textproduct: Detroit/Pontiac

KEY MESSAGES

- A little warmer today.

- Showers with a chance of thunderstorms tonight and Wednesday.

- Dry Thursday and Friday.

DTW THRESHOLD PROBABILITIES

* Low for ceiling 5000 ft or less through this evening.

* Low for thunderstorms on Wednesday.

PREV DISCUSSION

Issued at 300 AM EDT Tue Sep 8 2026

DISCUSSION...

A compact mid level low will track from southern Saskatchewan to northern Ontario today while the mid level ridge axis over Lower Mi exits east of the region. East-southeasterly low level wind fields across Se Mi early this morning will veer toward the south as a broad low to mid level anticyclone departs east. This will correspond to an influx of warmer air into the forecast area today. Increased cloud cover through the day associated with moisture advection around 850mb and increasing mid/high clouds from the west will result in overall increasing cloud trends, likely capping afternoon highs to the lower 80s.

Latest water vapor imagery across North America this morning shows a plume of moisture off the Pacific advecting into the Upper Midwest while Gulf moisture in the lower levels feeds into this same region. This is leading to a pool of very deep moisture; latest SPC meso analysis indicates precipitable water values of 1.7 to 2.1 inches extending across the central plains to upper Midwest. This deep layer moist axis will advance across Lower Mi tonight as the ridge axis flattens and the mean flow upstream turns more westerly. The corresponding increase in mid level moisture will support increasing shower chances during the night, mainly across the Saginaw Valley and thumb.

Forecast strengthening of an upper jet streak across the northern lakes Wednesday will support an expanding region of upper divergence and weak mid level frontal forcing across northern and central Lower Mi. The forcing within the deep moist axis will sustain rain chances through Wednesday as the mid level frontal boundary sinks southward into srn Lower Mi. One point of uncertainty to the Wednesday forecast involves the remnants of a potential convective complex expected to develop over ern Iowa/nrn Illinois tonight. An MCV from this feature would certainly enhance precip chances across srn Mi if it were to materialize. A deeper/slower mid level wave may also support a better influx of instability into the far southern portions of the forecast area Wed afternoon, supported by a few high res solutions. This in turn has allowed Wed CAPE probabilities to trend upward south of the I-94 corridor. The SPC Day2 convective outlook has thus nudged the area of Marginal Risk into Monroe County. Given the degree of deep layer moisture overhead Wednesday, if deep convection does materialize, intense rainfall rates will be of concern.

There is strong agreement that the deep layer moist axis and mid level frontal boundary will remain progressive as mid level west- northwest flow expands across the northern Great Lakes by Thursday, advecting a much drier airmass across Se Mi. Model soundings indicate subtle cold air advection will be offset by steep low level lapse rates to boost Thurs highs well into the 70s. Mid level ridging and associated surface high pressure will then build across the region, supporting dry conditions to end the work week.

MARINE...

High pressure drifts over the region through this morning maintaining benign marine conditions. South turning southwesterly winds strengthen tonight into Wednesday as seasonably strong low pressure system tracks across southern Canada into Hudson Bay. While a gust or two two could reach entry-level gales over central Lake Huron, winds are expected to peak around 30kts. Return of a humid airmass back to the region will support shower and thunderstorm chances for much of the day Wednesday before the attendant cold front crosses late evening. Moderate northwesterly flow follows for Thursday however only a glancing shot of cold advection and a rapidly diminishing gradient has high pressure builds caps winds aob 30kts.

DTX WATCHES/WARNINGS/ADVISORIES

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