698 FXUS63 KGRR 191858 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 258 PM EDT Wed Aug 19 2026 .KEY MESSAGES... - Drier and Comfortable Air on Thursday - Showers and Chance of Scattered Thunderstorms Late Week && .DISCUSSION... Issued at 258 PM EDT Wed Aug 19 2026 - Drier and Comfortable Air on Thursday The more humid air has been nudged south of the area along a weak cold front, and dew points are trending into the upper 40s to 50s for much of the area, especially in Central Michigan. With dew points still in the 60s this afternoon near I-94 and favorable lapse rates 850-700 mb, there is a slight chance for low-topped and isolated showers to develop this afternoon or tonight, especially closer to Jackson, as portrayed in a few of the HREF member CAMs. - Showers and Chance of Scattered Thunderstorms Late Week Global models continue to depict an upper-level trough digging from western Hudson Bay toward Michigan Fri-Sat, then cutting off a low over the central/northeast Great Lakes region Sun-Mon. Slightly warmer and more humid air should briefly nose back in on Fri before the next weak cold front passes through Fri night. Scattered showers and thunderstorms may develop in the vicinity of the front amid CAPE around 1000 J/kg (some ECE members depict MUCAPE as high as 2000 J/kg). Deep layer shear may be relatively modest, around 20 knots, limiting the severe weather potential. && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 145 PM EDT Wed Aug 19 2026 VFR conditions will generally prevail this afternoon across West Michigan, with only scattered 3-4kft CU anticipated. The exception will be at BTL/LAN/JXN, where occasional broken MVFR ceilings just below 3kft will be possible through roughly 20-21Z. Otherwise, expect CU to dissipate this evening, with only some patchy mid/high clouds expected thereafter, mainly along the I-94 corridor /AZO-BTL-JXN/. Mainly clear skies /VFR wx/ expected Thursday. Winds will remain light through the TAF period. Generally W-NW flow this afternoon will veer to NE by late tonight and continue Thursday. && .MARINE... Issued at 258 PM EDT Wed Aug 19 2026 Waves and swim risk remain low with light winds tonight and Thursday. Then Friday and through the weekend, there will likely be some medium-high swim risk areas, with winds increasing in the vicinity of low pressure slowly trekking across the Great Lakes. Beaches north of Grand Haven on Friday should have the higher swim risk, due to south winds. Northwest winds are favored Saturday and Sunday. Scattered thunderstorms are possible over the lake from late Friday into early Saturday. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...CAS AVIATION...Smith MARINE...CAS

NWS GRR Office Area Forecast Discussion