Storm Threat Ramps Up Wednesday Afternoon and Evening

We all know severe weather can occur at any time and during any month of the year.  But we are beginning to enter into northern Illinois and southern Wisconsin's peak severe weather season, which is mid-May through July.  Following a bout of severe weather Monday afternoon and evening, Tuesday brought a refreshing, but warm, break from the active weather.  That will be changing Wednesday with a storm system currently in the southwest that is expected to move into the Midwest by Wednesday afternoon.

Severe thunderstorms have been ongoing over Minnesota and Wisconsin to the north, and over the central and south-central Plains.  This is where the position of the jet stream lies.  The strongest winds within the atmosphere are located over the upper Great Lakes and over the Plains, while a dome of heat has developed over Illinois and the Gulf states.  This heat dome has pushed the jet stream north, leaving skies clear over most of northern Illinois and southern Wisconsin.

The severe threat remains to the west overnight Tuesday, but will ramp up for parts of the Midwest Wednesday afternoon and evening.  Low pressure responsible for the ongoing severe weather in the Plains will lift northeast into western Iowa by mid-morning Wednesday.  There could be a few showers and thunderstorms, non-severe, ongoing Wednesday morning over northern Illinois and southern Wisconsin but should move out by early afternoon.  Strong to severe thunderstorms are likely to develop over northern Missouri and southern Iowa by early afternoon with the arrival of the low pressure system. As the low moves into north-central Iowa by late afternoon Wednesday, thunderstorms will be moving into eastern Iowa and possibly western Illinois after 2pm/3pm.  The highest risk of severe weather will be closer tied to where the surface low is located and where the highest winds within the atmosphere reside.  Large hail, damaging winds and isolated tornadoes are all very well possible with the initial development of thunderstorms to the west.

As this line moves further east into north-central Illinois the threat will transition to more of a hail and wind threat.  Timeline of storm development will be from roughly 2pm to 10pm Wednesday.  Make sure you have a way to receive watches and warnings Wednesday and remain alert to changing weather.