textproduct: Detroit/Pontiac

KEY MESSAGES

- Thunderstorms will spread southward while increasing in coverage and intensity today and tonight. Isolated damaging wind gusts and locally heavy rainfall are the primary hazards. The best chance for the marginally severe storms looks to be across the Detroit Metro Area and points south this afternoon and evening.

- Dry weather with near-normal temperatures settles in for the weekend.

- A heat wave is possible next week (3 consecutive days of 90+ degrees).

DTW THRESHOLD PROBABILITIES

* Medium for thunder this afternoon and/or evening.

* Medium for ceilings at or below 5,000 feet this afternoon and evening

PREV DISCUSSION

Issued at 309 PM EDT Wed Jul 8 2026

DISCUSSION...

Gradual height falls into tomorrow as a series of upper level disturbances track through the Great Lakes region, helping to slowly drive the cold front and moisture plume over the northern Great Lakes south. Although the 850-700 MB Theta-E ridge does weaken and becomes less organized tomorrow. Will continue to favor the bulk of the shower and thunderstorm activity over the north half of the CWA this evening into tomorrow morning. In line with the 12z HRRR, it looks like the bulk of activity in the late afternoon will reside over the Detroit Metro area and locations south. Bulk of model solutions still only indicating MLcapes up around 1000 J/kg with weak wind shear (25 knots or less of 0-6 KM bulk shear). NAM remains one of the more aggressive solutions, with MLcapes of 1500-2000 J/kg. With higher DCAPE values and machine learning highlighting Detroit Metro area with damaging wind threat, marginal risk still looks justified. With weak mid level lapse rates and weaker wind fields, we would expect mostly strong, sub-severe thunderstorms with heavy downpours.

The cold front looks to reach the southern Michigan border by 12z Friday, and then more or less holds stationary or washes out. There is a low chance of some spotty leftover showers across south half of the CWA Friday morning, with a diurnal flareup possible in the afternoon as main 500 MB trough axis crosses Lake Michigan.

A building upper level ridge (~600 DAM at 500 MB) will establish over the Northern Plains this weekend. The ridge center looks to be far enough west that the Central Great Lakes will remain on the fringe and susceptible to a shortwave or two diving southeast from Central Canada, triggering isolated-scattered showers for the second half of the weekend into Monday. The upper level ridge then looks to fold over and an extension of the west-east axis arrives for Tuesday and lingers in Wednesday. Highs in the low to mid 90s looks likely both those days, but with manageable dew pts in the low to mid 60s expected, heat indices look to fall short of 100 degrees.

MARINE...

Southern Lake Huron, Lake St. Clair and Lake Erie shore look to remain relatively calm this evening through the overnight hours with a light breeze out of the southwest. Northern Lake Huron and the Saginaw Bay area have the possibility of some rain showers tonight, along with some modest wind flow veering from the south to southwest through the overnight hours. Winds can be expected to be in the 10 to 15 knot range this afternoon/evening, with gusts of 20 knots possible. Any thunderstorm threat this evening would be limited to the bay area, where locally strong wind gusts could occur.

Tomorrow we expect to have a weak low pressure system trek across North Lower Michigan, bringing the chance for showers and even an isolated severe weather threat from Saginaw Bay down to the Lake Erie shore. The main threat for any thunderstorms that could develop tomorrow would be damaging wind gusts. Nonetheless Lake Huron and Saginaw bay can expect light winds veering from the southwest to the north throughout the day tomorrow, with gusts of 15 to 20 knots possible depending on the positioning of the low pressure tomorrow. Lake St. Clair and Lake Erie shore can expect light winds as well tomorrow veering from the southwest to the west throughout the day tomorrow.

Friday onwards a high pressure system is expected to develop over the region, bringing warmer and calmer weather throughout the weekend.

HYDROLOGY...

A slow moving cold front settles through southern Lower Michigan Thursday and Thursday night, serving as the focus for numerous showers and thunderstorms, mainly Thursday afternoon and evening, with a chance of locally heavy rain across the area. Basin average rainfall of a quarter to half an inch is expected, with a chance of near 1 inch in scenarios with greater thunderstorm coverage. The slow movement of the front could also produce more than one round of thunderstorms leading to localized totals greater than 1 inch within a few hours time. Flooding potential in this scenario is still limited to minor flooding of urban and other prone areas. Scattered showers and a chance of thunderstorms lingers into Friday, mainly south of M-59, before coming to an end Friday evening.

DTX WATCHES/WARNINGS/ADVISORIES

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