textproduct: Detroit/Pontiac

KEY MESSAGES

- Two periods of light snow, each of which are forecast to produce an inch or two of accumulation, will affect the area. The first will be this evening and the second during the day Wednesday.

- Seasonally cold weather will persist into the weekend. The coldest temperatures will be New Years Eve evening into News Years Day with wind chills mainly in the single digits.

AVIATION

Ongoing cold air advection will continue to support lake effect stratus through the day with ceiling heights ranging between mvfr to low end vfr through the morning and early afternoon (2.5-4kft). Flurries to light snow remain possible through the morning. Periodic wind gusts around 25 knots continue but gradually decrease through the day as low pressure becomes farther removed from the Great Lakes region. For tonight, a clipper system will bring light snow snow to the terminals with accumulations totaling up to an inch. DTW THRESHOLD PROBABILITIES...

* High for ceilings below 5000 feet today.

PREV DISCUSSION

Issued at 304 AM EST Tue Dec 30 2025

DISCUSSION...

Low level wind fields will remain on a gradual diminishing trend during the morning with the continued departure of yesterday's storm system. Lingering lake aggregate troughing will however sustain a west-northwesterly gradient across Se Mi through the day, with a solid 20 knots residing in the mixed layer. This will maintain brisk conditions as daytime temperatures hold in the 20s with wind chills in the single digits and teens. Early day deep layer subsidence from 850mb up through 500 mb will lower inversion heights, allowing a decrease in remnant lake effect. Supersaturation wrt ice within remnant strato cu will support a few flurries.

The region of deep layer moisture noted on upstream satellite imagery over North Dakota is tied to a weak mid level short wave along the nose of an upper jet streak. This wave will traverse srn Lower Mi late this afternoon into the early portion of the overnight. Large scale isentropic ascent will remain weak and quite elevated (aob 700mb) within a relatively stable mid level profile. Despite the Canadian origin of this system, it does have relatively decent deep layer moisture; specific humidities of 1.5 to 2 g/kg are projected up through 700mb. The approach of this wave will force a more westerly low level flow which will add some enhancement off Lake Mi. Latest hi res guidance suggests this will be focused between the I-94 and I-69 corridors. Thermodynamic profiles suggest the potential for some good dendrites. The weak nature of the ascent argues for total snow accumulations (between 21Z today and 06Z Wed morning) for an inch or less. Localized accums up toward 2 inches are possible within any persistent lake enhanced bands.

This first round of light snow will be followed by a brief interval of subsidence early Wednesday morning before the next round of light snow arrives mid-late Wed morning. A more amplified mid level wave rotating around the deep upper low over Hudson Bay will track across Lake Superior into eastern Ontario. This will drive an arctic cold front across Se Mi late in the day Wednesday. Better mid level height falls and frontogenetical forcing will contribute to a broad region of light snow. There is the potential for a little bit of lake enhancement in advance of the associated arctic front. Probabilistic guidance is highly supportive of accumulations in the 1 to 2 inch range. Given the convective component due to steepening low level lapse rates, some isolated three inch amounts can not be ruled out. Within the increased mixed layer on Wednesday, model soundings suggest a fairly good core of 30 knot winds. While not advisory worthy, this will still make for brisk conditions with some blowing snow. The cold front will push south of the area around/shortly after 00Z with a fairly good push of arctic air arriving within north-northwest winds during the evening hours of New Years Eve, persisting into the start of the New Year. The near persistence of the upper low over eastern Canada will maintain seasonally cold conditions into the weekend.

MARINE...

Gales continue for a few more hours this morning as Monday's strong low pressure system exits toward the Atlantic coast. The system leaves behind diminished NW flow that is still able to maintain arctic air across the Great Lakes as the next much weaker low pressure system moves into Lake Superior tonight. This system brings a round of light snow tonight and Wednesday until moving eastward Wednesday night. The trailing cold front reinforces arctic air with an uptick in NW wind that is projected to remain below gales through Thursday. Sub gales, occasional snow showers, and freezing spray then persist over the central Great Lakes into next weekend.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Gale Warning until 11 AM EST this morning for LHZ361>363-421-422- 441>443-462>464.

Heavy Freezing Spray Warning until 11 AM EST this morning for LHZ361>363.

Lake St Clair...Gale Warning until 7 AM EST this morning for LCZ460.

Michigan waters of Lake Erie...Gale Warning until 7 AM EST this morning for LEZ444.