textproduct: Detroit/Pontiac

KEY MESSAGES

- Stretch of warm conditions throughout the work week with daytime temperatures in the 70s each day for most locations.

- Scattered to numerous showers and thunderstorms develop tonight. Potential exists for isolated severe storms capable of producing wind gusts to 60 mph and large hail. Locally heavy rainfall also possible.

- An active pattern will maintain periodic chances for showers and thunderstorms Tuesday through Thursday. Each episode brings the possibility for locally heavy rainfall.

- There is a Slight Risk for severe thunderstorms Tuesday night, mainly between 8 pm and 2 am. Storms will be capable of producing wind gusts to 60 mph, large hail and isolated tornadoes.

DTW THRESHOLD PROBABILITIES

* High for ceilings aob 5000 feet tonight and Tuesday.

* Moderate for thunderstorms early Tuesday morning.

PREV DISCUSSION

Issued at 252 PM EDT Mon Apr 13 2026

DISCUSSION...

Higher magnitude warmth within breezy southwest wind marking conditions late afternoon. High temperatures again arriving a solid 15 to 20 degrees above normal - mid to upper 70s most locations. General mid level stability will hold into the early evening hours as shortwave upper ridging propagates through, ensuring dry conditions persist into the early evening hours. Attention then turns to two seperate areas of focus for convective development and expansion tonight. Remnant convective cluster evident on water vapor and radar lifting northeast into northern IL now forecast by an increasing number of hi res solutions to maintain some degree of integrity as it ejects across southern lake MI/northern IN. This will occur with the backdrop of another period of nocturnal warm/moist air advection as 850 mb flow strengthens within southwest flow across the warm sector. Forecast now highlights an increasing potential for convective development/expansion within the 00z-06z window as associated ascent works through. Any late evening activity likely to be slightly elevated as nocturnal boundary layer cooling affords a standard stable near surface layer. With that, isolated deeper updrafts plausible given the steepness of lapse rates above the stable layer, with adequate bulk shear for greater organization. This maintains potential for some instances of larger hail and gusty winds, in addition to brief heavy rainfall. Additional convective organization and expansion expected this evening along/north of a frontal boundary extending across central WI. This activity likely to consolidate with time as it spills east/southeast into the early morning hours, but mixed signal yet on both trajectory and scale. Steep mid level lapse rates will maintain a risk for hail with any healthier cores. Latest SPC Day 1 outlook continues to highlight all of Southeast Michigan within a Marginal Risk for severe weather for tonight.

The resident airmass remains virtually unchanged heading into Tuesday. Some degree of stability may exist for a portion of the daylight period, pending the coverage and pace of exit of overnight activity. Solid diurnal destabilization likely by afternoon, at least across the south, where MLCAPE pushes 1500+ as temps again climb well into the 70s and dewpoint hovers in the lower 60s. Some evidence of a weak frontal zone or differential heating boundary bisecting the area. This could offer a lower coverage of convection for peak heating. Otherwise, still no evidence of more meaningful forced ascent materializing prior to 00z Tuesday evening.

Existing mid level southwest flow ripe with minor perturbations and bouts of greater moist isentropic ascent continue to present a favorable, yet challenging background environment to gauge convective potential locally Tuesday night. There remains strong model evidence for convective initation and expansion to occur in the vicinity of the frontal boundary across northern IL/southern WI and western lower MI Tuesday evening. Very supportive environment will exist for the maintenance and possible upscale growth of this activity into portions of southeast Michigan sometime within the 00z to 04z window. While the nocturnal timing brings lessening instability with time near the surface, MuCape projected to exceed 2000 j/kg. Frontal zone now draped across the Saginaw valley and thumb will offer a greater focus across this region. In fact, noteworthy backed/southeast low level flow at the frontal interface gives pause to the possibility for organized updrafts to rotate. A mix of discreet and multicellular clusters will bring the risk of all hazards - strong winds, large hail and isolated tornadoes. All of Southeast Michigan remains with a Slight Risk for severe weather Tuesday night. Some areas of heavy rainfall also a concern given expectation for efficient rates given high end moisture content /PW near 1.3"/.

Mild/moist airmass still entrenched Wednesday and Thursday. Outgoing forecast continues to highlight expectation for a high coverage of showers and thunderstorms Wednesday, but some downward revision in precip chances possible as greater focus may again hold to the south and west during the daylight period. Another nocturnal convective response likely Wed night as moisture transport increases along the nose of the low level jet. Periodic chances for additional showers and thunderstorms lasting into Thursday. Dry and continued mild Friday, then rain chances increase again early next weekend.

MARINE...

Shortwave ridging this afternoon has led to pleasant marine conditions under a modest southwest breeze. Pockets of 25 knot gusts are observed over land, but quickly drop off offshore where profiles are more stable. Attention turns to an upstream cluster of thunderstorms over northern Illinois that will track into southeast Michigan after sunset this evening. These storms will be capable of large hail to an inch, frequent lightning, and isolated gusty winds over 35 knots. This will be the first of several rounds of nocturnal thunderstorms this week as multiple waves of low pressure ripple along a stalled frontal zone. Each round of storms will bring potential for strong to severe storms to the southern half of Lake Huron, Lake St. Clair, and western Lake Erie. The front is forecast to hover around the Saginaw Bay area, with northerly winds emerging north of front and southwest winds for points south. Wind and wave concerns this week will be tied to thunderstorm activity.

HYDROLOGY...

An active pattern will bring periodic chances for showers and thunderstorms tonight through Thursday. Each episode brings the possibility for locally heavy rainfall, particularly where focused areas of thunderstorms develop. Rainfall amounts in excess of half an inch will be possible for a round of rain tonight. Additional rainfall between one and two inches currently forecast to fall between Tuesday and Thursday. While widespread flooding is not expected, some minor flooding of low lying, poor drainage and urban areas along with rises on area rivers are possible.

DTX WATCHES/WARNINGS/ADVISORIES

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