textproduct: Detroit/Pontiac

KEY MESSAGES

- Seasonable temperatures with lower humidity with exist through the early week.

- Next chance of showers and thunderstorms arrives Tuesday night into Wednesday.

DISCUSSION

Cool northeast flow over Lake Huron paired with early September sun has produced steep low-level lapse rates and a healthy coverage of diurnal cumulus today. Benign conditions continue this evening, with clouds giving way to clear skies tonight as high pressure strengthens and eases farther south into the region. This is driven by a rising geopotential height field associated with a longwave ridge centered over the Plains. As this ridge advances east into the Great Lakes, increasing stability maintains tranquil weather through Labor Day and into Tuesday. Clear skies and calm winds will bring lows into the 50s each night, with lingering low-level moisture offering potential for fog development. Seasonable highs in the 70s are expected again tomorrow, then a step up toward the lower 80s is forecast for Tuesday as flow emerges from the south/southeast.

The ridge flattens heading into midweek as a Pacific wave tracks across the Canadian Prairie. The dynamic forcing associated with this wave will hold well to the north of the region, sending a surface low across northern Ontario Tuesday night into Wednesday. Southwest flow ahead of the trailing cold front will bring increasing moisture and relatively high confidence for showers Tuesday night into Wednesday. A few storms will be possible as well, but models continue to favor weak lapse rates and muted instability. Boundary-parallel flow may contribute to some training of showers, and deep moisture (PWAT near 1.75" and 99th percentile integrated WV transport per Euro ensemble) brings potential for heavier rainfall rates at times. However, the bulk of ensemble QPF output favors a band of heavier rain farther south over the Ohio Valley where stronger convection plays a role. Breezy conditions follow frontal passage on Thursday morning, then high confidence exists for broad high pressure to re-establish by late week, signaling the return of pleasant early fall weather.

MARINE

Benign marine conditions continue through Monday and part of Tuesday due to vicinity high pressure promoting atmospheric stability. The next chance for increasing winds and waves arrives Tuesday afternoon, ahead of a seasonably strong low pressure system tracking across southern Canada into Hudson Bay. Robust Gulf-modified southwesterly low-level flow and the associated warm (then cold) front(s) should lead to rising thunderstorm chances midweek. Pre- frontal winds/waves should peak Wednesday afternoon with the possibility of borderline gusts to gales for portions of Lake Huron. Drier and cooler conditions are expected for the rest of the workweek with elevated northwest flow. Small Craft Advisories will likely be needed on Wednesday for most of the nearshore waters.

PREV DISCUSSION

Issued at 120 PM EDT Sun Sep 6 2026

AVIATION...

High pressure continues to expand into SE Michigan today with a light northeast flow off of Lake Huron contributing to SCT-BKN diurnal cu this afternoon. This cloud cover should wane through the evening before redeveloping again to a lesser extent Monday. Otherwise, persistence forecast with light northeast flow expected through the TAF period.

D21/DTW Convection...Thunderstorms are not expected through the TAF period.

DTW THRESHOLD PROBABILITIES...

* Low for ceilings aob 5000 feet today and tonight.

DTX WATCHES/WARNINGS/ADVISORIES

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