textproduct: Detroit/Pontiac

KEY MESSAGES

- Dry and pleasant weather conditions will persist into Wednesday.

- Areas of dense fog expected this morning and Tuesday morning.

- Rain chances increase during the latter half of the week with cooler temperatures expected.

DTW THRESHOLD PROBABILITIES

* Low for ceiling/visibility at/below 200 ft / 1/2 SM. this morning, and again early Tuesday morning.

PREV DISCUSSION

Issued at 338 AM EDT Mon Sep 28 2026

DISCUSSION...

Fog development is following a similar temporal cadence to yesterday as noted via Nighttime Microphysics RGB. The geographic footprint of the fog plume, however, is taking on a more southerly drift given the backed wind direction in comparison to yesterday while also showing signs of mechanical turbulence. Nonetheless, likely to see another localized area of dense fog for the Thumb areas and northeast suburbs as winds go calmer toward daybreak. MOS guidance is also still on track for another round of fog Tuesday morning, and more bullish than the past few days as remnant moisture from the deformation axis wraps around the high pressure center. This coincides with the high pressure center moving overhead which will minimize gradient flow for optimized radiative cooling/fog potential. Fog lifts and mixes out by mid-morning both today and Tuesday, extending the stretch of dry and seasonable fall weather for SE Michigan. Daytime highs both days expected to peak in the low- mid 70s under plenty of sunshine.

A pattern shift begins Tuesday on the western flank of the high noted by a wind shift to the southwest. This leads to modest thermal advection that peaks Tuesday night, boosting h8 temperatures from 10 C to 15 C by Wednesday morning. The first round of mid-level height falls approaches early Wednesday to bring thickening mid-level cloud to the region. By this point the east coast system will be dislodged and the low levels will be characterized by the western flank of broad eastern CONUS high pressure. This will be quite effective in stalling low level moisture transport to our west through much of the day Wednesday, keeping the majority of SE Michigan dry but cloudy with virga. The trend toward a drier forecast Wednesday also boosts the temperature forecast for Wednesday, with highs expected to climb into the mid-upper 70s.

Rain chances then increase Wednesday night and persist through at least Thursday as northern stream troughing phases with the broad deformation/trough axis over central CONUS. The low level height field tightens quickly Wednesday night as the trough approaches, leading to strengthening LLJ winds to about 50 knots by Thursday morning. On its own this causes breezy SW flow across SE Michigan Thursday where gusts to 25 mph are possible. The enhanced SW flow will also enhanced moisture transport into lower Michigan, which will be engaged by the deformation and approaching frontal forcing to bring rain to the region Thursday. Forcing will be defined primarily by deformation and WAA while lapse rates stay moist adiabatic, so expecting a light-moderate stratiform nature to Thursday's rain chances. That said, the impressive moisture axis (PWAT nearly 2.0") will take most of the day to sink south across Lower Michigan which could grind out 0.50-0.75" when all is said and done. That said, preceding dry weather and long duration rainfall limits flooding concerns with this rain.

A meaningful cool down is then expected Friday into the weekend post- front, with showers tapering off Friday. There is still some uncertainty as to how aggressively high pressure pushes in behind the fropa, which keeps low rain chances going through Friday. Temperature prospects for the weekend carry higher confidence, with highs only reaching the mid 60s and lows back into the 40s to start October.

MARINE...

High pressure to hold over the Great Lakes through tomorrow. This will cap wind gusts to or below 15 knots for most locations. Wind direction will mainly hold from the north to northwest today but will back to the south to southwest tomorrow after the passage of a warm front. The next chance for rain and possible some thunderstorms will return Wednesday and Thursday ahead of and along a cold front.

DTX WATCHES/WARNINGS/ADVISORIES

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