Isolated showers and thunderstorms are moving across southwest Iowa this afternoon and evening. The severe threat with these will be very low, but the better chance for severe weather will come on Tuesday and Wednesday. A warm front will be lifting to the north during the day on Tuesday, which will be the focus point for thunderstorm development. This warm front should be draped from northwest to southeast from around Omaha to Lamoni by 7pm CDT.
This warm front will continue to lift to the north during the evening hours on Tuesday. The cap should be strong enough, that it will hold storm development off until 7pm and there after. Any storms that do become severe, will have the potential to produce large hail and damaging wind gusts. This is why a slight risk has been issued by the Storm Prediction Center (SPC) for much of Iowa Tuesday.
The best severe weather chance will occur on Wednesday, and this will be mainly across eastern Iowa. This is where the SPC has issued an enhanced risk. Cities included in this enhanced risk include: Cedar Rapids, Davenport, Dubuque, Waterloo, Iowa City, Newton, and Marshalltown.
Showers and thunderstorms will be ongoing near the warm front Wednesday morning, but these SHOULD quickly dissipate by midday Wednesday. This will place down residual outflow boundaries that will enhance the severe weather potential when they interact with the warm front. Severe risks include large hail, damaging winds, and tornadoes. If these showers and thunderstorms stick around longer Wednesday than what is currently forecasted, this will have an effect on the severe weather potential.
Storms should initially be isolated, which is when the storms will have the greatest tornado potential, but will eventually merge and form a widespread damaging wind threat, possibly in the form of a derecho. Heavy rain will also pose a risk, which could lead to flash flooding. Storms will form after 4pm across eastern Iowa and will push off to the southeast into central Illinois.
There is a lot to keep track of over the next 24 to 48 hours. We will have our chase team deployed, so continue to follow our page for the latest updates.