textproduct: Detroit/Pontiac

KEY MESSAGES

- Frost is likely again tonight.

- Numerous to widespread showers with a rumble of thunder move in Tuesday afternoon and night.

- A warming trend carries temperatures above normal heading into next weekend.

DTW THRESHOLD PROBABILITIES

* None

PREV DISCUSSION

Issued at 355 AM EDT Mon May 11 2026

DISCUSSION...

Great Lakes weather is strongly influenced by cool central Canadian to Midwest high pressure that moves overhead this afternoon and then drifts eastward tonight. The surface high makes a more aggressive move into Lower Mi after the larger scale mid level trough moves eastward. The catalyst for progression is the passage of a small but intense mid level circulation that moves overhead this morning. This system is tapping the low to mid level theta-e gradient associated with the Ohio valley frontal remnants to bolster mid level cloud production. A few sprinkles are also in play toward the Ohio border during the morning while the clouds linger with enough coverage to substantially delay the diurnal heating influence on temperatures. Guidance max temps in the 50s look reasonable with the Tri Cities down to I-69 having a chance to overachieve as sun breaks out toward afternoon.

Tonight starts out with high pressure centered over Lower Mi and a pronounced 500 mb short wave ridge in place just west of Lake Mi. Confluent flow aloft forces deep subsidence across the central Great Lakes leading to a higher confidence scenario for clear sky compared to recent nights until cirrus arrives toward sunrise. The clear sky and calm wind set up efficient radiational cooling and high likelihood for another round of frost across the region except for the immediate Detroit area. Eastward departing high pressure and increasing clouds Tuesday morning are signs the next low pressure system is on schedule to bring showers in by afternoon. This system is still moving out of the Canadian Rockies this morning, however there is good agreement among the 00Z model runs that show the system benefiting from lee side cyclogenesis and upstream longwave amplification today and tonight. The strengthening process puts the system in good position to accelerate northward transport of Gulf modified air into isentropic ascent along and ahead of the low track. General thunder is supported by 850 mb LI dropping to around 0C in weak elevated instability across Lower Mi, ahead of the surface warm front still to our west by 00Z Wednesday. The surface low and frontal system then quickly move through the central Great Lakes Tuesday night while the 500 mb trough attempts to close off over southern Ontario. This trend in the models is less progressive and maintains a cold core upper trough/low influence over the central Great Lakes during Wednesday. Mid May daytime heating then supports at least scattered showers over SE Mi Wednesday afternoon and evening.

Despite the slower progression of the Wednesday system, the late week is still a transition period for the larger scale mid to upper level pattern. Extended range deterministic and ensemble systems show good agreement on a solution that shows the mean flow shifting from a high amplitude long wave trough over the Great Lakes and NE States to more of a zonal configuration from coast to coast. The height rises even into "just" a zonal flow add confidence to a meaningful warming trend for the Great Lakes heading into the weekend. A flip to above normal temperatures well into the 70s comes at the expense of predictability on precipitation systems made difficult by fast moving short waves within the larger scale zonal flow.

MARINE...

High pressure influence holds over the region today and tonight while maintaining light marine winds. Next low is set to sweep across the Great Lakes late Tuesday bringing widespread showers and a few chances for thunderstorms mainly over the southern Great Lakes. In advance of the system, southerly winds strengthen though with ongoing warm advection, thermal stability over the waters caps peak gusts around 30kts. Moderate NNW winds follow Wednesday as cooler air filters back in behind the low however a diminishing gradient holds wind under 30kts. High pressure briefly follows to close out the work week.

DTX WATCHES/WARNINGS/ADVISORIES

MI...Frost Advisory until 7 AM EDT this morning for MIZ047>049-053>055- 060>063-068>070-075.

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