An area of low pressure over Kansas is migrating northeast this morning, bringing a line of showers and thunderstorms across northern Missouri into southeast Iowa and Illinois. This activity is expected to remain under severe limits for the most part, however an isolated strong to severe cell cannot be ruled out. Additional elevated activity will be possible later this afternoon as moist air aloft and lift brings the potential for more showers and thunderstorms. The Storm Prediction Center has outlined a marginal risk of severe weather for today over most of the state for this reason. Isolated sporadic large hail and damaging wind events will be possible, especially over eastern Iowa, but the threat is relatively low for today.
Confidence in Wednesday’s forecast has increased immensely over the last 24 hours or so. Storms from Tuesday are expected to be gone from the area by Wednesday morning and allow for ample heating across the area. There may be some light rain or drizzle across the area, but this is expected to be fairly insignificant in coverage. A large cap will be in place early in the day, but is expected to erode as things heat up in the afternoon and things begin brewing across the midwest. With this large cap, things are expected to remain fairly isolated in coverage (will not be a widespread firing), and track east to northeast into Missouri and Iowa later in the day.
It is important to note that the environment that these storms will easily turns things significant very quickly. Very high instability, with moist air from the Gulf, and wind shear associated with the surface low moving into the state, will create the potential for very large hail, damaging winds, and tornadoes. The best area will be where the best instability and wind shear overlap (Missouri and far southern Iowa). Combining the peak of these ingredients will create a dangerous and embracive environment for any storms that do develop. But, again, these storms will be isolated in nature due to the large cap in place. It will important to watch any storms that develop. Most of this activity should remain south of Interstate 80. Isolated elevated storms may develop to the north, however this risk is low at this time.
There is potential for additional significant weather on Thursday. Things are still very uncertain due to the unsure results of how things will setup Tuesday and Wednesday. Showers and thunderstorms are expected to be continuing Thursday morning across the state (potentially elevated strong storms). Things are very conditionally dependent on how this sticks around in the early morning hours, or what boundaries are left behind, etc. It is very much an evolving forecast subject to change.
Current expectations has these thunderstorms exiting or dissipating quickly enough to allow for ample daytime heating and time for the atmosphere to once again destabilize. Storms should begin firing across eastern Iowa and western Illinois in the mid-to-late afternoon hours and trek eastward through the evening. Storms will likely be supercellular initially with large hail, damaging winds, and possible tornadoes. This will probably evolve into a Mesoscale Convective System overnight, or become linear – these details are still being ironed out and we should know more in the coming days.
Stay tuned to the Iowa Weather Network for the latest information on this evolving situation!
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