Steep Lapse Rates, Jet Support Ignite Evening Supercell Threat in Minnesota-North Dakota — SevereWX

Evening thunderstorms across north central through west central Minnesota and adjacent southeastern North Dakota are set to intensify into a notable severe risk.

The Storm Prediction Center's Mesoscale Discussion 1829 (issued 5:15 PM CDT) highlights a 60% probability of a watch, with storms potentially firing between 7-9 PM CDT (23-01Z) through midnight.

Rapid Refresh models show moderate instability building beneath steep mid-level lapse rates tied to warm elevated mixed layer air. This setup coincides with a 30-40 kt southwesterly 850 mb jet on the boundary's west side and 50-70 kt west-southwesterly flow at 500 mb, priming the environment for supercell structures.

A stalled low-level baroclinic zone could focus initiation, though stronger ascent trails westward. Storms might develop on the cool side or get undercut quickly by the front—but thermodynamic profiles still support large hail for hours before a frontal wave accelerates it east.

Most probable peak threats:

• Hail: 1.00-1.75 inches (golf ball size)
• Wind gusts: 55-70 mph
• Tornado intensity: Up to 90 mph (EF2)

Monitor radar closely this evening as convection ramps up. SPC coordinates with WFOs in Duluth (DLH) and Grand Forks (FGF).

Preparedness: Review your severe weather plan now—charge devices, enable Wireless Emergency Alerts, and identify your safe shelter spot (interior room, away from windows) if warnings issue.