textproduct: Detroit/Pontiac

KEY MESSAGES

- Temperatures will remain well below normal throughout the week. The coldest conditions arrive Thursday and Friday mornings with wind chill values bottoming out near or below zero.

- Arctic front will bring scattered snow showers this afternoon and evening, with accumulations from a dusting to under an inch.

AVIATION

Expansive area of stratus featuring a cloud base at IFR to lower MVFR will persist throughout the daylight period. This exists as prevailing southwest flow turns modestly gusty ahead of an approaching arctic front. Several hour window at any one location for possible light snow shower development this evening along the advancing cold front. Post-frontal wind shift to northwesterly with some lingering gustiness overnight. Some degree of low level drying with modest mixing will favor a trend toward VFR cloud as arctic air funnels into the region during the early morning hours Thursday. possible late tonight.

For DTW...Low stratus entrenched through the day. Window for brief snow shower development 23z-02z.

DTW THRESHOLD PROBABILITIES...

* High for ceiling at or below 5000 ft through tonight.

PREV DISCUSSION

Issued at 414 AM EST Wed Dec 3 2025

DISCUSSION...

Persistent anomalous upper troughing over Hudson Bay will maintain influence over the Great Lakes this forecast period, with prolonged well below normal temperatures expected through the rest of the week and into next week. A lobe of vorticity will swing around the upper low tonight, sending a reinforcing shot of arctic air across the region behind a strong cold front. Ahead of the front, brisk southwest flow will develop today as a LLJ passes overhead. The warm air advection associated with this jet will remain elevated and the resultant 15-25mph breeze will hold wind chills in the teens and lower 20s today even as temperatures peak in the lower 30s.

The front will reach the Saginaw Valley in the afternoon and track southeast through the evening hours. Model guidance continues to be very lean on QPF as there will be a lot of mid-level dry air to overcome before deeper saturation occurs, and most of the inbound sfc-700mb moisture will be pooling out ahead of the front where ascent is disorganized and shallow. A few light pre-frontal snow showers or flurries will be possible, then a quick round of trailing post-frontal snow showers follows later this evening as a brief intersection of steepening low-level lapse rates, boundary layer moisture, and frontal forcing occurs. A few hi-res runs produce around 30-50 J/KG of SBCAPE in the Saginaw Valley which would support a brief heavier burst of snow as a higher end scenario, but the overwhelming model signal is for a muted response with these showers. A dusting to a half inch of accumulation will be the most likely outcome through tonight. Additional flurries may continue overnight as the inbound cold air mass sends the DGZ down into the boundary layer with any lingering clouds capable of producing a few flakes.

Strong cold advection will keep the boundary layer well mixed tonight with northwest wind of 10-15mph sending wind chill below zero Thursday morning as temps plummet into the teens. High pressure spreading across the southern lakes will ease the wind and bring some sunshine on Thursday, but 925mb temps bottoming out near -14C will maintain biting cold conditions with highs topping out near 20. This is some 20 degrees below average highs and actually lower than our average lows for early December. The degree of dry air will hold any lake effect close to Lake Michigan and out of the local area.

The next lobe of arctic PV is slated to pivot across northern Ontario Friday night, sending a cold front across the northern lakes on Saturday. Ahead of this front, flow emerges once again out of the southwest which will force the thermal trough away and offer a warming trend from Friday into Saturday. A weak shortwave passing across the Great Lakes Friday night will bring a slight chance of snow, but the deeper moisture and ascent with this wave will be focused north of the local area. The trailing portion of the front will pass through later this weekend keeping below normal temps around well into next week. The upper pattern holds a stronger jet across the SE CONUS which leaves the Great Lakes in a relative lull pattern void of stronger systems. Ensemble guidance breaks down this pattern and brings in a more active storm track during the middle of next week.

MARINE...

High pressure will finish sliding to the east coast today with the next system set to move through today. Strong southwesterly winds ahead of a cold front will have gusts reaching 25 to 30 knots into the afternoon across central Lake Huron. A Small Craft Advisory is in effect for Sagainw Bay and around to Harbor Beach for these winds. A strong low pressure system over Hudson Bay will send the cold front through this afternoon into the evening with very cold arctic air entering the region in the wake of the front. The front will flip the winds around to the northwest while the arctic air increases the winds gusts of 30 to 35 knots possible Thursday morning. Most guidance still offers little support for wind gusts to reach gales for any notable amount of time during this period so will continue to hold off on any gale headlines and mention the potential for a few gusts to gales instead.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Small Craft Advisory until 4 PM EST Thursday for LHZ421-422-441.

Small Craft Advisory from 10 PM this evening to 4 PM EST Thursday for LHZ442-443.

Lake St Clair...None. Michigan waters of Lake Erie...Low Water Advisory from 10 AM this morning to 10 PM EST this evening for LEZ444.