Do tornadoes hit cities?!

SKY WATCH FRIDAY time! Please visit Klaus, Sandy, Ivar, Wren, Louise and Fishing Guy, the team for SKY WATCH FRIDAY (click the word to link and participate!) Thanks to Dot and Tom, who were instrumental in the success of this blogging event. You should definitely come fly with us! Yesterday's sky was a brilliant blue with strikingly contrasting well-defined "fair weather cumulus clouds". I love it when the sky looks that way. It makes you realize the depth of the atmosphere and it really demonstrates the massive expanse of our glorious sky.With all this fair weather and no recent severe weather and no severe weather in the forecast until Monday, I feel like I should catch everyone up on what this year has looked like so far, tornado-wise. If you are thinking that this year seems much less active than last year, you are very correct. Last year, at this time, we were being bombarded with a record YTD total of tornadoes for that point in the year.You see that, at March 18, 2009, we have had 87 tornado reports so far; whereas, last year at this time, we had seen approximately 500 (!!!) tornado reports. The WCM page with the SPC is a great resource for tornado climatology.

This page has charts of the latest preliminary severe storm reports, annual summaries, and links to comma-separated-value (csv) data files from the SPC severe weather database back to 1950.

Looking at the current trend against the averages and against previous years, you see that we are, so far, experiencing a much less active tornado year than in the past.



... which is a blessing for all the non-victims of the would-be potentially devastating storms. Yes, you can clearly see that things are trending well below average. That doesn't mean, mind you, that it won't happen, just means it hasn't.

I was asked a really terrific question yesterday regarding tornadoes and big cities... since we were talking about the Atlanta tornado and the following day's outbreak, being so close to the anniversary (what?! They brought it up!!!) Anyways, my God friend asked if tornadoes generally avoid cities. Here's the scoop on that... obviously, more populated areas are more aware of a tornado happening than rural areas where no one is around, so you will tend to see more reports in the higher populated regions. That doesn't, in any way, mean that populated areas are magnets for tornadoes... it only means that they are more realized in populated areas. Remember that a tornado is rated by the damage that it causes. If no one is there to see it and report it, and there was nothing in the area to be damaged, there will not be a tornado report. Now, back to the question... DO TORNADOES AVOID CITIES??

It is a myth that tornadoes never hit big cities. The fact is tornadoes have a long history of hitting big cities and when they do, they usually cause a great amount of damage because a lot more debris is generated. Tornadoes can form pretty much anywhere at any time...
~source

What I told me friend is that it's a matter of statistics, more tornadoes occur in tornado alley than any other area (they can and do happen ANY WHERE and ANY TIME, though!). The midwest is much less densely populated, so statistically, the likelihood that a tornado would be over a city rather than open land is greatly reduced when compared with the eastern part of the United States... but even in the eastern part of the country, the larger cities don't take up large areas, so downtown areas with tall buildings are a much smaller target making the probability of a direct hit very small. In that same sense though, a house in the middle of an open area has a less probable shot at being struck by a tornado than a large city just because of area alone. We saw this in Boston, GA, on February 19, 2009, when an approximately 400-500 yard wide EF3 tornado missed the house it passed by, by a hair.

Tornadoes can form just about any place. ~source

... and there is a history of them happening in big cities.

Here is just a small list of cities that have been hit by tornadoes:
Dallas, TX
Fort Worth, TX
Miami, FL
Los Angeles, CA (30 tornadoes since 1918)
Oahu, HI
Oklahoma City, OK (F5 Tornado)
Cincinnati, OH
Salt Lake City, UT
Nashville, TN
Birmingham, AL
St. Louis, MO (22 tornadoes in the past 40 years)
Sunnyvale, CA (right smack in the middle of Silicon Valley)
Wichita Falls, KS TX, thanks, Ken!
Washington DC
Atlanta, GA

One could make the argument that tall skyscrapers could affect the air flow patterns needed to sustain a tornado. But it’s probably unlikely that a few buildings which are a few hundred feet in size would have much of an affect on a supercell which can grow to heights in excess of 50,000 feet (9 miles) and be as big as Mount Everest. Even a tornado itself can be as wide as a mile or more. ~source

Basically, do tornadoes avoid cities??? No. Cities are just generally well placed.

Have a great day!
~Dewdrop