textproduct: Detroit/Pontiac

KEY MESSAGES

- Showers increase coverage tonight with a chance of thunderstorms.

- Showers become numerous to widespread Saturday as a cold front moves through the region. Scattered thunderstorms present a Marginal Risk of severe intensity Saturday afternoon.

- Breezy and cooler conditions arrive Sunday with a lingering chance for showers.

- Dry weather with slightly below normal temperatures start off the week on Monday.

DISCUSSION

Today starts out with high pressure centered to our east but still in control of conditions across SE Mi before it departs into the New England states this afternoon. The very beginning of weak southerly flow in the lower to mid levels shows signs of moisture transport in patchy mid level clouds under cirrus streamers during the morning. Mid and high clouds then increase in the afternoon, mainly toward the Tri Cities and west of I-75, as moisture transport increases modestly ahead of Midwest low pressure. Guidance high temperatures in the lower 80s are reachable given adequate sunshine at least through early afternoon.

The leading low amplitude 500 mb trough could touch off a stray shower late in the day, however potential becomes better organized this evening as the trough combines with deeper and slightly stronger SW flow within the warm sector moisture axis. Shower coverage is scattered to briefly numerous during the late night into Saturday morning as the center of low pressure reaches the Straits while pulling the cold front into Lower Mi. Frontal timing remains favorable for passage through SE Mi during Saturday afternoon peak heating with a boost of forcing from the primary mid level short wave. However even then, HREF mean surface based CAPE struggles to exceed 1500 J/kg at least partially due to high temperatures that also strain to reach 80 across the region. This instability profile combines with about 25 knots of westerly bulk shear for a standard multicell convective mode that carries a Marginal Risk of approaching severe intensity. Numerous to widespread coverage of showers focusing along the cold front has greater confidence until the system exits eastward early Saturday evening.

NW wind gusting around 25 mph post front reinforces cooler air across the region Sunday. A partly sunny/mostly cloudy sky with a stray shower are expected for much of the day as the low level thermal trough digs into the central Great Lakes. Cold advection brings 850 mb temps down into the single digits by Sunday night which makes low temperatures in the upper 40s reachable outside of the larger metro areas by sunrise Monday.

MARINE

Light easterly flow this morning gradually backs to the south- southwest through the day as high pressure peels off into New England. Meanwhile, low pressure organizes upstream with shower and thunderstorm chances beginning as early as this evening near the Mackinac Straits. Rain chances then spread across the rest of the marine zones overnight-Saturday. Periods of dry weather mix with multiple rounds of rain activity throughout the day before clearing out Saturday night as a cold front sweeps across the region. The front quickly shifts winds from the south to the northwest, which will pair with cold advection to produce gusty winds over Lake Huron Sunday and Monday. Strongest gusts around 30 knots are expected Sunday afternoon-evening, but will hold around 25 knots through Monday as well. Elevated waves are also expected, likely to exceed Small Craft Advisory thresholds from at least Outer Bay to Harbor Beach. A quieter pattern arrives Tuesday, but is quickly followed by the next system mid-week.

PREV DISCUSSION

Issued at 1206 AM EDT Fri Aug 21 2026

AVIATION...

VFR conditions are expected to prevail through the morning hours as high pressure moves through Michigan. A easterly wind component will become southerly this afternoon while holding between 5-10 knots. Mainly scattered high clouds through the rest of tonight with increasing coverage towards this evening. Ceilings should remain VFR as increasing scattered mid clouds arrive mid-day with a low chance for scattered showers tonight.

D21/DTW Convection... No convection is forecast for the period.

DTW THRESHOLD PROBABILITIES...

* None.

DTX WATCHES/WARNINGS/ADVISORIES

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