textproduct: Detroit/Pontiac

KEY MESSAGES

- Chance for drizzle or light rain this evening, mainly along or south of M59.

- Showers and thunderstorms return late Saturday into Sunday.

DTW THRESHOLD PROBABILITIES

* Low for ceiling 5000 feet or less tonight. Moderate Friday.

* Low for visibility restrictions of 1/2sm or less or ceilings at less than 300 ft.

PREV DISCUSSION

Issued at 337 PM EDT Thu Aug 13 2026

DISCUSSION...

Upstream MCS now entering Indiana will continue to progress east through the evening. Convective activity will stay locked to the CAPE gradient which resides across central Indiana and trails down into southwest Ohio. However, the associated stratiform region which extends through southern Lake Michigan will attempt to work across the southern portion of the cwa through the evening. A modest dry 10kft dry layer in the low to mid levels of the atmosphere will work to erode northern periphery of the ongoing stratiform rain, but there looks to be enough saturation to overcome this layer closer to the MI/OH border. The chance for this drizzle or light rain will extend north to M59, but the more favorable probabilities are hedged to the south. Some isolated rumbles of thunder cannot be ruled out noting elevated cape value aob 500 J/kg, but overall cape density is poor with a weak and elevated cap around 20 kft. Any prolonged activity is expected to hold just along or south of the state line, mainly across the Ohio Valley.

Limited forcing under diffuse high pressure brings mostly dry conditions tomorrow. The exception for very low end chances will again reside closer to the MI/OH border if the northern periphery of precipitation from low-level convergence encroaches into the cwa. Increasing shower and thunderstorm chances enter on Saturday with the best chances centered Saturday evening to Sunday morning. Initial shower and storm chances will be tied to lift along a warm front that will push through in the late afternoon to evening hours. W-E re-orientation of the llj will rapidly enhance moisture advection, increasing pw values aoa 2" by Saturday evening with 850mb dew points nearing 18C. Any subtle forcing will be capable of producing showers or storms, but any more widespread activity would likely be tied to maintenance and progression of a mcs originated from the Plains. Passage of this system and area of convectively enhanced low pressure will work to push a weak cold front across the Great Lakes on Monday. This will afford a window for drier conditions Monday- Tuesday along with slightly cooler temperatures with highs in the low 80s.

MARINE...

High pressure continues to build across the Great Lakes and Ontario leading to generally quiet conditions across the region. The high will be slowly shifting eastward eventually reaching the eastern lakes by Saturday morning. The stalled frontal boundary is still lingering to the south and will be the focus for another round of storms tonight, but it looks like most of the local area would avoid the convection. Once the high pushes off to the east Saturday, the next low will be developing to the west and should pass through the area in the evening and overnight. Winds will be light and variable tonight before becoming northeasterly Friday and increasing to 10 to 20 knots across southern Lake Huron. Winds then turn southerly late Saturday and increase to around 20 knots ahead of a cold front Saturday night. Winds then shift to the northwest on Sunday behind the front.

DTX WATCHES/WARNINGS/ADVISORIES

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