920 FXUS63 KGRR 262225 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 625 PM EDT Sun Apr 26 2026 .KEY MESSAGES... - Rain and Thunderstorms Monday Afternoon into Monday Night - Cooler and Mainly Dry Tuesday through Saturday && .DISCUSSION... Issued at 235 PM EDT Sun Apr 26 2026 - Rain and Thunderstorms Monday Afternoon into Monday Night Overall dry conditions are expected into early Monday afternoon. A decaying line of thunderstorms moves in from the southwest during the late afternoon. Instability and lift will be limited over the area. This initial round of rain ahead of our evening round could impact our marginal severe risk. We`ll have plenty of shear with the low and mid level jet, but instability is lacking. HREF keeps values below 1000 J/kg and doesn`t bring in the better instability until the line of showers and thunderstorms is already through the area. This timing difference really limits the potential for any stronger storms. The best window for any strong to severe storms would be between 8pm Monday and 2am Tuesday. Wind would be the primary concern largely south of I-96 with the best chances in far southwest Michigan. This area is consistent between the NCAR, GEFS, NSSL, Nadocast, and SPC outlooks. - Cooler and Mainly Dry Tuesday through Saturday We`ll remain under troughing through most of the week bringing cooler temperatures to the region. A couple shortwave troughs may spark off showers Tuesday night into Wednesday and Thursday night into Friday. High temperatures will largely be in the 50s with lows in the 30s. Frost will be possible starting Wednesday night. Be prepared to take care of any sensitive vegetation during this period of colder temperatures. && .AVIATION /00Z TAFS THROUGH 00Z TUESDAY/... Issued at 625 PM EDT Sun Apr 26 2026 Little impact to aviation expected through mid morning Monday as predominantly mid/high clouds and winds around 10 knots or less are expected. After around 13z wind gusts increase to around 25 knots from the southeast where they remain through the day. After 19z, a weakening line of showers with the potential for isolated thunderstorms will move across the terminals. Given the weakening trend with eastern extent, have limited MKG to prevailing showers at present going VCSH at the other terminals. Lowering cigs are expected but likely to remain VFR. The next round of showers and storms is forecast to arrive after 00z. && .MARINE... Issued at 235 PM EDT Sun Apr 26 2026 Southeast winds build tonight into Monday with gusts 25 to 30 knots Monday morning. Small craft advisory conditions are then expected to continue into Tuesday with winds becoming more westerly. Wave heights build to 4 to 8 feet Monday night as the winds shift to the southwest. Thunderstorms will also be possible late Monday afternoon into Monday night. Winds and waves will then subside Tuesday afternoon and remain below Small Craft Advisory conditions through the rest of the week. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...Small Craft Advisory from 8 AM Monday to 6 PM EDT Tuesday for LMZ844>849. && $$ DISCUSSION...RAH AVIATION...Thomas MARINE...RAH

NWS GRR Office Area Forecast Discussion