Can tornado history data predict where tornadoes will occur in the future?

Between 1950 (the first year comprehensive records were kept) and 2009, more than 53,000 tornadoes have been recorded into the official tornado records of the U.S. National Weather Service.

Seems like a lot of useful data, right?  Indeed, it is.  Further, most every tornado record includes a location, a date, a path length, even a Fujita F- or EF-rating.  It would appear we've got more than enough data to define trends as to which locations are more likely to see a tornado. 

Tornadoes where you live? 
Search 60 years of records!

Certainly we know that you're more likely to see a tornado in Oklahoma than Oregon.  Oklahoma is in the heart of Tornado Alley. Nearly 3,200 tornadoes have been recorded in the Sooner State over the past 60 years - an average of 53 per year.  By comparison, Oregon has recorded an average of 2 per year in that same period.

But can we predict patterns over a smaller area - inside a state, or perhaps within a single metropolitan area or city?  Perhaps, but there are some significant challenges.

Look at the map of Texas on this page, and see where tornadoes have been recorded since 1950.  Almost 7,800 have been spotted in the Lone Star State, more than any other state.  On the map, you'll see more tornadoes have been recorded in the Panhandle, north Texas along the Red River, east Texas and central Texas.  Fewer tornadoes have been spotted along the Rio Grande and in southwest Texas.  But there's a start difference between where tornadoes have been spotted in great numbers, and where they haven't.  Why?

Four reasons why the map and the data can deceive:

1. Population: Count this as fact. More tornadoes are spotted nearer to where more people live.  If a tornado strikes anywhere within 30 miles of Dallas-Fort Worth (metro population approximately 6 million), hundreds or thousands of people will experience it.  Much of southwest Texas is sparsely populated.  Fewer people equals fewer reports.
    
2. Proximity: This may be hard to make out on the image, but there's a distinct congregation of tornado reports along the Interstate 35 corridor that stretches between Dallas-Fort Worth and San Antonio.  Not only are there a lot of cities on that stretch of road (Dallas, Fort Worth, Waco, Austin and others), but there are thousands and thousands of cars and trucks that drive the road every day, and have done so for 50 years.  More drivers equals more eyeballs on the sky, and that equals more tornado reports along that corridor than perhaps 15 miles on either side of that corridor.
    
3. Chaser territory:  This last factor will impact data from the past 20 years in particular, as chasing has become a popular activity. Serious chasers will go anywhere there's a storm, for sure.  But they tend to flock most to places where tornado viewing conditions and road networks are optimal.  No doubt the Texas Panhandle is a primary tornado target, even though outside of Amarillo and Lubbock there aren't many people who live there.  Chasers love to go there because you can see 20-30 miles of flat-landscape horizon, and the extensive road network makes it easy to keep up with storms as they move.  Those 2 conditions make it more likely that tornadoes that do form will be spotted and recorded.
    
4. There's one more factor to consider: time.  As common as we think tornadoes occur, they are still relatively rare.  No matter where you live, the chance that a tornado has passed over the spot where you sit right now, within the past 60 years, is almost nil.  Tornado researchers I've talked to say they would like to see 1,000 years of tornado data to make some statistically-accurate observations that could lead to better knowledge of where tornadoes are most likely to form.

Despite these 4 limitations, the 60 years of tornado data we've collected for you here on TornadoAlleyLive's "Twister Data" page is most illustrative in showing you where tornadoes are generally more likely to form.  Search away - tell us what you find in your own searches.