850 mb Jet Arc Sets Stage for Supercell Hail, Tornadoes in Minnesota-North Dakota — SevereWX

850 mb Jet Arc Sets Stage for Supercell Hail, Tornadoes in Minnesota-North Dakota

A strengthening low-level frontal zone draped across north central and west central Minnesota into southeast North Dakota is lining up for a serious severe weather show tonight. The SPC's Mesoscale Discussion 1829 highlights thunderstorm development kicking off around 7-9 PM CDT, potentially evolving into supercells under ideal wind dynamics.

Strong south-southwesterly winds at 850 mb (30-40 knots) align with 50-70 knot west-southwesterly flow aloft near 500 mb, providing the shear for storm organization. Steep mid-level lapse rates and growing instability beneath a capping layer will support intense updrafts, favoring large hail up to 1.75 inches (apple-sized), damaging wind gusts of 55-70 mph, and tornadoes peaking at 90 mph (low-end EF2).

While stronger lift trails westward, convection could still fire near the boundary's cool side before a frontal wave accelerates it east. Even if undercut, hail risk lingers into the evening.

Most probable peaks: Hail 1.00-1.75 inches, winds 55-70 mph, tornadoes up to 90 mph.

Watch issuance odds sit at 60% through midnight CDT. Areas from Grand Forks, ND, westward across central MN to near Duluth are in play—stay tuned to radar.

Preparedness: Review your severe weather plan, ensure mobile alerts are on, and know your safe spot. Have helmets or pillows ready for hail protection. Follow @SevereWXnet and local NWS for updates.