textproduct: Detroit/Pontiac

KEY MESSAGES

- Breezy and cooler conditions arrive today with scattered showers through Sunday night.

- Dry weather Monday into Tuesday with a warming trend. The next chance of showers and storms is possible late Wednesday and Thursday .

DISCUSSION

A series of embedded shortwave maxima will dig directly into the central Great Lakes bolstering a closed 560 dam H5 trough through Monday night. Progs show 850mb temperatures bottoming out at +7C which will largely support high temperatures in the lower to upper 70s range the next couple of days, some 3 to 6 degrees below normal. Beefiest of the absolute vorticity maxima will arrive this afternoon with a direct path into the cwa while turning to a negative tilt. Forecast environmental profile shows main limiting factor for today will be very modest midlevel lapse rate structure at 5.5 C/km preceding the absolute vorticity. NWP supports upward vertical motion beginning to deepen after 18z with height falls rapidly pushing to the southeast of Southeast Michigan. Will require a good amount of lift to fight off the subsidence and all signs suggest shower and possible thunderstorm activity being relegated to the far southeast cwa mainly between 21-00z. Guidance looks again underdone. Again, modest lapse rates do not suggest much CAPE density this afternoon and no severe weather is expected.

Closed low pushes eastward leading to 1000-500mb geopotential height rises and surface high pressure Monday. Only real item of note will be the potential for early to mid morning rain showers possible for the northern Thumb region/Huron County as good model signal exists for highly cyclonic flow and confluence downwind of Saginaw Bay and Lake Huron.

Great day Tuesday for outdoor interests with high around 80 and surface dewpoints in the 50s. High confidence in very favorable weather with upper level confluent flow supporting strong surface ridging.

Broad upper level jet streak and associated absolute vorticity wave packet is forecasted to push into the Great Lakes region Wednesday and Thursday. Uncertainty exists on most likely time window for precipitation onset as there will be a dry column preceding the wave. Temperatures are expected to be near late August averages Thursday and Friday.

MARINE

Breezy post-frontal northwest flow to persist today and into the better part of tomorrow as cooler air is ushered into the Great Lakes. Sustained winds of 20 to 25 knots with gusts up to 30 knots are expected, the strongest of which will be found across north- central and central Lake Huron where the fetch is more favorable. Some isolated gust potential to low-end gales cannot be ruled out for Lake Huron, but will preclude any Gale headlines given very low confidence to achieve any prolonged period of gales. Otherwise, rain showers and some isolated thunderstorms will be possible today along with a very low chance for a waterspout, most favorable across Lake Huron. High pressure will start to build into the region late tomorrow and will settle over the Great Lakes by Tuesday. Process of this high pressure moving in will start to relax wind speeds and gusts, leading to light winds by Tuesday.

PREV DISCUSSION

Issued at 1209 AM EDT Sun Aug 23 2026

AVIATION...

A northwesterly wind and cold advection is supporting lingering scattered showers and isolated thunderstorms activity moving across southeast Michigan early tonight. This activity is now east of the terminal corridor. Predominately VFR conditions exists within this environment which should carry through most of the tonight with the exception of possible MVFR conditions developing across PTK/FNT and maybe up to MBS. Gusts to around 20 knots start around 14Z this morning and last through much of the afternoon. Ceilings should remain low VFR with a low probability for scattered showers and possibly some isolated thunder during the afternoon.

D21/DTW Convection...Low potential for isolated thunderstorm focused between 20Z and 00Z.

DTW THRESHOLD PROBABILITIES...

* Low in thunderstorms this afternoon.

* Moderate in ceilings aob 5000 feet today.

DTX WATCHES/WARNINGS/ADVISORIES

MI...Beach Hazards Statement through Monday afternoon for MIZ049.

Lake Huron...Small Craft Advisory until 4 PM EDT Monday for LHZ421-441>443.

Small Craft Advisory until 4 AM EDT Monday for LHZ422.

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