textproduct: Grand Rapids

KEY MESSAGES

- Showers and Thunderstorms This Evening

- Drying out and cooling off this Weekend

- Rain Possible Tuesday

DISCUSSION

Issued at 318 PM EDT Fri Sep 4 2026

- Showers and Thunderstorms This Evening

The radar this afternoon shows scattered thunderstorms in an area of isentropic ascent along and moisture advection from southern Wisconsin into southwest Lower Michigan. The convective-allowing models such as the hi-res ARW and FV3 show the storms across southern Wisconsin moving east-southeast this evening and traversing the southern half of the forecast area. This is reflected in the forecast, although tweaks may be needed of course thanks to the inherent uncertainty in modeling convection that we have seen the past several days.

- Drying out and cooling off this Weekend

A developing Omega block across the CONUS this weekend results as the central U.S. heat dome is bookended by cut off lows across the NE and NW CONUS. This lowers heights across the central Great Lakes and allows surface high pressure to build in from the northeast with lower temperatures and dew points and a very fine Labor Day weekend from Saturday through Monday. In face, morning lows on Sunday and Monday could be in the upper 40s to lower 50s across the northern half of the forecast area.

- Rain Possible Tuesday into Wednesday

The surface high retreats east eastward by Tuesday as the Omega block breaks down. The low across the Pacific NW kicks east and flattens the upper high, with surface low pressure tracking across the northern Great Lakes. Return flow of moisture and a surface warm front should kick off some showers and thunderstorms late Tuesday into Wednesday. Another round of storms will be possible as a cold front moves through late Wednesday.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 210 PM EDT Fri Sep 4 2026

With this morning's thunderstorm complexes out of the picture, the flight categories are mostly improving to VFR, except for MVFR ceilings expected to hang on around Mount Pleasant (MOP), and perhaps a patch or two of clouds between 500 and 2,000 feet developing over the next hour or so elsewhere.

Tonight will likely bring worsening ceilings or visibility spreading southwest into the TAF sites from that same Mount Pleasant cloud deck, becoming IFR at some point late tonight (after approx 03 to 06 Z) then improving to MVFR after 13 Z. Also, lingering instability and moisture/clouds at or above 4,000 feet in Southwest Michigan may develop scattered thunderstorms near MKG, AZO, and BTL between 01 and 08 Z.

MARINE

Issued at 318 PM EDT Fri Sep 4 2026

Showers and thunderstorms could bring brief heavy rain and gusty winds from Grand Haven to South Haven this evening, then fair weather with light offshore winds, generally less than 15 knots, can be expected for Saturday through Monday. High pressure will move east on Tuesday and winds will be on the increase, with a Small Craft Advisory possible.

GRR WATCHES/WARNINGS/ADVISORIES

MI...None. MARINE...None.