textproduct: Detroit/Pontiac

KEY MESSAGES

- There is a Marginal Risk for Severe Thunderstorms this evening for areas near the Ohio border. Main threats are large hail and gusts to 60 mph.

- Above normal temperatures through the second half of the week.

- Additional chances for showers and thunderstorms Friday.

DTW THRESHOLD PROBABILITIES

* Very low for thunderstorm occurrence this evening.

PREV DISCUSSION

Issued at 320 PM EDT Wed Apr 22 2026

DISCUSSION...

High pressure to the north extends south through the majority of the CWA until it runs up against a stalled front wavering along the I 94 corridor. A weak low over southern Lake MI, seen as a swirl of low clouds on satellite, is forecast to release along the front through the afternoon. The region south of the front is a moisture rich (dewpoint in the 60s), moderately unstable 1000-1500 J/kg SBCAPE), low shear (6KM bulk shear ~20 knots) environment supportive of convective development similar to what we saw last evening. Convection has already began over southern Lake MI which is now drifting into SW lower MI and northern IN. Low level lapse rates are good combined with surface convergence along the boundary which will help storms develop through the heat of the day. First storm of the day had an impressive hail core with it and with the instability and lapse rates, hail should continue to be a concern. Low shear will hamper things a bit but cool air aloft will keep a mention of strong wind gusts as well. SPC has upgraded the DY1 outlook to a Marginal Risk across Lenawee and Monroe counties to account for the slightly higher confidence for strong to severe storms this afternoon/evening.

Amplified longwave pattern shifts eastward on Thursday, with ridging encompassing the Great Lakes. A very energetic upper level trough with multiple vort maxes rotating about each other will cause the pattern to briefly stall with the moisture axis along the upper MS River valley and into the Midwest. Subsidence looks to cap the area most, if not all of the day as the front to the south gets drawn back north. There are some CAMs that offer some isolated showers during peak heating but soundings suggest we'll be too stable and surface dewpoints only in the 40s to low 50s will also limit shower potential.

Next chance for widespread showers and thunderstorms arrives late Friday through Friday night as strong westerlies rounding the base of the long wave trough provide an eastward push to the leading arc of vorticity releasing from the parent trough. This combined with the ridge axis crossing the area allowing for southerly return flow to bring mid to upper 50 dewpoints back into the region. A surface low will develop along the extension of the warm front and then track through the region Friday night. SPCs SWODY3 still has most of the region with General Thunder during this period. Current QPF for this period is around a half inch in the 18 hour period.

High pressure builds back Saturday and will persist into Monday before the next spoke of the trough rotates through the region. Highs will be in the 70s through the end of the week before settling back in the 60s this weekend into next week.

MARINE...

Weak stalled frontal boundary offers a shot at a few thunderstorms over Lake Erie this evening. Otherwise the central Great Lakes holds under high pressure tonight through Thursday maintaining benign marine conditions. Developing low pressure over the upper Midwest eventually pushes into the Great Lakes Friday night-Saturday supporting the next chances for wider spread showers and thunderstorms. In advance of the low Friday, southeasterly winds strengthen with gusts around 30kts possible over the northernmost waters of Lake Huron as winds funnel toward the Straits. Another area of high pressure then builds in later this weekend.

DTX WATCHES/WARNINGS/ADVISORIES

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