textproduct: Detroit/Pontiac

KEY MESSAGES

- Showers with some embedded thunderstorms likely this evening, ending late tonight. There is a Slight Risk of severe storms along and south of the I-94 corridor. All hazards possible (wind, hail, and tornadoes), but hail is most favorable for any stronger storms.

- Colder air arrives tonight and Friday, followed by a steady warming trend through early next week.

DISCUSSION

For this evening... Widespread showers and embedded thunderstorms to expand along and in the wake of an advancing cold front as stronger large- scale ascent increases in conjunction with an approaching 700mb jet. The greater severe weather threat remains conditional and partially tied to a narrow and limited time window within the warm sector, focused mainly south of I-94.

Forecast soundings highlight impressive bulk shear values ranging between 70-80 knots through the afternoon and evening, which is readily apparent within storm relative hodographs, noting the elongated extension from 1km through 6km, with a significant streamwise component. That said, the conditionality of strong to severe storms will be tied to the rapid cold frontal progression and associated cold air intrusion which will undercut any late afternoon activity and favor a transition from surface-based storms to elevated convection. This creates a setup where any storm able to briefly remain rooted within the warm sector just ahead of the front could organize quickly and produce a window for severe weather. All storm modes would be possible in this scenario, which includes an isolated tornado, damaging wind gusts (60+ mph) and/or large hail (2+ inches). However, the current response relative to the latest 12Z cams has been relatively muted under copious cloud cover and under some scattered early afternoon rain showers.

Thus the more favorable evolution for today trends toward elevated convection after the surface cold front moves through, which is now just north of I-94. The primary hazard with this setup would be large hail with any severe thunderstorm development. The aforementioned strong kinematics in the 1-6km layer and mid-level lapse rates 7-8C/km with modest MUCAPE does bring the potential to see 2+ inch hailstones in a higher-end scenario through the evening, again favored around I-94 and south. Some low end chances for hail to an inch will be possible north through M59 where mid-level lapse rates are weaker. Rain and thunderstorm chances end from north to south between 8PM to around Midnight. Strong cold air advection in the wake of the cold front drops overnight lows into the 20s.

Continued caa tomorrow with 850mb temperatures ranging from -5 to - 10C by 18Z will hold temperatures in the low 40s through the Metro region down to the MI/OH border and into the low 30s to upper 20s within the Thumb under the cooler northeast flow. Passage of a shortwave late Friday through Saturday morning brings low chances (20%) for snow showers. High pressure fills in across the Ohio Valley on Saturday supporting dry weather with return flow from the departing high then bringing in warmer air through the early week period.

MARINE

A cold front moves through the central Great Lakes today with showers and thunderstorms developing ahead of the boundary. Locally higher winds/waves are possible in some storms, and a few could intensify to meet thresholds for Marine Weather Statements and/or Special Marine Warnings. Should storms intensify, strong wind gusts of 34+ knots are possible, particularly during the evening hours for the southern waterways (Lake St. Clair and western Erie). Post- frontal cooling will be stark, but a decrease in low-level northerly flow should limit nocturnal mixed-layer gustiness to 30 knots or less. Modest on-shore post-frontal gradient winds still support Small Craft Advisory level waves through Friday. Winds and waves expected to remain in-check over the weekend with mainly dry conditions into Monday.

HYDROLOGY

Showers and scattered thunderstorms are expected through the evening hours as a cold front sweeps through Lower Michigan. Consensus model guidance QPF totals generally between 0.25 and 0.75 inches through Thursday evening, with the higher totals near the southern Michigan border. Highly localized totals nearing an inch or more cannot be ruled out with any stronger thunderstorms. Highly localized flooding in urban small streams and/or ponding of water in poor drainage areas will be possible with any thunderstorms.

PREV DISCUSSION

Issued at 228 PM EDT Thu Mar 26 2026

AVIATION...

A cold front currently dropping south through the region is draped from Lansing to Pontiac to Mount Clemens. The front is expected to drop south into Ohio by roughly 21-22Z. Expecting the bulk of surface based storms to occur south of the region but elevated portions of the front will light up over the next few hours through this evening providing chances of showers and thunderstorms. After the precipitation, cold air advection will surge which looks to result in a period of IFR stratus before the drier air can scour it out late tonight into Friday morning. Winds flip around to the north in the wake of the front and hold through the end of the forecast.

DTW Convection....Scattered thunderstorms are forecast across the airspace after 20Z for a few hours. After the first couple hours of more isolated storms, there could be a more organized line of storms south of DTW which could impact the Toledo region between 21Z and 00Z.

DTW THRESHOLD PROBABILITIES...

* High for cigs below 5000 ft this afternoon and tonight.

* Moderate in thunderstorms this afternoon and evening.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Small Craft Advisory from 10 PM this evening to 4 PM EDT Friday for LHZ421-441>443.

Small Craft Advisory from 10 PM this evening to 10 AM EDT Friday for LHZ422.

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