NE Iowa-NW Wisconsin Supercells Eye EF3 Tornadoes, Very Large Hail as Watch Nears Issuance — SevereWX

SPC Mesoscale Discussion 1674 signals prime severe setup across northeast Iowa into northwest and north-central Wisconsin.

Storms are poised to ignite by late afternoon along a cold front, where rich moisture, steep lapse rates, and 50-60 kt shear favor supercell development. SPC pegs the most probable peak tornado intensity at 120-145 mph—spanning strong EF2 to low-end EF3 strength. Very large hail of 1.50-2.50 inches (golf ball to tennis ball size) looms large, alongside damaging wind gusts to 65-80 mph, especially if storms cluster.

A capping inversion has delayed initiation so far, with cumulus fields hugging the front amid ongoing mid-level convection from southern Minnesota spilling into prior MCS outflow. Lift from a northern Minnesota shortwave trough will tip the scales this afternoon, targeting the front-outflow intersection.

Uncertainties linger on exact timing and location, but the overall environment screams supercells with all severe modes on the table—including significant tornadoes. Tornado watch issuance odds sit at 95% within the next few hours (valid through 2100Z/4 PM CDT).

Impacts could peak late afternoon into evening. Affected WFOs include MPX, ARX, DLH, MKX, GRB, MQT.

Stay prepared: Monitor radar closely, have multiple alert sources, secure outdoors, and know your safe room or shelter plan. Act fast if warnings hit—strong tornadoes demand respect.