729
FXUS63 KGRR 170946
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
446 AM EST WED DEC 17 2025
KEY MESSAGES
- WARMER AIR HAS ARRIVED...RAIN EXPECTED THURSDAY
- WINTER WEATHER EXPECTED THURSDAY NIGHT INTO FRIDAY MORNING
- WINDY CONDITIONS LIKELY ON THURSDAY
DISCUSSION
ISSUED AT 342 AM EST WED DEC 17 2025
- WARMER AIR HAS ARRIVED...RAIN EXPECTED THURSDAY
WARMER AIR HAS ALREADY ARRIVED IN SOUTHWEST MICHIGAN WITH
TEMPERATURES HOLDING IN THE MIDDLE TO UPPER 30S AT 300AM. WE
EXPECT HIGHS TODAY TO NOT BE MUCH HIGHER THAN CURRENT READINGS
ACTUALLY AS COLD AIR ADVECTION OCCURS FOR A SHORT TIME BEHIND THE
PASSAGE OF A COLD FRONT. HIGHS ON THURSDAY SHOULD RISE INTO THE
40S IN THE STRONG SOUTHERLY FLOW OF AIR AHEAD OF A COLD FRONT. THE
WARMEST AIR IS IN OUR AREA FOR ROUGHLY 8-12 HOURS BEFORE BEING
SHUNTED TO THE EAST WITH THE NEXT COLD FRONT. WE LOST A SMALL
AMOUNT OF SNOW YESTERDAY WITH THE SUNSHINE AND THAT SHOULD OCCUR
AGAIN TODAY WITH HIGHS IN THE 30S. A MORE APPRECIABLE SNOW PACK
LOSS SHOULD OCCUR ON THURSDAY WITH RAIN (0.25 TO 0.50) AND
TEMPERATURES IN THE 40S. WE STILL HAVE 7 INCHES OF SNOW ON THE
GROUND HERE AT THE OFFICE AS OF MIDNIGHT AND WE EXPECT TO SEE A
NET LOSS AS WE WORK THROUGH TODAY AND TOMORROW. NEIGHBORHOOD
ROADS AND SECONDARY ROADS THAT ARE SNOW COVERED NOW WILL CERTAINLY
BECOME SLUSHY. AS FOR THE CHANCE OF FLOODING DUE TO RAIN AND
SNOWMELT, WE ARE STILL NOT EXPECTING THAT DUE TO THE LACK OF
HEAVY RAIN, TEMPERATURES NOT RISING ABOVE 50 AND THE SHORT
DURATION OF THE WARM AIR. A FEW RIVER SITES WILL SEE SOLID WITHIN
BANK RISES BUT NO FLOODING IS ANTICIPATED AT THIS TIME.
- WINTER WEATHER EXPECTED THURSDAY NIGHT INTO FRIDAY MORNING
A BRIEF PERIOD OF WINTRY WEATHER IS EXPECTED THURSDAY NIGHT INTO
FRIDAY MORNING BEHIND A STRONG COLD FRONT. THERE WILL BE A DRY
SLOT THAT MOVES THROUGH BEHIND THE STRONG COLD FRONT THURSDAY
EVENING, BUT DEEPER WRAP AROUND MOISTURE WORKS BACK IN OVERNIGHT.
THE 12 HOUR PERIOD FROM 100AM FRIDAY TO 100PM FRIDAY LOOKS TO BE
THE BEST CHANCE AT SOME LAKE EFFECT SNOW AND LIGHT ACCUMULATIONS.
MOISTURE IS A BIT SHALLOW, MORE CONFINED TO THE 1000-850MB
LAYER, BUT THERE IS A PERIOD AROUND 700AM ON FRIDAY WHERE THE
MOISTURE DEPTH INCREASES. WIND DRIVEN SNOW SHOWERS CAN BE EXPECTED
LATE THURSDAY NIGHT AND FRIDAY MORNING. ACCUMULATIONS OF 1 TO 3
INCHES OF NEW SNOW ARE POSSIBLE DURING THIS TIME NEAR AND WEST OF
HIGHWAY 131. THE SNOW SHOULD RAPIDLY END IN THE MIDDAY HOURS ON
FRIDAY AS MOISTURE IS SWEPT TO THE EAST AT THE SAME TIME THE UPPER
CYCLONIC AXIS MOVES EAST AS WELL.
