A substantial threat tomorrow for severe weather exists, especially across the southern half of The Storm Prediction Center in Norman, OK has this area under a slight risk. Although the lowest grade of risk, the probabilities are a little higher than what we’ve seen in recent days and weeks. Usually we see a minimal threat of around 15%. But in this case they are higher as instability over Iowa on Wednesday could produce a strong complex of severe thunderstorms.
The graphic to the right shows the current probabilities. These are general risks and do not specify which type of severe weather is possible. You can see the area under a 30% risk highlighted in red is primarily focused just south of Iowa, but it is close enough to be a concern especially for areas south of Interstate 80. At this time, its expected all modes of severe weather are possible over this area tomorrow afternoon. That includes large hail, strong damaging winds and a few tornadoes.
Forecasted shear values for the risk area look good for supercells to develop. If an isolated cell or two can get going during the afternoon hours, we would see an increased risk for tornadoes in the first hours of the outbreak.
At this time it’s unclear how long this severe weather threat will last after sunset, but it’s something that will need to be closely monitored throughout the day and night on Wednesday. We’ll continue to track the latest forecast runs and bring you updates when needed. We’ll also work with area storm chasing and storm spotting crews that may be out during tomorrow’s storms.