textproduct: Detroit/Pontiac

KEY MESSAGES

- Dry weather with near-normal, pleasant temperatures returns for Thursday and Friday.

- Mainly dry weather continues through the weekend, accompanied by slightly above-normal temperatures.

DISCUSSION

A moist airmass in place, as the 12z DTX RAOB checked in with a PW value of 1.99 inches. Thick cloud cover and numerous to widespread showers tracking through southeast Michigan have limited instability, and thus thunderstorm development has been hard to come by. Do not expect any severe storms as MLcape remains under 1000 J/kg through the remainder of the day, and SPC Day 1 has adjusted the marginal risk south.

Showers end by early this evening as the 850-700 MB Theta-E ridge is on track to drop south of the border this evening, with much drier air advecting in through Friday morning, when PW Values bottom out around 0.5 inch. With this drier air mass and a 1018 MB surface high over southeast Michigan, efficient radiational cooling areas will likely see min temps aoa 50 degrees, warming into the upper 70s during the day under mostly sunny skies.

The large anti-cyclone in place on Friday will be slow to exit east, and associated 850-700 MB Theta-E trough looks to hold through Saturday morning before a weak cold front and moisture axis approaches from the western Great Lakes. Warm mid levels (up to 9 C at 700 MB) and weak low level convergence certainly could support a mainly dry frontal passage Saturday evening/night, or even a washing out boundary that promotes some fog development. Outgoing NBM pops are under 15 percent Saturday through Sunday.

MARINE

Cold front gradually crosses the central Great Lakes this evening ending further shower/storm chances. Moderate northwesterly flow follows for Thursday however only a glancing shot of cold advection and a rapidly diminishing gradient has high pressure builds in caps winds below 30kts. High pressure then drifts overhead through Friday night leading to benign marine conditions to close the work week.

PREV DISCUSSION

Issued at 149 PM EDT Wed Sep 9 2026

AVIATION...

Edge of upper level Pacific jet streak has carved out a developing frontal zone over Southeast Michigan this afternoon. Widespread VFR to MVFR shower activity is in place over the forecast area the first couple/few hours of the period. A lot of uncertainty whether or not MVFR ceilings will develop southward into the Detroit terminals. Based on ceiling height trends at KMBS and KFNT kept 2.5kft agl ceilings at DTW late this afternoon. Building high pressure tonight will cause winds to weaken and may bring some light br/hz at daybreak Thursday.

D21/DTW Convection...Low chance for a thunderstorm this afternoon.

DTW THRESHOLD PROBABILITIES...

* Moderate in ceilings aob 5000 feet today.

* Low for thunderstorms today.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Small Craft Advisory until 10 PM EDT this evening for LHZ421-422- 441.

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