textproduct: Detroit/Pontiac

KEY MESSAGES

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

- Potential for lake effect snow showers through tonight, particularly between M 59 and I 94. Accumulation from a dusting to locally up to 2 inches possible.

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

- Another round of accumulating snow arrives late Tuesday night and Wednesday, impacting the AM commute.

- Arctic air returns Friday and remains across the area through the weekend. Potential for minimum wind chill to fall below -15F Saturday and Sunday mornings.

UPDATE

No critical changes needed to the forecast or the messaging. Been dealing with the lone inland penetrating lake effect band that is now impacting portions of northern Metro Detroit. Quite the band with the observation of less than 1 mile at PTK and witnessing the snow here at the office. Did issue an SPS with the band extremely narrow in scale. Snowfall accumulations within localized areas could be a quick 1 to 2 inches. There is a conversation that could be had whether or not to roll some of the counties in the Winter Weather Advisory over to a Cold Weather Advisory. Given the consistent messaging which included wind chills in the text, the decision is to keep it simple and keep the Winter Weather Advisory in effect overnight.

PREV DISCUSSION

Issued at 649 PM EST Mon Jan 19 2026

AVIATION...

Loss of daytime heating with a concurrent lowering of low-midlevel inversion heights will significantly decrease the depth of convection this evening. This change is expected to impact the organization of snow banding over Southeast Michigan the first couple of hours of the period. Have already seen reflectivity largely push north of the Detroit sites with relatively benign conditions at the moment. Complicating factors has been the clearing trend in satellite. For continuity, will afford more time and maintain a pessimistic tone with TEMPO IFR visibility restrictions the first 3 hours of the taf period in light snow showers at Detroit terminals. Did remove the Prob30 group for visibility less than 1SM after 06z. For PTK did stay aggressive with visibility restrictions in light snow based on positioning of modeled 1000-850mb convergence. The airmass remains cold and given the steepness of the lapse rates, snow showers will remain possible at any location throughout the night. Will monitor trends and amend as needed.

For DTW...Latest observations trends suggest lake effect plume migrating north of the airfield. Will afford some more time and continue to forecast IFR visibility restrictions in light snow at DTW. Will monitor observation trends to get a handle on where lake effect banding could setup.

DTW THRESHOLD PROBABILITIES...

* Medium in ceilings aob 5000 feet through tomorrow.

* High for precip type being snow.

PREV DISCUSSION... Issued at 332 PM EST Mon Jan 19 2026

DISCUSSION...

High magnitude cold air advection well underway late this afternoon. The ongoing advective process within a firm west-northwest gradient contributing to cratering wind chill in blustery conditions as improving convective depth captures a 30-35 knot wind field just off the surface. Gusts peaking into the 40 to 50 mph at times. Lake Michigan moisture flux in west-northwest flow yielding a solid downstream lake effect response within the background of mid level cyclonic flow, as focused areas of convergence continue to direct scattered to numerous bursts of snow showers into the typically prone belt between I-69 and I-94. Perpetuation of this activity expected through tonight in some form, but with some nocturnal contraction and possible strengthening of convergence supporting a transition toward one or more dominant linear bands. Inherent variability in accumulation potential with expectation for some fluctuation in trajectory, duration and magnitude. Less ideal microphysics with snow growth above the dgz may favor a drier and more powdery/granular snow carrying less accumulation efficiency. Dusting to less than an inch most locations, but with locally higher amounts plausible within heavier bursts within the M-59 to I-94 corridor. Minimum in wind chill Thursday morning arrives in the vicinity of -10 to -15 most locations. The thumb region and areas south of I-94 are most vulnerable to a dip below this mark. All told, combination of lingering gustiness this evening, continued lake effect potential and the notable drop in wind chill into tonight best highlighted with the ongoing Winter Weather Advisory to maintain a consistent message.

Modest 24 hour recovery in the upper height field noted Tuesday and Tuesday night, as the governing lower height anomaly temporarily retreats northward. Prevailing low level westerly flow with arctic air entrenched will maintain some degree of downstream lake moisture flux through the daylight period. The existing lake cloud maintains the possibility for some very light snow/flurry production, but with limited accumulation potential given unsupportive microphysics inherent within the resident arctic profile. Daylight wind chill holding below zero degrees. The arctic cold will moderate slightly into Tuesday night as warm air advection briefly takes hold, with coldest conditions likely during the evening before slowly rising.

Shortwave noted on water vapor late this afternoon ejecting southeast across British Columbia projected to accelerate through the base of the broader central Canadian longwave trough over the next 36 hours, reaching the great lakes Wednesday morning. Associated ascent tied to ongoing warm air advection arrives locally early Wednesday morning. Supportive moisture quality and depth to generate a period of accumulating snow. Probabilistic data points to a general accumulation residing mainly within the 1 to 2 inch range. The advective process will bring temps back into upper 20s/lower 30s, offering a brief reprieve before the trailing cold front arrives late in the day. Increase in wind magnitude within the immediate post-frontal environment may bring some gustiness to 40 mph Wed afternoon. Yet another wave embedded within the northwest flow could present a quick shot for accumulating snow Thursday morning.

Polar low set to take residence just north of lake Superior to finish the work week. Attendant arctic front marking the coldest air of the season /850 mb temps below -30C/ currently projected to arrive Friday. The frontal feature, possibly in conjunction with still less-defined shortwave energy, may offer another round of light accumulating snow. More noteworthy will be the extended stretch of high magnitude cold expected to persist through the remainder of the forecast period and likely right through the end of the month. Multiple days of sub-zero wind chill with the likelihood of headline worthy readings at times.

MARINE...

A low pressure system producing strong gusts and freezing spray for much of the central Great Lakes exits into Quebec tonight. This allows the pressure gradient to slowly relax this evening which causes gusts to drop below gales, as expected. The Heavy Freezing Spray Warning remains in effect tonight and into Tuesday given the resident arctic airmass and prevailing winds holding near 25 knots across the open waters of Lake Huron. Another extension in time may be needed for the Heavy Freezing Spray Warning for the rest of Tuesday given the latest sustained wind trends and expected unmodified air/water temperatures. The region remains locked into a large-scale troughing pattern throughout the week maintaining very cold conditions, elevated winds/waves, areas of heavy freezing spray, and periods of snowfall. The next period for potential gales arrives Thursday amidst another arctic boundary with some combination of Small Craft Advisories possible for portions of the nearshore waters.

DTX WATCHES/WARNINGS/ADVISORIES

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

Lake Huron...Heavy Freezing Spray Warning until 4 PM EST Tuesday for LHZ361>363- 462>464.

Gale Warning until 10 PM EST this evening for LHZ362-363-421-422- 441>443-462>464.

Lake St Clair...None. Michigan waters of Lake Erie...Low Water Advisory until 10 PM EST this evening for LEZ444.