312
FXUS63 KGRR 172006
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
306 PM EST WED DEC 17 2025
KEY MESSAGES
- RAIN DEVELOPS THURSDAY, WARMER
- LIGHT SNOW THURSDAY NIGHT/FRIDAY
- LIGHT SNOW NORTH SATURDAY NIGHT
DISCUSSION
ISSUED AT 306 PM EST WED DEC 17 2025
- RAIN DEVELOPS THURSDAY, WARMER
WARMER AIR WILL CONTINUE TO ADVECT NORTHWARD INTO THE CWA TONIGHT
AND THURSDAY. THE SNOWPACK WILL CONTINUE MELTING; WE'VE LOST 2
INCHES SINCE LAST NIGHT AT THE WFO. RAIN WILL DEVELOP LATE TONIGHT
AHEAD OF A STRONG COLD FRONT AS STRONG ISENTROPIC LIFT QUICKLY
SATURATES THE COLUMN. MODELS HAVE BEEN CONSISTENT FOR A FEW DAYS
IN DEPICTING AROUND 0.4 INCHES OF RAINFALL BEFORE THE COLD AIR
QUICKLY POURS IN LATE THURSDAY. WE'LL LOSE A DECENT AMOUNT OF THE
SNOWPACK, BUT PROBABLY NOT ALL OF IT. AT THIS POINT WE DON'T SEE
MANY RIVER ISSUES WITH THE RAIN. THE LARGEST IMPACT MAY BE PONDING
ON ROADS NEAR CLOGGED STORM DRAINS. HIGHS THURSDAY WILL BE IN THE
MID 40S.
- LIGHT SNOW THURSDAY NIGHT/FRIDAY
H8 TEMPERATURES QUICKLY FALL FROM +6C TO -14C THURSDAY NIGHT.
THERE'S ROUGHLY 15 HOURS FROM 03Z-18Z FRIDAY WHERE CONDITIONS WILL
BE FAVORABLE FOR LAKE EFFECT SNOW; HIGHEST AMOUNTS WILL BE WEST OF
US-131 AND GENERALLY NORTH OF I-96. HOWEVER, STRONG BOUNDARY LAYER
WINDS WILL PUSH SOME OF THE SNOW SHOWERS INLAND. ACCUMULATIONS
EAST OF US-131 SHOULD BE A HALF INCH OR LESS.
- LIGHT SNOW NORTH SATURDAY NIGHT
LAKE EFFECT SNOW SHOWERS WILL END BY LATE AFTERNOON/EARLY EVENING
FRIDAY AND HIGH PRESSURE WILL QUICKLY BUILD INTO THE REGION.
ANOTHER COLD FRONT WILL PUSH ACROSS THE CWA SATURDAY AFTERNOON.
GIVEN THE LOW NORTH OF LAKE SUPERIOR, THERE WON'T BE A LOT OF
MOISTURE TO WORK WITH; A 30 PERCENT CHANCE OF LIGHT SNOW WITH THE
FRONT SATURDAY NORTH OF I-96.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1224 PM EST WED DEC 17 2025
MVFR CIGS ALONG I94 AND AT GRR SHOULD CLEAR BETWEEN NOW AND 19Z
WITH VFR EXPECTED THE REST OF THE DAY. NOTABLE IMPACTS TO AVIATION
IN THE FORMS OF WIND, CIGS, AND VISBYS ARE EXPECTED STARTING LATE
TONIGHT/EARLY THURSDAY MORNING. INCREASING NON-CONVECTIVE LLWS IS
EXPECTED AFTER 05Z AS A LOW- LEVEL JET STRENGTHENS WITH WINDS AT
2KFT AS HIGH AS 60 KNOTS. GUSTS WILL INCREASE TO 25-30 KNOTS AS
WELL, FIRST AT MKG AND AFTER 09Z AT INLAND TERMINALS. AFTER 09Z, A
SURGE OF HIGHER DEWPOINTS ACROSS OUR MELTING SNOWPACK WILL BRING
WIDESPREAD IFR AND LOWER CEILINGS ACROSS THE TERMINALS. JXN WILL
BE THE LAST TO SEE IFR CONDITIONS NEAR 18Z. AFTER 12Z, RAIN
SHOWERS WILL CAUSE VISBYS TO FALL TO MVFR/IFR GIVEN THE HIGH
MOISTURE AVAILABILITY ALREADY IN PLACE.
MARINE
ISSUED AT 306 PM EST WED DEC 17 2025
THE APPROACH OF A DEEP LOW PRESSURE SYSTEM TONIGHT WILL CAUSE
SOUTHWEST TO INCREASE TO GALES WHICH WILL CONTINUE THROUGH
THURSDAY. THUS, NO CHANGE TO THE GALE WARNING CURRENTLY SET TO
BEGIN TONIGHT. WE'LL LIKELY NEED A SMALL CRAFT ADVISORY FRIDAY
THROUGH SATURDAY ONCE THE GALES SUBSIDE BUT WAVES REMAIN HIGH.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR
LMZ844>849.
GALE WARNING FROM 1 AM THURSDAY TO 7 AM EST FRIDAY FOR
LMZ844>849.
DISCUSSION...04
AVIATION...THOMAS
MARINE...04
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