textproduct: Detroit/Pontiac

KEY MESSAGES

- Showers and a few embedded strong thunderstorms work through southeast Michigan this evening into Sunday morning.

- Dry Monday, but showers and possible storms return Tuesday afternoon and late Wednesday/Wednesday night.

- Heaviest rainfall looks to be Wednesday night, with the potential to exceed 1 inch.

DTW THRESHOLD PROBABILITIES

* Low for a thunderstorm after 08z Sunday.

PREV DISCUSSION

Issued at 356 AM EDT Sat Jun 13 2026

DISCUSSION...

Mostly clear skies start the day, but regional radar showing a cluster of showers upstream over the Midwest highlights what's to come later this evening as a cold front moves in. Dry conditions prevail locally today as Ohio Valley high pressure and zonal flow aloft maintain stable conditions, but there is a low probability for some showers in the northern Saginaw Valley and Thumb midday as a surge of low-level theta-e arrives from the south. Low to mid-level southwest flow strengthens as the high migrates toward the Appalachians and the cold front approaches from the Midwest. High temps are forecast to reach the mid to upper 80s with the southwest wind becoming gusty to 20 to 30 mph by mid-late afternoon. Parts of the Saginaw Valley and Thumb could see gusts up to 35 mph as daytime mixing taps into higher momentum within a LLJ passing across northern Lower MI.

A spoke of vorticity rotating around the closed low over northern Ontario induces a period of gradual height falls this evening, causing the cold front to sink southward into the area. This will trigger a broken line of showers with embedded thunderstorms late this evening. The highest coverage looks to set up north of I-69 where a feed of marginal instability will be directed and CIN will be lowest. A window for isolated strong to severe storms and briefly heavy rain exists between 11pm to 4am while overlap exists between frontal forcing, marginal SBCAPE, and deep layer wind shear of 35 to 40 kt. Primary threat appears to be wind gusts of 45 to 60 mph given the storm mode and available momentum in the column. Signal among ML severe weather probability tools corroborates the SPC Day 1 Marginal Risk for the area. Showers with embedded thunder will continue overnight as the front progresses southward and weak low pressure develops along it.

A flare-up in shower activity is forecast Sunday morning as PVA and divergence aloft spread in ahead of the mid-level shortwave arriving from the Midwest. Frontogenetical forcing will contribute to some enhancement of lift on the cool side of the front and some areas may see multiple rounds of moderate showers. Coverage will then gradually taper off through the afternoon with post-frontal temperatures much cooler in the upper 60s near the lakeshore and 70s elsewhere.

Longwave troughing aloft dominates the Great Lakes early next week with temperatures remaining on the cool side of average. Dry conditions are favored Monday, then showers and storms reenter the picture Tuesday through Thursday as a series of shortwaves traverse the region. There is a signal for a more vigorous wave to track through late Wednesday into Thursday, with potential for heavy rainfall and/or severe weather in the region as divergence aloft and strong kinematics accompany the wave. LREF grand ensemble data indicates a 30% chance for portions of the area to exceed 1" during this period.

MARINE...

High pressure has expanded across the southern Lakes while a cold front over the northern Lakes starts drifting south reaching Central Lake Huron this evening. This will help keep a fairly tight pressure gradient in place across the region today with southwesterly winds gusting to around 30 knots over Saginaw Bay and the tip of the Thumb this afternoon. A Small Craft Advisory is in effect through 10pm to account for the wind and waves. The front will also offer a round of showers and thunderstorms affecting northern Lake Huron through the day, and the rest of the area through the night. The front then sweeps east by Sunday morning. Winds will stay elevated around 20 knots, but out of the northwest Sunday.

HYDROLOGY...

Scattered to numerous showers and storms are expected tonight through early Sunday as a slow moving cold front tracks southward across the area. Most areas are forecast to receive a quarter inch or less of rainfall. Localized areas that see repeated rounds of moderate showers/storms may receive in excess of 1 inch and ponding of low-lying or poor drainage areas is possible.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Small Craft Advisory until 10 PM EDT this evening for LHZ421-422- 441.

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