textproduct: Detroit/Pontiac

KEY MESSAGES

- Warming trend today and Tuesday with highs around 60 degrees Tuesday.

- Rain chances increase late Wednesday into Thursday, with an unsettled pattern continuing into the weekend.

- A much colder airmass arrives Thursday, triggering lake effect rain and snow showers late Thursday through Saturday.

DTW THRESHOLD PROBABILITIES

* None.

PREV DISCUSSION

Issued at 402 AM EST Mon Nov 9 2026

DISCUSSION...

Lake aggregate stratus and light shower activity associated with the departing low continue to impact the northern Saginaw Valley and Thumb this morning. Will see this moisture vacate SE Michigan through the morning as high pressure drifts overhead and winds back to the southwest. The backing winds initiate a period of warm advection this afternoon that boosts h8 temperatures by roughly +5 C, although slightly displaced from peak heating so highs still only reach the mid 50s. Another low amplitude wave and weak front quickly move through tonight, although the surface trough is shallow with minimal impact on the thermal gradient. Tuesday is another dry day, with an even deeper layer of static stability than today. This affords plenty of sunshine and full realization of the warm advection to bring highs into the low 60s.

The back half of the work week becomes more unsettled, driven on the large scale by amplification of the geopotential height field. Longwave troughing becomes established across eastern CONUS, with the bulk of height falls occurring Wednesday as a Pacific wave ejects out of the Intermountain West. The ensemble envelope is still clustered into a few different solutions, depending on if the surface low takes a direct path toward SE Michigan or dives south across the Ohio Valley. Both solutions generate rain opportunities for SE Michigan, although the latter is associated with elevated frontal forcing and would likely result in a narrower area of precipitation. NBM chance PoPs are reflective of the uncertainty, including some of the dry solutions as well where the low tracks even further south across the Tennessee Valley.

Higher confidence item with this setup is the strong cold advection that follows Thursday into the weekend. Highs during this timeframe will be in the 40s and lows in the upper 20s to low 30s. Coldest morning looks to be Saturday, corresponding to the core of the thermal trough settling overhead. The strength of cold advection will also activate lake moisture flux behind the low, with northerly flow showing a convergent signal across the major axis of Lake Huron especially Friday. Even with above freezing temperatures, dewpoints hovering near 32 F and wet bulb zero heights between 1.0-2.0 kft agl mean snowflakes cannot be ruled out especially if higher intensity rates develop.

One of the key features of this time period will be a deep upper low that anchors over Quebec, causing any inbound shortwaves to shear out and fragment as they encounter the sharp deformation zone on the western flank of the low. This causes each impulse to deflect south into the Upper Midwest/Great Lakes region, where any phased or well- timed impulse could provide enough synoptic ascent to enhance the lake effect. This equates to an unsettled precipitation forecast Thursday into the weekend even for interior portions of Lower Michigan.

MARINE...

Low pressure over western Quebec and its cold front exit the central Great Lakes early this morning. Cold advection slowly wanes, although favorable mixing depths above relatively warm lake waters may allow a few morning gusts to approach gale-force for the central Lake Huron waters. Higher winds and waves will be slower to decline across the southern Huron nearshore zones, supporting an extension of Small Craft Advisories until later today. Occasional wave heights will hold well above 4 feet into the midday hours. The pattern quickly shifts and becomes more stable as high pressure briefly builds in later today, leading to 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...Small Craft Advisory until 10 AM EST this morning for LHZ421.

Small Craft Advisory until 4 PM EST this afternoon for LHZ441>443.

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