As we discussed on Thursday, the severe potential that is in the works for today has a few uncertainties to work through. All of which have to do with the cluster of showers and storms that are pushing through eastern Iowa this morning. First, how much of a cap or “atmospheric lid” develops following this morning’s thunderstorm chances.
Secondly, if this cluster were to produce an outflow boundary (a boundary consisting of rain-cooled air being pushed down from a thunderstorm), where would it exactly set up. These are questions that will be answered as the day progresses, which is why it’s going to be important to be weather ready this morning and then again as we inch closer towards dinnertime.
Of the two rounds that are possible today, the early round features the lowest threat for severe weather. As for timing, guidance brings the early round through between sunrise and noon, with heavy downpours, gusty winds, and frequent cloud to ground lightning being the biggest concerns. If we do manage to get in on the second and stronger round late this afternoon into early tonight, damaging winds and large hail will be the bigger threats.
Again, the tornado threat is low, but will be highest along any outflow boundary. Overall, the severe outlook locally hasn’t changed much over the last 24 hours as the Storm Prediction Center kept all of N. Illinois and S. Wisconsin under a level 2 slight risk. Highs will end up a degree or two warmer than Thursday, with most in the upper 80s.
The associated cold front slides into the region early tonight, with dry conditions filtering in behind it. This will leave us with a good amount of sun for Saturday, with high temperatures landing in the mid to upper 80s. Clouds increase into Sunday as our next storm system dives into the western Great Lakes.
But it won’t be until Sunday evening into early Monday morning where we see a chance for a few showers, possibly a few isolated thunderstorms enter the equation. Highs due to the increased cloud cover and rain chances will only peak in the low 80s, cooling into the upper 70s for Monday and Tuesday.