textproduct: Detroit/Pontiac

KEY MESSAGES

- Occasional snow showers this weekend through early next week with light accumulations. The most widespread snow shower activity will be Sunday night into Monday, when 1-3" inches is expected.

- Frigid and blustery conditions Monday with potential for snow squalls and winds gusting 30-40 mph.

- Dangerously cold wind chills of -5 to -15F Monday night/Tuesday morning.

- Another light round of snow likely on Wednesday.

AVIATION

Cold cyclonic flow due to large scale troughing will keep the environment conducive for lake effect/enhanced clouds throughout the period. Forecast soundings show a substantial midlevel inversion with a base down to the 4.0 to 5.0 kft agl level. Satellite trends support moisture ducting below this inversion to the south towards the Detroit terminals. Went decidedly more pessimistic with ceilings for the southern forecast area with low VFR tonight It remains possible that moisture/thetae advection in the 1.5 to 3.0 kft agl layer could contribute to a significant amount of MVFR stratus Sunday. The RAP is very bullish and does have agreement with the NAM. Precipitation is still timed to hold off until after 00z 12/19.

For DTW...Current satellite trends support VFR ceilings moving into DTW. Low confidence in ceiling heights but enough model support for MVFR after daybreak Sunday. Light snow is expected to hold off until Sunday evening.

DTW THRESHOLD PROBABILITIES...

* High in ceilings aob 5000 feet tonight and Sunday.

PREV DISCUSSION

Issued at 937 PM EST Sat Jan 17 2026

UPDATE...

No critical changes are needed for the gridded database or the messaging this evening. Weak 1000-850mb convergence downwind of Lake Michigan has been producing flurries and light snow over the Tri Cities and the Thumb. Based on traffic data there has not been much consequence to travel.

PREV DISCUSSION... Issued at 245 PM EST Sat Jan 17 2026

DISCUSSION...

Upper level ridge (586 DAM at 500 MB) just offshore of British Columbia/Pacific Northwest will persist through the weekend and then slowly break down next week. This amplified pattern will allow several shots of Arctic air to spill into the Great Lakes region, with the notable shot of cold air arriving on Monday. Question then becomes how much will the unfrozen Lake Michigan modify the airmass, as it looks like there will be enough moisture flux to support clouds and snow showers Monday evening/night with the persist westerly flow, which likely holds temps mainly above zero and wind chills above 15 below for Tuesday morning. 850 MB temps progged to bottom out and hold in the -23 to -25 C range.

Today's cold shot (-21 C at 850 MB) over the Midwest will passing south through the Ohio Valley this evening/tonight. Tightening baroclinic zone over Lower Michigan with dry/arctic air spilling across the southern Michigan up to the M-59 corridor tonight with southwest low level winds. Sufficient cold air, convergence, and moisture (925-850 MB specific humidity around 1.75 g/kg over Central Lower Michigan to Saginaw Bay) to support continued lake enhanced light snow shower activity to persist across Tri-Cities regions and locations north of I-69. Accumulations of a dusting to one inch as any forcing intersecting the dgz is expected to be short lived.

The low level forcing with the arctic front for the end of the weekend on the other hand, will reside mostly in the DGZ. Steep low level lapse rates as we head into Monday also generates modest cape, supportive of snow squalls as the top of the boundary layer taps into stronger winds of 40+ knots. Inversion heights aoa 8 kft and model consensus indicating 24 hr qpf around tenth of an inch Sunday night-Monday supports 1-3 inches of snowfall with good snow to liquid ratios (20 to 25:1) anticipated. Narrow/small scale- convective elements also likely not being picked up properly by bulk of the solutions, which may support a few localized higher amounts as well. Local probabilistic guidance and euro ensembles both indicating peak wind gusts of 35-40 mph during the day, and a winter weather advisory may have to be considered to capture the snow and wind. Winds and snow shower coverage will gradually wane as we head into Monday evening as subsidence behind the exiting 700 MB trough/cold pool (-30 C) kicks in. None- the-less, there is a good signal (925 MB Omega) for a prolong lake effect band to set up in the vicinity of the M-59 corridor, possibly south to the I-94 corridor, per 12z NAM. Another very narrow/highly localized strip of 1-3" is in play, although tough to gauge the impacts of the very dry associated with the arctic airmass and survival of the band this far east. Surface dew pts outside of the lake plume will be aob zero, which sets the stage for subzero lows. Ultimately, will count on surface winds and enough clouds to keep temps in zero to 5 degree range for now, with minimum wind chills of -10 to -15 F.

Height rises and return southwest flow around high pressure over the Mid Atlantic supports temps steady or actually rising Tuesday night before yet another clipper brings light snow on Wednesday. Cold air behind this system for Wednesday evening into Thursday looks slightly warmer compared to Monday.

MARINE...

Small Craft Advisories remain in effect around the tip of the Thumb through tonight due to the combination of stronger (30kt) west- southwest winds and subsequent waves. This flow has also led to falling water levels in the western Erie basin warranting a short- fused Low Water Advisory through this evening. Gradient only partially slackens Sunday nudging southwesterly winds down closer to 20-25kts. Next clipper tracks into the northern Great Lakes latter half of Sunday deepening as it slides into eastern Ontario. Associated arctic front drops across the central Great Lakes Monday afternoon ushering in the coldest airmass of the winter season thus far. There is a 3-5 hour period along/following the frontal passage for northwesterly gusts to reach gales over at least a portion of the region tied to a 40-45kt LLJ wrapping around the base of the low. Exact placement of this feature isn't particularly well defined in current models however is generally favored to set over the southern half of the region. Gale Watches are in effect from the central waters of Lake Huron down to Lake Erie as a result. Areas of moderate to heavy freezing spray also likely in this timeframe.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Gale Watch from Monday morning through Monday evening for LHZ362- 363-421-422-441>443-462>464.

Small Craft Advisory until 4 AM EST Sunday for LHZ421-441.

Lake St Clair...Gale Watch from Monday morning through Monday evening for LCZ460.

Michigan waters of Lake Erie...Gale Watch from Monday morning through Monday evening for LEZ444.

Low Water Advisory until 1 AM EST Sunday for LEZ444.