textproduct: Detroit/Pontiac

KEY MESSAGES

- Winter Weather Advisory tonight through Tuesday morning for a combination of winter hazards.

- Snow showers tonight into Monday expected to produce 1-3" inches of accumulation.

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

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

- Another round of accumulating snow on Wednesday, impacting the AM commute.

- Potential for below zero temperatures early next weekend.

AVIATION

Increasing absolute vorticity within reinforcing polar trough will result in large scale lift, top down saturation and seeder feeder to Southeast Michigan beginning this evening. Expecting a fairly quick expansion of light snow soon after 00-01z. QPF amounts will remain relatively light, but high liquid to snow ratios will likely lead to snow accumulations after onset. From this vantage point, preference is more for MVFR ceilings and IFR visibilities. Confidence is low but will monitor trends. Precipitation is then expected to transition to snow shower activity beginning after 08z in response to cold air advection between 4.0 and 10.0 kft agl. Convective heights are expected to increase markedly with potentially convectively unstable lapse rates between 3.0 and 7.0 kft agl. The potential will exist for intermittent heavy snowfall rates and potential snow squalls particularly in the 10-15z time window. The other story is west winds increasing during the late morning gusting to 35 knots. Will be adding prevailing groups for IFR visibility restrictions with BLSN. The potential does exist, however, for I 94 or I 96 lake effect banding after 18z and continuing into Monday evening.

For DTW...Light snow is forecasted to begin around 01z this evening. Potential then existS for snow showers between 11-15z some of which may be heavy with snow squalls. West winds will increase in excess of 30 knots with restrictions to visibilities due to BLSN. Lake effect banding is likely late Monday afternoon and Monday evening with uncertainty and low confidence in duration.

DTW THRESHOLD PROBABILITIES...

* High in ceilings aob 5000 feet today. High tonight and Monday.

* Moderate to exceed crosswind thresholds Monday morning and afternoon.

PREV DISCUSSION

Issued at 250 PM EST Sun Jan 18 2026

DISCUSSION...

The deep upper level (~480 DAM at 500 MB) over Hudson Bay will continue to slowly wobble/descend south, setting us up for a frigid week over the Great Lakes region. Euro ensembles suggesting early next weekend will be the coldest of the period, with actual air temperatures potentially reaching 10 degrees below zero.

The first in series of upper level waves racing through the Midwest this afternoon and tracking through the western Ohio Valley this evening. This wave will provide broad support/waves of isentropic ascent, coupled with southwest flow off Lake Michigan adding some moisture to support widespread snow showers this evening and tonight. Still, moisture is limited, with 850-700 MB specific humidity averaging 1 g/kg, but still would to expect to grind out 1 to 2 inches tonight. The arctic front looks to be swinging through southeast Michigan 11-14Z tomorrow morning, as -30 C cold pool at 700 MB moves overhead. Strong westerly flow, steepening low level lapse rates during the day, and inversion heights around 10 kft will set the stage for snow showers and potential snow squalls during the day. Looking at the soundings and forecasted mixing, confidence is high in wind gusts at least reaching around 40 mph. Blowing snow will be a factor for locations that see fluffy 2+ inches from tonight's and tomorrow's snow.

A fast moving shortwave 500 MB trough is now forecasted to swing through Monday evening/night. This adds confidence and concern for a prolong lake effect band(s) to set up in the vicinity of the M-59 corridor, south to the I-94 corridor. Very narrow/highly localized strip of 1-3" is in play, but tough to gauge whether the band remains stationary or moves around a bit to lessen amounts at any one location. NAM soundings indicating the super-saturation with respect to ice hanging around -20 C, outside of DGZ, but can not be fully trusted in this scenario.

This second trough/wave will drive 850 MB temps down into the -23 to -26 C range for Tuesday morning, per 12z Canadian/NAM/Euro blend. Thus, even with lake clouds streaming through much of the CWA, still expect temps to be around zero for locations near the southern Michigan border and across the Thumb region. With winds hanging around 10 mph, wind chills approaching -15 F can be expected. Debated a long time on a winter weather advisory to capture the snow squalls and strong winds on Monday leading to blowing snow, and the cold wind chills Monday night-Tuesday morning. Although each weather element falls just short of criteria and this will be a long duration headline, the snow squall concern is high, as well as the potential long duration snow shower activity in the middle tier of counties. Wind chills should still get into the 10 to 15 below zero range. Not much of a warmup during Tuesday, as daytime highs in the mid teens looks fine based off latest guidance.

Yet another shortwave will quickly track in from the Midwest Tuesday night and arrive on Wednesday over Lower Michigan. This system will have an actual surface reflection and strong low level jet, which will make for a good warm advection pattern. Snow looks to be developing near daybreak Wednesday, with another 1-3/2-4 inch type snowfall in store. 850 MB specific humidity looks to peak out between 2-2.25 g/kg, as the low undergoes modest amplification as it moves through the Central Great Lakes, per Euro.

MARINE...

Next clipper system is working across the northern Great Lakes this afternoon, eventually tracking along the far northern Lake Huron shoreline into eastern Ontario tonight. As it tracks toward Ontario, the low will undergo modest deepening (from 1010 mb to 1001mb) resulting in a tightening gradient focused over the southern half of the region. This supports gales developing over the southern Great Lakes by Monday morning into the afternoon before the system begins to peel away in the evening. For Lake Huron, gale potential remains tied to the arctic cold front offering a 3-5hr window to see gusts in excess of 34kts. Given its proximity to the low center, the far northern waters have the lowest chance to see gales and have been kept out of the warnings as a result. Due to the stronger winds and cold airmass, heavy freezing spray is likely in all non-ice covered waters of Lake Huron. While gale potential tapers off by Monday evening with the departure of the clipper, the region will remain under broad troughing over the eastern continent allowing additional systems to track over/near the region maintaining at least moderate winds (>20kts), snow showers, and freezing spray through most of the week.

DTX WATCHES/WARNINGS/ADVISORIES

MI...Winter Weather Advisory from midnight tonight to 10 AM EST Tuesday for MIZ047>049-053>055-060>063-068>070-075-076-082-083.

Lake Huron...Heavy Freezing Spray Warning from 7 AM to 10 PM EST Monday for LHZ361>363-462>464.

Gale Warning from 11 AM to 10 PM EST Monday for LHZ362-363-421-422- 441>443-462>464.

Lake St Clair...Gale Warning from 7 AM to 7 PM EST Monday for LCZ460.

Michigan waters of Lake Erie...Gale Warning from 7 AM to 7 PM EST Monday for LEZ444.

Low Water Advisory from 7 AM to 10 PM EST Monday for LEZ444.