Recap of storms Tuesday morning

Right around 5am a line of strong thunderstorms moved across southern Wisconsin and northern Illinois knocking down trees and power lines causing several thousand to lose their power. 

These storms originated northwest of here in Minnesota late yesterday evening and began to gain a little momentum as they moved southeast.  A stationary front to the south helped provide the instability needed for these storms sustain themselves through not only Illinois but Indiana and Ohio as of late this morning.  Dry air aloft is something meteorologists look for when storms develop on the radar.  This is because some of that dry air, as well as stronger winds, can be transported down to the surface and can typically cause stronger winds along the leading edge of the thunderstorm.  Also, the fairly tight front edge reflectivity gradient (where the radar color changes) was noticeable also indicating that there were strong winds aloft likely being transported down to the surface. 

Warnings had been issued for southwestern Wisconsin around 3am, with warnings for Green county shortly after 4am.  As the storm continued southeast the leading edge began to bow out as in entered far northwest Winnebago county.  The strongest part of the storm moved from Beloit/South Beloit to the Roscoe/Rockton area with damaging wind gusts between 55-65 mph.  As the storm moved southeast it began to pick up a little momentum as it entered Boone and McHenry counties and winds were clocked over 65 mph in Harvard, IL.  At the same time there was further development along the southern edge of the storm as it moved through northern Ogle and DeKalb counties.  Wind gusts in those locations were also near 60 mph, if not higher.

The storms completely moved out of the viewing area around 6:30am as they continued east towards Chicago.  Some may classify this storm as a derecho, which is a long-lived wind producing storm.  In fact, the storm is now located in southern Ohio! 

For the remainder of the afternoon cloud cover may thin some with temperatures rising into the mid 80s.  With the stationary boundary still in place there may be an isolated storm or two later this afternoon, but a better chance arrives tonight, especially north, as the front lifts into Wisconsin by Wednesday morning.