textproduct: Detroit/Pontiac

KEY MESSAGES

- A Dense Fog Advisory is in effect along/south of I-69 through 8 AM.

- Low probability for severe weather today with conditional thunderstorm chances across the north and south.

- Mainly dry conditions develop Thursday through most of Saturday.

- Renewed chances for showers and thunderstorms late Saturday into Sunday.

DTW THRESHOLD PROBABILITIES

* High for ceiling 5000 feet or less this morning.

PREV DISCUSSION

Issued at 359 AM EDT Wed Aug 12 2026

DISCUSSION...

Southeast Michigan remains positioned along the active periphery of a broad ridge currently centered over the southern Plains. Modest northwest flow aloft lingers as several shortwave perturbations work through the mean flow later today. The resident airmass remains moist and conditionally unstable, characterized by surface dewpoints in the upper 60s while a stalled frontal boundary lingers over Lower Michigan. With dewpoint depressions near zero and little to know gradient flow, areas of locally dense fog should continue for several more hours early this morning. Opted for a last minute Dense Fog Advisory along/south of I-69.

Forecast confidence remains low regarding convective evolution over the next 12 hours, in line with the last few days. Latest CAM solutions imply preference toward a persistence forecast approach, focusing on areas south of I-94 as a High Plains MCS should survive into the Ohio Valley. This runs contrary to SPC's Marginal Risk highlighting locations north of I-94. However, scattered activity cannot be ruled out for the northern portion of the CWA once the aforementioned front drifts southward as a weak cold front. The forcing along the frontal slope could trigger some attendant pop-up showers/thunderstorms within an area of stronger shear, steeper mid- level lapse rates, and higher instability. A water-loaded core or overachieving updraft may suffice for a borderline severe wind gust or hailstone. AI/ML models differ significantly, emphasizing the uncertainty between both areas of focus. Coverage should wane late this evening or early tonight.

The existing synoptic ridge axis begins to roll eastward Thursday, but will be reinforced by amplification over western CONUS. Mainly dry conditions are forecast for Thursday with high pressure building in, albeit the Ohio border area could still be susceptible to glancing convection from the perpetual MCS train tracks rolling through Indiana and Ohio. Low predictability exists to close out the week and over much of the weekend as flow weakens aloft and the longwave ridge gets flattened by a Canadian wave. The best chance for another moisture/warm advection surge arrives late Saturday into early Sunday as the Canadian trough tracks into Ontario with a cold front extending into the Great Lakes. Potential exists for organized convection with the frontal passage. A wind shift from south to northwest and a drop in temperatures and dewpoints to follow by early next week.

MARINE...

Weak wind fields will remain in place through Thursday as a frontal boundary hangs around the Great Lakes region before dropping south Thursday night. Periodic chances of showers and thunderstorms will persist through that timeframe. Any strong thunderstorms will have the potential to produce hail and winds in excess of 35 knots. With the lighter winds, there are some weak signals for patchy dense fog over Lake Huron at times, through confidence remains low.

A large area of high pressure builds into northern Ontario Thursday night, allowing north-northeast winds to increase on Friday. Winds are expected to reach at least 20 knots over southern Lake Huron, which may allow waves to approach 4 feet over the southern basin. The ridge extending from the high slides through Friday evening, supporting lighter winds into Saturday morning. Southerly winds will then peak out around 20 knots ahead of a cold front Saturday night, with winds shifting to west on Sunday behind the front.

DTX WATCHES/WARNINGS/ADVISORIES

MI...Dense Fog Advisory until 8 AM EDT this morning for MIZ061>063- 068>070-075-076-082-083.

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