textproduct: Detroit/Pontiac

KEY MESSAGES

- A chance of thunderstorms will exist this evening into Tuesday and again on Wednesday, with greater potential near the Ohio border. Isolated storms may become severe, capable of producing damaging winds, large hail, and heavy rainfall.

- Dry weather is expected to end the workweek.

- Renewed chance of storms and heavy rainfall over the weekend.

DISCUSSION

Subsidence behind the shortwave this morning dried out the mid levels and the cap has held strong thus far. ACARS data out of DTW shows waning CIN however, now around 25 J/kg. Although the low level wind fields are weak, any localized convergence boundaries (lake breeze) could serve as a focal point to support isolated thunderstorms. Banking on dry mid levels and lag of well defined trigger to keep coverage limited, as hi res solutions are also muted. Of course, an outflow boundary(s) could trigger renewed activity. In any event, it appears there is a better chance tonight toward the southern Michigan border.

Fast northwest upper level flow over the Great Lakes region through Thursday, with embedded impulses/upper level PV filaments tracking out of the Northern Plains potentially triggering convection. The main moisture/instability axis is located over the northern Ohio, which favors the bulk of the storms in that area. However, if upper level waves are sufficiently strong, the southwest low level jet will be able to displace activity farther north into southern Lower Michigan. There are a few models suggesting the I-94 corridor to the southern Michigan border will see some shower/thunderstorm activity tonight as K indices peak out around 40 C as 850 MB winds increase aoa 30 knots, but remain mostly westerly. The subtle direction shift from due west and exact location of the jet core will make all the difference on location of activity. Otherwise, with at least moderate instability/capes (MLcapes 2000 J/kg) to tap into along with decent mid level lapse rates, a marginal risk of severe seems reasonable.

An even stronger upper level wave is progged to come out of the Midwest on Tuesday, supporting higher pops and farther northward placement by Tuesday afternoon. Still, if the system goes upscale faster around Chicago, another dive to the southeast remains a good possibility, focusing the chances for severe storms and heavy rain south of border. Thus, the Ohio Valley has been put into enhanced risk in the day 2 SPC outlook.

Gradually building 500 MB heights to close our the workweek as an upper level ridge axis arrives Friday night (AOA 588 DAM per euro ensembles). There ridge is still not strong enough to cap activity, as another strong shortwave and surface reflection are progged to move into the Western Great Lakes by Saturday. A risk of strong storms and heavy rainfall exists over the weekend. Timing, duration, and axis of heavy rainfall remain, however, as UKMET, Canadian, and Euro models depict significant differences.

MARINE

A stalled front near the southern Michigan border will continue to be a focus for multiple rounds of thunderstorms over the next couple days. This will mostly affect Lake Erie and Lake St Clair but there is a chance later this afternoon that storms could affect areas farther north into southern Lake Huron as well. Outside of any convection, high pressure to the north of the front will provide generally light and variable winds through mid week at 10 knots or less. Later in the week, a weakly organized area of low pressure becomes develops across the Northeast, followed by high pressure of 30.1 inches gradually dropping southeast across the central and eastern Great Lakes. This will favor an uptick in northwest winds Thursday and Friday.

PREV DISCUSSION

Issued at 1252 PM EDT Mon Aug 10 2026

AVIATION...

Brief MVFR stratocu with limited coverage transitions to increasing cumulus during the afternoon on the heels of weakening subsidence that trailed the morning storm complex. Low end VFR ceiling is most likely toward the weak front stalled near the Ohio border which also provides a diffuse focus for a stray thunderstorm late in the day or this evening. There is also a chance of storms again late tonight and early in the morning, mainly near and south of DTW, as the stalled front remains the focus and/or runway for activity that develops upstream toward the mid MS valley. Trends even farther west and later tonight also have a chance to carry eastward into southern Lower Mi Tuesday afternoon.

D21/DTW Convection... Time windows for a chance of thunderstorms are focused mainly late this afternoon, late tonight, and again Tuesday afternoon.

DTW THRESHOLD PROBABILITIES...

* Low for thunderstorms this evening, overnight, and Tuesday afternoon.

* Moderate for ceiling 5000 feet or less this afternoon.

DTX WATCHES/WARNINGS/ADVISORIES

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