345 FXUS63 KGRR 010445 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 1145 PM EST Wed Dec 31 2025 .KEY MESSAGES... - Accumulating Snow Through Tonight - Light Snow Showers Thursday Evening - Snow or Mixed Precipitation Possible Sunday into Monday && .DISCUSSION... Issued at 313 PM EST Wed Dec 31 2025 - Accumulating Snow Through Tonight An upper low moving across Lake Superior is helping push through a surface cold front across Lower Michigan this afternoon, with synoptic lift and abundant low level moisture moving over Lake Michigan to provide a flare up in lake enhanced snowfall. Some blowing snow has also been observed at airport observation sites such as MKG. Saturation of the DGZ with 3-6 ubar/s of lift per the 18z RAP13 guidance is moving through at this time with decent snowflake growth bringing visibilities down to 3/4 mile at times at numerous airports including GRR, LAN, and AZO. NAM12 925-850mb omega values look intense for a time from BIV to AZO and LWA between now and 00z or so. During this period, higher impacts to travel are likely for anyone venturing out this New Year`s Eve. Beyond 00z, lake effect snow showers will migrate closer to the coast as low level flow shifts from W to NW. Some lighter lift within a saturated DGZ continues for the lakeshore counties plus Lake and Kalamazoo into tonight, but not for Newaygo/Kent/Barry. Given a dropoff in snow shower activity for those three counties, have decided to trim back the expiration time of the Advisory to 10pm tonight, while leaving the rest of the counties at 7am Thursday. The evening shift can reevaluate as needed. Additional accumulations between now and 10pm for Newaygo/Kent/Barry look to be 1"-2", with 1"-4" through Thursday morning for the remainder of the Advisory area. - Light Snow Showers Thursday Evening The lake effect snow showers should either wind down completely or be reduced to flurries later Thursday morning before another brief flare up Thursday afternoon into the evening. This is the result of a subtle upper shortwave showing up in the numerical guidance and some light snow occurring at the surface (MN into WI) underneath an 850mb thermal gradient. This features moves over the lake after 18z Thursday and 1000-700mb RH increases from below 60% to nearly 100% between 18z Thursday and 03z Friday. With light lift noted in this layer, some lake effect snow showers will likely redevelop with around 1" of new accumulation possible. - Snow or Mixed Precipitation Possible Sunday into Monday Attention then turns to the next system slated to impact the state Sunday night into Monday. Unlike recent systems, this one will emanate from the SW United States and ride up over a developing upper ridge as seen at 500mb across the central U.S. on Sunday. Warm air advection is indicated at 850mb with -10C to start the day but around 0C to end it. At the surface, a warm front is forecast to lift through the region Sunday night into Monday. A strong LLJ of 50 kts will accompany this synoptic system. WAA snow and potentially mixed precipitation could occur especially near and north of I-96. Current ECE probabilities for 1" or more across this region is 60-80% and 3" or more is 20-30%. Can`t rule out mixed precipitation either with the elevated warm layer nosing in. While this doesn`t look like a significant storm yet, it could impact Monday travel conditions. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1145 PM EST Wed Dec 31 2025 Key changes: - None before 12Z - Added PROB30 for MVFR restrictions in snow Thursday afternoon VFR conditions should prevail at all terminals overnight with the possible exception of MKG, which could see intermittent MVFR ceiling restrictions with lake effect snow (LES). Visibility restrictions with LES should be limited given its weakening and disorganized nature. Only other change was to mention PROB30 at all terminals due to an expected uptick in lake enhanced snow Thursday afternoon. GRR Airport DSS Update No changes to the airport briefing information provided from the day shift. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Winter Weather Advisory until 7 AM EST Thursday for MIZ037-038- 043-050-056-064-071-072. MARINE...Small Craft Advisory until 7 PM EST Thursday for LMZ844>849. && $$ DISCUSSION...Hoving AVIATION...TJT

NWS GRR Office Area Forecast Discussion


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