792 FXUS63 KGRR 040831 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 330 AM EST Thu Dec 4 2025 .KEY MESSAGES... - Periods of light snow possible late Friday into Sunday - Accumulating snow possible with systems Tuesday and Wednesday && .DISCUSSION... Issued at 330 AM EST Thu Dec 4 2025 - Periods of light snow possible late Friday into Sunday The last of the light snow associated with the front that came through yesterday is just about to exit the forecast area as of 330 am this morning. The low level flow will remain from the NW today, with 850 mb temps down in the negative mid teens C. There is plenty of over lake instability, however building subsidence will push inversion heights down. This will result in a small layer of moisture in the DGZ, which should produce nothing more than flurries/very light snow showers with trace accumulation. Our next system will be affecting the forecast area beginning later Friday and Friday night. The responsible feature for this round of precipitation is a short wave that is currently over British Columbia. As has been the pattern for the last few days, this short wave or clipper system embedded in the NW flow aloft will bring light precipitation. This system itself will be moisture starved as it moves over the area. SW flow ahead of the system will add some moisture and instability from Lake Michigan to potentially produce a couple of inches of snow focused on the NW corner of the area. Elsewhere inland, we are looking at accumulations up to an inch. After a brief break for most of Saturday after the system moves out early, the next short wave in the series will dive down Sunday morning and clip the area. This short wave looks to phase with another wave coming from the Rockies to bring more light snow to the area. Amounts with this setup look similar to the Fri/Fri night event with limited moisture available once again. - Accumulating snow possible with systems Tuesday and Wednesday We see a mostly dry period come about Monday as a fairly strong sfc ridge and confluent flow aloft provide stronger subsidence over the area. Can`t rule out a few flurries near the lakeshore with 850 mb temps in the negative mid teens C again. The subsidence will really limit the degree of saturation of the DGZ to limit snow shower potential. We are watching the potential for a couple of impactful systems that could affect the area on Tuesday and Wednesday. The upper air pattern looks to amplify a bit as a stronger ridge builds of the eastern Pacific and Western U.S.. Instead of the rather flat upper flow from the NW, a couple of stronger short waves will dive SE over the region. These short waves will be quick hitting, but will pack a punch. The first one will have cold enough air for Lake Michigan to potentially enhance it a bit. The second short wave is forecast to be a tad further south, but will have some warmer air to work with. There is enough warmer air that we could see some rain mix in over the far southern portion of our forecast area. Timing of these waves/frontal systems 6-7 days out is problematic, especially in a fast flow like we have. We have an idea though of some potentially impactful weather that we can fine tune as we get closer to that period. && .AVIATION /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 1140 PM EST Wed Dec 3 2025 As prefrontal moisture moves eastward, post frontal northwesterly flow filters in. Light snow at LAN are the vestiges of this warm front. Strong northwesterly flow is moving over Western Michigan with northwest winds at BIV, GRR, MKG, AZO and BTL. That northwest flow will overtake JXN and LAN by 09Z. MVFR vsbys are possible in light snow through 10Z. MVFR cigs are possible through 15Z with improving conditions after. && .MARINE... Issued at 330 AM EST Thu Dec 4 2025 We have decided to hoist a Gale Warning for the northern marine zone for late tonight through Friday morning. A Small Craft Advisory remains in effect through 7 pm this evening for the entire nearshore. This is associated with the cold air moving in behind the front that moved through yesterday. Winds will taper off today, and waves may actually drop off early enough that the Advisory may be able to be cancelled early. After a brief break in the wind with a sfc ridge moving by the area, winds will ramp up tonight ahead of the next system moving toward the area. The strongest winds will be across the north. There is some potential that the Gale may be needed for another zone or two, but the confidence is not there yet. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...Small Craft Advisory until 7 PM EST this evening for LMZ844>849. Gale Warning from 10 PM this evening to 10 AM EST Friday for LMZ849. && $$ DISCUSSION...NJJ AVIATION...Maczko/Ceru MARINE...NJJ

NWS GRR Office Area Forecast Discussion