textproduct: Detroit/Pontiac

KEY MESSAGES

- Summer-like temperatures continue through Wednesday.

- The warm air carries a low chance of showers and thunderstorms late Wednesday as a cold front settles through SE Michigan.

- Temperatures return closer to late May normals from Thursday through next weekend.

- No rain is currently expected during the late week through next weekend.

DISCUSSION

Ideal late May weather across SE Mi is driven by surface high pressure centered on the Ohio border to mid Atlantic coast. The air mass carries above normal warmth but lower humidity enabling afternoon highs in the lower and mid 80s across the region. This despite a veil of increasingly opaque cirrus resulting in filtered afternoon sunshine, except for the Tri Cities where a longer period of full sun and newly developing SW flow is having a greater effect on the warming trend.

Dry and mild conditions continue this evening, ahead of a backdoor cold front as it settles southward over the northern and central Great Lakes. James Bay low pressure is pulling the front slowly southward keeping it on schedule to enter SE Mi early in the morning. It then nearly stalls toward the Ohio border due to the approach of a trailing mid level short wave. This wave catches up to the otherwise shallow frontal zone to provide a boost of support for scattered showers and a rumble of thunder. HREF mean indicates some pooling of surface based instability along and south of the front around 21Z Wednesday afternoon. Greater values toward the Ohio border are still sub 1000 J/kg, worthy of an isolated mention in the forecast south of the I-96 corridor.

Passage of the mid level wave drives the front aggressively into the Ohio valley Wednesday night as broad and strong high pressure builds over nearly the entire Great Lakes by Thursday morning. The air mass is cooler but not by much compared to the strength of the surface high, and especially compared to recent temperature swings so far this month. Guidance high temperature projections drop back toward normal values in the lower 70s while north wind gusting near 20 mph keeps the Lake Huron shoreline much cooler.

The surface high is powered by larger scale subsidence in NW flow aloft that is downstream from the blocky 500 mb Plains ridge. This ridge becomes centered on the northern Plains and Midwest by Friday to maintain dry weather in Lower Mi through the late week period. Consensus of extended range deterministic models then brings a larger low pressure system into Quebec and a reinforcing cold front through the Great Lakes during Saturday.

MARINE

A cold front has dropped south across Lake Superior this morning and will begin dropping through Lake Huron this evening. South of the front, the winds will get a little gusty through the evening reaching 20 to 25 knots. This will mostly affect Saginaw Bay. The front will continue southward tonight into Wednesday passing through Lake Erie Wednesday afternoon. Winds will flip around to the north- northwest behind the front tonight. Another area of high pressure builds into the region behind the front as well and will lead to varying winds throughout the end of the week. There may be periods with enhanced onshore northeast winds, which may elevate wave activity in nearshore zones at times.

PREV DISCUSSION

Issued at 1252 PM EDT Tue May 26 2026

AVIATION...

Expect primarily high clouds around this afternoon and evening with southwest winds. Winds will be strongest at MBS, where gusts to 20 knots are expected. A dry cold front will sink south tonight, resulting in light northerly or variable winds into Wednesday. The front is forecast to stall near the southern Michigan border tomorrow, which could serve as the focus for a few showers/isolated thunderstorms late in the day.

D21/DTW Convection...Very low chance of a thunderstorm late tomorrow afternoon.

DTW THRESHOLD PROBABILITIES...

* None.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None.