textproduct: Detroit/Pontiac

KEY MESSAGES

- Mostly dry conditions and warmer temperatures today.

- Showers and thunderstorms tonight and tomorrow will pose a locally heavy rainfall threat.

- Wednesday and Thursday will see hot and humid conditions along with additional thunderstorm chances.

DTW THRESHOLD PROBABILITIES

* Low for cigs aob 5000 feet this evening becoming high by Tuesday morning.

* Low for thunderstorms 05z through 16z Tuesday. Medium after 16z Tuesday.

PREV DISCUSSION

Issued at 400 AM EDT Mon Jun 8 2026

DISCUSSION...

Surface high pressure slides through the eastern Great Lakes today with the high amplitude ridge to follow. Dry conditions are expected to hold throughout the bulk of the daylight hours while still under the influence of the high pressure. An increase in mean thickness today will lead to a bump in afternoon high temperatures this afternoon into the mid and upper 80s for most of the area.

A lower amplitude wave will be lifting into the Midwest being drawn northward by the larger trough over the Canadian Rockies. The increasing low level jet flow with this approaching wave will lead to moisture transport of rich moisture environment with ties to the Gulf into Michigan tonight and tomorrow. Initial sign of this moisture will be with increasing cloud cover and POPs creeping into southwest portions of the CWA late this afternoon. Greater POPs look to hold off until after 8 pm this evening as scattered activity arrives with the lead ascent. Likely showers and scattered thunderstorms expected during the day Tuesday supported by larger scale ascent with the wave moving overhead and increasing diurnal instability. PWATs are expected to climb to around 2.00 inches, which will be well above climatological norms and ranking around the 99th percentile, while surface dewpoints climb to the mid/upper 60s to low 70s. Forecast soundings continue to indicate tall skinny CAPE profiles, weak cloud layer winds, and warm cloud depth. The result will be convection that will pose a locally heavy rainfall threat given the impressive moisture that will available along with the slower storm motion. The overall severe threat will remain low given the weak shear profiles, but isolated strong winds will remain possible given the potential for water loaded downbursts.

Return flow becomes established Wednesday east of troughing extending across the northern plains into the upper Midwest. This will lead to strong low level warm advection that will send 850 mb temperatures to around 20C. Forecast will continue to highlight the mid to late week heat and humidity. NBM continues to be on the higher side of guidance, but airmass will be supportive of temperatures well into the 80s and possibly low 90s as surface dewpoints hold in the 60s to low 70s. This would put heat indices that will approach 100 degrees if the higher temperatures look to verify. The higher temperature outcome will be dependent on the convective potential and associated cloud cover both Wednesday and Thursday. Stronger southwest flow with increasing bulk shear and moderately strong instability elevates the severe weather potential both Wednesday and Thursday/Thursday night.

MARINE...

High pressure will center over New England this morning which will back wind direction from east to southeast. Winds will remain light with dry weather expected for most of the day. A weak low pressure system will arrive late tonight into tomorrow which will bring scattered to numerous showers and a chance for some embedded thunderstorms. There will be some additional chances for rain showers and thunderstorms Wednesday into Thursday. The overall pressure gradient will stay weak, holding wind gusts aob 20 knots through the middle of the week, with some localized stronger gusts possible with any thunderstorms.

HYDROLOGY...

A moisture rich environment will pose a locally heavy rainfall threat late tonight through Tuesday. Majority of ensemble members put QPF amounts within 0.25" to 0.75", but the environment will be supportive of pockets of 1.00" to 2.00" rainfall amounts or greater. Thus, highly variable amounts are expected across southeast Michigan. Convective rainfall rates will have potential to reach 1.00" or greater at times, especially during the day Tuesday. Low confidence exists at this time as to where these heavier pockets of rainfall would fall, but the environment will certainly support isolated flash flooding potential especially if it occurs over any urban areas or flood prone areas.

DTX WATCHES/WARNINGS/ADVISORIES

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