Not something we usually see this late in June, but a strong, spring-like storm system is set to unleash on the Upper Midwest tonight and again tomorrow. Earlier we touched on what to expect later today and tonight across Iowa. Now we want to focus on the more serious outbreak set for Monday and Monday night across parts of the state.
To the left you can see a large portion of Iowa under a moderate risk for severe weather. This risk is in association with a storm system that will track across the state. A strong cap should kill off tonight’s thunderstorms towards sunrise on Monday and prevent new storms from developing until at least after 4pm.
During that timeframe, the atmosphere will quickly destabilize once again, with massive amounts of energy available to storms as well as deep layer shear, a building block to supercell development. Of great concern is the latter of those ingredients. With the potential for a “triple point” somewhere over Iowa (the point where a cold, warm and occluded front intersect), and a explosive atmosphere all set up, the threat of violent tornadoes is especially high along the warm front expected to set up somewhere between Highways 30 and 20.
To the right you can see the risk probabilities for Monday are high for much of Iowa. Of even greater concern is the fact storms may not get their act together in Iowa until the evening hours. This, along with the primed atmosphere, will support a long duration severe threat over much of the state into the overnight hours. Unfortunately this includes a tornado threat which is of special concern at night when tornadoes are harder to detect.
All in all Monday overall is shaping up to be an ominously quiet day with explosive storms as it comes to an end. At this time we are working to set up a storm chase team to deploy into the region under the greatest threat. We’ll continue to provide updates on tomorrow’s potential as often as we can. But please keep in mind we’re also monitoring tonight’s severe weather threat and that must come first. Please stay up to date with the latest forecast and stay with us for the latest on this potentially dangerous day.