158 FXUS63 KGRR 041737 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 137 PM EDT Sat Apr 4 2026 .KEY MESSAGES... - Chance of storms this afternoon - Colder Sunday-Tuesday with light snow possible - Showers/storms late week && .DISCUSSION... Issued at 136 PM EDT Sat Apr 4 2026 - Chance of storms this afternoon A cold front extends south over Lake MI across CHI and south along the IL/IN border. Radar shows abundant showers moving northeast across the cwa ahead of the front. The main concern this afternoon is the thunderstorm potential. A warm front is lifting north across the southern row of counties and this may result in the far southeast cwa seeing some warmer more buoyant air for a few hours late this afternoon. CAMs indicate we`ll see some convective development, but stronger storms remaining south of the cwa. Eastern Calhoun and Jackson counties have the highest likelihood of seeing a stronger storm this afternoon where MUCAPE values are closer to 800 j/kg. Once the cold front sweeps through late afternoon, that`ll put an end to the thunder threat. - Colder Sunday-Tuesday with light snow possible Once the cold front moves through, temperatures will drop. H8 temperatures around 12c this afternoon will fall to -8c by Sunday morning and -14c by Tuesday morning after a secondary cold front. Lake effect rain/snow showers will develop and move inland Sunday. Some wet snow will mix in with the showers. Highest chance to see some snow is later Monday and Monday night after the secondary cold front moves through. Minor accumulations are possible, mainly over the northern portions of the cwa. Highs Sunday through Tuesday will be in the lower to mid 40s. - Showers/storms late week Another cold front is progd to move across the state Thursday and potentially stall out over the cwa. Similar to last week, we could see a couple rounds of showers and thunderstorms as waves of low pressure ride northeast along the frontal boundary and this could exacerbate ongoing flooding across the region. Of course, if parts of the cwa could remain in the warm sector, then chances for strong to severe storms would also increase and it`s something we`ll be watching. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 136 PM EDT Sat Apr 4 2026 Rain showers will gradually diminish from northwest to southeast during the afternoon. A cold front moving across the region may also generate a thunderstorm. IFR conditions are expected through late afternoon before rising to MVFR during the evening. Latest visible loop sows clearing occurring behind the cold front over parts of Missouri and that clearing may try to work its way north across the terminals for a few hours around midnight, before lower MVFR cigs wrap back into the region. Breezy west winds are expected through much of the period. && .MARINE... Issued at 136 PM EDT Sat Apr 4 2026 Once the cold front moves across the lake around 6 pm, winds will become westerly and gusty. Waves will increase accordingly to around 7-8 feet by Sunday morning. Winds will diminish Sunday afternoon and waves will decrease; the small craft advisory remains in effect until 8 PM Sunday. Another cold front will move across the lake Monday and waves will increase again. Another small craft advisory may be needed then. && .HYDROLOGY... Issued at 136 PM EDT Sat Apr 4 2026 Rainfall of 1-3 inches across Southwest Michigan in the past 24 hours adds to the previous accumulations for a roughly 4-6 inch rainfall total over the last week. Additional rainfall will generally be 0.25" or less through mid afternoon, though up to 1" is possible under any thunderstorms. This rainfall for the most part should not significantly exacerbate the poor drainage flooding that developed this morning. With the heaviest rain across the Grand River basin, this will lead to river flooding over the next several days. River Flood Warnings have been issued for the Grand River and its tributaries in Lansing, the Portage River at Vicksburg, the Muskegon River at Newaygo and Bridgeton, the Grand River at Comstock park, and the Thornapple River at Caledonia and Hastings. For the most part rivers will peak at minor flood stage, with the exception of Comstock Park and Robinson Township (the latter of which is in a watch) where moderate flooding is forecast. The high water will work its way through Grand River system over the next several days, with flooding forecast along the Grand River from Ionia to Grand Rapids, to Robinson Township. Given flooding is 48-96 hours away for these areas, river flood watches have been issued, with the potential for warnings as we get closer to the event. Numerous other rivers will reach Action Stage over the coming days, some like the Muskegon River at Evart getting close to minor flood stage. People near area rivers should monitor the latest National Weather Service forecasts. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...Small Craft Advisory until 8 PM EDT Sunday for LMZ844>849. && $$ DISCUSSION...04 AVIATION...04 MARINE...04 HYDROLOGY...Thomas

NWS GRR Office Area Forecast Discussion


Free website templates courtesy of JustDreamweaver.com