textproduct: Detroit/Pontiac

KEY MESSAGES

- A stray shower or thunderstorm early this evening gives way to a dry and warm night.

- Additional showers and perhaps a thunderstorm clip the area toward sunrise or early in the morning. An isolated strong storm capable of damaging winds is possible though overall potential is low.

- Better chances for storms Monday evening ahead of an approaching cold front. A few severe storms producing damaging wind gusts are possible.

- More seasonably average airmass returns for midweek.

DTW THRESHOLD PROBABILITIES

* Low for ceiling at or below 5000 feet tonight and Monday.

* Low for thunderstorms this evening, Monday morning, and Monday afternoon/evening.

PREV DISCUSSION

Issued at 300 PM EDT Sun Jul 26 2026

DISCUSSION...

Heat and humidity have returned today with most of the area now seeing temps in the upper 80s and dewpoints in the upper 60s. Model advertised elevated warm layer was sampled by the 12Z KDTX RAOB at 725mb providing a modest cap to convective potential this evening. While CAMs suggest around 1000 J/kg of both SB/MLCAPE available late day, they struggle to overcome said cap and generate much more than an isolated pop-up shower/storm. Afternoon radar trends appear to confirm this with only isolated pop-up light showers thus far. As such, its more likely that the vast majority of the area stays dry this evening. The conditional severe chance if any updraft can break through the warm layer is likewise low this evening as column winds below 700mb hold aob 20kts confining the bulk of shear above 3km. For the late evening-overnight period, there has been notable convergence amongst high-res models in the CAPE gradient failing to cross Lake Michigan, instead stalling along the WI shoreline. This results in developing MCS(s) over the western Lake Superior basin to exhibit a due south drift in track along Lake Michigan entirely missing SE MI (aside from perhaps some light trailing stratiform showers clipping portions CWA). While the forecast tonight will still keep a slight chance (15-20%) mention for rain, severe chances are now looking to be minimal.

How exactly Monday panes out will depend on the progression of tonight's storms over the western Great Lakes, in large part their affects on the CAPE gradient. With the current favored scenario of a Lake Michigan track, this effectively pinches off southern lower MI instability confining main reservoir to WI/IL Monday. With weak lower level winds still in place, advection of this gradient east is slow, not reaching central southern MI until Monday late afternoon pushing the main local convective window back towards ~22-00Z. Still a good spread in outcomes wrt to the robustness of said convection however given the stronger synoptic setup (ie mid-level trough digging into the central Great Lakes and an associated surface cold front dropping south) would expect at least scattered thunderstorm coverage locally. For severe potential, forecast soundings show only marginal improvements in low level winds relative to today (~5kt increase) again confining the majority of shear around/above 3km. Magnitude of available instability is still uncertain given the dependency of advection, but shear profile does not lend confidence in severe storm chances.

MARINE...

Still opportunity for isolated/scattered showers/thunderstorms to go up the rest of the evening and tonight, as the Central Great Lakes resides on the outer fringe of a very strong upper level ridge centered near the Four Corners region. A low pressure system then tracks across the northern Great Lakes during Monday. Thunderstorm activity continues to increase in coverage and intensity with this system, especially along the trailing cold front that brings a chance of severe thunderstorms as it moves through the region. Outside of storms, wind and waves are low until the northerly wind shift post front late Monday night into Tuesday when speeds likely reach 25 to 30 knots over southern Lake Huron. Small craft advisories will likely be needed as elevated waves build over the southern Lake Huron Basin. Winds slowly diminish on Wednesday as large area of high pressure over the Western Great Lakes slowly advances east, arriving on Thursday. This will assure dry conditions for those days.

HYDROLOGY...

Convective rainfall chances will increase Monday afternoon and peak Monday evening. Locally intense rainfall rates will be possible with any convection. There is the potential for a couple rounds of showers/thunderstorms over some areas during this time period. Probabilities for a quarter to one inch of rain are moderate to high. The chances for locations to exceed an inch are low (less than 20 percent) at this time.

DTX WATCHES/WARNINGS/ADVISORIES

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