475 FXUS63 KGRR 121131 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 631 AM EST Fri Dec 12 2025 .KEY MESSAGES... - Lake Effect Snow through the Weekend - Arctic Air this Weekend, Warming Trend Next Week && .DISCUSSION... Issued at 310 AM EST Fri Dec 12 2025 - Lake Effect Snow through the Weekend A quick moving shortwave trough will move through this evening bringing with it a round of snow. Within the southwest flow this afternoon, a band of snow showers is expected to develop around the Muskegon area. There initially could be some freezing rain as moisture flirts with the dendritic growth zone. Deeper moisture moves in during the late afternoon and early evening along with positive vorticity advection. Winds will also shift to the west northwest. This will cause snow showers to spread along the lakeshore and expand eastward. Deep moisture will be brief as shown in 700mb moisture fields and soundings which will limit amounts. Snowfall rates will largely be about 0.1 inch per hour with 0.25 to 0.50 inch per hour possible between 7pm and midnight. Overall amounts along and west of US-131 are expected to be in the 1 to 3 inch range through Saturday morning. The probability of 4 inches or more is low (20 to 30 percent) with isolated higher probabilities of 40 percent as seen in the WPC super ensemble and HREF. Therefore not planning any headlines at this time. Saturday afternoon a clipper system passes mainly to our south bringing another front through the region. We`ll have to monitor the track as it could potentially bring higher amounts to southwest Michigan, otherwise light lake effect snow and flurries will continue into Sunday with amounts largely under an inch and 1 to 2 inches along the lakeshore through Sunday afternoon. With the snowfall and cold temperatures as mentioned below, any snow will cause slick conditions. - Arctic Air this Weekend, Warming Trend Next Week Cold air filters in for the weekend with 925mb temperatures around -15 C resulting in lows in the single digits Saturday night and Sunday night and highs in the teens on Saturday and low 20s on Sunday. Wind chills will be around 0 and in the single digits below 0 potentially hitting minus 10 Saturday morning into Monday morning. Slight improvements in the wind chills are possible Sunday afternoon with the "warmer" temperatures. The overall pattern shifts to more westerly flow next week bringing milder temperatures with highs in the 30s Tuesday and then upper 30s to 40s Wednesday and Thursday. Looking at the cluster analysis there is some uncertainty with the timing and strength of the shortwave troughs and ridges in the flow. With these shortwaves there is the potential for rain/snow. With any rain we`ll need to monitor the timing. With the cold ground there could the be potential for freezing rain even with air temperatures above freezing. && .AVIATION /12Z TAFS THROUGH 12Z SATURDAY/... Issued at 631 AM EST Fri Dec 12 2025 Largely overcast skies are expected with ceilings around 3000 feet. Lake effect snow is expected to develop this afternoon toward MKG then LDM and then expand south and east around 00Z to 06Z tonight. Snowfall rates will largely be around 0.1 to 0.25 inch per hour but isolated spots may see 0.5 inch per hour toward the lakeshore. Winds will also pick up this evening from the west northwest with gusts 20 to 30 knots with the higher gusts along the lakeshore. With the snow ceilings will lower around 1500 feet with MVFR visibilities. The probability of IFR visibilities with the snow are 20 to 30 percent. Total snowfall amounts into Saturday morning are expected to be in the 1 to 3 inch range along and west of a AZO to GRR to RQB line. Isolated higher amounts are possible toward the lakeshore. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...Small Craft Advisory from 7 PM this evening to 7 PM EST Saturday for LMZ844>849. && $$ DISCUSSION...RAH AVIATION...RAH

NWS GRR Office Area Forecast Discussion