textproduct: Detroit/Pontiac

KEY MESSAGES

- Strong cold front moving through Sunday brings a good chance of showers and perhaps a thunderstorm near the Ohio border.

- A significant cool down follows the front with below normal temperatures for Monday.

AVIATION

Persitent area of MVFR stratus held within prevailing southeast flow will gradually vacate the region through the afternoon as winds veer to southwest and greater warming commences. VFR holds this evening and overnight as periods of thicker mid level cloud move through at times. An increase in wind speed off the surface will introduce a window of low level wind shear early tonight. Frontal boundary forecast to settle southward across the area late tonight into Sunday morning. The initial frontal passage will lead to wind shift to northerly with a few widely scattered showers possible. Trailing area of deeper low level moisture will bring renewed MVFR stratus and a better chance of rain from late morning into the afternoon.

DTW THRESHOLD PROBABILITIES...

* High in ceilings aob 5000 feet through mid afternoon. Low Sunday morning, then medium Sunday afternoon.

PREV DISCUSSION

Issued at 305 AM EDT Sat Mar 21 2026

DISCUSSION...

It was a sneaky warm day yesterday, as highs ranged from around 50 degrees over the northern Thumb region to mid 70s along and south of I-94. Clouds dissipated for an extended period, and the 12z DTX sounding did indicate the potential to exceed 70 degrees. Another tight north-to-south temp gradient is expected on Sunday, but there is growing model consensus with the frontal boundary slipping south of the border by noon Sunday; thus, probably only looking at a 20- degree temp gradient vs. a potential 30+ degrees.

Strengthening warm advection pattern today as low pressure slides into the western Great Lakes. 850 mb temps are forecasted to rise into the lower teens early this evening. However, surface winds look to remain slightly back out of the south-southeast, allowing the cool waters of Lake Erie/St. Clair to come into play and keep most of Southeast Michigan stuck in the 50s for highs. However, areas west of U.S. 23 will have a shot to punch into the 60s late in the day, though confidence remains low.

Sunday: Deterministic ECMWF and its ensemble members (EPS) continue to highlight a potent cold front slowly sagging south through the Great Lakes. The primary challenge remains the exact timing of the fropa (frontal passage) and the resulting high-temperature spread. A robust thermal gradient will be in place; current guidance suggests 925/850 mb temperatures of 16+C ahead of the boundary, allowing southern zones (closer to the Ohio border) to potentially flirt with the 60s if the slower frontal timing materializes. Conversely, locations north of I-69 will likely remain capped in the 40s, as northerly winds off the cool waters of Lake Huron increase.

Precipitation-wise, showers are likely to develop along the boundary. The EPS mean suggests modest instability (a few hundred J/kg of CAPE) will be available in the warm sector, supporting a slight chance of thunderstorms along the southern Michigan border. As the front fully clears the region Sunday evening, a brief changeover to a rain-snow mix is possible on the back edge as 850 mb temps crash toward -10C Sunday night, though warm ground temperatures will preclude any meaningful accumulation. Low-level moisture depths look very shallow and may lead to a loss of ice nuclei, potentially resulting in some drizzle/freezing drizzle rather than organized snow.

Monday: Upper-level troughing settles over the Great Lakes to start the work week. Strong surface high pressure tracking through the Ohio Valley will maintain dry but chilly conditions for Monday. Highs will struggle to exit the upper 30s to lower 40s under a mix of sun and lingering stratocumulus, as 850 mb temps hold around -10C.

By Tuesday and Wednesday, the Euro ensemble suite shows the ridge axis shifting toward the eastern seaboard, allowing for a transition to southwesterly return flow. This will facilitate a gradual airmass modification. Expect highs to recover into the upper 40s-lower 50s by Wednesday. While a weak mid-level shortwave may ripple through the zonal flow late Wednesday, moisture return looks meager at this stage, keeping the forecast predominantly dry.

MARINE...

A ridge of high pressure passing overhead this morning gradually gives way to the next clipper that reaches western Lake Superior this afternoon. This system brings a chance of rain and snow across northern Lake Huron today into tonight while wind increases out of the southeast at around 15 kt. The low crosses Lake Huron overnight, then drags a strong cold front south across the rest of the region on Sunday with additional rain showers and potentially a thunderstorm. Stronger north to northeast wind develops in its wake, reaching 20 to 25 kt late Sunday into Sunday night. Highest confidence in gusts to around 30 kt will be across Saginaw Bay due to the favorable fetch. A building wave field across southern Lake Huron will likely necessitate a Small Craft Advisory for the nearshore. Strong high pressure builds in behind the front on Monday, then the next cold front is expected by late Tuesday.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Small Craft Advisory from 10 AM Sunday to 4 PM EDT Monday for LHZ421-441>443.

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