After a very warm and sunny day, an active weather pattern will be on store for the end of the week. A weak cold front will be passing through the state this evening into tomorrow and will then stall out across southern Iowa by Wednesday afternoon. This cold front will have no real impact on temperatures as our highs will be in the mid 80’s to lower 90’s across the state. By afternoon Wednesday, the heating of the day will begin to form isolated showers and thunderstorms along the stalled cold front. There will be enough instability that storms will have the potential to be strong to severe with large hail and damaging winds the primary threat. This is why the Storm Prediction Center has outlined a marginal risk of severe weather across southern Iowa near this stalled front.
As we lose the heating of the day Wednesday, storms will begin to weaken. Then our focus will then shift to Thursday, which appears to be a more active day. Right now there is still some concern with the severe threat on Thursday. The greatest concern will revolve around the decaying storms Wednesday night.
Using current model guidance though, it does appear that enough instability will build back into the state after Thursday morning, that a line of storms will develop across western Iowa and will track to the east. The main threats Thursday afternoon into evening will be large hail and damaging winds.
However, the bigger concern will be for flash flooding as heavy rain totals will be expected by Thursday night. Over the next three days, rainfall totals of 1″ to almost 4″ of rain will be possible, with the greatest totals falling across northwest Iowa. Currently there are no watches, but some will need to be issued in the coming days if this forecast holds.