It’s certainly been a while since we last spoke of an organized severe weather threat around Iowa. We’ve seen a lot of hit and miss thunderstorms, a nice collection of strong thunderstorms, and a few borderline severe thunderstorms here and there. But, it looks like mother nature has a well thought out plan for Sunday, with all modes of severe weather possible.
The Storm Prediction Center in Norman, Oklahoma has posted an enhanced risk of severe weather for the day Sunday. Models have come into decent agreement with a strong upper trough building into the central United States on Sunday, alongside an associated cold front. As this upper trough builds into the area, temperatures will reach the low to mid 80s with dew points in the upper 60s and low 70s, which will help as the atmosphere quickly destabilizes in the afternoon with rapid thunderstorm development expected in the evening. Decent 40-50 knot southwesterly flow on top of low-level southeasterly winds will produce strong shear that will support rotating storms, in addition to the large hail and locally damaging wind threat.
As storms develop in the afternoon, they are expected to start out discreetly with the isolated tornado and large hail threats peaking during this time before cells are expected to form a squall line with an associated damaging wind threat. The best chance for storms will be west of I-35, but storms may continue as they go east of I-35.
Flash flooding is also a large concern. The ground is currently very saturated from previous nights storms with no stop in the rain expected today. A mostly clear Saturday will help things somewhat, but the ground will still be saturated nonetheless and flash flooding will be likely, especially along low-lying areas. Current flash flood guidance shows that two to three inches of rain within six hours could cause flash flooding. Therefore, you should be ready to seek higher ground if necessary once Flash Flood Warnings are issued.
Stay tuned to the Iowa Weather Network for the latest information!
Henry Luker | Lead Forecaster