textproduct: Detroit/Pontiac

KEY MESSAGES

- Mostly dry today with low shower chances tonight near the Ohio border.

- Temperatures return to near normal this weekend with dry weather.

- Very hot and humid conditions are likely next week as heat indices could exceed 100F, especially Tues into the late week period. Potential exists for thunderstorms during this time as well.

DTW THRESHOLD PROBABILITIES

* Low for ceiling at or below 5000 ft today and tonight.

PREV DISCUSSION

Issued at 252 AM EDT Fri Jun 26 2026

DISCUSSION...

Shearing PV anomaly continues to peel away from the Great Lakes this morning, leaving Lower Michigan within a cyclonic surface flow pattern. While synoptic moisture largely exited with the wave, flow off of Lake Huron has established a mix of low stratus/fog across northern and central Lower Michigan that will slowly spread south through the early morning hours. Cloud trends quickly improve with daybreak as late June sun angle efficiently mixes boundary layer moisture with an otherwise dry/stable column aloft. Seasonably cool conditions expected again today with highs in the mid-70s (even cooler in cloudy spots). Cool conditions will be reinforced as cloud cover redevelops this afternoon from both diurnal cu development and remnant convective cirrus from whatever perturbations survive this far east.

Remnant baroclinic zone from yesterday's low is active with convection this morning, stretching from New England to the southern Plains where another low has developed. Plenty of moisture pooling around this low will advect into the Ohio Valley tonight, but stalls just shy of the state line up against the 1020 mb surface high. This allows just a glancing period of moist isentropic ascent along deformation axis overnight near the Ohio border that could squeeze out a few showers. That said, do expect mostly virga as a combination of shallow moisture, weak ascent, and neutral to weakly stable lapse rates will struggle to produce rates capable of overcoming the existing dry low levels. Column stays much drier further north, affording quality radiative cooling conditions especially toward the Saginaw Valley/Thumb regions. This reintroduces fog potential Saturday morning, especially given E-NE flow off the of Saginaw Bay/Lake Huron

Generally neutral thermal advection pattern expected this weekend, with a gradual warming trend back toward normal highs (low 80s) by Sunday. SE Michigan remains on the north side of the deformation axis, maintaining a feed of dry synoptic air from Ontario to limit precipitation chances.

Major pattern transition then commences late Sunday-Monday as a deep upper low moves into the Pacific Northwest and ridging amplification intensifies over eastern CONUS. By Monday afternoon, projections are for 500mb heights to reach ~594 dam over the Ohio Valley. This sets the stage for a hot and humid airmass across SE Michigan with potential for multiple consecutive days of mid-upper 90s high temperatures and even higher heat indices from Tuesday through the rest of the work week. A handful of EPS/CMCE members push highs into the low 100s, although that is difficult to do in SE Michigan and will require limited cloud cover/thunderstorm activity which have low predictability this far out. Nonetheless, heat headline criteria looks very much in reach for next week across southern Lower Michigan.

MARINE...

High pressure building into the western lakes and will encompass most of the region by this morning. The high holds over most of the area through the weekend but there is a low looking to clip the southern Great Lakes Friday afternoon and evening. The rain shield may impact Lakes Erie and St Clair. In the wake of that low, the high will expand back across the Great Lakes tonight, bring warmer and calmer weather along with it for the upcoming weekend.

DTX WATCHES/WARNINGS/ADVISORIES

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