textproduct: Detroit/Pontiac

KEY MESSAGES

- Rain chances increase early Sunday morning. Initial onset of precipitaiton brings a chance for some freezing rain, more favorable along or north of M59, before transitioning to all rain.

- Widespread rainthrough the remainder of the day Sunday. Potential exists for heavy rainfall to develop with totals ranging between 1- 2" pending where the heavy rain axis develops.

- A powerful arctic cold front moves through Monday morning. Flash freeze potential exists behind the front, along with wind gusts of 45-55 mph and snow showers.

- Colder conditions exist Tuesday and Wednesday. Minimum wind chill in the single digits.

AVIATION

A broad region of mid level subsidence will reside across Southeast Michigan through the day. This will sustain sfc high pressure across the eastern Great Lakes, leading to light variable winds trending light southeasterly this afternoon and evening. A solid stratus deck has remained in place across much of the Great Lakes region, trapped under a deep low level inversion. Not much change in the inversion is forecast through the day, suggesting a persistence forecast for the stratus deck into tonight. There have been some fluctuations in ceilings across the IFR/MVFR threshold. Subtle dry air advection into the boundary layer is expected to trend conditions toward prevailing MVFR today.

DTW THRESHOLD PROBABILITIES...

* High for ceiling below 5000 feet today and tonight.

PREV DISCUSSION

Issued at 342 AM EST Sat Dec 27 2025

DISCUSSION...

Weak surface high pressure over the Great Lakes to quickly wash out into Ontario and Quebec this afternoon. Mid-level ridge to hold across the state into the evening. Stable conditions maintains dry weather while an established strong low level inversion holds widespread stratus. Temperatures ride into the mid 30s for an afternoon high.

A potent upper-level wave over British Columbia will drive south into the continental northwest through the day today. Initial cyclogenesis will commence over the Rockies ahead of this feature as flow interacts with the higher terrain. Low pressure will begin to take form late tonight into Sunday morning over the central Plains and will track through the Ohio Valley early Sunday. This will initially remain broad and disorganized as the ~600mb dynamic tropopause anomaly lags behind this surface feature. Initial impacts across SE MI will be commencement of first some light precipitation on the leading edge of the theta-e gradient as it progresses through the mid morning hours Sunday. Surface temperatures will be close to the freezing mark, increasingly so for the northern half of the cwa with this initial precipitation arc while a warm nose above 0C holds in place. This brings some lower end freezing rain concerns with initial onset before temperatures work their way above freezing through the later morning hours. Quickly thereafter, deep-layer isentropic ascent will commence over SE MI and will likely hinge and pivot near or south of I-69 as an elevated warm front briefly becomes quasi- stationary. This will result in widespread rainfall, the heaviest of which will fall along this pivot point, where totals of 1-2" become increasingly likely by end of day tomorrow. A low chance for isolated thunderstorms will be possible along the heaviest rain axis. P-type will be all rain as temperatures steadily rises into the 40s, up into the 50s closer to the Metro region and MI/OH border by the evening.

Attention will then turn back to the aforementioned wave/trough feature as orientation turns from a positive to negative tilt, catching up to the surface low, which will be a catalyst for rapid deepening and significant pressure falls right over Michigan. Pending any major timing adjustment, this would briefly bring peak temperature highs closer to Midnight with the stout southerly flow, where a push into the mid to upper 50s will be possible closer to the border, possible through the Metro region, hinging on how far north the surface warm front makes it. Low pressure will continue to deepen across the state before occluding across Ontario. 12 hour 1000-500mb height falls show a -20dam change over Lake Huron by 12Z monday. Rapid deepening and exit of the low will prog a powerful arctic front with deep vertical continuity to sweep through Monday morning, which will result in a rapid 20+ degree temperatures drop to below the freezing mark in a short 3-5 hour window.

First to note -- This will lead to some flash freeze concerns as overnight lows settle in the mid 20s noting the prior day high-end rainfall potential. While strong winds will accompany the front, talked about shortly, there is concern that the magnitude of the thermal drop will outpace any evaporation, even with early day temperatures well above freezing. Second, mixing depths immediately sharpen with the frontal passage noting lapse rates toward 9.5C/km up through 900mb, tapping into a magnified low-level jet. This will facilitate highly efficient momentum transport and brings the likely for initial wind gusts aoa 40 mph. After passage of the front, there is a brief window where dry slotting will hamper precipitation, but wrap around moisture from the low and introduction of lake moisture off of Lake Huron will bring snow chances through the late morning into the evening hours Monday. Windy conditions continue through the day Monday where peak gust potential between 45-55 mph is looking increasingly likely as the Great Lakes reside in deep cyclonic flow with a strong pressure gradient in place and strong llj overhead. Potential for some embedded squall-like snow showers will be in possible during daylight hours. Highly variable snowfall totals are expected end of day Monday with higher end amounts up to 1-2" inches.

Into Tuesday morning, breezy conditions continue along with lighter snow shower potential, but magnitude of wind speeds decrease through the day as low pressure vacates the area. Monday highs peak in the low 30s with Tuesday highs in the mid 20s. Wind chills drop into the teens to single digits Tuesday morning with the stronger winds.

MARINE...

A diffuse pressure pattern exists within a ridge extending into the Great Lakes from Quebec. This maintains tranquil conditions early today with wind then organizing out of the southeast by this afternoon as the ridge eases eastward. A strong low pressure system will lift across the region Sunday before crossing northern Lake Huron Sunday night into Monday morning. Southeast to east wind of around 15 to 25 kt and widespread rainfall precedes this system, then a strong cold front marks the arrival of arctic air on Monday. There is high likelihood for gusts to gales as strong west to northwest wind ensues through the day, and a Gale Watch has been issued. There is the potential for a brief period of gusts to storm force on Monday depending on the strength/track of the low. Snow squalls and freezing spray also develop on Monday and are likely to persist through the middle of next week as the arctic northwest flow pattern persists.

HYDROLOGY...

Widespread rain to expand across SE MI throughout Sunday. Some prolonged heavier rainfall is expected through the afternoon hours generally along or south of I-69. Basin averaged rainfall totals around 1.5 inches are expected within this axis of heavier rain. Some localized higher totals nearing 2 inches will be possible with any isolated thunderstorms. For locations north of this heavier rain axis, accumulations generally hold under 1 inch. This could lead to some minor flooding of prone low lying and urban areas.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Gale Watch from Monday morning through Tuesday morning for LHZ361- 362.

Gale Watch from late Sunday night through Tuesday morning for LHZ363-421-422-441>443-462>464.

Lake St Clair...Gale Watch from Monday morning through Tuesday morning for LCZ460.

Michigan waters of Lake Erie...None.