Updated Monday evening weather

There's been no shortage of significant weather this past week, and tonight was no exception.  What started as building thunderstorms this afternoon and evening, turned into a tornado warning for Lee County.  Now, tonight's atmospheric set up was nothing like that of last Monday when a supercell thunderstorm produced an EF2 tornado in Woodhaven Lakes.  The atmospheric set up tonight was more conducive for brief tornadoes and weak funnel clouds, but dangerous nonetheless. 

A shift in the jet stream pattern over this past weekend allowed for an extensive ridge to build across the Northwest, causing record breaking heat in the Northwest, and a cooler weather pattern across the Midwest.  But, what that cooler pattern has allowed for are many upper level lows to spin down from the northwest.  While the atmosphere isn't necessarily primed for active and severe thunderstorms, each low that comes down from the northwest causes just enough spin in the atmosphere for thunderstorms to develop causing rotation. 

While the severe threat remains low, there are thunderstorms moving through Southwest Wisconsin and Northeast Iowa.  Should these hold together, they will make it into Northern Illinois between 9pm and 10pm.