textproduct: Detroit/Pontiac

KEY MESSAGES

-Dry and Warm early week: Temperatures reach well into the 50s Monday through Wednesday, with lower 60s likely on Tuesday.

-Mid-week uncertainty: Rain chances increase late Wednesday into Thursday, but models disagree on exact locations and coverage.

-Cold shift late week: A much colder airmass moves in Thursday, holding highs in the 40s into the weekend. The drop in temperature over the warm lake waters brings the season's first solid chance for lake-effect rain and snow showers late Thursday through Saturday.

DTW THRESHOLD PROBABILITIES

* Low for ceiling at or below 5000 ft tonight.

PREV DISCUSSION

Issued at 331 PM EST Sun Nov 8 2026

DISCUSSION...

The upcoming 7-day period is defined by a distinct two-phase evolution of the hemispheric upper-air pattern across North America: an initial fast, low-amplitude pseudo-zonal/progressive regime through Wednesday, followed by a major amplification into a deep Eastern CONUS longwave trough late week.

(Monday through Wednesday) An energetic Pacific jet stream will maintain broad west-northwesterly to quasi-zonal flow across the central and eastern United States to start the work week. A shortwave trough passing north across Ontario on Monday will push a moisture-starved cold front through lower Michigan, followed by brief shortwave ridging into early Wednesday. Subsequent Pacific- origin shortwave impulses traversing the northern plains will build 500mb heights aloft, reinforcing strong low-level warm air advection (WAA). As such, Tuesday/Wednesday could end up a bit warmer than currently forecast depending on the timing and track of upstream shortwaves traversing the Midwest. Excellent ensemble clustering yields high confidence for Tuesday, with expected high temperatures climbing into the upper 50s to lower 60s supported by 925 mb temperatures in the upper single digits to near +10C under westerly low-level flow.

Model guidance and ensemble members begin to diverge on the position and phasing of cyclogenesis developing over the Ohio Valley on Wednesday and tracking into the Central Appalachians by Thursday. In fact, current solutions (e.g., 12z Canadian/UKMET/ICON/Euro) keep the northern and southern stream branches separated longer, keeping the primary low pressure and bulk of moisture suppressed through the southeastern United States.

(Thursday night through Sunday) Strong cold air advection (CAA) behind the departing surface system will scour out the mild Pacific airmass on Thursday. Southeast Michigan will reside firmly in the core of the cyclonic upper-level trough by Friday. Steepened low- and mid-level lapse rates combined with thermal contrast (850 mb temps dropping to -6C to -8C) over the warm Great Lakes waters will setup robust lake-effect precipitation structures. This brings the first legitimate potential for lake-effect rain and snow showers across the CWA. High temperatures will fall back into the 40s, slightly below Mid-November climatological normals.

MARINE...

Ontario low pressure is on-track to cross into western Quebec this evening, with its cold front draped southwestward. As the front works across the central Great Lakes during the overnight hours, post-frontal gradient winds veer northwesterly. The ensuing cold advection promotes favorable mixing depths above relatively warm lake waters, allowing gusts to reach gale-force for the northern half of Lake Huron. Given that low-level winds should be bound between 35 and 40 knots, gusts likely hold within a similar range. Higher winds and waves are also expected for all nearshore zones, supporting the continuation of Small Craft Advisories through tonight. Expect periods of gusts at/above 25 knots and waves in excess of 4 feet. The pattern quickly shifts and becomes more stable as high pressure briefly builds in Monday, leading to weaker winds backing southwesterly. Troughing returns Tuesday as the next clipper brushes the northern shores of Lake Superior, with its attendant cold front passing through and shifting winds toward the WNW. Note that the frontal passage is expected to be mainly dry. Some potential exists for additional Small Craft Advisories. High pressure then returns Tuesday night into Wednesday with weaker winds and lower wave heights.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Gale Warning until 4 AM EST Monday for LHZ361-362.

Small Craft Advisory until 4 AM EST Monday for LHZ421-422-441>443.

Lake St Clair...Small Craft Advisory until 10 PM EST this evening for LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory until 10 PM EST this evening for LEZ444.