710 FXUS63 KGRR 141958 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 258 PM EST Thu Nov 14 2024 .KEY MESSAGES... - Drizzle and showers ending tonight - A few showers and unseasonably mild through early next week - Cool and rainy middle next week, snow showers late week && .DISCUSSION... Issued at 258 PM EST Thu Nov 14 2024 - Drizzle and showers ending tonight Low pressure transferring to the Atlantic coast this evening with showers moving east and drizzle slowly decreasing. High pressure builds in by Friday with some lingering lake effect rain showers in northerly flow but these will be light and largely remain offshore. - A few showers and unseasonably mild through early next week An amplified large-scale weather pattern continues this weekend, with a ridge of high pressure over much of the eastern CONUS and a sharp trough in the western CONUS. Michigan falls into broad southwesterly flow starting this weekend as the ridge axis slides to our east. A fast-moving and fairly weak system moves through the upper Great Lakes Saturday night, bringing a few showers and gusty southwest winds to West Michigan, but overall having a pretty minor impact on us. The more consequential movements in the atmosphere during this time will be a developing cutoff low near the desert southwest, sitting in the base of the amplifying longwave trough. - Cool and rainy middle next week, turning to snow showers late week Guidance is in good agreement that by Monday morning the cutoff low near the four corners will eject rapidly to the northeast and head toward the Great Lakes. The main impact for us will primarily be another round of widespread beneficial rain for the day Tuesday. This low pressure will be filling/weakening as it moves our direction, and the remnant low stalls over Wisconsin through Wednesday. At the same time, a vigorous upper trough approaches quickly from the west during this timeframe and will capture the leftover storm system in Wisconsin. This combined system turns into a large and slow-moving low pressure system that will begin anchoring a longwave trough over the Great Lakes for the 2nd half of next week... possibly continuing through next weekend. While this will keep showers in our area for several consecutive days, the bigger impact will be the ushering in of the first winter- like temperatures of the season on the backside of the low. There is still pretty significant spread among the global models on exactly where the upper low migrates, which will determine how quickly the cold air rushes into Michigan, but at this point it looks like late Friday into Saturday is the best bet - kicking off lake effect snow bands and likely bringing the first snowflakes of the year to most areas. It`s too early to spend much time thinking about any lake effect snow accumulations, but it`s definitely in the realm of possibility and will be a main focus of the forecast as we get closer in time. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1235 PM EST Thu Nov 14 2024 This set of forecasts will have impacts to aviation throughout the entire period. The main impact will be IFR/LIFR through the period with low clouds expected to hang on through 18z Friday. The widespread rain has moved east of all of our terminals as of 1730z this afternoon. What is left behind is lower ceilings, and now some developing drizzle that is reducing the visibilities. We expect the drizzle to hold on or even develop this afternoon, and eventually improving some this evening and tonight as the low moves by. IFR/LIFR low clouds will likely persist at most of the terminals until Friday. The exception to this is KMKG where a NNW flow will bring some locally drier air in. We are expecting the low clouds to lift up into the lower MVFR range toward the end of this period, to just after the end of the period. && .MARINE... Issued at 258 PM EST Thu Nov 14 2024 Conditions will continue to the relatively placid on Lake Michigan until Sunday when southwest winds will quickly ramp up to abo0ut 30 knots as low pressure approaches. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...Ostuno/AMD AVIATION...NJJ MARINE...Ostuno

NWS GRR Office Area Forecast Discussion