We will closely be monitoring the weather by Saturday afternoon into the overnight hours. This is because a cold front will be approaching the state, which will bring the likelihood of severe weather. This includes the chance of large hail, damaging winds and even a few tornadoes. This afternoon, the Storm Prediction Center upgraded the severe weather outlook to an enhanced risk.
Saturday will start off dry and sunny, which help supply the fuel for storm development by Saturday afternoon. Models are showing a good amount of instability building into the western half of the state by 4pm. CAPE values (Convective Available Potential Energy) will be over 3,000 J/kg, which help for rigorous storm development starting out across northwest Iowa.
The models are showing storm development across northwest Iowa by 6pm Saturday. Initially, it appears that these storms will be isolated. This is when the greatest risk for tornadoes will occur, and also the reasoning behind the upgrade to an enhanced risk of severe weather across northwest Iowa. One of the things we will be closely watching overnight is where these storms initially develop. It is always possible that storms will develop further east, or west. But wherever storms initiate, will have the greatest tornado potential.
By 8pm, storms will begin to develop further to the southwest along the cold front, into western Iowa. However, by this time, storms will begin to line out as the cold front advances to the east. This will place the main threats of severe weather at damaging winds and an isolated large hail event. An isolated embedded tornado in this line may be possible across western Iowa, however, this will be a low threat. As storms continue to push off to the east through the evening hours, they will begin to weaken in intensity. This should leave eastern Iowa out of the crosshairs.
As always, we will be closely monitoring the weather over the next 24 hours. We have our chase teams on standby as they will be heading out tomorrow morning. We will have storm team coverage tomorrow afternoon, so continue checking back to iowachase.com for the very latest.