textproduct: Grand Rapids

KEY MESSAGES

- Scattered Showers and Thunderstorms this Afternoon

- Cooler with Slight Chances (20 percent) for Showers Sunday

- Midweek Rain Chances

DISCUSSION

Issued at 200 PM EDT Sat Aug 22 2026

- Scattered Showers and Thunderstorms this Afternoon

The upper level trough will continue to move through lower Michigan today. The front is currently around a Midland to Battle Creek line and shifting east. Expect isolated to scattered showers and thunderstorms along and ahead of the front before it clears later this afternoon. We'll still be under the upper level trough until tonight with some positive vorticity advection moving through the flow. Moisture is limited, but can't rule out an isolated shower this evening. Northwest winds pick up behind the front with gusts around 20 to 30 mph before the inversion builds in this evening.

Warmer lake temperatures with dropping 850mb temperatures may keep the air mass unstable enough along the lakeshore for some spotty showers into early Sunday (20 percent chance).

- Cooler with Slight Chances (20 percent) for Showers Sunday

The upper level low will remain over the eastern Great Lakes continuing some slight chances (20 percent) in the northwest flow. Another surge of positive vorticity advection is expected to move through the afternoon which could add additional support for shower development along with some diurnal shallow instability. The best chances will be north of I-96 and taper off Sunday evening.

Northwest winds will continue to be breezy with gusts to 30 mph during the day. Temperatures will be a little cooler than today with highs in the upper 60s to low 70s.

- Midweek Rain Chances

A shortwave ridge moves in for the beginning of next week but it will be short lived. Heights begin to fall with the approaching trough Wednesday into Thursday. Warm air advection may spark off showers and thunderstorms late Tuesday night into Wednesday morning, otherwise the best chances (50 to 70 percent) hold off until Wednesday night when the trough axis is expected to move through. A lull is possible Thursday morning before chances increase (30 to 50 percent) again with the daytime heating Thursday afternoon.

Monday will be the coolest day of next week with highs in the 70s. Temperatures then warm into the low 80s for the rest of the week. Low temperatures will largely be in the 50s with some spots dropping into the 40s Monday and Tuesday morning.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 740 PM EDT Sat Aug 22 2026

Pesky/stubborn showers and thunderstorms continue across parts of West Michigan early this evening, as cooler air aloft slowly works into the region. TAFs will support a risk for convection through 01-02Z at LAN and MKG, though restrictions should be limited. With setting sun, lingering clouds /should/ diminish with clear to partly cloudy skies /VFR WX/ for the duration of the night. NW wind gusts to around 20 kt at 00Z will also quickly diminish.

Caveat to tonights quiet weather... and as previously discussed, with 850 mb temps falling to 7-8C and water temperatures of +21-22C, influence of Lake Michigan will need to be monitored overnight, especially at MKG. Some lake clouds and even a pop up lake effect shower will be possible overnight, but is not reflected in any TAFs at this time.

With much cooler air aloft, expect an uptick in CU /3-5kft/ after 14-15Z Sunday areawide, and NW wind gusts of 20-25 kt will develop after 14-15Z.

MARINE

Issued at 200 PM EDT Sat Aug 22 2026

High Swim Risk and Small Craft Advisory conditions continue through Sunday. Northwest winds with gusts to 30 knots will cause waves to continue to build into Sunday with wave heights peaking around 5 to 7 feet Sunday afternoon. Waterspouts will also be possible tonight into early Sunday morning with the best chances toward southern Lake Michigan.

Winds and waves slowly come down Sunday night into Monday. Another period of Small Craft Advisory and High Swim Risk conditions is possible Wednesday along with our next chance for showers and thunderstorms.

GRR WATCHES/WARNINGS/ADVISORIES

MI...Beach Hazards Statement through Sunday evening for MIZ037-043- 050-056-064-071. MARINE...Small Craft Advisory until 11 PM EDT Sunday for LMZ844>849.