textproduct: Detroit/Pontiac

KEY MESSAGES

- Bitter cold temperatures for the weekend into Monday.

- The coldest period looks to be Saturday night and Sunday morning, when wind chill readings are forecast to drop to 5 to 15 degrees below zero.

- A couple opportunities to get a little light snow, particularly this evening/tonight and on Monday. Otherwise, localized snow along the southern Michigan border Saturday afternoon, and along the eastern Thumb shoreline Sunday.

- A dramatic warmup is then forecasted Tuesday-Thursday next week, as temps likely push aoa 40 degrees, setting the stage for potential rain.

AVIATION

Moisture remains trapped below an inversion based at approximately 4.0 kft agl for the Detroit taf sites this morning. Mid to upper level high pressure will pass eastward through portions of the northern Lake Huron basin today. VFR conditions today and this evening with strengthening and lowering subsidence between 2.5 and 14.0 kft agl. Strong static stability will then be slow to erode tonight as moisture in advance of an arctic front advects across the region. Seeding of ice crystals aloft will fall into an airmass in the lowest 5.0 kft agl that will be supersaturated with respect to ice. Not a significant amount of lift but enough saturation and microphysics to help generate some snowflakes in the 3 to 11z time window north to south.

For DTW...Mainly VFR ceilings today and this evening. A potential for brief MVFR light snow Saturday morning.

DTW THRESHOLD PROBABILITIES...

* High for ceiling at or below 5000 ft this morning with lower confidence in scattering of clouds today. High tonight.

PREV DISCUSSION

Issued at 248 AM EST Fri Dec 12 2025

DISCUSSION...

A shortwave tracking through far southern Lake Michigan has helped sustain clouds over much of southern Lower Michigan, holding temps in the low to mid 20s at press time. Areas which cleared out, northern Thumb region, tanked into the single numbers. Inversion heights are forecasted to lower slightly, thus still opportunity for low clouds to scour out and temps to dip, but there is also some high clouds noted across the area.

Strong PV Anomaly over the Central Canada with additional upper level energy coming out of the Gulf of Alaska on track to move through the Central Great Lakes Saturday and Saturday night. Bitter cold arctic airmass will overspread Lower Michigan, with -30 to -32 C advertised at 700 MB, with Lake Michigan modified 850 MB temps of -20 C or slightly colder for second half of the weekend. Meanwhile, aggressive height falls tracking through the northern Great Lakes this evening, tapering off toward the southern Michigan border. None- the-less, with west-southwest flow coming off Lake Michigan and the low level convergence/fgen of the arctic front moving through, a period of scattered-numerous snow showers looks likely as 1.75-2.0 g/kg of 850 MB specific humidity tracks through Saturday evening- night. With short lived forcing at any given location (<3 hrs), would expect accumulations of a dusting to less than an inch. Excellent drying and subsidence to follow frontal passage, with mean 850-700 MB dew pts depressions of 25 C taking hold over the bulk of southeast Michigan. This will be key, as very strong Jet streak (90- 100 knots at 500 MB) and another impressive 500 MB height fall center tracks through the northern Ohio Valley during Saturday/Saturday evening. Locations along and especially south of I- 94 could get clipped with the northern fringe of the snow shield, but the forcing/airmass is colder than the DGZ, and snowflakes should be fine, and thus would only expected another dusting to perhaps an inch right along the border.

As usual with the very dry arctic airmass, tough to gauge how much lake clouds/light snow showers/flurries make it eastward Saturday night, as surface dew pts of -15 to -20 F spread into Wisconsin. Even if skies do in fact clear out, looks like surface winds will not be able to fully decouple, with light surface winds preventing temps from cratering much below zero. Euro ensembles indicating 40- 50 percent chance of 2M temps dropping at or below zero over central sections of the CWA at 12z Sunday. None-the-less, that will place wind chills in the 10 to 15 below zero range. Will have to keep a close eye on the eastern Thumb shoreline on Sunday as winds do look to veer around to the north-northwest as the mid level cold pool/wave exits the Central Great Lakes.

Shortwave coming over the top of the upper level ridge over the Rockies swings through Lake Huron on Monday. Pretty good isentropic ascent progged with just enough moisture to support light snow showers, epsecially as one heads north. Right now, 00z Canadian looks to be one of the more aggressive solutions, with 5 hundreths to a tenth of an inch of qpf. NBM pops have at least increased to more solid chance pops.

Warm air breaking off from the upper level ridge off the West Coast next week as the upper level flow transitions to the zonal over the northern Conus by mid week. NBM temps indicating low to mid 40s by Thursday with a good chance of rain as next deepening low pressure system enters the picture.

MARINE...

Elongated area of high pressure remains centered over the region today before sliding southward into the Ohio Valley this evening into tonight. This will provide a brief period of lower winds and wave heights today which ramp back up tonight in advance of the next low pressure system. This low will track across Ontario Friday night while pulling an arctic front across the region. This very cold airmass will again bring increased westerly winds across the area with wide spread gusts to 30 knots across much of Lake Huron and sporadic gusts to gales possible during the weekend as 850 MB temps plummet to -20 C. At a minimum, another round of Small Craft Advisories will need to be issued at some point for tonight through much of the weekend as the arctic air holds over the region. This cold airmass and elevated winds will also lead to potential snow squalls and freezing spray as well.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Small Craft Advisory from 10 PM this evening to 4 AM EST Monday for LHZ421-441.

Small Craft Advisory from 10 PM this evening to 4 PM EST Saturday for LHZ422.

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