textproduct: Detroit/Pontiac

KEY MESSAGES

- Dry Friday with scattered showers and isolated general thunderstorms on Saturday.

- Additional rainfall chances focused across Lower Michigan Sunday evening into Monday.

- Slightly below normal temperatures are expected into the weekend.

DTW THRESHOLD PROBABILITIES

* Low for ceilings at or below 5 kft this evening. Medium Friday afternoon.

PREV DISCUSSION

Issued at 346 PM EDT Thu Jun 18 2026

DISCUSSION...

Cooler cyclonic flow over the area today with an 115+ knot upper level jet extending out of the PacNW through the eastern Great Lakes. This has supported a high coverage of clouds across the area this afternoon. Steepened lower level lapse rates have also supported gusty winds to around 35 to 40 mph. Gusty conditions should ease this evening as stable conditions develop with the inbound surface high pressure and the stronger lower level jet winds move off to the east. While the environment is lacking deeper moisture, the northwest flow and weak CAA presents low end PoPs for possible isolated shower activity through remainder of the afternoon. A cloud clearing trend is expected tonight bring mostly clear skies and lows down into the low/mid 50s.

Surface high pressure with low amplitude low level ridge will lead to dry conditions for tomorrow. Less cloud cover and slightly warmer 850 mb temperatures should lead afternoon high temperatures generally around the mid 70s. A weak shortwave is progged to pass within the northwest flow of the broader trough and arrive locally on Saturday. Slight improvement in moisture with marginally improved instability and lapse rates should be enough to support scattered showers and isolated thunderstorms. The better environment for thunderstorms looks focused north of I-69.

Stable conditions will mark the start of Sunday as a convective system organizes upstream around the Mid-Mississippi River forced by a mid-level wave passing through the central plains, strong low level jet, and moisture convergence. The northern periphery of this MCS looks to clip lower Michigan Sunday evening into Monday. Forecast shows weak lapse rates and little to no instability, so a severe weather threat should be limited with heavy rainfall being the main focus. There is still room for a shift in the rainfall axis, but heaviest rainfall is currently forecast to set up across IN and OH. Temperature forecast over the weekend into next week looks somewhat steady with highs in the 70s and overnight lows in the 50s.

MARINE...

Breezy west flow persists for the remaining daylight hours in the wake of a departing low pressure system. Wind gusts ranging between 20-30 knots will be likely and Small Craft Advisories remain in place through tonight. A ridge of high pressure will build in late tonight through tomorrow morning which will relax the pressure gradient and will reduce wind speeds and gust potential. An upper- level disturbance quickly passes through in the morning and early afternoon which will bring chances for rain showers and a low chance for an embedded thunderstorm. A weak area of high pressure will then hold through the weekend before low pressure arrives over the Ohio Valley early Monday morning, bringing rain and thunderstorm chances along with elevated wind gusts, particularly across the southern Great Lakes through Lake Erie and Lake St. Clair.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Small Craft Advisory until 8 PM EDT this evening for LHZ421-422- 441>443.

Lake St Clair...Small Craft Advisory until 8 PM EDT this evening for LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory until 8 PM EDT this evening for LEZ444.