textproduct: Detroit/Pontiac

KEY MESSAGES

- Below normal temperatures continue through the week. Highs in the 20s and overnight lows in the teens will be prevalent from Monday onward.

- Light accumulating snow tonight, with 1 to 2 inches expected for Metro Detroit and areas south.

- Dusting of snowfall or light snow accumulation will be possible late Wednesday ahead of an approaching cold front.

AVIATION

NW low-level flow (2-6 kft AGL) backs W overnight which supports decreased lake stratocumulus. In the absence of cloud aloft, a period of SKC will occupy portions of the airspace into Monday morning as lower column ridging moves in. VFR conditions extend through most of Monday while high cloud streams in and descends throughout the daylight hours. This saturation process occurs in response to an approaching upper level wave tracking south of the state. Light winds organize out of the SE ahead of inbound precipitation. Expect another round of snowfall Monday night into Tuesday with lower visibilities and longer duration for the southern terminals. Very light winds could back easterly as snowfall gets underway. IFR ceilings and visibilities are likely to the south with MVFR over PTK, and possibly FNT. MVFR ceilings/visibilities are most uncertain for MBS, at least through 06Z.

For DTW...Clearer skies overnight and a decrease in winds, eventually backing southerly. Weak low pressure system approaches Monday evening bringing snowfall and ceiling/visibility impacts amidst light ESE winds.

DTW THRESHOLD PROBABILITIES...

* High for ceiling at or below 5000 ft Monday evening and overnight.

* High for precipitation type as snow Monday evening and overnight.

PREV DISCUSSION

Issued at 245 PM EST Sun Nov 30 2025

DISCUSSION...

Radar returns have been diminishing with the snow/trough rotating through Saginaw Bay and now advancing through the northern Thumb region with a little light snow (dusting to 1 inch). Subsidence, drying, and clearing follows for tonight under northwest winds, but some transient clouds downwind off Lake Michigan and even flurries can't be rule out with this cold airmass (negative low to mid teens at 850 MB). Otherwise, with the fresh snow cover and winds going calm, mins in the teens look to be an easy call (assuming skies go mostly clear), with single numbers likely across the normally colder/better radiating locations. See MAV guidance and regional GEM 2 M temps.

The deep and large upper level low over Hudson Bay will continue to support a progressive pattern this week, directing a series of waves coming out of the Gulf of Alaska and diving southeast into the Rockies. The current upper level energy over the Rockies/500 MB trough will be arriving late Monday. The issue is there is two distinct upper level waves embedded in the large scale trough, with the southern wave and surface low tracking through Tennessee/Kentucky taking with it the bulk of the moisture. Specific humidity in the 850-700 MB layer struggles to get to 1.75 g/kg along the southern Michigan border. None-the-less, the mid level jet does look to clip southern Lower Michigan, providing sufficient elevated forcing with saturation with respect to ice. Do think we can grind out a half an inch to 2 inches in the Monday evening/night time frame, supported by our local probabilistic guidance, with the I-94 corridor and points south seeing the highest totals.

Shortwave ridging on Tuesday with the next cold front on track to move through late Wednesday. Little in the way of height falls and moisture argues for just a chance of snow showers/dusting of snow. Good cold advection behind the front, with 850 MB temps forecasted to drop into the negative mid teens on Thursday, per 12z Euro. This will set the stage for highs only in the 20s and mins Friday morning in the single numbers. Strengthening southwest flow to end the work week will allow for moderation, but temps still below normal into the weekend. Will have to watch a Gulf Coast system passing to our south on Friday as it heads into the Mid Atlantic States Friday night. Phasing with the northern Stream appears to be too late at this point.

MARINE...

Secondary cold front is pushing south of Lake Huron around time of discussion before eventually clearing the southern Great Lakes this evening. Strong northwest flow follows in the immediate wake of the front supporting a 4-6hr period of 35-40kts across the central and southern portions of Lake Huron. Outside of the Gale Warned zones, some brief gales are likely over the Saginaw Bay (with Sag Bay Light already reporting some) as well as over western Lake Erie in preceding SW/WSW flow. For Erie however, window direction favors the bulk of gales occuring over the open waters. Small Craft Advisories are in effect for through late evening for the remaining nearshore waters due to potential gusts to 30ks.

Sprawling ridge of high pressure aggressively builds in tonight supporting a fairly rapid diminishing trend in winds across the region. High center is set to swing across the Ohio Valley Monday maintaining light flow for the southern half of the central lakes. As for the northern, broad low pressure over the Hudson Bay compresses the gradient across the northern Great Lakes preventing a true relaxation of the wind field resulting in persistent southwest gusts up near 20kts Monday/Monday night. A system trailing the high crosses the Ohio Valley late Monday-Tuesday offering light snow chances but otherwise brings minimal local marine impacts. Next significant system arrives Wednesday as a strong arctic cold front drops out of northern Ontario resulting in both strong preceding southwest winds and trailing northwesterly winds as the coldest air of the season thus far moves over the Great Lakes. Currently, greatest chances (~50%) at seeing gusts to gales occur during the preceding southwest aided by longer fetch over the central portions Huron.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Small Craft Advisory until 7 AM EST this morning for LHZ421-441>443.

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