A widespread severe weather outbreak is anticipated this afternoon for most areas west of the Interstate I-35 corridor. Several tornadoes, very large hail to three inches, damaging winds to 80 MPH, and flash flooding are all threats tonight. 

A deepening low pressure center is expected to move into Ontario this afternoon along an unseasonably strong mid-to-upper level trough in the midwest. Trailing southward from this will be a cold front, draped over western Minnesota, western Iowa, eastern Nebraska, and northwestern Kansas. The frontal boundary will move to the east-to-southeast through the afternoon and evening hours and will likely reach the eastern portions of the state late tonight. A very moist airmass will also exist ahead of this front and will lead to a moderately-unstable atmosphere during peak heating. This strong instability in combination with strengthening deep-layer wind fields and strong height falls associated with the deepening trough will create an environment very favorable for severe weather.

Storm development is expected to occur by mid-to-late afternoon across western Iowa and into Minnesota as the first impulse of energy arrives to the area. This will likely increase in coverage and strengthen as the strong trough pulls into the area. Initially, these should be discrete supercells, as strong deep-layer shear will be available. This will lead to the primary threats being very large hail and potentially several tornadoes across the enhanced risk area. As the trough continues deepening and stronger height falls and forcing is made available, storms will likely form a linear squall line or bow echo from Minnesota into Iowa and pose a primary threat of damaging winds overnight.

The Storm Prediction Center currently has an enhanced risk of severe weather over most areas west of Interstate 35. It would not be particularly surprising if this was upgraded to a moderate risk at later updates at 8:00 a.m. or noon.

The best plan of action right now is to be ready. Make sure your NOAA Weather Radio is operational, review your tornado and severe weather safety plans, and stay tuned to the Iowa Weather Network for the latest updates.