textproduct: Detroit/Pontiac

KEY MESSAGES

- Dry and warm tomorrow with temperatures reaching the upper 80s to near 90 degrees.

- Showers and thunderstorms are likely to develop Thursday afternoon and Thursday night. High humidity will bring a threat for locally heavy rainfall with any storm.

- Seasonable temperatures and dry conditions return this weekend.

- A heat wave is possible next week (3 consecutive days of 90+ degrees).

DISCUSSION

Surface ridge and drier air held strong over Lower Michigan most of the day, but the eastern half of the CWA finally saw some SCT-BKN CU development this afternoon as surface dew pts pushed into the 60s. Very dry mid levels (12z DTX 700 MB dew pt depression checked in at 36 C) will preclude any shower/thunderstorm activity.

Upper level energy/jet forcing tracking through the Great Basin, northeast through the northern Rockies and into northern Ontario tonight. Multiple shortwaves are present, but the main 850-700 MB Theta-E ridge and moisture axis (PW values 1.75-2 inches) will remain around the Straights through the day on Wednesday. The last vestiges of 850-700 MB Theta-E trough will hold over southeast Michigan to provide another dry and warm day as temps push into the upper 80s.

The cold front/moisture axis will sag south Wednesday evening into Thursday, providing the focus for showers and thunderstorms. A stronger shortwave tracking through Iowa will likely slow the southward progression of the cold front over southern Lower Michigan, which could allow for repeated rounds of showers and thunderstorms Thursday and Thursday night- even potentially into Friday if the stronger Canadian model is to believed. As usual, the 12z NAM most aggressive with instability building during Thursday, with MLcapes reaching 2000+ J/kg, along with just enough 0-6 bulk shear of 30-35 knots to draw concern for severe storms. However, other models are more subdued. With weak mid level lapse rates and weaker wind fields, we would expect mostly strong, sub-severe thunderstorms, though isolated, precip loaded marginal severe downbursts are possible given the higher DCAPE values indicated. With good moisture (PW values around 1.75"/700 MB dew pts in excess of 2 C), heavy rain and localized flooding are a concern with repeated rounds of storms. But right now, no clear signal indicated, as euro ensembles struggle to even support qpf aoa 0.5" in a 24 hour period.

A building upper level ridge over the Northern Plains during the weekend will be the main weather story, with this heat dome pushing into the Upper Mississippi River Valley/Western Great Lakes early next week. Another heat wave is possible next week for southeast Michigan, but the exact strength and location of ridge center will have to be worked out, as we could end up on the outer fringe and be susceptible to the ridge riders diving southeast from Central Canada.

MARINE

High pressure continues to sit atop the Great Lakes today into Wednesday, allowing light winds and dry conditions to persist. A front will bring rain and the possibility for a thunderstorm Thursday into Friday. This will also provide the best chance for slightly breezy conditions with gusts around 20 knots. As this front moves out of our region Friday, we see another high pressure entering the region into the weekend, providing calmer and drier conditions.

PREV DISCUSSION

Issued at 120 PM EDT Tue Jul 7 2026

AVIATION...

An elongated area of high pressure extends from MO into northern Lower MI this afternoon. Light north to northeast wind prevails across the local area with the Detroit TAF sites forecast to briefly flip to southeast as the lake breeze moves in later this afternoon. Coverage of diurnal cumulus will remain highest across the east where moisture is enhanced by the marine layer, with any broken ceilings predominantly VFR going forward. The cu field dissipates this evening with winds going light and variable as the high pressure settles overhead. The remnant enhanced moisture axis sets up the eastern and southern forecast area for potential development of ground fog early Wednesday morning, with forecast data supportive of several hours of MVFR to IFR visibility before daytime mixing ensues shortly after daybreak. Light southwest wind and prevailing VFR are expected Wednesday.

D21/DTW Convection... Thunderstorms are not forecast today or tonight.

DTW THRESHOLD PROBABILITIES... * Medium for ceiling at or below 5000 feet this afternoon.

DTX WATCHES/WARNINGS/ADVISORIES

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