The Storm Prediction Center in Norman, Oklahoma has posted a moderate risk of severe weather over southern Iowa today. A trough that was near the California Coast yesterday will quickly eject eastward into the Upper Midwest overnight. A strong upper jet trigger alongside this trough with a stationary front from the Ohio Valley through the Central Plains. The main area of concern will be near a boundary that is expected to setup in southern Iowa or northern Missouri today where the severe weather and tornado threat will be highest.

We continue to see classic ingredients for a severe weather day with warm temperatures in the low to mid 80s across southern Iowa with dew points in the upper 60s to low 70s, showcasing the rich Gulf moisture that will be supportive of thunderstorm development and potential flash flooding. There is a bit more certainty on the location of the boundary which is now expected to setup across central through southern Iowa. This will be the gunpoint for thunderstorms and when combined with strong instability and a strengthening low level jet, storms will likely create a large area of organized thunderstorms with supercells likely.

We are expecting storms to begin developing in the late afternoon hours tonight across Nebraska and eventually evolve into a Mesoscale Convective System. At it pushes east, damaging winds to 70 MPH, very large hail to two inches in diameter, and tornadoes will all be possible, if not likely. Flash flooding is also a possibility with the ground already being saturated from the previous nights storms with any additional rain likely causing localized flooding. Flash Flood Watches may not come later tonight.

Stay tuned to the Iowa Weather Network for the latest information on this system.

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Henry Luker | Lead Forecaster
Jeff Wilcox | Senior Forecaster