textproduct: Detroit/Pontiac

KEY MESSAGES

- Dry and seasonable conditions for much of today.

- A low chance of showers and thunderstorms starting late afternoon across the Saginaw Valley and Thumb, with a greater potential for showers with isolated thunderstorms for all of southeast Michigan tonight.

- A few lingering showers possible early Wednesday, then turning drier again with temperatures slightly below normal for the end of the week.

DTW THRESHOLD PROBABILITIES

* Low for ceiling at or below 5000 feet this afternoon into the evening, medium tonight, and high tomorrow morning.

* Very low for thunderstorms tonight.

PREV DISCUSSION

Issued at 333 AM EDT Tue Aug 18 2026

DISCUSSION...

Pleasant again today as the region starts the day under the influence of departing high pressure. Subtle change from yesterday is the establishment of deep layer westerly flow into southern lower MI with the departure of said high. This nudges temps up a couple degrees with highs around the mid 80s as well as a modest increase in humidity with dewpoints creeping back to the lower to mid 60s. Increasing afternoon cloud cover marks the arrival of a cold frontal boundary dropping through the Great Lakes. High res models continue to key on a prefrontal trough feature sliding over northern lower MI/Lake Huron generating isolated to widely scattered showers/thunderstorms. While the best potential stays north of the area, the Saginaw Valley/Thumb hold on its southern fringe offering some late afternoon rain chances, particularly north of M-46. Main window for SE MI as a whole however comes late evening-overnight as the surface cold front reaches the Straits/northwestern Lake Michigan. Frontal boundary expected to generate a healthy coverage of convection over the western Great Lakes however local arrival in the western CWA looking to be between 00-03Z. Late in the diurnal window in addition to signal convection outpaces driving instability, increases uncertainty to what degree thunderstorms can maintain themselves while crossing the state. Areas west of I-75/US- 23 stand the best chance at thunder given the earlier timing supporting higher residual CAPE. While an isolated stronger cell capable of gusty winds can't be ruled out due to marginally favorable kinematics (unidirectional shear around 30kts), the thermodynamic setup (lapse rates under 6.5 C/km & ~500 J/kg of elevated CAPE) is unfavorable for severe storms.

Scattered to numerous showers with isolated thunder work across the area for the rest of the night before the cold front clears to our south first part of Wednesday morning. Passage of a secondary cold front daytime Wednesday could generate a few afternoon showers, though most of SE MI stays dry. Drier weather holds through the remainder of the work week as surface high pressure slides directly across lower MI. Unsettled pattern eventually returns Friday night into the weekend as a mid-level shortwave dropping out of the Canadian Prairie reaches the Great Lakes amplifying overhead upper troughing.

MARINE...

Southwest flow briefly becomes established this morning as high pressure washes out across the eastern Great Lakes. Winds remain light for most locations through the afternoon, but localized stronger gusts around 20 knots will be possible in the Saginaw Bay given the more favorable fetch.

More active weather returns this afternoon and evening with the passage of a cold front. Showers and thunderstorms will be likely with the front as winds veer from southwest to northwest in the wake of the front. A slight uptick in winds are expected along and behind the front as cooler conditions filter in. Wind gust of 20 to 25 knots will be likely with the frontal passage. High pressure will then fill back in on Thursday, tempering wind speeds for the day.

DTX WATCHES/WARNINGS/ADVISORIES

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