textproduct: Detroit/Pontiac

KEY MESSAGES

- The Heat Advisory is in effect until 8 PM EDT.

- EGLE has declared an Air Quality Alert today due to Canadian wildfire smoke reaching the surface and the resultant rise in PM2.5.

- A few isolated thunderstorms are possible this afternoon and evening.

- Increasing chances for showers and thunderstorms Friday and Saturday.

DTW THRESHOLD PROBABILITIES

* Low for thunderstorms this evening.

PREV DISCUSSION

Issued at 315 AM EDT Wed Jul 15 2026

DISCUSSION...

An expansive plume of Ontario wildfire smoke will spread south across the region today, reaching the northern forecast area during the late morning and afternoon hours before expanding south later this evening. Arrival of smoke coinciding with the greater portion of the diurnal heating cycle could temper projected forecast highs by 1-3F, relative to adjacent locations that stave off the smoke a little longer. Of higher impact, light northerly flow off Lake Huron and northeast flow off Saginaw Bay will further blunt max temperature potential. This combination will likely bring temperature high values a little closer to normal values within the Thumb and locations just downwind of the Bay. For the majority of locations outside of the lake and early day smoke influence, well above normal temperatures return with highs peaking in the mid 90s, possibly upper 90s within the urban corridors. This will produce heat indices aoa 100 degrees and as a result, a Heat Advisory remains in effect until 8PM EDT.

Most locations are expected to remain dry under mostly sunny skies beneath an elevated mixed layer cap. However, a brief window emerges between roughly 20Z (4PM) to 02Z (10PM) when the cap relaxes somewhat in the vicinity of a weak low-level convergence axis setting up from near Jackson northwest towards Lansing and Grand Rapids. This introduces a low chance (15-20%) of an isolated shower or thunderstorm, favored along and/or south of the I-696 to I-96 corridor. The aforementioned cap and dry mid-levels bring low confidence for CI leading to organized convection. However, this environment will be sitting on 2000-3000 J/kg of CAPE and around 30 knots of 0-6 km bulk shear. Should an isolated storm overcome the cap and exhibit organization, it would be capable of producing localized strong wind gusts. This remains a highly conditional scenario.

The influence of an expansive lake breeze/back door cold front late tonight will bring some mild relief for overnight temperatures producing more seasonal values with lows dropping to the low to mid 60s outside of the urban Metro region. Diffuse high pressure under strong mid- level subsidence will bring dry conditions tomorrow and haze with the lingering wildfire smoke. The expansion of wildfire smoke across SE MI will likely temper forecasted high potential again, bringing some higher confidence for highs holding in the mid to upper 80s, outside of the urban Metro region and Saginaw Valley where 90s may be achievable. The lower humidity values will preclude any heat headlines tomorrow. Increasing chances for showers and storms enter Friday and Saturday will arrival of some better Gulf moisture along with eventual passage upper-level wave/low pressure system.

MARINE...

Hot high pressure retains partial influence over the Central Great Lakes early this morning. A weak backdoor front drops through today allowing winds to eventually veer to the northwest behind the front. Wind speeds still only top out around 20 knots through this evening, more so over the northern half of Lake Huron. A couple pop-up storms are possible along the frontal boundary and/or any lake breeze development late this afternoon. The probability of severe weather with any isolated storms is low. Northwest winds at or below 20 knots expected Thursday. Lower confidence forecast through the weekend due to conflicting model guidance regarding the location and magnitude of a weak surface low passing through Lower Michigan will impact wind trends and thunderstorm potential. Prevailing winds should remain below criteria through the forecast period.

DTX WATCHES/WARNINGS/ADVISORIES

MI...Heat Advisory until 8 PM EDT this evening for MIZ047>049-053>055- 060>063-068>070-075-076-082-083.

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