Chicago Dodged a HUGE bullet

[Joel Wright]

As far as the urban heat island effect goes, just how substantial is this difference, say a few hundred feet above the surface and upward? Obviously heat rises, so there would likely be some of this "extra heat" rising upward into the column. However, as it rises, wouldn't it begin to dissipate somewhat, and become more consistant with the outlying ambient airmass? Just how deep into the atmosphere is this heat island effect?

 

[Danny Neal]

Supercells on May 10, 2003 in the Chicago area were moving NE into a lake cooled environment. The area had been held in the upper 60's and lower 70's as far inland as Dekalb or so. Outlying areas were able to warm into the upper 70's or lower 80's. There was not much weakening in the storms that approached that evening towards 11pm. I remember my area being tornado-warned at 11:30pm for strong rotation and a violently rotating wall cloud confirmed by spotters.

Also I've heard something about the August 28, 1990 storm being influnenced by a lake boundary, I don't remember exactly where though.

i remember that, i remember sitting around maple park watching continuous lightning to my Northwest, like i said the boundary can work for or against the development of rotation, in this case it didnt really harm it but the best example i can think of is April 20th 2004 the tornado had just gone through Joliet and spotters reported a tornado over I 55 and weber road, i was sitting 10 miles to the NOrtheast of that point, i didnt get a single drop of rain and saw two flashes of lightning, looking back at the radar watch how immediately the storm just DIED as it hit southwest cook county, it hit that lake zone and that was the end.