962 FXUS63 KGRR 272038 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 338 PM EST Thu Nov 27 2025 .KEY MESSAGES... - Lake Effect Snow Continues through Tonight - Widespread Accumulating System Snow Expected Saturday into Sunday && .DISCUSSION... Issued at 337 PM EST Thu Nov 27 2025 - Lake Effect Snow Continues through Tonight Our ongoing lake effect event has unfolded according to plan with significant wind, snow totals that have been modest (4.8 inches at White Cloud as of this morning) and slippery travel. Earlier today we tapered the headlines a bit...downgrading the Warnings to Advisories and ending some of the more inland counties. We are currently getting the typical diurnal inland surge to the snow showers due to horizontal roll convection, but we feel after dark this will contract more towards the lakeshore or at least into the western couple tiers of counties. The upper cyclonic axis is pushing back southward this afternoon which is giving a boost to the lake effect once again. When lake effect snow is occurring within the cyclonic side of the upper jet it gets a synoptic scale boost aiding both coverage and intensity usually. We have seen an uptick in both this afternoon. BUFKIT overviews especially at MBL, BIV, LWA and BEH show solid depth of moisture at least to 6,000 feet and higher up north to 10,000+ feet tonight. Lift remains in the DGZ, so lake effect snow will continue unabated into Friday morning. We are thinking another 1-2 in most spots within the advisory with 2-4 inch amounts very possible. With temperatures near of below freezing and trend down into the lower 20s tonight slippery travel will continue. Bottom line, holding onto the Winter Weather Advisory through the night or 7am Friday. - Widespread Accumulating System Snow Expected Saturday into Sunday We have gone ahead and issued a Winter Storm Watch from Saturday morning through Sunday morning. The snow looks to move in through the course of Saturday morning reaching peak intensity Saturday afternoon and especially Saturday evening. The scenario remains consistent in that a Colorado low will move our direction on Saturday with warm air advection snow breaking out well in advance of it. The warm air advection/isentropic upglide snow is longer lasting than most systems. Most lows of this type give us a 6-12 hour burst of waa snow with this being more 12-18 hours. The DGZ is 5,000-8,000 feet deep which is solid and the lift is very deep stretching from just off the deck through 20,000 feet. Flake size will likely be larger with riming and accretion aiding snow accumulations a bit. We feel 6+ inches will occur over much of the forecast area, with the the exception being the U.S. 10 corridor which may come in just below those totals. Right now the heaviest swath looks to occur from our southwest CWA near Holland and South Haven through Grand Rapids and Lansing towards Alma. In the southwest areas near and south and west of GRR totals may exceed 8 inches. We have time to nail down amounts as this is starting out in the 4th period and lasting into the 5th period. This will be a widespread, shovel/plow worthy snow. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1255 PM EST Thu Nov 27 2025 West-northwest winds with lake effect snow showers continue into tomorrow. Expecting snow showers to morph and at times loosely organize into cells or bands, creating VFR variable IFR conditions this afternoon into tonight. Ceilings will range between 1,500 and 4,000 feet. Visibility will dip into IFR locally within the relatively heavier snow bands. && .MARINE... Issued at 337 PM EST Thu Nov 27 2025 Winds continue to gust to gale force up and down the shoreline although the trend is definitely down. Our Gale Warning goes until 100am and we have decided to maintain that end time to allow the evening shift some leeway in case the gales persist a bit longer. We will need a Small Craft Advisory once we end the Gale Warning and that will likely need to be carried into Friday evening. To wrap up this past event...the Southern Lake Michigan Buoy peaked at 13.5 feet (significant wave height). Significant wave height correlates to the highest 1/3 of waves rolling through the buoy. So higher waves existed within the spectrum of what was occurring out there. In westerly flow we likely had higher waves in our nearshore waters given 40 more miles of fetch downwind of the buoy. With our nearshore buoys out for the season we do not know exactly what the waves peaked at but in the 14-20 foot range is likely. In terms of wind, the highest gusts were 63 mph at Big Sable Point and the Grand Haven Light, 62 mph at the Saugatuck Pier, 61 mph at the St. Joe Pier and 60 at the Muskegon Pier. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Winter Weather Advisory until 7 AM EST Friday for MIZ037>039- 043>045-050-056-064-065-071>073. Winter Storm Watch from Saturday morning through Sunday morning for MIZ043>046-050>052-056>059-064>067-071>074. MARINE...Gale Warning until 1 AM EST Friday for LMZ844>849. && $$ DISCUSSION...Duke AVIATION...CAS MARINE...Duke

NWS GRR Office Area Forecast Discussion