278
FXUS63 KGRR 172330
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
630 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 /00Z TAFS THROUGH 00Z FRIDAY/
ISSUED AT 630 PM EST WED DEC 17 2025
VFR CONDITIONS ARE ONGOING AT PRESENT, WITH NO SIGNIFICANT
OPERATIONAL IMPACTS UNTIL AFTER 04Z. THEN, A STRONG LOW-LEVEL JET
WITH WINDS IN EXCESS OF 60 KNOTS MOVES IN AROUND 2KFT PROVIDING
PERSISTENT LLWS FOR POTENTIALLY MUCH OF THE TAF PERIOD DEPENDING
ON HOW GUSTY WINDS GET. GUSTS TO AT LEAST 30 KNOTS ARE LIKELY
BEGINNING LATE THIS EVENING AT MKG AND EARLY THURSDAY AT THE
INLAND TERMINALS. AFTER 09Z, MVFR CIGS DEVELOP AS MOIST AIR
SPREADS OVER OUR SNOWPACK. RAIN ARRIVES AFTER 12Z BRINGING
WIDESPREAD IFR CONDITIONS, WITH THE WORST VISBYS FOCUSED ON A 1 OR
2 HOUR WINDOW FOR EACH SITE. GIVEN THE AMPLE LOW-LEVEL MOISTURE
RESTRICTIONS DUE TO MIST PERSIST BEYOND THE SHOWERS BEFORE THE
NEXT ROUND OF RAIN ARRIVES.
A COLD FRONTAL RAIN BAND THEN CROSSES THE TERMINALS AFTER 17Z
BRINGING IFR AND POTENTIALLY CONDITIONS TO THE TERMINALS. WINDS
MAY BE BRIEFLY ENHANCED ALONG THE FRONT AS WELL. GUIDANCE
SUGGESTS THAT MOST IMPROVEMENT IN CONDITIONS WILL BE AFTER THE END
OF THE TAF PERIOD BEHIND THE FRONT.
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...GALE WARNING FROM 1 AM THURSDAY TO 7 AM EST FRIDAY FOR
LMZ844>849.
DISCUSSION...04
AVIATION...THOMAS
MARINE...04
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