textproduct: Detroit/Pontiac

KEY MESSAGES

- Seasonable temperatures with dry weather through most of the day today.

- Increasing chances for showers and storms tonight through tomorrow. Shower and storm chances continue through the early week.

- Humidity builds for the early to mid week period.

DTW THRESHOLD PROBABILITIES

* None.

PREV DISCUSSION

Issued at 326 AM EDT Sat Aug 29 2026

DISCUSSION...

Rapid thunderstorm development is ongoing across the northern Plains early this morning along the nose of a strengthening southerly LLJ. This activity is expected to organize into an MCS and progress through the Upper Midwest today before traversing into the Great Lakes tonight into early tomorrow. Given little to no instability across the Great Lakes, a weakening trend of this complex remains favored, although latest hi-res guidance brings some increasing confidence that portions of the MCS can reach Southeast Michigan.

This southerly low-level flow across the Plains will fold from Iowa into Wisconsin through the morning hours and while the aforementioned MCS is expected to outpace the nascent moisture source, the nocturnal reinforcement of the LLJ could support redevelopment or reinvigoration of showers and embedded thunderstorms along the backside of the MCS despite limited instability. This can support rain and thunderstorm chances into the early afternoon across SE MI. Additionally this corridor of enhanced theta-a will strengthen isentropic ascent along or north of the I-69 corridor, providing continued support for showers and thunderstorms into the latter half of the day. Development along this convergent boundary in the afternoon/evening would likely be a little more localized. Overall there remains uncertainty regarding how these individual potential rounds of precipitation will evolve and overlap, but confidence has increased in a considerably more unsettled Sunday.

Given the above, confidence is increasing that NBM temperatures are likely overdone on Sunday. An active convective pattern and persistent cloud cover will limit meaningful insolation. If the more active setup plays out as projected, highs will be capped in the 70s, with low 80s possible only where coverage is reduced for a longer period of time.

A very moist and active pattern will persist in the early and midweek period. Ensemble guidance highlights strong west to east integrated water vapor transport across the region into Wednesday. PW values of 1.75 to 2.00" and warm-cloud depths approaching 13kft will support efficient rainfall production. Mid-level disturbances within quasi-zonal flow under this setup will bring multiple opportunities for showers and thunderstorms. Repeated convection along the same areas will bring a localized flooding risk. In the same regard for Sunday temperatures, early week highs will be conditional on cloud coverage and shower chances. Temperatures will likely need to be tempered down if new guidance highlights SE MI as a susceptible corridor for repeated precipitation.

MARINE...

Influence of high pressure wanes this morning as it shifts to the Northeast with the central Great Lakes holding on its westernmost fringe. This allows for modest southwest winds to develop during the day with gusts holding aob 20kts, save for central Lake Huron where favorable fetch could allow for up to 25kts. Active pattern returns by Sunday as developing low pressure over the northern Plains lifts a warm front through the area ushering in a more humid airmass leading numerous shower/storm chances Sunday into Monday.

DTX WATCHES/WARNINGS/ADVISORIES

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