199 FXUS63 KGRR 081859 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 259 PM EDT Wed Jul 8 2026 .KEY MESSAGES... - Slow moving front brings rain tonight and Thursday - Upper High builds in early next week && .DISCUSSION... Issued at 258 PM EDT Wed Jul 8 2026 - Slow moving front brings rain tonight and Thursday Thunderstorms ahead of the cold front have shown a weakening trend last couple hours as they move over Lake Michigan and we do not expect significant rain or thunder until closer to midnight as the front sags in from the northwest. Severe and excessive rainfall threats are low overnight as the front moves through with limited instability, shear and deep moisture, but the southern zones could see some resurgent convection on Thursday morning. With deeper moisture pooling south of the front, any training of thunderstorms could bring minor flooding. Showers could linger through Friday afternoon across the southern zones as the front becomes parallel to the upper flow and slows down or stalls. - Upper High builds in early next week Large scale subsidence and drying begins over the weeknight as an upper high builds across the Northern Plains and edges into Lower Michigan. Expect a spell of hot and dry weather for early next week before heights fall as an upper trough amplifies across eastern Canada. && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 141 PM EDT Wed Jul 8 2026 The ongoing cluster of storms over Central Lake Michigan is forecast to move just south of MKG. Otherwise, thunderstorms from Wisconsin look to arrive after 02z across Central Michigan. Impacts to GRR/MKG remain low in confidence so will maintain existing PROB30s. Scattered showers and storms then continue overnight mainly north of GRR/MKG/LAN with greater coverage possible later Thursday morning. There`s a signal for a line of storms to develop near JXN/LAN after 15z, which given low confidence have included PROB30s for now. Any storms may contain brief increases in wind and wind shifts. Otherwise expect mainly west or southwest winds aob 10 knots. && .MARINE... Issued at 258 PM EDT Wed Jul 8 2026 Scattered thunderstorms with gusty winds and heavy downpours will be moving southeast across Lake Michigan tonight into Thursday morning. Otherwise, conditions will continue relatively tranquil into the weekend. As high pressure builds in on Thursday into Friday, north winds could gust to 20 knots, otherwise winds should remain at 15 knots or less. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Air Quality Alert until midnight EDT tonight for MIZ050-056-057- 064-065-071. MARINE...None. && $$ DISCUSSION...Ostuno AVIATION...Thomas MARINE...Ostuno

NWS GRR Office Area Forecast Discussion