24 Hours has passed since our last update, and things continue to look like they are marching towards an outbreak of severe weather over the Upper Midwest. The Storm Prediction Center has left all of Iowa under a slight risk for severe weather on Saturday, however confidence in building this risk potential may have to be upgraded as early as tomorrow.
As we stated yesterday, a strong storm system will move into the region, bringing a warm front Saturday morning. Along that front, a transition to warmer conditions and a chance for a shower or two. The big question mark comes in the “dry slot.” Will areas south of that front get out from under the clouds during the morning and afternoon hours, allowing the atmosphere to heat up and destabilize.
Then, Saturday afternoon and evening, a cold front will sweep across the state triggering a wave of thunderstorms. All models continue to indicate an environment supportive of supercells capable of producing tornadoes. The overall threat from tornadoes remains uncertain. At this time it appears a handful of tornado producing storms may develop, later turning into an evening damaging wind event with an additional isolated tornado possible.
In the graphic to the right, you see how the SPC is breaking down the severe weather probabilities. A large 30% area is highlighted, encompassing nearly all of Iowa. This is the very high end of a slight risk this far out, and an upgrade to a moderate risk for some areas cannot be ruled out as early as tomorrow morning.
Saturday night, the cold front will push through, as it does the precipitation will quickly follow. Of course, with three days worth of forecast periods to go there remains some uncertainty. But the conditions expected over Iowa on Saturday and the relative confidence and consistency in the forecast models is a very ominous sign.
We plan to deploy chase teams on Saturday and bring you live video coverage from the field as we track these storms. We also hope to provide you with more frequent updates as this potential outbreak draws closer.