textproduct: Detroit/Pontiac

KEY MESSAGES

- Snow is expected later tonight, mainly north of M-59. Accumulation around 1 inch occurs along the I-69 corridor and increases to 2-3 inches in the Tri Cities and northern Thumb region.

- A warming trend gets underway tomorrow as high temperatures rise above freezing. High temperatures are then projected to climb steadily through the 40s mid to late week.

- A system Tuesday morning may bring a brief period of mixed precipitation.

AVIATION

Warm front on pace to lift across southeast Michigan tonight. This will support a period of light snow development mainly between 04z and 09z. Forecast will continue to highlight a greater probability with more notable reduction in visibility and accumulation potential at MBS/FNT. Potential for the southern expanse of this moisture axis to glance across the Detroit corridor. Intervals of MVFR stratus will exist through this period. Drier low level conditions emerge within the wake of front, offering a window of VFR through mid morning Monday. Expansion of low stratus anticipated late morning into the afternoon, affording renewed MVFR conditions. Modest winds from the south tonight, becoming southwesterly Monday.

For DTW... Window for light snow is focused between 05Z and 08Z. Trace amount of accumulation is the most likely scenario for the terminal area as rates remain light.

DTW THRESHOLD PROBABILITIES...

* High for ceiling aob 5000 feet early tonight. Low late tonight through Monday morning. High again Monday afternoon and evening.

* High for snow as precip type.

PREV DISCUSSION

Issued at 346 PM EST Sun Jan 4 2026

DISCUSSION...

Surface high pressure will slide to the east into the evening with a rather potent, compact shortwave arriving right on its heels tonight. This wave on the northern periphery of the ridge will have a good pace to it as it tracks from the northern plains today and through the central Great Lakes by the end of tomorrow morning. A baroclinic zone will be a focal point for surface cyclogenesis and a wing of isentropic ascent ahead of the wave. Increasing moisture will accompany the wave with 850-700 mb specific humidity maxing out in the 3-4 g/kg which support QPF output in the 0.15 to 0.25 inch range. Of note, latest QPF guidance has dropped slightly with far northern locations less likely to reach 0.30 inches. The best forcing and vertical motion tied with good moisture will be north of I-69 with the higher QPF amounts. Thermal profiles are cold enough for an all snow p-type to start this event, though warm advection will help draw low-mid level temperatures closer to 0C. This should lead to a more normal snow ratio around 10:1 and 11:1. This overall set up will lead to snowfall rates nearing 1 inch per hour along and north of the M-46 corridor, but expect that the duration of these rates will be brief (1-2 hours or less) given the pace of the system. Snowfall begins across northwest portions of the CWA by around 10-11 pm this evening moving out of southeast Michigan by about 5-6 am. Snowfall totals of 2 to 3 inches are forecast for the Tri-Cities and northern Thumb tapering down to around an inch across the I-69 corridor with little to no accumulation down to the I-94 corridor. Majority of hi-res with the 12Z model suite point towards only minor adjustments in snowfall totals. Thus, will forego any winter weather advisory with this forecast package as the minor adjustments have not changed current thinking on headlines.

Dry air intrudes on the back side of this system and begins to strip moisture from the DGZ. If the remaining low level moisture is able to support drizzle, it would lead to potential freezing drizzle through the remainder of the morning hours tomorrow until temperatures can rise above freezing. This would most likely be across the Thumb and maybe the Tri-Cities. Any impacts appear to be minimal with the fresh snow and the limited QPF of a trace to one hundredth possible in that time. It will be something to monitor in case observational trends can increase confidence in greater traffic impacts.

Warm advection brings temperatures above 0C at 850 mb Monday into Tuesday clearing out the arctic airmass and marking the beginning of a warming trend that carries through mid-week. West to southwest low to mid level flow will carry a shortwave energy originating from the California coast today into the Great Lakes early Tuesday. There will be a short period (~3 hours) around sunrise Tuesday morning when a wintry precipitation mix will be possible as temperatures are forecast to be just below freezing at the onset of precipitation. Temperatures are expected to quickly warm above freezing by the end of morning bringing an all rain p-type with any precipitation Tuesday afternoon.

High pressure is expected to bring dry conditions for Wednesday as high temperatures for the afternoon range from the mid 30s across the north and low 40s near the southern MI border. Late week will see the next low pressure system lifting out of the southern plains into the Great Lakes, but differences in both timing and synoptic features bring some uncertainty with the set up and what to expect with respect to precipitation type and amounts.

MARINE...

An active upper level pattern sends another clipper system across the northern Great Lakes late tonight, bringing widespread snow to Lake Huron overnight that tapers in intensity further south. Weak surface connection affords little impact to the surface pressure gradient, keeping winds light as they trend south this evening ahead of the low. Warmer air arrives behind the clipper to transition precipitation type over to rain or a rain-snow mix as the next system arrives Tuesday. This system has better surface roots, with forecast central pressure around 1000mb as it reaches the local waters. That said, the projected track of the low is right across Lower Michigan which keeps wind concerns outside of the Great Lakes. High pressure then fills in through mid-week to keep marine areas headline-free through the forecast period.

DTX WATCHES/WARNINGS/ADVISORIES

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