textproduct: Detroit/Pontiac

KEY MESSAGES

- A Frost Advisory remains in effect for portions of Southeast Michigan until 8 AM.

- Cool and mainly dry today, but isolated showers are possible at times between the afternoon hours and the early overnight period.

- Temperatures recover into the 60s on Friday with a few overnight showers possible to the south.

- Warmer Saturday with showers and thunderstorms increasingly likely during the afternoon and evening.

DISCUSSION

System-relative isentropic descent and drying within the 5-12 kft AGL layer is evident in early morning GOES imagery as a partial clearing line advances southwestward across Southeast Michigan. A broken mid-level cloud layer based from 7-11 kft AGL resulted in inefficient nocturnal cooling during the first half of the night. Temperatures are still hovering in the low to mid 40s for some areas under the Frost Advisory, particularly for points southeast of a line from Owosso to Port Huron. Meanwhile, shortwave troughing embedded within the southern extent of retrograding vertically stacked low pressure over Hudson Bay ushers in a final dose of seasonably cold Canadian air. Even though the core of the thermal trough resides over northwest Ontario, KINL 07.00Z RAOB indicated a 500 mb of -28C while positioned along the gradient, approximately 7C colder than the KDTX RAOB. The glancing cold advection should offer a slight boost to cooling prior to sunrise, appropriately timed as skies finally trend clearer.

For the rest of today, additional cyclonically curved low amplitude shortwaves move atop Lower Michigan into the afternoon and evening hours while fringe surface ridging attempts to build beyond Southwest Michigan. Low potential exists for isolated pop-up diurnal showers as a lean channel of 850-700 mb moisture spreads into southern Lower, arriving in time for the diurnal cycle. 07.00Z solutions have trended notably lower with the initiation of isolated showers and QPF footprint for the PM hours, compared to 24 hours ago. In spite of healthy lapse rates, forecast soundings reflect well-advertised low-level dryness, suggesting higher confidence in scattered virga than actual showers. Today will be the coolest day of the week as highs should struggle to break out of the mid 50s. Becoming breezier later in the day as lower column winds rise ahead of the next wave while a deep mixed-layer supports downward momentum transfer. Brief gusts of 20-30 mph should conclude by late evening. An embedded shortwave feature in-two moves from northern Indiana into northern Ohio early tonight with meager ThetaE advection. Perhaps enough lift/moistening will ensue for a secondary sparse light rain response, for some locations across the southern half of the forecast area.

High amplitude longwave troughing persists across eastern North America on Friday with perturbed geopotential height field in place throughout the Great Lakes. Temperature profiles begin to moderate as lower column flow orients southwesterly. A wave along the lee side of The Rockies moves across the southern Plains on Friday, leading to increasingly confluent low-level trajectories. This introduces a plume of higher ThetaE air into the southern part of the state and even a bit of instability as PWATs rise. Warmer Saturday with southwest flow locked-in ahead of a cold front connected to a chain of weak surface lows moving through central Michigan. Timing has moved up with the frontal passage, now favored Saturday afternoon. Standard post-frontal northwesterly wind shift, drier conditions, and a cooler airmass arise to close out the weekend. Unsettled pattern continues early next week as Hudson Bay low remains stationary, eventually getting forced out by a progressive Pacific Northwest speed max.

MARINE

Minimal marine concerns in the next few days as we are locked in with a broad upper level trough through that time. Weak pressure gradient at the surface due to high pressure building in from the south, will keep winds light, generally under 20 knots through Friday. There will be several weak systems over the region during this time as well but really only amounting to low chances of precipitation. The next notable cold front will come through on Saturday bringing increased winds and thunderstorm chances.

PREV DISCUSSION

Issued at 1152 PM EDT Wed May 6 2026

AVIATION...

VFR ceiling above 5000 ft maintains considerable coverage across Lower Mi leading up to midnight. An earlier flare-up of returns on radar toward the Tri Cities and northern Thumb proved to be a substantial virga footprint, save a sprinkle, due to very dry air below cloud base as shown in the 00Z DTX sounding. These cloud conditions are set up by a smaller scale mid level circulation rounding the southern fringe of the Hudson Bay long wave trough. Passage of this wave leads to decreasing clouds late tonight and in the morning until the next mid level feature arrives in the afternoon. This brings a return of VFR clouds above 5000 ft during the afternoon into Thursday evening with a boost of afternoon instability capable of a few sprinkles east of the terminal corridor. The associated diffuse surface pressure field supports light W-NW wind through the period.

D21/DTW Convection...No thunderstorms expected through Thursday.

DTW THRESHOLD PROBABILITIES...

* None

DTX WATCHES/WARNINGS/ADVISORIES

MI...Frost Advisory until 8 AM EDT this morning for MIZ047>049-053>055- 060>063-068-069-075-082.

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