- WINDY CONDITIONS LIKELY ON THURSDAY
AT THIS POINT NOT THINKING STRONG WINDS ARE A SLAM DUNK ON
THURSDAY. BUFKIT OVERVIEWS DO NOT SHOW US MIXING INTO ADVISORY
LEVEL WINDS. IT LOOKS MORE LIKE 15-25 MPH WINDS OUT OF THE SOUTH
WITH GUSTS TO 35-40 MPH. SO IT WILL CERTAINLY BE BRISK JUST NOT
SURE WE WILL REACH 45 MPH GUSTS OVER ALL OF THE AREA. THE BETTER
CHANCES FOR WIND GUSTS AT OR OVER 45 MPH WILL BE ALONG THE
LAKESHORE AND THEN TOWARDS LAN/AZO/BTL AND JXN. NO WIND HEADLINE
PLANS JUST YET.
AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
ISSUED AT 1137 PM EST TUE DEC 16 2025
THE TERMINALS ARE ALL VFR TO START THIS FORECAST PERIOD, WITH JUST
HIGH CLOUDS CURRENTLY OVER THE AREA. A WEAK FRONT DROPPING DOWN
WILL BE BRINGING SOME LOWER CLOUDS OVER THE AREA. JUST HOW MUCH
COVERAGE WE SEE IN THE LOW CLOUDS IS SOMEWHAT UNCERTAIN WITH
DISAGREEMENT AMONGST THE DATA. GIVEN THE FRONT IS EXPECTED NOT TO
GO FAR, THERE IS A BETTER CHANCE THE LOWER CLOUDS WILL PERSIST,
ALTHOUGH THERE MAY BE BREAKS IN THE LOWER CLOUDS AT TIMES RIGHT ON
THROUGH TOMORROW AFTERNOON. KAZO AND KBTL MAY NOT SEE THE
CEILINGS HANG ON AS THE FRONT STARTS MOVING BACK TO THE NORTH AND
AWAY FROM THOSE TERMINALS.
WE TOOK THE LOW LEVEL WIND SHEAR OUT OF THE FORECAST FOR TONIGHT.
WE HAVE WIND GUSTS AT JUST ABOUT ALL OF THE TERMINALS, KEEPING THE
DIFFERENCE BETWEEN THE SFC AND 2K FT AGL LOW ENOUGH TO NO MENTION
IT AT THIS TIME. WE WILL SEE A STRONGER WIND CORE MOVE OVERHEAD AT
THE END OF THIS FORECAST PERIOD, AND SFC WINDS WILL REMAIN MORE
DECOUPLED THAN TONIGHT. WE HAVE ADDED LOW LEVEL WIND SHEAR TO THE
FORECAST AFTER 01-03Z THU.
MARINE
ISSUED AT 446 AM EST WED DEC 17 2025
WE HAVE GONE AHEAD AND ISSUED A GALE WARNING FROM TONIGHT THROUGH
THURSDAY AND INTO FRIDAY MORNING. A PERIOD OF STRONG WINDS ARE
EXPECTED ON LAKE MICHIGAN IN ASSOCIATION WITH DEEP LOW PRESSURE
SYSTEM THAT WILL MOVE THROUGH THE GREAT LAKES OVER THE COURSE OF
THE NEXT 48 HOURS.
WE ARE IN THE FALLING STAGE OF THE MOST RECENT EVENT AND WAVES ARE
EXPECTED TO FALL BELOW 4 FEET THIS AFTERNOON IN OUR NEARSHORE
WATERS. WINDS INCREASE RAPIDLY THIS EVENING, LIKELY REACHING GALE
FORCE OVERNIGHT OUT OF THE SOUTH. SOUTH GALES WILL PERSIST THROUGH
THURSDAY BEFORE VEERING TO THE SOUTHWEST AND WEST INTO THURSDAY
NIGHT. THE STRONGEST WINDS ARE POSSIBLE ON THURSDAY, 40 KNOTS,
BEFORE BECOMING WEST GALES TO 35 KNOTS THURSDAY NIGHT. WAVES OVER
10 FEET ARE EXPECTED A FAIR AMOUNT OF THE TIME FROM TONIGHT
THROUGH THURSDAY NIGHT.
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...DUKE
AVIATION...NJJ
MARINE...DUKE
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