038 FXUS63 KGRR 301046 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 646 AM EDT Mon Mar 30 2026 .KEY MESSAGES... - Strong to Severe Thunderstorms Tonight into Tuesday - Wintry Mix Wednesday Transitioning to Rain Thursday - Another Round of Rain this Weekend && .DISCUSSION... Issued at 328 AM EDT Mon Mar 30 2026 - Strong to Severe Thunderstorms Tonight into Tuesday Tonight into Tuesday Morning: There is a slight chance (20 to 30 percent) for pop up showers and thunderstorms along I-94 this afternoon with some 850mb convergence. Otherwise our first round for thunderstorms will be Tonight into Tuesday morning. MUCAPE values of 1500 to 2000 J/kg advect into the region with lift from the low level jet and the warm front over the area. Overall storms will be elevated with 700-500mb lapse rates around 7 to 8 C/km. Large hail will be the main concern with the strongest storms, however with 40 to 50 knot winds at 925mb, can`t rule out some stronger winds. The HREF focuses most of the precipitation along and north of I-96. Therefore have the higher chances (60 to 80 percent) in this area with 40 to 50 percent PoPs further south. There is a signal for storms to move east early Tuesday morning with the low level jet, however some other solutions linger chances later into the morning causing some uncertainty with how exactly Tuesday morning will play out. Tuesday Afternoon into Tuesday Night: Our chances for severe thunderstorms will highly depend on what happens Tuesday morning. As mentioned before, there are various solutions with how Tuesday will play out. If we clear out during the late morning early afternoon, instability will be able to recover with the potential for more surface based storms vs elevated. Isolated storms would be possible before congealing into a line segment with the front as shown in some of the CAM solutions. With 40 to 50 knots of shear and around 200 m2/s2 of storm relative helicity; damaging winds, large hail, and tornadoes would all be possible. However if we see storms continue over the area our chances for severe storms would decrease with less instability available and storms remaining elevated. The longer duration of rain and thunderstorms could lead to some localized amounts toward 2 inches where storms train over the longest. The best chances for this would be along and north of I-96. - Wintry Mix Wednesday Transitioning to Rain Thursday There could be some lingering rain showers Wednesday in southern Michigan, otherwise dry conditions are expected with highs in the 40s. Colder temperatures Wednesday night will set the stage for rain and freezing rain. There will be a significant warm nose at 850mb that would melt any snow/ice, but surface temperatures will be around 32 along I-96 with temperatures below 32 north. Areas along the lakeshore may remain warm enough limit ice accumulations. The warm front then moves north Thursday with areas transitioning to rain during the morning and afternoon. There is still some uncertainty with the exact amounts, but ice amounts would be highest on elevated surfaces. Keep up to date with the forecast as any ice accumulations could be impactful. - Another Round of Rain this Weekend There is agreement on a deep trough moving through the regions Saturday into Sunday. Some differences in timing, but overall rain and maybe a few thunderstorms move in Saturday with a cold front moving through Saturday night into Sunday. Cold air will advect in on the backside of the low with the potential for snow to mix in as Sunday morning as temperatures fall. Sunday will likely be windy as well with winds from the northwest. && .AVIATION /12Z TAFS THROUGH 12Z TUESDAY/... Issued at 646 AM EDT Mon Mar 30 2026 VFR conditions are expected today with southwest winds gusting up to 20 knots this afternoon. Continued the PROB30 for afternoon pop up showers and thunderstorms for AZO, BTL, and JXN. After 00Z thunderstorms will be possible with the best chances after 06Z. With uncertainty with the coverage of thunderstorms and whether they`d actually hit any one TAF site kept the mention to PROB30. The best chances for thunderstorms (60 to 80 percent) are north of the TAF sites overnight into early Tuesday morning. && .MARINE... Issued at 328 AM EDT Mon Mar 30 2026 Southerly winds continue today with waves around 1 to 2 feet. Southwest winds increase tonight into Tuesday as the low approaches with lighter winds in the northern zones. Small Craft Advisory conditions are expected from Whitehall to the south before extending north as the cold front moves through Tuesday evening. Thunderstorms are also expected tonight into Tuesday with the potential for strong to severe storms. Small Craft Advisory conditions likely linger into Friday with another system tracking through the region. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...Small Craft Advisory from 8 AM Tuesday to 8 AM EDT Wednesday for LMZ844>847. && $$ DISCUSSION...RAH AVIATION...RAH MARINE...RAH

NWS GRR Office Area Forecast Discussion