textproduct: Detroit/Pontiac

KEY MESSAGES

- Mild and breezy Monday. A chance of thunderstorms late Monday and Monday night.

- Showers expected Tuesday.

- Much colder temperatures Tuesday through the end of the week.

DTW THRESHOLD PROBABILITIES

* Low for thunderstorms Monday evening.

* Low for ceiling 5000 ft or less in thunderstorms Monday evening.

PREV DISCUSSION

Issued at 337 PM EDT Sun May 3 2026

DISCUSSION...

Warm front passed to the north overnight allowing for a couple days of warm advection with gusty southwesterly winds. A shortwave trough passing over the region this afternoon/evening will bring an opportunity for some light showers, but better chances will occur north and south of the region as we lie in between the compact vort max to the north and a narrow ribbon of vorticity streaming through the Ohio Valley. There is a weak connection between the two features with some mid level theta e advection leading to a period of clouds through the day. There remains a slight chance of precipitation with the moisture plume as it advances through, though dry air aloft and at the surface will limit the coverage and intensity to any showers that develop.

Additional warming on Monday as thermal ridge slides through bringing 850mb temps up to 10C into the region. Warm air advection and good deal of sun will lead to highs into the low to mid 70s. Weather starts to take a turn in the evening and overnight as the next longwave trough dropping into the Midwest pushes a cold front toward Lake MI. The approaching trough will cause the mid level height field overhead to tilt from zonal flow to southwest flow drawing a shortwave northeastward through the Ohio Valley and clipping far SE lower MI. This wave will pull an unstable airmass northward around 00Z with MUCAPE around 1500 J/kg. There will be good shear around 40 knots and strong lapse rates as well. Hires models are starting to suggest a cluster of strong storms breaking the cap and lifting up through the region south of I94. These storms would be capable of strong winds and large hail. Stronger LLJ then lifts north just ahead of the surface cold front stretching from Saginaw Bay to southern Lake MI which is expected to flare up with activity as convergence increases with good shear in place. Some elevated instability will be present atop a stable BL so severe chances will be minimized.

The front will be very close to exiting MI by Tuesday morning before stalling. Another shortwave will lift up along the front through the afternoon resulting in a long duration rainfall occuring through most of the day...for some locations. Looks to be a fairly sharp cutoff to the NW as dry air surges in behind the front. Latest guidance has come down a bit in total QPF from over an inch to now 0.5-0.75 inch.

Troughing hold through the latter half of the week bringing a return to the below normal, 50 degree high temps through that stretch. There will be additional opportunities for rain as well as a few weak waves advancing through the area.

MARINE...

Breezy southwest flow continues through the day producing gusts on the order of 20 to 25 knots. Small Craft Advisories remain in effect through tonight, with the only change being an extension of Small Craft Advisory duration across western Lake Erie and Lake St. Clair as elevated gust potential lingers overnight. Isolated to scattered showers will continue across Lake Huron through tonight. After a lull in gusts during the mid to late morning hours tomorrow, breezy conditions will return later in the afternoon and evening with gust potential reaching again into the 20-25 knots range, favored across the Saginaw Bay and Lake St. Clair to Lake Erie. Renewed Small Craft Advisories may be needed. Otherwise a cold front will move through tomorrow evening into early Tuesday morning. A line of showers and possible embedded thunderstorms will be likely along the front. Ahead of the front focused across Lake St. Clair and Lake Erie, some stronger isolated to scattered thunderstorm development will be possible in the afternoon and evening. Any stronger storm will be capable of producing wind gusts aoa 34 knots. Wind direction veers to the northwest by Tuesday in the wake of the front.

HYDROLOGY...

Showers and a few thunderstorms are forecast to develop across the region Monday night and persist into the day Tuesday along a slow moving cold front. Latest model guidance and probabilistic guidance suggests high probabilities for total rainfall between a quarter inch and three quarters inch. There is low to moderate confidence that rainfall totals will reach an inch generally across metro Detroit/Ann Arbor and points south, with low confidence totals will exceed an inch and a half. While initially convective, the rain is forecast to transition toward a more steady light to moderate rain on Tuesday. This will keep hourly rainfall rates generally light.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None.

Lake Huron...Small Craft Advisory until 10 PM EDT Monday for LHZ421-422.

Lake St Clair...Small Craft Advisory until 4 AM EDT Monday for LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory until 4 AM EDT Monday for LEZ444.