Sunday is here and the severe threat remains. That does not mean that all questions are answered, but I will certainly do my best. The Storm Prediction Center is holding firm on the slight risk without upgrading to moderate and rightfully so. The main reason is instability. With a night filled with showers and thunderstorms, the atmosphere is quite stable.
For that to change, we need a strong southerly flow, now locked on the other side of a warm front making its way north from Missouri. Current trends indicate the front will push north of eastern Iowa. Provided early morning convection pushes out of the area, we should see a few hours of clearing which would allow for rapid heating and an increase in dew points.
As the cold front pushes through the state, we could see initial development in western Iowa by mid afternoon. Once the storms get going, it’s a matter of movement. As I called for on Friday (but didn’t see it happen), we should see storm move relatively slow at first. These disorganized supercells could rapidly develop into tornado producers. As the front begins to push east, cells will become better organized and take a linear or bow shape. Once this happens the primary threat will shift to wind. Heavy rain will also remains a possibility and flash flooded could be a threat. Fortunately for eastern Iowa, near drought conditions this month provides ample room in the soil for heavy rains.
As for chase plans, we are planning to head to central Iowa in the morning, reassess the situation and go from there. Be sure to keep it here for the latest as our next round of severe weather comes together.