Are Tornadoes Getting Bigger?

A couple months ago, I watched several clips of tornadoes from the huge April outbreak that occurred down South this year. I've seen several storm documentaries over the years, but two images always stayed with me: the giant Moore, Oklahoma, tornado in 1999 and a less destructive, yet impressive 1.25 mile wide tornado that came through Comfrey, Minnesota during March of 1998. The width of each tornado was significant and in the case of the Moore, Oklahoma, tornado I remember seeing footage of what looked like tiny objects flying around in the air around the main funnel. Those tiny objects, however, were cars and trucks. At the time, the Moore tornado was one of the largest and strongest on record.

After watching the footage of the storms that ravaged the South, I was surprised at how wide some of the storms were. Several of the twisters appeared to be around a mile wide. Was something fundamentally changing in our weather patterns to start generating bigger and bigger storms?

Climate change debates aside, I decided to do some basic research into tornado widths. Here is an incomplete list of what I found:

Tornado	Date of Event	Width (Miles)	Rating
Waco, Texas	5/11/1953	0.33	F5
Blackwell, Oklahoma	5/25/1955	0.28	F5
Udall, Kansas	5/25/1955	0.74	F5
Topeka, Kansas	6/8/1966	0.5	F5
Tracy, Minnesota	6/13/1968	0.09	F5
Lubbock, Texas	5/11/1970	1.2	F5
Super Outbreak - Xenia, Ohio	4/3/1974	0.5	F5
Super Outbreak - DePauw, Indiana	4/3/1974	1	F5
Barneveld, Wisconsin	6/7/1984	0.25	F5
Andover, Kansas	4/26/1991	0.34	F5
Chandler, Minnesota	6/16/1992	0.75	F5
Jarrell, Texas	5/27/1997	0.75	F5
Comfrey, Minnesota	3/29/1998	1.25	F4
Bridge Creek-Moore, Oklahoma	5/3/1999	1	F5
Hallam, Nebraska	5/22/2004	2.5	F4
Greensburg, Kansas	5/4/2007	1.7	EF5
Elie, Manitoba	6/22/2007	1.1	F5
Parkersburg, Iowa	6/25/2008	0.7	EF5
Greeley, Colorado	5/22/2008	1	EF3
April 25-28, 2011 outbreak - Smithville, Mississippi	4/27/2011	1	EF5
April 25-28, 2011 outbreak - Tuscaloosa, Alabama	4/27/2011	1.5	EF5
Joplin, Missouri	5/22/2011	1	EF5

Then I graphed the results:

This, of course, is not an exhaustive analysis of all F3-F5 (or EF3-EF5) tornadoes, but it gives you a basic idea of where this may be headed. Granted this is not scientific by any means, but it does make one wonder: are even bigger ones on the way? More twisters seem to be approaching and surpassing the one-mile wide mark. A one-mile wide tornado can do an immense amount of damage in a hurry...just look at what happened to Greensburg, Kansas in 2007 and Joplin, Missouri in 2011. For a small town, one of these storms could easily wipe it off the map.

I've also noticed, too, that the size of the hailstones seems to be growing. In this area, it used to be rare to hear about golf-ball size hail. Now, I'm hearing of more and more incidents where the hail is tennis ball, baseball, or even softball size. As a result, the property damage reports have increased quite a bit.

How about your area? Is the weather getting worse or more violent? What do you think is causing these changes?