textproduct: Detroit/Pontiac

KEY MESSAGES

- Scattered to numerous thunderstorms are forecast today, some of which may be capable of producing damaging wind gusts.

- Dry and a little cooler weather will dominate the mid week period.

DTW THRESHOLD PROBABILITIES

* Low for ceiling at or below 5000 feet today and tonight. High by Tuesday morning.

* Medium for thunderstorms this afternoon-evening. Low overnight.

PREV DISCUSSION

Issued at 301 AM EDT Mon Jul 27 2026

DISCUSSION...

The potential for clusters of showers/thunderstorms today and continued spread among hi res solutions in their forecast evolution of convection during the first half of the day leads to continued uncertainty with respect to timing and severe weather potential. Frequent meso anaylsis throughout the day will be in order to fully guage severe potential through the course of today.

Overnight meso analysis indicates the edge of the elevated mixed layer extending into Lower Michigan, contributing to 0-3km MU CAPE of 1500 to 2000 J/kg. Regional radar mosaic shows an axis of convection extending along the edge of the mid level cap and within the gradient of a high instability axis extending from the Arrowhead of Minnesota down to northeast Wisconsin. Another cluster of thunderstorms over eastern Upper Mi is tied to a mid level short wave impulse, forecast to slide across Lake Huron and portions of Se Mi early this morning. This will at least offer the potential for elevated convection to slide into portions of the forecast area from the north early. Veering of the low level inflow across the western Great Lakes this morning will attempt to drive an influx of higher sfc based instability into southern Lower Mi. This will be contingent upon the evolution of convection across Wisconsin/NE Minnesota and the extent of any elevated morning convection dropping into the area from the north. The potential for the aforementioned convection to the northwest to evolve into a forward propagating MCS with a robust rear inflow jet has resulted in SPC upgrading SW Lower Mi and the swrn portions of the DTX CWA from a slight to enhanced risk.

Stronger larger scale ascent along the nose of a 110 knot upper jet and additional mid level short wave energy will arrive across srn Mi late this afternoon and evening. This will support a high probability of showers and thunderstorms. Severe weather potential during this time period will have a large dependance on the coverage of early day convection and the efficiency with which it erodes the instability resorvoir if at all. The variation in how hi res solutions handle early day convection also results in a wide array of forecast storm relative helicity and mid level shear values. This again highlights the importance frequent meso analysis will have during the course of the day.

Mid level trough amplification across the eastern Great Lakes overnight into Tuesday will drive cooler and less humid air into Lower Mi, which will persist through mid week. Model soundings suggest the depth of diurnal cu development on Tuesday may support a few light showers/sprinkes. Mid level anticyclonic flow and sfc high pressure will envelop the region by Wednesday, warranting a dry forecast.

MARINE...

A low pressure system tracks across the northern Great Lakes today. Thunderstorm activity continues to increase in coverage and intensity with this system, especially along the trailing cold front that brings a chance of severe thunderstorms as it moves through the region in the afternoon and evening. Outside of storms, wind and waves are low until the northerly wind shift post front late today night into Tuesday when speeds likely reach 25 to 30 knots over southern Lake Huron. Small craft advisories will likely be needed as elevated waves build over the southern Lake Huron Basin. Winds slowly diminish on Wednesday as large area of high pressure over the Western Great Lakes slowly advances east, arriving on Thursday. This will assure dry conditions for those days.

HYDROLOGY...

Shower and thunderstorms will be possible at any time today. More widespread convection is expected from late afternoon through evening. Intense rainfall rates will be possible with some of the thunderstorms. Probabilities for total rainfall between a quarter inch and three quarters inch are moderate to high. Probabilities for rainfall totals over an inch remain low (less than 20 percent). However, some localized higher totals are certainly possible.

DTX WATCHES/WARNINGS/ADVISORIES

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