textproduct: Detroit/Pontiac

KEY MESSAGES

- Chance (20%) for light snow showers through the morning with very low end chance for spotty freezing drizzle. Little to no snow/ice accumulation expected.

- Widespread light snow expected Sunday morning into early afternoon. Snow accumulations to range between a half-inch to two inches for most locations.

- Below normal temperatures continue this week, the coldest of which arrive Monday and Tuesday. Wind chill temperatures drop to or below zero Monday morning.

- Active weather pattern continues into the midweek period where additional snow chances will be possible.

DISCUSSION

A slow moving cold front will progress across SE MI through the morning hours which will bring the chance for some isolated to scattered snow showers. Forcing is relatively weak along the frontal boundary so snowfall amounts will be generally confined to trace amounts, up to a dusting. Dry air subsidence will work its way down along and within the wake of the front which will subtly diminish the integrity of moisture within the dgz, bringing very low-end chances for spotty freezing drizzle through the morning. Dry air advection and enhanced subsidence in the wake of the front will then bring dry weather for the remainder of the day with temperatures increasing to around the freezing mark for afternoon highs. Wind chill temperatures will stay in the 20s given wind gusts peaking around 15 mph this afternoon.

Attention will then turn to a clipper system set to travel through the southern Great Lakes and northern Ohio River Valley tomorrow morning, bringing widespread light snow. Initially, weak system relative isentropic ascent will commence in the mid- levels early Sunday morning in anticipation of the approaching system which will bring the chance for flurries or very light snow for portions of the cwa. Moist isentropic ascent is then fortified through the southern half of the cwa favored from 700mb through 500mb which will expand accumulation snowfall chances from south to north while concurrently pva increases through the northern-third of the forecast area, filling in snow chances through the north. This combination will bring widespread light snow across SE MI with snowfall accumulations ranging between a half- inch to two inches by the afternoon. Two caveats for higher end snowfall totals will revolve around any mesoscale convergent signatures and/or lake enhancement from Lake Huron.

A subset of hi-res modeling picks up on a brief period of frontogenetic forcing favored in the late morning to early afternoon hours that can bring some highly localized enhanced snowfall rates which would be capable of producing a narrow band with totals approaching 3 inches. Predictability of this materializing and potential location of event is low at this time but the greater potential will be aligned with the better moisture convergence from I-94 south. Lake convergence over Lake Huron also brings some low end chances for totals of 2-3" within the northern Thumb, particularly Huron County. Lake convergent bands are expected to stay offshore, but some solutions do briefly clip the northern Thumb.

A polar high pressure will then fill in late Sunday into Monday. Clearing skies, light winds, and snow cover will bring about efficient radiational cooling Monday morning, dropping lows into the single digits and wind chills to or below zero. Little relief on Monday as highs stay capped in the 20s and wind chills returning to the single digits Tuesday morning. The middle of the week will remain active as a series of clipper systems again target SE MI. The first will arrive Tuesday morning, bringing renewed chances for light snow accumulation. The second clipper system quickly follows up late Tuesday into Wednesday morning. Ensembles highlight pretty strong convergence regarding track and intensity of this second clipper system, with the track moving over Michigan with a strong and quick upper-level wave accompanying the system. This will bring the likely chance for widespread wintry precipitation, but favored p-type will subject the degree or warm air advection downstream of the low. A wintry mix of rain/snow is favored at this time given modeled thermal profiles.

MARINE

Winds will slowly decrease today and veer to the west-northwest as a cold front washes out over the region. This will lead to light winds tonight, 15 knots or less. Yet another cold front and surge of cold air to move in during Sunday, as low pressure tracks through the northern Ohio Valley. Widespread light snow around Sunday morning trending toward more localized snow squalls late Sunday as 850 MB temps lower into the negative mid teens. Northwest winds gusting between 25-30 knots appear likely late in the day. However, winds then look to veer to the north-northeast fairly quickly and weaken Sunday night as high pressure quickly builds in for Monday morning. None-the-less, large waves of 6+ feet will build over the southern Lake Huron. Some of these larger waves look to clip the nearshore waters of Lake Huron as winds veer around, and expect another round of small craft advisories to be issued.

PREV DISCUSSION

Issued at 1147 PM EST Fri Dec 5 2025

AVIATION...

A weak 850-700mb frontal boundary and isentropic ascent has led to prevailing stratus at 4.0-6.0 kft agl across much of Southeast Michigan. Weak and disorganized shortwave energy pushing across the state has resulted in a flare up of lake enhancement light snow in vicinity of the Lake Michigan shoreline while activity here has been relegated to a few flurries. Forecast soundings support that dry air will hold below 4.0 kft agl throughout much of the overnight before moisture advection in advance of a cold front finally results in moistening in the 1.5 to 4.0 kft agl layer. There is an obvious lack of qpf signal over Southeast Michigan but there is a potential for light precipitation including light freezing drizzle or mist south of I 69 sometime between 12-16z Saturday. Confidence is too low that it will occur to include in the tafs. MVFR ceilings are expected Saturday afternoon.

DTW THRESHOLD PROBABILITIES...

* High for ceiling at or below 5000 ft tonight and Saturday.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Small Craft Advisory until 10 AM EST this morning for LHZ421-422- 441.

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