Widespread severe weather capable of damaging winds, large hail, and even a few tornadoes will be possible late Sunday and again on Monday stretching from the eastern Dakotas into the Ohio River Valley.
On Sunday, morning convection will still be ongoing, but this will quickly dissipate. This will allow the atmosphere to recover and become unstable which will help redevelop storms late Sunday. The main threat for severe weather will exist from central Minnesota into extreme northeast Iowa. The primary threats on Sunday will be damaging winds. However, early on, if a cell is allowed to stay isolated, then there could be a very small window for a tornado potential. This very low tornado potential would stay in Minnesota as storms will have lined out by the time they enter into northeast Iowa.
The greater threat appears to be on Monday, and this will include a greater threat for damaging winds, large hail and a few tornadoes. Storms will be exiting the region Monday morning which will allow for ample time for the atmosphere to become unstable. There is still some uncertainty with how Monday will unfold. The Storm Prediction Center has outlined an enhanced risk of severe weather from eastern Iowa into north central Tennessee. This is where the greatest chance of severe weather will be. The Storm Prediction Center is monitoring two potential scenarios.
The first scenario is that storms will redevelop along the warm front/outflow boundaries from earlier storm Monday afternoon. This is when super cells would be possible, with very large hail, and a few tornadoes possible. There is some concern for a significant tornado threat, but this will all depend on the outflow boundaries, which is one of the many uncertainties.
The second possible scenario is that storms will form late in the day near the surface low over Iowa and expand south/southeastward into Illinois. This area appears to have the potential for particularly damaging straight line winds from late afternoon through the evening and early morning hours. A hail threat would also be likely.
There is still much to be monitored over the next 24 to 48 hours, so continue to check back here at iowachase.com for the very latest.