textproduct: Grand Rapids

KEY MESSAGES

- Afternoon Showers Today

- Dry Monday/Tuesday, Showers and Thunderstorms Wednesday

DISCUSSION

Issued at 149 PM EDT Sun Aug 23 2026

- Afternoon Showers Today

Moisture from Lake Michigan, steep low level laps rates providing around 200 J/kg of CAPE, along with mid level support from the upper level low are sparking off isolated to scattered showers. These will be largely north of a Ludington to Jackson line before the inversion builds in this evening and we lose our surface based instability. Thunderstorms are not expected.

- Dry Monday/Tuesday, Showers and Thunderstorms Wednesday

Pressure heights increase Monday into Tuesday as the upper level low over the eastern Great Lakes shifts east. Northwest winds will continue for Monday with gusts to 20 mph. Tuesday winds will be lighter and more variable. High temperatures will be in the 70s Monday and warm to around 80 for Tuesday. Low temperatures will be in the 40s and 50s.

Southerly winds build in ahead of our next shortwave trough that is expected to slowly move through Wednesday. Warm air advection and the low level jet will feed into the area with instability around 1000 J/kg. Shear values only look to be around 25 knots, therefore confidence in storms becoming severe is low. Long range ensemble clusters are in good agreement that most of the rain ends by Thursday morning, although we could see another round of diurnal showers similar to today Thursday afternoon. The probability of a half inch of rain in 24 hours during this time is less than 20 percent.

Friday ensembles are in good agreement to expect dry conditions but confidence decreases over the weekend as we remain in transitional flow where a few weak shortwaves could bring additional chances for showers and thunderstorms.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

Issued at 730 PM EDT Sun Aug 23 2026

VFR conditions will prevail through Monday at all West Michigan TAF sites. Lingering diurnal cloudiness early this evening will diminish quickly, as will the northwest breezes currently gusting to around 20 kt. Skies will then be mainly clear for the duration of the night, with a light W/NW wind.

Monday will see scattered 4-5 kft CU form again after 15Z, as northwest winds increase to 10 to 15 kt. Less gustiness is expected Monday compared to Sunday.

MARINE

Issued at 149 PM EDT Sun Aug 23 2026

Wave heights around 4 feet have been observed this afternoon with northwest winds gusting around 20 knots. Expect Small Craft Advisory and High Swim risk conditions to continue into this evening before winds and waves subside tonight. Wave heights could remain around 4 feet north of Big Sable after midnight.

Northwest winds 10 to 20 knots Monday will keep wave heights around 2 to 3 feet. Moderate Swim Risk conditions are expected through Monday afternoon before wave heights fall below 2 feet Monday night into Tuesday. The next chance for Small Craft Advisory and High Swim Risk conditions will be Wednesday which matches up with our next chance for showers and thunderstorms.

GRR WATCHES/WARNINGS/ADVISORIES

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