951 FXUS63 KGRR 182318 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 618 PM EST Thu Dec 18 2025 .KEY MESSAGES... - Rain changing to snow showers tonight, windy - Up/down temps through weekend, then warmer && .DISCUSSION... Issued at 300 PM EST Thu Dec 18 2025 - Rain changing to snow showers tonight, windy Based on updated snow accumulations and expected wind, we included all of the lake shore counties plus Kalamazoo county in the winter weather advisory. Regional radar shows a band of rain including a narrow cold frontal rain band moving across eastern Wisconsin and Illinois. This rain will move over the cwa this evening just ahead of the cold front. H8 temps near +8c will quickly fall to -14c by 06z. We expect lake effect snow to develop around 03z and continue into Friday morning. As boundary layer winds transition from west to northwest, snow will impact all of the lake shore. Gusty winds will continue tonight info Friday morning as high pressure rushes in behind the front. 3hr MSL pressure changes increase from 2-3mb/3 hr to 5-6mb/3hr by 15z Friday. Strongest winds winds will be along the lake shore and gust to 40 mph. Travel impacts are expected as the snow and wind combine to produce blowing/drifting. Accums along the lake shore will range from 1-3 inches north of Muskegon to 2-4 south of there. Elsewhere, accumulations around a half inch are possible. The core of the cold air moves out quickly after 18z Friday and the snow will end. - Up/down temps through weekend, then warmer Highs Friday will be in the mid 20s. By Saturday, southwest winds ahead of the next short wave will push temperatures into the mid 30s. Light snow is possible with the short wave north of I-96 but little in the way of accumulations are expected. Behind the short wave Sunday, temperatures will be in the lower 20s. Sunday looks dry with high pressure in control. A building high over the central US will send heights and temperatures upward next week from the 30s Monday to the 40s Tuesday through Christmas. && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 618 PM EST Thu Dec 18 2025 The pre and along frontal rain showers have brought IFR cigs and a mix of IFR and MVFR visbys to the terminals which will continue until the front clears the terminals. As the front moves through from west to east over the next several hours, cigs will lift to sub fuel-alternate MVFR and remain there through the rest of the TAF period. Lake effect snow showers then develop with initial MVFR followed by IFR favored at MKG and AZO which are in the favored Snowbelts for this flow pattern. Further inland at GRR/BTL, lower confidence in IFR impacts has led to PROB30s for now for IFR conditions with prevailing MVFR. MVFR conditions are also likely at LAN/JXN when snowbands reach the terminals. Snow winds down early Friday afternoon with MVFR cigs prevailing through the end of the TAF period. Gusts to 30 knots tonight from the west to west northwest may also support areas of blowing snow further reducing visibilities. && .MARINE... Issued at 300 PM EST Thu Dec 18 2025 A gale warning remains in effect until 7 am, at which time a small craft advisory will be needed. It`s possible that the gale warning will be extended a few hours Friday morning. A tight pressure gradient is in place as deep low pressure moves through the Great Lakes which is producing the strong winds. Wind and waves will be hazardous to small craft through the weekend. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Winter Weather Advisory from 10 PM this evening to 1 PM EST Friday for MIZ037-038-043-050-056-064-071-072. MARINE...Gale Warning until 7 AM EST Friday for LMZ844>849. && $$ DISCUSSION...04 AVIATION...Thomas MARINE...04

NWS GRR Office Area Forecast Discussion