textproduct: Detroit/Pontiac

KEY MESSAGES

- Dry conditions today give way to accumulating snowfall late tonight and into Sunday.

- Winter weather advisory for locations along and south of M-59 tomorrow with winter storm warning for Monroe county. - Very cold conditions continue next week with additional Cold Weather Advisories possible.

UPDATE

Extreme/record setting cold (-24F low at FNT) and dry air in place over southeast Michigan will be slow to dislodge, which makes for tough call when snow "starts"/overspreads southeast Michigan tonight/tomorrow morning. Increasing 925-850 MB southeast winds tonight, but Lake Erie is mostly frozen over and will not be a significant player. Should see a lot of virga and mainly flurries/very light snow showers tonight, but light accumulating snow should begin 8-12z in the southern counties. Still, the peak of the snowfall will occur during the afternoon/late in the day with the upper level jet forcing arriving. Although there are no big differences between 12z HRRR/NAM/Regional GEM, the very tight moisture gradient still makes for a challenging forecast. Forecast soundings during much of Sunday now indicating saturation/forcing hanging around in the -10 to -12 C layer, not the ideal sweet spot for stellar snow to liquid ratios. Model clustering of the low coming out of the Gulf Coast States indicates a sw-ne track through West Virginia and now just east of Pittsburgh PA Sunday evening, and washing out as the coastal low takes over. Bulk of the models still indicated 24 hr QPF reaching up to half an inch over southern Monroe county, and even with snow to liquid ratios in mid/uppper teens, a 5- 8 inch snowfall seems doable for Monroe, and will go with a winter warning. A high end advisory will be issued for 4-7 inches for Lenawee, Washtenaw, and Wayne counties. Will also carry a winter weather advisory for the M-59 corridor for 2-4 inches/isolated up to 5. The end time will be 5z Monday/midnight. Southern Lake Huron has significant ice cover, which complicates the potential lake effect bands Sunday night as the low level flow goes northerly. Confidence is low in any significant bands impacting the eastern Thumb region, and this is something later shifts can look at.

PREV DISCUSSION

Issued at 634 AM EST Sat Jan 24 2026

AVIATION...

Ridge of surface high pressure is centered over Lower Michigan this morning. Calm to slightly westerly winds in place will eventually emerge out of the east today. The increasingly easterly trajectory is expected to keep any Lake Michigan stratocumulus west of the taf sites today. High cloud with some transparency this morning will give way to increasing top down saturation and mid cloud by this evening. The next winter storm will lift northward towards the Detroit taf sites tonight. Low confidence and high uncertainty exists on when snowflakes will begin reaching the ground at DTW. Have pushed back the TEMPO group until 09-12z with any IFR conditions holding off until after 12z Sunday.

DTW THRESHOLD PROBABILITIES...

* Medium for ceilings aob 5,000 feet early Sunday morning.

* High in precipitation type of snow.

* Low in in ceilings of 200 ft or visibilities of 1/2SM in falling snow before 12z Sunday.

PREV DISCUSSION... Issued at 430 AM EST Sat Jan 24 2026

DISCUSSION...

Very cold start today across Southeast Michigan, and for much of CONUS, as clear overnight skies lie atop a bona fide arctic airmass. This has led to initial readings well below 0F, but since gradient winds are weak (predominantly AOB 5 knots) the difference between air temperatures and wind chill values has mostly been minimal. The Cold Weather Advisory should be allowed to expire by 10 AM as wind chills increase above -15F for the rest of the day. Gradual thermal moderation is already underway within the column, marked by 850 mb temperatures warming from -27C (per 24.00Z KDTX RAOB), to the minus teens (Celsius) by this afternoon. This translates to a marginally warmer day, with daytime highs in the upper single digits, in spite of increasing cloud cover. Mesoscale 1043 mb surface ridge dislodges from southwest Lower Michigan later today and migrates eastward, eventually flipping light winds easterly by this evening.

Continuing to monitor the next opportunity for accumulating snowfall late tonight into Sunday as highly amplified northern and southern stream troughing phase over the southern Plains, before the composite wave ejects into The Northeast by Monday. Local isentropic surfaces steepen and moisten with time as the ThetaE ridge lifts out of the Ohio Valley and into the Lower Peninsula tonight. Light snow begins to spread north of the Michigan/Ohio border sometime between 03Z and 06Z Sunday, well downstream of the actual wave features. The more substantial CVA should still be west of the Mississippi by 12Z Sunday. Given the lack of more meaningful dynamics, initial overnight accumulations (south of I-94) should hold below an inch. The moderate to briefly heavy snowfall rates are not expected until Sunday afternoon, after the lead VortMax clips the southeast edge of the CWA.

As expected with a narrowing time horizon, consensus model data has sharpened wrt the QPF gradient. Latest deterministic, ensemble, and ML guidance show agreement in the expected range of QPF. Areas south of I-94 will likely get between 0.20 and 0.40 inches of liquid equivalent, while the sharp gradient with northwest extent keeps total QPF to around a few hundredths across the Tri-Cities. Regarding snow-related headlines, opted to hold off on an advisory (or watch/warning for Monroe or Wayne Counties) tonight to allow an additional cycle of model data. At the very least, an Advisory will likely be needed for most counties across the southern half of the forecast area where forecast soundings maintain deep saturation through the DGZ. The main limiting factor will be the lack of stronger ascent which keeps average totals in the 2-4 inch range, but decreases sharply north of I-69. The exceptions will be over Monroe and Wayne counties where vertical velocities could produce rates on the order of a half inch per hour. This leads to non-zero potential in approaching Warning criteria, but the latest SLR trends closer to 15-1 and few 7+ inch solutions preclude a Watch. Some uncertainty exists with how long snowfall continues Sunday night, and the extent to which post-event lake effect impinges on the forecast area. Another quarter to half inch is possible late Sunday into Monday.

Daily lake effect snowfall chances in-play for much of next week as colder than normal conditions persist. Several reinforcing shots of arctic air and supporting disturbances aloft offer additional opportunities for wind chills dropping below -15F, therefore future Cold Weather Advisories may be warranted. Daytime highs are capped in the teens during the next 7 days.

MARINE...

The maintenance of a heavy lake effect snow band will persist across north to north central Lake Huron through the afternoon as low-level convergence persists within a corridor of unstable conditions. A strong high pressure system to then settle in across the Great Lakes though the day. This will bring a period of lighter winds through the weekend.

Across the southern Great Lakes, light snow will begin to expand across the region through Sunday as an expansive low pressure system arrives across the Appalachia region. The departure of this low pressure system into the western Atlantic will reinforce arctic air across the Great Lakes, which will increase wind speeds through the early and midweek period.

DTX WATCHES/WARNINGS/ADVISORIES

MI...Winter Weather Advisory from 9 AM Sunday to midnight EST Sunday night for MIZ063-068>070.

Winter Weather Advisory from 5 AM Sunday to midnight EST Sunday night for MIZ075-076-082.

Winter Storm Warning from 5 AM Sunday to midnight EST Sunday night for MIZ083.

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