The main reason tornadoes avoid big cities is that taken as a % of total land in the Midwest (main area where tornadoes strike) it’s a very small number.
I think Cecil once did a column about the “LaPorte weather anomoly” but my search didn’t turn one up.
Here in tornado alley I can tell you from experience that most tornados hit the suburbs. But the City of St. Louis is 61 square miles, while St. Louis County is 495 square miles, so the “suburbs” may just be a bigger target to hit. I do know that there have been at least three tornados on record that plowed right through the center of the city. Also, in many older areas the central city tended to be on a river while the suburbs were on higher ground, so it could also be that the funnel clouds may not always dip low enough to hit low ground.
Downtown Memphis is supposedly safe from tornadoes because it is built on a bluff that shields the area from the tornadoes that sweep in from Arkansas. However, parts of town within a few miles of downtown have bit hit, as have the suburbs.
“For the purpose of this study, the Chicago area is defined as McHenry, Lake, Kane, DuPage, Cook, Kendall, Will, and Lake (IN) counties.”
That’s not Chicago.
With one very minor exception, all of Chicago is located in Cook County, and covers only about 25% of that. Further, buildings in Chicago (or any of the mentioned counties) over 10 stories are concentrated in area of about 5 square miles. (Chicago covers 228 square miles.) I am aware of only 2 tornadoes that have ever caused significant damage in Chicago, and both were on the outskirts.
The eight-county area mentioned in the link was mostly farmland until relatively recently (a lot still is), and of the parts that are now urban, single-family homes and one or two story commercial buildings predominate.
Okay, my impression that cities were immune is clearly a result of my sampling error. Besides this:
which no doubt accounts for a lot of it, there’s a bias on the part of news reports to show the worst, most damaged results of any disaster. From the linked reports I read (not all of them, I admit) but in general when a tornado actually went through the center of a big urban area, the reported damage consisted of broken windows, limbs broken off trees, and some roof damage. Clearly high-rise building are ‘sturdier’ in whatever way it takes to resist tornado damage.
In contrast, one-story suburban houses often lose their entire roofs, and often whole sections of walls as well. And ‘manufactured housing’, as the trailer-home industry wants them called, seem to basically explode when a tornado passes over.
Given that the urban damage isn’t all that photogenic, I bet even when a tornado does hit a city, what is shown on screen is shots of the more damaged suburbs while the fact that the city was hit is just mentioned verbally.
Arial photo of part of the May 3rd F5 damage. Note the complete destruction of homes in the path. I was involved in the clean up / rebuild of one neighborhood (West Moore, OK). Let me tell you, the destruction was very severe. In some places (Bridgecreek, OK), the concrete roads were blown away. Yeah, the wind took the freakin’ road!
I think that’s right, for the most part, but last summer we had straight line winds through the whole city including most definitely downtown that knocked out power in some parts for weeks. We had gusts of 75-95 miles an hour. Like a category one hurricane.
There’s a few pictures here. http://www.david-albert.biz/Storm2003/NewPaper.html
Although I can’t find the date, there was a small tornado that touched down in Downtown L.A. about 15 years ago. It did most of its damage around the Convention Center.