213 FXUS63 KGRR 082345 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 745 PM EDT Tue Sep 8 2026 .KEY MESSAGES... - Showers and isolated thunderstorms expected this afternoon into Wednesday - Low chance of rain Saturday - Additional showers and storms Monday && .DISCUSSION... Issued at 201 PM EDT Tue Sep 8 2026 - Showers and isolated thunderstorms expected this afternoon into Wednesday Radar shows a line of showers ahead of a cold front approaching the northwest CWA at present, which should slowly expand south and east into the evening and tonight. HREF mean MUCAPE shows just a few hundred joules suggesting little severe threat though scattered thunderstorms are possible. High PWATs and 30+ knots of shear may be sufficient to support gusts over 30 mph with water loaded downdrafts and heavy rainfall. The front will clear the area Wednesday afternoon taking the rain and thunder chances with it. Up to 1/4" of rain is expected south of I96 with 1/4"-1/2" expected north. Dry air behind the front along with high pressure will keep fair conditions in place later Wednesday through Friday. - Low chance of rain Saturday Our next chance of precipitation, albeit a low one, arrives Saturday as a weak shortwave drives a front through. Between the best dynamics being displaced from the area, and little in the way of moisture return ahead of the front, PoPs are low with little precipitation favored to occur. - Additional showers and storms Monday A stronger system takes aim at the region Monday as the upper-level jet moves south into the region. A deepening low associated with this will lead to potentially breezy conditions as well as the chance for showers and storms. NBM probabilities suggest a 30-40% chance of over 1" of rainfall, highest across the northwest CWA, so will need to monitor for potential heavy rainfall. && .AVIATION /00Z TAFS THROUGH 00Z THURSDAY/... Issued at 745 PM EDT Tue Sep 8 2026 Tonight, ceilings will generally be VFR, and there may be just enough instability within the cloud layer to promote convective cells and moderate rain showers which would temporarily bring visibility to MVFR or perhaps IFR. Recently there have been a few lightning flashes about 15 miles south of MKG. There may be isolated thunderstorm cells among the scattered rain showers tonight through Wednesday morning, but confidence is too low to introduce prob30 TS beyond the next few hours. Ceilings Wednesday morning will deteriorate to MVFR from north to south, and possibly dip to IFR north of MKG-GRR-LAN. && .MARINE... Issued at 201 PM EDT Tue Sep 8 2026 Ongoing Small Craft Advisory/Beach Hazards Statement look to be in good shape. Increasing southwest winds will support gusts to around 25 knots and 3-6 foot waves between tonight and Wednesday Evening. Highest waves expected near and north of Holland. Isolated thunderstorms are also possible over the waters tonight. Winds diminish Wednesday night and stay below hazardous levels before increasing again on Saturday. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Beach Hazards Statement through Wednesday evening for MIZ037-043- 050-056. MARINE...Small Craft Advisory until 8 PM EDT Wednesday for LMZ846>849. && $$ DISCUSSION...Thomas AVIATION...CAS MARINE...Thomas

NWS GRR Office Area Forecast Discussion