textproduct: Detroit/Pontiac

KEY MESSAGES

- Freeze Warnings are in effect tonight for the Thumb and portions of the Tri Cities. A Frost Advisory is in effect tonight for the remainder of Southeast Michigan.

- Numerous to widespread showers with a rumble of thunder move in Tuesday afternoon and night. No severe weather is anticipated although small hail will be possible.

- A warming trend carries temperatures above normal next weekend.

DTW THRESHOLD PROBABILITIES

* Very low for thunderstorms early Tuesday night.

PREV DISCUSSION

Issued at 222 PM EDT Mon May 11 2026

DISCUSSION...

Canadian surface high pressure will center over the Great Lakes aggregate this evening, only drifting to Lake Erie and Lake Ontario midday Tuesday. Strong signal exists in evening marine layer/lake breeze release off of Lake Huron westward into the cwa. High confidence exists in calm wind environment developing with ideal radiative cooling conditions tonight. The question comes down to whether or not the interior Thumb down into northern Macomb county will need a Freeze Warning versus a Frost Advisory. Otherwise, Frost Advisory will be needed. Will make headline decisions later on with neighbor collaboration considerations.

Compact upper level jet streak packet with sharp cyclonic curvature to the speed maxima will dig into the Great Lakes Tuesday. Latest trend of the model data supports greatest low level warm advection and 850mb frontogenesis will push through the northern cwa in vicinity of and to the north of Saginaw Bay between 15-20z. Looking at high based lead isentropic ascent activity early on and the gridded forecast has greater than 60% PoPs. Not expecting a long duration of precipitation during daylight hours with mean RH in the forecast soundings struggling to saturate in the lowest 7.0 kft agl. A big narrative with this system will be low dewpoints that will ultimately limit instability. Forecasted 2m dewpoints are not expected to climb above 50 degrees until 03z Wednesday with MUCAPES only rising to 400-500 J/kg from northwest to southeast between 01- 07z Wednesday morning. A steepening of lapse rates in the lowest portion of the column will be possible across the southern forecast area around the 06-07z time window, which could allow for some gusty west winds with some outlow contribution (40 mph or less). Otherwise, small hail will be possible with activity along with a brief heavy downpour. Absolute shortwave energy within the composite trough axis and associated cold midlevel air will support scattered rain shower activity through Wednesday afternoon and evening.

The combination of upper level confluence and rising geopotential heights will support another period of surface high pressure late Wednesday night through a good portion of Friday. Below normal daytime temperatures are expected Thursday.

Progressive Pacific jet streak and airmass is then expected to push into the state for next weekend. Reasonably high confidence signal exists for a milder and higher dewpoint airmass over the area. Lots of uncertainty with regards to timing and duration of rain shower activity from late Friday through the weekend. Latest model data has less coverage for the synoptic scale warm advection rain activity late Friday here over Michigan with low confidence then brewing because of a favorable pattern for convection and MCS systems upstream over the Northern Plains. High temperatures next weekend could very well end up near 80.

MARINE...

High pressure centrally located over the Great Lakes will depart and wash out across New England through tomorrow morning. This will maintain light winds through today and will reorient wind direction from the southeast by tomorrow morning. A low pressure clipper system will then progress from the northern Plains into lower Michigan late Tuesday into early Wednesday. The pressure gradient will strengthen as a result and will increase the magnitude of southeast flow, producing gusts ranging 20 to 25 knots. This will quickly elevated wave heights aoa 4ft across the Lake Huron shoreline and through the Saginaw Bay, where Small Craft Advisories are now in place. Passage of the low will veer wind direction from southeast to northwest on Wednesday. Rain showers with some embedded thunderstorms will be likely this system. A lull in wind speeds and wave heights will be likely as the low progresses directly over the state. However, the northwest flow will accelerate cold air advection, improving mixing depths and likely bringing renewed gust potential towards 25 knots late Wednesday into Thursday.

DTX WATCHES/WARNINGS/ADVISORIES

MI...Freeze Warning from midnight tonight to 8 AM EDT Tuesday for MIZ047>049-054-055-062-063-070.

Frost Advisory from midnight tonight to 8 AM EDT Tuesday for MIZ053- 060-061-068-069-075-076-082-083.

Lake Huron...Small Craft Advisory from 4 PM Tuesday to 4 AM EDT Wednesday for LHZ421-422-441>443.

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