textproduct: Detroit/Pontiac

KEY MESSAGES

- A cold and snowy pattern will dominate this weekend and next week.

- Light snow south of M-59 and toward Port Huron this morning, then light snow in the Saginaw Valley and Thumb this evening. Accumulations of generally a dusting up to 1 inch.

- Frigid and blustery conditions Monday and Tuesday with potential for snow squalls. Wind chills near or below 0 degrees Monday morning through Wednesday morning.

- Dangerously cold wind chills near -15F will be possible Monday night/Tuesday morning.

AVIATION

Cold front sweeping through this morning is bringing a period of snow showers for the first few hours of the forecast. Though mainly MVFR, there are a few obs dipping to IFR for both CIG and VSBY. These showers may produce a dusting to a couple tenths of snow this morning. Drier conditions then attempt to spread across southern MI but westerly flow off Lake MI will try to continue to produce light snow showers through the afternoon. This should mainly affect MBS and FNT, possibly PTK, which could experience prevailing light snow through much of the afternoon. Later this evening a band of snow over northern lower will pivot and drop into MBS and possibly FNT before drifting off to the east possibly bringing a light coating of snow.

For DTW...The front will bring snow showers through about 15Z before pushing east. Drier air then lifts in from the southwest with the bulk of moisture off Lake MI holding north of the airspace. Low confidence in any window of snow beyond the morning activity so will hold off on any additional mention.

DTW THRESHOLD PROBABILITIES...

* High for ceiling 5000 ft through this evening. Low for tonight.

* High for precipitation type of snow.

* Low confidence in visibility restrictions to 1/2sm in falling snow today.

PREV DISCUSSION

Issued at 336 AM EST Sat Jan 17 2026

DISCUSSION...

Lower Michigan sits beneath a stalled upper longwave trough and multiple embedded shortwaves will bring periodic chances for light snow showers throughout the weekend as colder air gradually filters in. Moisture pooling ahead of a cold front pushing east across the state this morning will bring an uptick in light snow coverage mainly south of M-59 and toward the eastern Thumb through about 10AM. Up to around a half inch is most likely with this activity. Breezy southwest flow will continue to direct the Lake Michigan moisture plume mainly along and north of M-59 which carries the highest confidence in any light snow shower activity this afternoon. Temps near freezing at press time will fall slightly into the mid/upper 20s for much of the day before the cold air gains more traction and sends temps to the teens tonight.

As the stalled surface low over the northern Great Lakes begins to peel east this afternoon, a passing shortwave looks to help budge the Lake Superior surface trough and send it southeast across northern Lower Michigan. This offers a more defined signal for light snow for the northern Saginaw Valley and Thumb this evening, with around 0.5 to 1 inch of accumulation. Mainly flurries on Sunday as moisture depth remains shallow/disorganized but with occasional bouts of supersaturation within the DGZ. Deeper moisture then accompanies a clipper system Sunday night with widespread light accumulating snow likely across all of SE MI. Ensemble probabilities support a dusting to around 1 inch of accumulation for most, though a few spots getting closer to 2 inches will be within reach.

Much colder arctic air arrives Monday into Tuesday as the core of sub -20C 850mb temps pivot across the area. LREF ensemble probabilities indicate a 40-50% chance for 850mb temps to dip below -25C which is near the daily record minimum per SPC sounding climatology. Blustery conditions will accompany the frigid air mass as high pressure builds into the Ohio Valley, maintaining a stout gradient. Daytime soundings Monday have all the hallmarks of a classic snow squall setup: deep boundary layer mixing up to nearly 10 kft with steep low-level lapse rates, marginal SBCAPE, 30 to 40 kt wind, and supersaturation wrt ice and UVV within the DGZ. Snow shower generation within this environment is supported by synoptic height falls and PVA, low-level fgen, and moisture flux off Lake Michigan. SNSQ parameter above 1 confirms potential for near whiteout conditions at times. The signal for surface convergence suggests highest potential for squall activity will lie within the I- 94 to M-59 corridors.

With the arctic air and persistent gusty WSW wind, wind chill falls below 0F Monday morning and stays below 0 through Tuesday night before rebounding on Wednesday as actual temp rises from the teens to the 20s. Monday night into Tuesday morning remains a target for potential Cold Weather Advisory issuance for parts of the area as low temps bottom out near 0F and wind chill approaches -15F. NAEFS and ECMWF ensemble data shows high confidence in longwave trough persistence over the Great Lakes through the week, favoring continuation of below normal temps despite the slight warm-up midweek. Signal is emerging for widespread snow on Wednesday with the next clipper passing through.

MARINE...

Low pressure exits into ON/QB today with modest southwesterly winds amidst a constricted pressure gradient. This leads to heightened waves across portions of the southern Lake Huron nearshores, thus another Small Craft Advisory was issued. Weak troughing competes with high pressure on Sunday to keep winds and waves elevated. A large and deepening low pressure system races through Sunday night into Monday offering the next opportunity for gusts to gales amidst a strong surge of arctic air. Freezing spray issues are also expected during this very cold and windy period.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Small Craft Advisory from 1 PM this afternoon to 4 AM EST Sunday for LHZ421-441.

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