606 FXUS63 KGRR 062025 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 325 PM EST Sat Dec 6 2025 .KEY MESSAGES... - Clipper system light snow tonight into Sunday morning - Southwest flow lake enhanced snow Monday night - Clipper system snow Tuesday night into Wednesday - Additional snow chances Thursday into next Saturday && .DISCUSSION... Issued at 325 PM EST Sat Dec 6 2025 - Clipper system light snow tonight into Sunday morning A mid level shortwave is working out of the Rockies and into the Plains this afternoon which has already allowed for surface low pressure to form in Nebraska. Light snow is broken out ahead of the low across SD/MN/IA. The low will move eastward tonight into the Ohio Valley, filling as does. Snow is still expected to move into Southwest Lower Michigan overnight and persist into Sunday morning. This looks to mainly be a 100am to 100pm event. Liquid equivalent amounts are not high (0.05 to 0.15). A weakening system will move into the area with smallish liquid equivalent, so snowfall will be on the light side as well. We are expecting an inch or two in most locations. Cannot rule out a total towards 3 inches in a few spots, but this does not look to be the norm. - Southwest flow lake enhanced snow Monday night The prevailing upper flow for much of the next 7 days will be some variation of northwest which leads typically to clipper systems this time of year. That is the case with this time frame as well, with multiple clipper systems to bring rounds of light snow and occasionally colder air. Monday night into Tuesday morning the next clipper in the series affects West Central Lower Michigan with a southwest flow lake enhanced event which will bring accumulating snow to areas like Ludington, Pentwater and Baldwin. The surface low and upper shortwave pass off to the north, so that is where the more impactful snow will fall. The aforementioned areas may see 1-3 or 2-4 inches with this short duration event. Highest snow totals in our area of responsibility will likely be across Mason, Oceana and Lake counties. - Clipper system snow Tuesday night into Wednesday The strongest system of the 7 day forecast looks to be another clipper Tuesday night into Wednesday. Aloft a strong shortwave plows in from the west during this time frame. Down at the surface, a deep low for a clipper will pass right through the heart of the state moving through Central Lower Michigan most likely. Wednesday morning, the low is centered somewhere near Mt Pleasant using an aggregate of the operational models with a depth around 988mb. A formidable low for sure. The heaviest swath of precipitation usually falls near and to the north of the low track of a clipper and that is what the models are indicating with this system as well. Quite a bit of time before we deal with this system and we will be watching trends closely. If the track comes a little further south, more of the forecast area will get into the heavier precipitation. Even on the current track though, Central Michigan is in line to see sizable accumulations of snow (possibly 4-7 inches). Again, this could include more of Southwest Lower Michigan if the track trends southward. This is a bit of a warmer system as the stronger low pulls in warm air from the south, therefore the I-96 corridor to the south will likely see a rain/snow mix with this event. Again, trends in the models will be everything with regard to type and amounts of precipitation. - Additional snow chances Thursday into next Saturday Another weak clipper system passes well off to our south on Thursday with chances that most of the precipitation stays in that direction as well. A period of lake effect snow then looks to set up from Friday into Saturday as progressively colder air infiltrates the area on northwest winds. A significant batch of cold air works into the plains during this period which will put Southwest Lower Michigan into -10C to -20C air at 850mb. This will put delta t`s over the lake in the 17 to 27 C range which is high to extreme. Lake effect will continue with likely a small flake size. As we get into this temperature setup road conditions tend to deteriorate as highs are held at best in the 20s. The surface pattern Friday into Saturday is indicative of a very cold air lake effect setup as we see lee side troughing near the Great Lakes due to thermal affects. Plenty of light snow and light accumulations with the potential for higher impact poor road conditions. Bottom line, the forecast over the next 7 days very much speaks winter! Meaning, there are multiple chances for accumulating snow and a couple shots of colder air. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1151 AM EST Sat Dec 6 2025 Satellite and observational trends suggest ceilings will bounce around 3kft over the next few hours for MKG and GRR before those terminals and LAN climb to VFR for a brief time this evening. Widespread snow moves in from the west tonight as a low pressure system tracks south of the area. Conditions will deteriorate to MVFR then IFR at all terminals after 06z. There is a 10% chance of LIFR conditions, likely dependent on whether some lake enhancement can add to snowfall rates. Snow winds down with conditions improving to MVFR at MKG, GRR, and LAN after 15-17z with the other terminals remaining IFR through the end of the TAF period. West to northwest winds to 10 knots today will become light and variable tonight into Sunday morning as the low passes across northern Indiana/Ohio. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...Small Craft Advisory until 7 PM EST this evening for LMZ844>849. && $$ DISCUSSION...Duke AVIATION...Thomas

NWS GRR Office Area Forecast Discussion