566
FXUS63 KGRR 181733
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1233 PM EST THU DEC 18 2025
KEY MESSAGES
- WARM, RAINY AND WINDY TODAY
- TRANSITION BACK TO SNOW AND COLD LATE THURSDAY, EARLY FRIDAY
- ROLLER COAST TEMPS WITH LIGHT SNOW THIS WEEKEND
DISCUSSION
ISSUED AT 334 AM EST THU DEC 18 2025
- WARM, RAINY AND WINDY TODAY
WARM AIR ADVECTION CONTINUES WITH WARM SOUTHERLY FLOW OVERNIGHT
INTO THURSDAY. SFC TEMPS ALONG THE LAKESHORE AND THROUGH THE I 94
CORRIDOR REMAIN ABOVE FREEZING WITH RAIN EXPECTED TO OVERSPREAD
THE REGION LATE MORNING AND THROUGH THE AFTERNOON. QPF AMOUNTS
REMAIN AROUND A QUARTER OF AN INCH TO A HALF AN INCH.
- TRANSITION BACK TO SNOW AND COLD LATE THURSDAY, EARLY FRIDAY
BOTTOM LINE UPFRONT. HAVE ISSUED A WINTER WEATHER ADVISORY FOR
LAKE EFFECT SNOW, FLASH FREEZE AND GUSTY WINDS. THOSE CONDITIONS
WILL CAUSE HAZARDOUS DRIVING CONDITIONS FOR MASON AND LAKE
COUNTIES, THOUGH THERE IS THE POTENTIAL FOR OCEANA AND MUSKEGON.
A STRONG UPPER LEVEL LOW WILL TRACK THROUGH THE REGION TONIGHT
INTO FRIDAY MORNING. THAT STRONG UPPER LEVEL TROUGH WILL COINCIDE
WITH A STRONG GRADIENT THROUGH THE MID LEVELS. THE BIGGEST
CONCERN WILL BE THE RAPID TRANSITION TO COLD TEMPERATURES. 850MB
TEMPS GO FROM +5C EARLY EVENING TO -15C BY MIDNIGHT. COUPLE THAT
WITH MID LEVEL MOISTURE AND STRONG FLOW ACROSS THE LAKE AND THEIR
IS A RECIPE FOR DECENT LAKE EFFECT SNOW. HEAVIEST SNOW WILL BE
THROUGH THE NW, ESPECIALLY ALONG US 10. THE COLD AIR CONTINUES TO
ADVECT OVERNIGHT INTO FRIDAY MORNING WITH MID LEVEL TEMPS DROPPING
TO NEAR -20C. BETWEEN THAT ARCTIC AIR MASS MOVING OVER A +4C LAKE
AND THAT IF FURTHER EVIDENCE FOR LAKE EFFECT SNOWFALL.
BEST SNOWFALL RATES SHOULD BE NORTH OF HART AND JUST EAST OF
LUDINGTON AND WILL BE IN THE OVERNIGHT HOURS INTO EARLY FRIDAY
MORNING. THE STRONG LLJ COULD BRING GUSTY WINDS AS HIGH AS 35KTS
WITH THE SNOW WHICH COULD FURTHER REDUCE VISIBILITIES.
ELSEWHERE, SNOW IS EXPECTED, ALONG WITH GUSTY WINDS, HOWEVER THEY
WILL BE LESS IN AMOUNT AND WEAKER WINDS.
SNOW SHOULD TAPER OF MID TO LATE FRIDAY MORNING AS FLOW WEAKENS
AND A THERMAL RIDGE MOVES TO THE EAST.
- ROLLER COAST TEMPS WITH LIGHT SNOW THIS WEEKEND
THAT THERMAL RIDGE WILL BRING WARM AIR ADVECTION INTO SATURDAY.
HOWEVER, IT WILL BE WEAKER THAN TODAY'S SO HIGHS WILL REBOUND ONLY
INTO THE MID TO UPPER 30S.
ANOTHER WEAK CLIPPER WILL SWING ACROSS NORTHERN LOWER MI
SATURDAY INTO SUNDAY. LIGHT SNOW WILL BE POSSIBLE ALONG THE US 10
CORRIDOR.
AVIATION /18Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 1233 PM EST THU DEC 18 2025
THE INITIAL BAND OF RAIN IS BRINGING PREDOMINANTLY MVFR CONDITIONS
TO THE TERMINALS AT PRESENT. A NARROW BAND OF HEAVIER RAIN THEN
MOVES THROUGH THE TERMINALS LATER THIS AFTERNOON INTO THIS EVENING
ASSOCIATED WITH COLD FRONTAL PASSAGE. UPSTREAM OBSERVATIONS
SUGGEST WIDESPREAD IFR CIGS, AND OBS WARRANTING A TEMPO FOR
BORDERLINE LIFR CONDITIONS AT ALL TERMINALS. A BRIEF INCREASE IN
WINDS AND SUDDEN SHIFT FROM SOUTH TO WEST IS LIKELY AS THE FRONT
CROSSES THE TERMINALS. GUSTS TO 35 KNOTS AS WELL AS LLWS CONTINUE
THROUGH THE AFTERNOON. TONIGHT, AFTER THE FRONT CLEARS, LAKE
EFFECT SNOW SHOWERS DEVELOP CONTINUING THROUGH FRIDAY MORNING.
AROUND 12Z WINDS BECOME MORE NORTHWESTERLY CONCENTRATING SNOW
SHOWERS TO MAINLY THE LAKESHORE (INC. MKG) AND AZO/BTL. POST
FRONTAL CIGS WILL BE MVFR AREAWIDE WITH MVFR AND LOWER VISBYS IN
LAKE EFFECT SNOW SHOWERS.
MARINE
ISSUED AT 335 AM EST THU DEC 18 2025
WINDS CONTINUE TO RAMP UP OVERNIGHT AND CONTINUE TO EXPECT AN
INCREASE TO GALES TODAY INTO FRIDAY. WE'LL LIKELY NEED A SMALL
CRAFT ADVISORY FRIDAY THROUGH SATURDAY ONCE THE GALES SUBSIDE BUT
WAVES REMAIN HIGH.
GRR WATCHES/WARNINGS/ADVISORIES
MI...WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 1 PM EST
FRIDAY FOR MIZ037-038.
MARINE...GALE WARNING UNTIL 7 AM EST FRIDAY FOR LMZ844>849.
DISCUSSION...CERU
AVIATION...THOMAS
MARINE...CERU
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