textproduct: Detroit/Pontiac

KEY MESSAGES

- Widespread showers and thunderstorms this morning through tomorrow morning. Additional chances Monday afternoon into Tuesday. - Severe storms are not expected, but there is potential for a swath of locally heavy rainfall focused across the Thumb that may bring localized flooding concerns this morning through Monday morning.

- Slight warmer temperatures and increased humidity during the early to mid week with unsettled weather pattern remaining.

DTW THRESHOLD PROBABILITIES

* Low in thunderstorms this morning and afternoon.

PREV DISCUSSION

Issued at 317 AM EDT Sun Aug 30 2026

DISCUSSION...

Brief period of increasing subsidence will mark this early morning period as high based scattered shower activity from decaying MCS continues to decrease in coverage. Attention quickly turns to an expanding area of precipitation this morning that will continue through today. Widespread/numerous showers and scattered thunderstorms will be forced along a warm frontal zone and theta-e ridge with additional support from the low level jet, though strongest LLJ winds hold to the west. The warm front sets up over Lower Michigan this morning then lifts northward towards the I-69 corridor later today focusing the higher coverage of showers with time across northern Lower Michigan and southeast through the Thumb. The overall airmass will be quite moist as dewpoints climb into the 60s and PWATS values increase to 1.75 inches or greater across southeast Michigan while approaching 2 inches over the Thumb. Overall severe threat will be very limited with the lack of surface instability and mean MUCAPE values generally around 500 J/kg or less, peaking later this afternoon and evening. Main concern will be for repeated rounds of showers and thunderstorms that could bring locally heavy rainfall. After a brief period of lower QPF potential later this evening, an additional uptick in convective potential occurs late this evening through Monday morning as a cold front then drops into northern lower Michigan support a corridor of more focused forcing. While shear will remain favorable, severe potential again looks limited given the weaker instability. Locally heavy rainfall will continue to be the main concern.

Model consensus puts the axis of heavier precipitation focused along and north of a line from Midland to Port Huron. Average total rainfall amounts to around an inch are forecast in this axis starting this morning (12Z) to early Monday afternoon (18Z). A localized swath of 2 to near 4 inches of total rainfall will be possible across parts of the Thumb, which is highlighted well in the HREF 24-hr QPF ensemble localized probability-matched mean. Amounts to half an inch are forecast down to roughly the M-59 corridor and a quarter inch or less south of M-59 down to the southern border.

Southeast Michigan will reside on the northern end of a ridge during the early to mid-week period. Slight increase in heat and humidity will arrive with the persistent west-southwest low to mid level flow. Embedded shortwaves within this flow around the ridge will continue to offer chances of precipitation into mid-week. Given the pattern and potential for continued chances of rainfall and increased cloud cover, current NBM forecast temperatures are probably on the high side mid-week if that pans out. Michigan will remain in a corridor of higher PWATs, which keep the potential for localized heavy rainfall as a concern during this stretch and daily organized convective chances will depend on the degree of instability that is able to develop each day.

MARINE...

We continue the transition out of high pressure today with as a developing low pressure system over the northern Plains begins to impact the area. The leading warm front has lifted into southern Michigan and will keep overcast skies and rain chances through the day. In addition, a cold front will be drifting southward toward the northern Great Lakes adding to the forcing which will drive precipitation chances. Winds will largely be from the south today with max gusts around 20 knots. Winds turn more southeasterly on Monday while remaining mostly below 20 knots before turning westerly on Tuesday.

DTX WATCHES/WARNINGS/ADVISORIES

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