textproduct: Detroit/Pontiac

KEY MESSAGES

- Cool today and Thursday with daytime highs in the 50s and overnight lows in the 30s; some morning frost is possible on Thursday.

- Mainly dry today and Thursday, but isolated late afternoon and/or evening showers are possible.

- Temperatures recover over the weekend with additional rain chances; potential exists for thunderstorms Sunday.

DTW THRESHOLD PROBABILITIES

* None

PREV DISCUSSION

Issued at 358 AM EDT Wed May 6 2026

DISCUSSION...

The final round of light showers is finally winding down along the Michigan/Ohio border as persistent 800-750 mb system-relative ascent and axis of ThetaE advection drift eastward and exit. Several continental wave mergers are underway early this morning, but the most significant is occurring with the northern and southern stream longwave troughs over the Mississippi Valley. As the day progresses, the resultant unified jet axis will extend an impressive distance, some 3,000 miles between the Baja Peninsula and Labrador Sea. Southeast Michigan will be situated adjacent to the western edge of the jet streak, and between associated lobes of vorticity. Governing barotropic low slowly retrogrades over Hudson Bay today which helps direct colder air aloft into the Great Lakes region. Benign conditions are favored with this configuration at least through the midday hours. A packet of mid-level height falls along a shortwave trough positioned within the mean flow is directed into Lower Michigan. No meaningful precipitation response is expected with this feature as a more zonal orientation to tropospheric flow ushers in drier Canadian air throughout the day. Diurnal mixed-layer will be fairly developed, extending to the 7-9 kft AGL layer, but capping above ensures nil instability. At most, could see some virga in some vertically mature cumuliform clouds. Nocturnal cloud fraction aloft will dictate frost potential late tonight into Thursday morning.

Anticyclonically curved surface pressure gradient extends into southern Lower on Thursday while the next embedded shortwave trough takes aim at the Tri-State area. Non-zero chance for some pop-up diurnal showers as a ribbon of 850-700 mb moisture spills into the lower peninsula during the afternoon heating cycle. Both coarse and high resolution 06.00Z solutions include isolated to scattered showers/QPF. Thursday is also shaping up to be the coolest day of the week marked by 850 mb temperatures of -3C to -6C. Highs should struggle to break out of the mid 50s. Late-day gustiness arises as lower column flow increases amidst favorable mixing profiles, but nocturnal cooling should outpace advective cooling after low veers northwesterly, ending 20-25 knot gusts by late evening.

The unified jet axis orients equatorially through the Tennessee Valley on Friday, modified by the next shortwave digging into the Mid-Mississippi Valley. Weak surface reflection is noted in NWP with precipitation shield clipping the southern forecast area Friday, and into the overnight hours. Thermal moderation with upward trend in PWATs aligns with NBM guidance of Chance PoPs at this juncture. Warmer Saturday with southwest flow ahead of a late weekend cold front. A period of showers and thunderstorms is probable in relation to the frontal passage.

MARINE...

Winds are expected to stay on the light side (under 20 knots) for the rest of the work week as a weak pressure gradient lingers. This is despite a cooler airmass in place, with sub zero 850 MB temps.

A pattern of weak clipper systems brings periodic chances for showers which will continue into the weekend as milder air and higher moisture levels arrive. As it stands now, this leads to Saturday night being the primary window for showers and isolated thunderstorms as a cold front slowly moves through the region.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Small Craft Advisory until 10 AM EDT this morning for LHZ421-441.

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