
SITE STILL INDICATING A MVFR CEILING AT 1800 FEET. THE WINDS WILL
VEER TO THE WEST ONCE AGAIN THIS AFTERNOON AND EVENING AND THE
MVFR CEILINGS WILL EXPAND ONCE AGAIN THROUGH ALL OF THE TAF SITES.
THE TAF SITES SHOULD LARGELY STAY PRECIPITATION FREE THE NEXT 24
HOURS.
AS FOR THE WIND IT WILL GET GUSTY THIS MORNING FAIRLY QUICK WITH
ALL SITES DEVELOPING GUSTS BETWEEN 20-30 KNOTS BY MIDDAY OR 16Z OR
SO. WINDS WILL SUBSIDE TO BACK BELOW 10 KNOTS ONCE AGAIN BY 00Z
THIS EVENING.
MARINE
ISSUED AT 356 AM EST MON DEC 15 2025
WE ARE STILL LOOKING GOOD FOR A BORDERLINE / SHORT DURATION GALE
EVENT THIS MORNING. MIXING DEPTH LOOKS TO TAP INTO 34-38 KNOTS
BETWEEN 7AM AND 1PM. THAT IS THE TIME FRAME WHERE WE SHOULD SEE
OCCASIONAL GALE GUSTS AT OUR LAKESHORE MARINE OB SITES LIKE BIG
SABLE POINT, MUSKEGON GLERL, HOLLAND NOS AND SOUTH HAVEN GLERL.
WINDS RAMP DOWN FAIRLY QUICK IN THE EARLY TO MID AFTERNOON WHICH
IS WHEN WE WILL BE ABLE TO DOWNGRADE INTO A SMALL CRAFT ADVISORY.
ANOTHER SHORT DURATION GALE EVENT LOOKS POSSIBLE TUESDAY EVENING.
THESE GALE EVENT ARE DUE TO SURFACE LOW PRESSURE SYSTEMS ZIPPING
EAST ACROSS CANADA IN ZONAL FLOW. AS EACH SYSTEM SLIDES BY TO OUR
NORTH THE PRESSURE GRADIENT TIGHTENS FOR A TIME WHEN COMBINED WITH
SURFACE HIGH PRESSURE TO OUR SOUTH. WAVES WILL PUSH TO AROUND
10-12 FEET IN BOTH EVENTS IN SOUTHWEST FLOW. HOLLAND TO THE NORTH
WILL BE WHERE THE LARGEST WAVES WILL BE FOUND.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...GALE WARNING UNTIL 3 PM EST THIS AFTERNOON FOR LMZ844>849.
DISCUSSION...DUKE
AVIATION...DUKE
MARINE...DUKE
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