textproduct: Grand Rapids

KEY MESSAGES

- Dry and less humid today

- Showers with some thunderstorms Friday into the weekend

DISCUSSION

Issued at 240 AM EDT Thu Aug 20 2026

- Dry and less humid today

Today should feature dewpoints ranging from the upper 40s over central interior Lower Michigan to the upper 50s farther south along the I-94 corridor. This will feel noticeably drier to many. Maximum temperatures will range from near 80 to the lower 80s, with maximum apparent temperatures about the same or even slightly less where dewpoints are lower. Another and more robust measure of potential heat stress, known as the WetBulb Globe Temperature (WBGT), gives a reading of lower 70s for this afternoon. So all of this is to say that it should feel relatively comfortable outside today.

- Showers with some thunderstorms Friday into the weekend

Certainty is growing that we will see showers and thunderstorms moving through the forecast area Friday night and exiting to the east of the area by Saturday afternoon, yielding a dry Sunday. The exception may be the immediate lakeshore, particularly the Sable Points area, where lower tropospheric cooling may be sufficient for lake effect sprinkles.

The growing certainty is related to the most recently available ensemble guidance, which shows a mean solution of meridionally deeper upper troughing that's particularly pronounced into the Ohio Valley region. The expectation still is that this trough will become a cutoff low centered somewhere over the north-central Great Lakes region. The more amplified solution at this location means more of an equatorward component of the flow aloft over Lower MI, which is a drier pattern and suggests precipitation will remain shunted east of our forecast area after Saturday afternoon. However, it should be noted that ensemble solutions from as recently as yesterday morning and afternoon showed a sizable number of members forecasting precipitation through Sunday. So, although there is growing confidence for a dry Sunday, this is far from certain.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 102 PM EDT Thu Aug 20 2026

SCT to BKN Cu have developed in the 4-5kft range and will persist through the evening before diminishing. Northeast winds this afternoon go light and variable overnight with a low (10-20%) chacne of shallow MVFR fog at AZO, BTL, and JXN. The only exception for wind will be a northwest lake breeze through sunset at MKG. Winds increase out of the southwest Friday with an approaching warm front, causing ceilings above 10kft to develop.

MARINE

Issued at 240 AM EDT Thu Aug 20 2026

No concerns in the short term. Winds and waves could meet Small Craft Advisory thresholds by Friday afternoon, mostly around the Sable Points, due to persistent and moderately strong winds from the south-southwest over Lake Michigan.

GRR WATCHES/WARNINGS/ADVISORIES

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