textproduct: Detroit/Pontiac

KEY MESSAGES

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

- Arctic front will bring the potential for snow showers late Wednesday, with some minor accumulation possible.

AVIATION

Light snow near Detroit comes to an end over the next 1 to 2 hours as Ohio Valley low pressure passes east and high pressure begins to ease in from the west. The pressure gradient will remain weak this morning, keeping abundant low level moisture in place. An area of LIFR fog/stratus is likely to linger across the Saginaw Valley while MVFR visibility in mist lingers elsewhere. Weak flow then begins to organize out of the west to southwest this afternoon, allowing any visibility restrictions to mix out. Ceilings will be variable and carry a high amount of uncertainty today, but overall MVFR stratus is the dominant signal in model guidance. May see some periods of VFR at times this morning and afternoon. Predominant MVFR is favored overnight.

For DTW...Snow exits east early in the forecast with MVFR conditions likely through mid morning. Low confidence on timing of any periods of VFR today.

DTW THRESHOLD PROBABILITIES...

* High for ceiling at or below 5000 ft through the forecast.

* High for precipitation type as snow this morning.

PREV DISCUSSION

Issued at 300 AM EST Tue Dec 2 2025

DISCUSSION...

Area of light accumulating snow impacting mainly areas from M-59 southward early this morning on pace to vacate from west to east over the next 2-4 hours. Trailing lower amplitude mid level trough will track through during the morning period. Satellite trends confirm recent sounding data in maintaining a higher degree of low level saturation anchored to this feature beneath a strengthening inversion. Shallow convective depth with neutral thermal advection suggests limited potential for additional snow shower or flurry activity going forward today. Given no meaningful adjustment in the resident thermal profile, expectation remains for highs to arrive around 30 degrees again today. Forecast will remain pessimistic on cloud cover into tonight, noting greater likelihood for emerging westerly flow to draw the residual lake Michigan moist plume back into the area. A few inconsequential flurries around as moisture depth improves. Magnitude of this cold airmass will again support lows in the teens many locations despite a lower probability of witnessing open sky.

Polar low anchored over Hudson Bay will remain influential in local conditions through the latter half of the week. Stronger vorticity lobe pivoting through the cyclonic periphery will dig southeast and across the great lakes Wednesday night. Brisk conditions develop Wednesday as the southwest gradient strengthens ahead of the inbound attendant arctic front. Gust potential muted by low inversion heights as modest warming commences atop the shallow mixed layer. Probability of snow showers will increase from northwest to southeast from late afternoon into the evening hours, focused primarily along the advancing convergence axis. Accumulation potential from a dusting to half inch. Greater signal for snow squall potential remains to the north and across lake Huron based on projection of low level cape and fgen collocated with the stronger frontal convergence. With that, a few bursts of higher intensity snow showers will remain possible through this time.

High magnitude cold defined by temperature readings near 20 degrees below average will mark the Thursday and Friday periods as the arctic airmass takes firm residence. This will translate into single digit wind chill during the daylight hours, with a minimum in wind chill sub-zero for many locations both Thursday and Friday mornings. Little change in the overall pattern ensures well below average cold sticks around this weekend and likely well into the following week. A series of shortwaves cascading over the prevalent central Pacific ridge will dive into the mean trough. Pattern still subject to higher degrees of uncertainty in time and space for defining additional snowfall chances as these waves migrate downstream from Friday night onward. Assessment of recent ensemble guidance points to lower end but equal chances for meaningful forcing to enter the area anytime within the Friday night through Monday window. Synoptic scale moisture quality will remain on the lean side given the Pacific origin within a predominant mid level west-northwest flow. Forecast will continue to simply highlight a broader, low chance with further refinement likely as greater consensus on track and magnitude materialize with time.

MARINE...

High pressure will continue to push off towards the New England region with lighter winds prevailing over Southern portions of the Great Lakes. Over the northern Great Lakes, persistent southwest flow will continue as a broad low pressure system continues to reside over the Hudson Bay region. Next significant system arrives Wednesday as a strong arctic cold front drops out of northern Ontario resulting in both strong preceding southwest winds and trailing northwesterly winds as the coldest air of the season thus far moves over the Great Lakes. Limited potential for a brief period of gales within the southwest flow Wednesday precludes a gale watch at this time. Increasing wave action will bring an extended period of small craft conditions across Saginaw Bay and the nearshore waters of Lake Huron

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Small Craft Advisory from 9 PM this evening to 4 PM EST Thursday for LHZ421-422-441.

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