502 FXUS63 KGRR 171211 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 711 AM EST Wed Dec 17 2025 .KEY MESSAGES... - Warmer air has arrived...rain expected Thursday - Winter weather expected Thursday night into Friday morning - Windy conditions likely on Thursday && .DISCUSSION... Issued at 342 AM EST Wed Dec 17 2025 - Warmer air has arrived...rain expected Thursday Warmer air has already arrived in Southwest Michigan with temperatures holding in the middle to upper 30s at 300am. We expect highs today to not be much higher than current readings actually as cold air advection occurs for a short time behind the passage of a cold front. Highs on Thursday should rise into the 40s in the strong southerly flow of air ahead of a cold front. The warmest air is in our area for roughly 8-12 hours before being shunted to the east with the next cold front. We lost a small amount of snow yesterday with the sunshine and that should occur again today with highs in the 30s. A more appreciable snow pack loss should occur on Thursday with rain (0.25 to 0.50) and temperatures in the 40s. We still have 7 inches of snow on the ground here at the office as of midnight and we expect to see a net loss as we work through today and tomorrow. Neighborhood roads and secondary roads that are snow covered now will certainly become slushy. As for the chance of flooding due to rain and snowmelt, we are still not expecting that due to the lack of heavy rain, temperatures not rising above 50 and the short duration of the warm air. A few river sites will see solid within bank rises but no flooding is anticipated at this time. - Winter weather expected Thursday night into Friday morning A brief period of wintry weather is expected Thursday night into Friday morning behind a strong cold front. There will be a dry slot that moves through behind the strong cold front Thursday evening, but deeper wrap around moisture works back in overnight. The 12 hour period from 100am Friday to 100pm Friday looks to be the best chance at some lake effect snow and light accumulations. Moisture is a bit shallow, more confined to the 1000-850mb layer, but there is a period around 700am on Friday where the moisture depth increases. Wind driven snow showers can be expected late Thursday night and Friday morning. Accumulations of 1 to 3 inches of new snow are possible during this time near and west of Highway 131. The snow should rapidly end in the midday hours on Friday as moisture is swept to the east at the same time the upper cyclonic axis moves east as well. - Windy conditions likely on Thursday At this point not thinking strong winds are a slam dunk on Thursday. BUFKIT overviews do not show us mixing into advisory level winds. It looks more like 15-25 mph winds out of the south with gusts to 35-40 mph. So it will certainly be brisk just not sure we will reach 45 mph gusts over all of the area. The better chances for wind gusts at or over 45 mph will be along the lakeshore and then towards LAN/AZO/BTL and JXN. No wind headline plans just yet. && .AVIATION /12Z TAFS THROUGH 12Z THURSDAY/... Issued at 712 AM EST Wed Dec 17 2025 A mixture of VFR and MVFR conditions are occurring at 12z across Southwest Lower Michigan. Confidence is not high in how the lower clouds evolve today as guidance is mixed. A batch of MVFR ceilings continues to sink south through the area this morning. The question is how long these ceilings remain in place as it looks like they will make it all the way to the I-94 TAF sites. MVFR ceilings are likely at all TAF sites this morning, which will tend to try to clear out from west to east this afternoon. Another surge in lower ceilings will occur late tonight as warm air surges in over colder ground and snowpack. This will result in IFR and potentially lower clouds late tonight. && .MARINE... Issued at 446 AM EST Wed Dec 17 2025 We have gone ahead and issued a Gale Warning from tonight through Thursday and into Friday morning. A period of strong winds are expected on Lake Michigan in association with deep low pressure system that will move through the Great Lakes over the course of the next 48 hours. We are in the falling stage of the most recent event and waves are expected to fall below 4 feet this afternoon in our nearshore waters. Winds increase rapidly this evening, likely reaching gale force overnight out of the south. South gales will persist through Thursday before veering to the southwest and west into Thursday night. The strongest winds are possible on Thursday, 40 knots, before becoming west gales to 35 knots Thursday night. Waves over 10 feet are expected a fair amount of the time from tonight through Thursday night. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...Small Craft Advisory until 3 PM EST this afternoon for LMZ844>849. Gale Warning from 1 AM Thursday to 7 AM EST Friday for LMZ844>849. && $$ DISCUSSION...Duke AVIATION...Duke MARINE...Duke

NWS GRR Office Area Forecast Discussion