textproduct: Detroit/Pontiac

KEY MESSAGES

- Gradually increasing chances for showers and possibly some thunderstorms through tomorrow. Heavy rainfall leading to localized flooding is possible, mainly along and south of the I-94 corridor.

- Dry early next week before showers return Wednesday.

DTW THRESHOLD PROBABILITIES

* Low for ceiling 5000 feet or less this morning, high tonight into Sunday morning.

* Low for thunderstorms this evening and again Sunday morning.

PREV DISCUSSION

Issued at 300 AM EDT Sat Aug 15 2026

DISCUSSION...

A bit more clarity with the forecast, as the lead shortwave over the Midwest not as strong as forecasted yesterday and will result in a flatter wave tracking near or just south of the southern Michigan border this afternoon/evening. Sufficient instability to support severe storms is not expected to cross north of the border (supported by the machine learning). Although, it still is a close enough call for SPC to maintain the marginal risk for Lenawee and parts of Washtenaw/Monroe counties. Rain shower are still likely along and south of I-94, with chances then diminishing as one heads north. There is still some potential for 500 MB heights to close off, which would enhance showers and allow for a slower progression tonight. However, vast majority of solutions still highlight well under 1 inch of rain.

The second wave coming out of the central Plains looks to be the stronger one now, moving through southeast Michigan during the favorable Sunday afternoon period. This should assure a greater coverage of showers across southeast Michigan, as associated surface reflection moves right through the middle section of the CWA. With MLcapes aoa 1000 J/kg and 700 MB dew pts around 8 C, torrential rain causing localized urban and low-lying flooding is a concern. However, activity looks progressive enough. Also, weak mid level lapse rates and 0-6 KM bulk shear values under 30 knots look to limit severe chances.

Dry weather returns for Monday and Tuesday as large a high pressure over the western Ohio Valley extends into southeast Michigan underneath west-northwest upper level confluent flow.

A large upper level low/trough centered over Hudson Bay will direct a strong Pacific shortwave and strengthening surface low through the central Great Lakes on Wednesday, per 00z Euro. Cool Canadian air will follow, with 850 MB temps bottoming out around 6 C by Friday.

MARINE...

Area of high pressure is now centered over the eastern Lakes this morning. This high should keep the area mostly dry while winds veer to the east and remain below 15 knots ahead of the next system. A warm front will lift through this evening with winds responding by veering southeasterly and increasing with gusts to around 20 knots. There is a chance of showers and thunderstorms in the late afternoon across Lake Erie and Lake St Clair, with lesser chances further north where dry air lingers from the ridge. Increased chances of precipitation tonight as a weak system works east along the state line. Higher chances of rain across the whole region on Sunday as a low tracking through the northern Great Lakes pulls a cold front through the area. Winds then shift to the northwest on Sunday behind the front.

DTX WATCHES/WARNINGS/ADVISORIES

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