Wednesday afternoon weather update

A slight risk for strong to severe thunderstorms remain possible across southern Wisconsin as well as northern Illinois.  Most of this afternoon should remain quiet with cloud cover thinning a little by mid-afternoon.  Thunderstorms from this morning have produced an outflow boundary across central Illinois and this may be the focus for storm development later today, however, current showers south may slow the northward progress of that boundary/front until later this evening. 

We're going to be watching a few subtle upper level disturbances currently in the central Plains.  As these lift northeast today they may interact with that outflow boundary/warm front as it lifts north.  This is what could cause a few pop up type thunderstorms by late afternoon.  There is also a stationary boundary out west that will be the focal point for storm development closer to Nebraska and western Iowa.

Clearing is already beginning to take place out west in Iowa where instability has increased significantly, but temperatures may be too warm aloft to get storms to develop right away.  The second image on the left is the WRF model run for tonight around 10pm.  This particular model keeps the area clear from any activity until after 7pm.  A likely scenario is storms will begin to develop out west as these little subtle disturbances lift northeast along the stationary boundary and move east.  As they move east the biggest severe weather threat for us would be large hail, wind and heavy rain.

The third image shows precipitable water amounts (amount of water in the atmosphere).  Dew points right now are nearing 60° or higher so any storm that does develop has a lot of moisture in the atmopshere to work with.  These numbers will probably increase over northern Illinois and southern Wisconsin as the afternoon progresses.

Trying to pinpoint where exactly storm formation will take place remains tricky.  We'll keep updates coming through the afternoon and evening so be sure to keep checking back.