textproduct: Detroit/Pontiac

KEY MESSAGES

- Increasing chances for showers and possibly some thunderstorms tomorrow. Heavy rainfall leading to localized flooding is possible, particularly along and south of the I-94 corridor.

- Showers and thunderstorms chances continue through Sunday.

DISCUSSION

Outside of a very low chance for a stray shower along a convergent lake boundary derived from Lake St. Clair/Lake Erie, dry conditions continue under the influence of a high pressure system that will progress across Ontario. Attention will turn back to active conditions across the upper Mid-west/Plains surrounding organization and progression of an MCS/MCV. Progression of this system into the southern Great Lakes/Ohio River valley is expected through the day tomorrow, into the evening hours. Specifically for the southern Great Lakes, the thermodynamic environment remains unfavorable for organized strong convection. Pre-storm environment highlights essentially absent surface-based instability with MUCAPE building to a few hundred J/kg towards I-94 through the day. The more meaningful instability gradient is expected to develop and hold across central Indiana through southern Ohio, which is where the bulk of convective activity is expected to reside. If any developing MCV takes a slightly more northern trajectory relative to modeled guidance, this could locally augment ascent and modify the kinematic/thermodynamic environment and bring stronger storm potential, but current guidance offers little indication that these meso processes would be sufficient to over the broad scale deficiencies. This scenario is highlighted in the latest SWODY2 where a marginal risk for severe weather holds along/south of I-94.

Much more plausible will be increasing rain shower chances as deep moisture increases ahead of the system. PW values rise aoa 2 inches, near the 99.5th percentile w.r.t August climatology. Aforementioned weak instability with poor mid-level lapse rates should limit convective potential, though some isolated embedded thunder and locally heavy rainfall remains possibly given the nature of the subtropical airmass. Rain and thunderstorm chances to continue through Sunday with better instability in place. Passage of this system with convectively enhanced low pressure will help to push a weak cold front across the region. Rain chances end after passage of the front late Sunday night to Monday morning. Drier conditions are favored through the early week period with highs holding in the low 80s.

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MARINE

High pressure now centered over northern Lake Superior on its way to the eastern Lakes by Saturday morning. Winds are mostly under 10 knots across the waters but northeasterly flow could lead to some locally higher gusts in Saginaw Bay and southern Lake Huron this afternoon and evening. Winds then turn southerly late Saturday and increase to around 20 knots ahead of a cold front that will sweep through Saturday night. This front will bring the next chance of thunderstorms to the region as well. Winds then shift to the northwest on Sunday behind the front.

PREV DISCUSSION

Issued at 148 PM EDT Fri Aug 14 2026

AVIATION...

Predominately VFR conditions expected to prevail through this TAF period. High coverage of lower diurnal cumulus have developed over bulk of TAF sides, excluding MBS. Isolated pop up showers are being supported within a weakly forced environment. Coverage of showers should remain isolated enough to keep mention out of TAF sites for now. High pressure has lead to some variability to the winds across the southern metro terminals, but a light E/NE wind will become more dominate into the late afternoon and tonight. D21/DTW Convection...No thunderstorms anticipated during the taf forecast period.

DTW THRESHOLD PROBABILITIES...

* Low for ceiling 5000 feet or less through this afternoon.

DTX WATCHES/WARNINGS/ADVISORIES

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