textproduct: Detroit/Pontiac

KEY MESSAGES

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

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

DISCUSSION

Sfc high pressure will strengthen as it expands across the Great Lakes today through Labor Day amid rising mid level geopotential heights across the region. Northeasterly low level winds circulating around this sfc high have been advecting a drier airmass across Se Mi, characterized by sfc dewpoints in the 50s. Mid level subsidence will suppress diurnal mixing depths this afternoon capping afternoon highs in the 70s. Steep low level lapse rates and flow off Lake Huron will also result in a fair amount of diurnal cumulus this afternoon. The influence of the sfc high and mid level ridging will sustain a dry forecast through Tuesday. As the sfc high pressure departs across the eastern Great Lakes Labor Day into Tuesday there will be a gradual veering of the low level flow from easterly to southerly by Tuesday, supporting a gradual warming trend. The influence of the sfc high and broad subsidence will maintain relatively tranquil conditions to end the holiday weekend and start the work week. Recent rainfall, an easterly component to the surface winds off the lakes and nocturnal boundary layer decoupling suggests some semblance of a fog potential the next couple of nights.

Damping of the mid level ridge axis over the Great Lakes is forecast mid week as a progressive longer wavelength trough originating from the Pacific Northwest drives a cold front across the forecast area in the Tuesday night/Wednesday time frame. A narrow axis of deep layer moisture is forecast to advect into Se Mi along/ahead of this front. While strong mid level wind fields will contribute to adequate deep layer shear, GFS/ECMWF ensemble members indicate an overall weakly unstable environment across Se Mi. This would potentially limit the thunderstorm and severe weather risk. Shower chances will still remain warranted, with ensemble members suggesting the higher rain chances across the northern portions of the forecast area where models indicate a little better kinematic forcing.

MARINE

Favorable marine conditions are forecast through the rest of the weekend as high pressure settles over the central Great Lakes. This will promote stable and mainly dry conditions into early next week with prevailing tranquility. The next chance for increasing winds and waves arrives Tuesday night into Wednesday ahead of a low pressure system. Strengthening Gulf-modified southwesterly flow and the low's associated warm then cold fronts should lead to rising thunderstorm chances midweek.

PREV DISCUSSION

Issued at 151 AM EDT Sun Sep 6 2026

AVIATION...

Quiet night across the region as high pressure has a firm grip on the area in the wake of the cold frontal passage. Mainly VFR conditions are expected with the drier northeast flow, but temps are quickly falling now as the winds drop off so there is a chance of some shallow fog. Will monitor satellite trends and obs to see if a short period of reduced vsbys needs to be added this morning. Diurnal cu will develop this afternoon for several hours before skies again go clear tonight.

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

DTW THRESHOLD PROBABILITIES...

* Low for ceilings aob 5000 feet tonight and Sunday.

DTX WATCHES/WARNINGS/ADVISORIES

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