textproduct: Detroit/Pontiac

KEY MESSAGES

- Above average temperatures persist into the weekend.

- Strong cold front moving through Sunday afternoon 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.

DISCUSSION

Morning shortwave is in the process of departing to the eastern seaboard as its trailing cold front crosses SE MI this afternoon. Fropa occurs without much fanfare as surface high pressure quickly builds over lower MI in its place. Ridge axis is slow to cross southern lower MI Saturday keeping cooler northeast turning easterly flow in place for the first half of the day. This sets up a cool/cold day for lakeshore areas, especially the Thumb, with highs held firmly within the 40s (areas immediately along the lakes could fail to get out of the 30s). Highs for interior areas will depend on the degree of lingering cloud cover. Given forecast soundings advertising some degree of lingering low/mid cloud for much of the day, erred on the cooler side lowering NBM temps to the lower 50s.

Respectable cold front sags through the Great Lakes Sunday as a shortwave ripples along it over the northern Great Lakes. This sets the stage for a strong thermal gradient across the local area daytime Sunday. High sensitivity exists to the speed of the front, however good confidence that areas north of I-69 remain capped in the 40s for high temps with areas south of M-59 being able to reach the 50s. If the front is sufficiently slow, areas near the Ohio border still have a shot to see temps top out in the 60s instead. Front also brings the area's next chance at rain with scattered showers working through over the course of the day. In the slower frontal progression scenario, at least a few hundred J/kg of CAPE would be possible across the southernmost areas supporting an isolated thunderstorm or two. Front clears SE MI in the evening Sunday ending any additional precip chances. Strong trailing cold advection allows for a brief changeover to a rain-snow mix on the backedge before precip tapers off- no accumulation.

Upper troughing settles over the Great Lakes Monday dropping 850mb temps near -10C keeping resultant highs below average in the lower 40s. Strong high pressure tracking over the Ohio Valley/southern Great Lakes maintains drier conditions to start the new work week with moderation toward late March normals Tuesday as the center shifts to the eastern lakes.

MARINE

Drier conditions expected this evening as the morning clipper system departs. Northwest flow has developed in its wake and will linger through mid-day Saturday until high pressure drifts across the Great Lakes. Flow pivots clockwise around the high, settling out of the southeast by Saturday evening ahead of the next clipper system. This brings the next opportunity for mixed precipitation over Lake Huron Saturday night, which expands south through the day Sunday as a cold front drops through. A few thunderstorms are plausible for the southern marine zones with the fropa. Wind gust potential is generally limited by stable thermal profiles, with highest gusts to 30 knots expected for Saginaw Bay as northeast flow aligns with the long axis of the bay. The main marine concern is elevated waves reaching the Lake Huron shoreline latter half of Sunday as winds flip to the northwest post-front. Expansive high pressure then builds in to start the work week.

PREV DISCUSSION

Issued at 139 PM EDT Fri Mar 20 2026

AVIATION...

Generally clear skies prevail through the early afternoon with veering low-level flow enhancing cold air advection, which will work in mvfr stratus tonight. There is some signal for ifr stratus stratus development overnight with the better signal across kptk to kfnt with the higher terrain. This shallow boundary layer moisture will likely hold through the morning hours under a sharp low level inversion until low-level flow veers southerly, which will then work to lift ceilings heights and scour our low-level cloud cover through the late morning to afternoon hours.

DTW THRESHOLD PROBABILITIES...

* High in ceilings aob 5000 feet this evening and overnight.

DTX WATCHES/WARNINGS/ADVISORIES

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