textproduct: Detroit/Pontiac

KEY MESSAGES

- The Air Quality Alert remains in effect through Midnight tonight due to persistence of wildfire smoke causing hazardous air quality.

- Improvement of smoke concentration begins tonight as wind shifts SW after passage of a warm front.

- Thunderstorm potential increases with scattered coverage Friday and Friday night. Severe intensity is not expected.

- There is a Marginal to Slight Risk of severe intensity thunderstorms as coverage becomes numerous Saturday afternoon and evening.

- Dry weather with cooler temperatures and lower humidity moves in by Sunday.

DTW THRESHOLD PROBABILITIES

* High for ceilings at or below 5000 feet today.

* Low in visibilities below 1/2 mile this morning.

PREV DISCUSSION

Issued at 404 AM EDT Fri Jul 17 2026

DISCUSSION...

We remain under the main plume of smoke from the wildfires burning over northern MN and Ontario to start the day. Overnight, AQI scores continue to hover in the 300-500 range which is the most dangerous "Hazardous" category. This will continue through the first part of the day, before a warm front lifts through southern MI this evening, flipping surface winds around to the southwest which should push the denser smoke out of the region bringing improved conditions for tonight. The Air Quality Alert remains in effect through midnight tonight.

Attention then turns toward the next trough diving SE through central Canada and into the northern Great Lakes Saturday. This trough will break down the ridge that's been locked over the region and bring the next chance of thunderstorms. The surface reflection out ahead of the trough will track along the international border today with a warm front extending SE from northern MN to roughly CHI this morning. The front will get pulled northeast through southern MI today. Models continue to advertise isolated to scattered coverage of thunderstorms later this afternoon into the evening as the front passes. Very warm low levels will cap any early storms from developing, with best timing of some elevated activity from about 2p to 8p. SPC continues to highlight the region as General Thunderstorm due to storms likely being elevated, low CAPE values around 500 J/kg and shear in the 20 to 30 knot range. Will have to watch any storm that tries to latch onto the front itself though.

Better chance of storms, and strong to severe storms, will come on Saturday as the cold front drop SE through the region. Frontal timing look to be in the 10am (Mid MI) to 4pm (Detroit Metro) window. Strong low level jet increasing to around 40 knots overhead will help fuel storms. CAPE will surge to aoa 2500 J/kg per most models with bulk shear exceeding 30 knots. There also looks to be strong surface convergence and a narrow but intense vorticity axis dropping through along the front. With the timing of the front reaching Metro Detroit, SPC Day 2 has extended the Slight Risk area northward to include locations along and south of a line from Howell to Port Huron. Main risk will be damaging wind with a 2% Tornado risk as well. PWATs nearing 2 inches with surface dewpoints in the low 70s will offer plenty of moisture for storms to produce brief heavy downpours, but progressive storm motion should reduce flooding threats.

Cooler conditions with northerly flow sets up in the wake of the cold front starting Saturday evening leading to high temps around 80 on Sunday. Ridge tries to build back eastward into the Great Lakes early in the week, but another strong Canada trough will suppress the ridge and bring troughing over the region for the latter half of the upcoming work week. There will be potential for storms on a couple days as some mid level waves pass over, otherwise expecting cool conditions with highs possibly struggling to rise out of the 70s.

MARINE...

Visibility reductions to 1 nm or less persist across the entire central Great Lakes today due to dense Canadian wildfire smoke, therefore, the Dense Smoke Advisory has been extended. Weak low pressures systems emerge over the northern Plains and Lower Ohio Valley this morning, eventually converging on the Great Lakes region. This leads to more active weather with periods of showers and thunderstorms later in the day. Smoke begins to clear late tonight as the southern system dissipates along a lifting warm front, flipping winds south-southwesterly. A secondary, and more robust, low pressure system passes through The Straits and across northern Lake Huron on Saturday. This drags an attendant cold front through the waterways, causing gusts within the southern Lake Huron nearshores to exceed 25 knots. A Small Craft Advisory may be needed with subsequent forecast updates. High pressure then builds back into the region late Saturday and Sunday supporting drier conditions and prevailing winds below headline criteria for rest of the weekend.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Dense Smoke Advisory until 4 PM EDT this afternoon for LHZ362-363- 421-422-441>443-462>464.

Dense Smoke Advisory until 9 AM EDT this morning for LHZ361.

Lake St Clair...Dense Smoke Advisory until 4 PM EDT this afternoon for LCZ460.

Michigan waters of Lake Erie...Dense Smoke Advisory until 4 PM EDT this afternoon for LEZ444.