This was a quiet yet memorable year for tornadoes in the United States. With around 900 tornadoes on the books, here are some interesting maps that show all of the areas hit by tornadoes in 2014, from the twin tornadoes in Nebraska to storms nearly a mile wide in Mississippi.
At the end of June, we took a mid-year look at how the tornado season played across the country, and up to that point we had seen 922 reported tornadoes and 1,229 tornado warnings. Since then, we've seen those numbers grow by a few hundred each. As of December 16, we've seen 1,322 reported tornadoes and 1,840 tornado warnings across the entire United States and even Puerto Rico.
Here are all of the tornado reports from across the country between January 1 and December 16. It's important to remember that actual tornadoes are different from reported tornadoes. The National Weather Service records every report of a tornado as an individual tornado—often when we see long-track tornadoes like those that occur in Oklahoma or Alabama, spotters will call in 25 reports on the same tornado. Those appear as 25 individual tornadoes when you look at storm reports, not just one. It takes a ground survey by meteorologists to confirm both the existence and the path and strength of a tornado.
These 1,322 tornado reports will likely come down to around 900 when the final data is crunched. However, the data itself isn't bad! It gives us a great look at where the most intense outbreaks occurred this year, as well as where tornadoes were most likely to occur over the past twelve months. I created a heat map of the tornado reports to give you a better idea of where we saw the most activity this year.
Far and away, the largest outbreak this year happened in Dixie Alley back at the end of April. Stretching roughly from Jackson, Mississippi northeast through Alabama and into Tennessee, Dixie Alley is a part of the United States that is susceptible to some of the worst tornado outbreaks in history. The area's weather stayed true to form this year; the outbreak produced 84 tornadoes that killed 35 people and injured hundreds more.
Elsewhere in the United States, we saw tight clusters of tornadoes form in northeastern Nebraska, which is where the now-infamous "twin tornadoes" (pictured at the top of this post) occurred, around the Denver area (which is common), as well as places like eastern North Carolina and even northern California.
Aside from the obvious look at reported tornadoes across the country, we can look at the frequency of tornado warning polygons to get a good idea of where the atmosphere was most favorable for rotating thunderstorms this year. A tornado warning is issued in three instances: 1) when meteorologists detect strong rotation on Doppler radar that signals a storm could produce a tornado; 2) when meteorologists detect debris lofted into the atmosphere, which is virtual confirmation that a tornado is on the ground; and 3) when spotters confirm the existence of a tornado.
Most tornado warnings are false alarms. The number of false alarms is somewhere up around 70%, which is a huge problem both for accuracy and, most importantly, public trust. The "crying wolf" effect is a very real hazard when it comes to severe weather events, and many offices are consciously trying to cut down the number of false alarms.
2013 and 2014 have been extremely quiet tornado years when compared to the past decade, and the trend shines through when you look at tornado warnings. The above chart shows the total number of tornado warnings issued in the United States between 2005 and December 16, 2014. The quietest was 2013 with 1,831 warnings, and this year is just barely ahead.
Not that that's a bad thing, of course.
Through December 16, we've seen 1,840 tornado warnings across 43 of the 50 states. Most of the warnings were issued east of the Rockies, which makes sense when you think about weather patterns in the United States. The greatest density of tornado warnings occurred across Dixie Alley and northeastern Colorado—in fact, Weld County, Colorado is the most tornado-prone county in the United States.
I combined all of the tornado warnings and tornado reports issued across the country and broke it down into regions so you can get a better look at who was affected the most.
There is an enhanced risk for severe weather (including tornadoes) across the Deep South this afternoon. However, the data in this post stops at December 16, so it does not include any warnings or reports issues today. I will cover those separately in another post if conditions warrant. Keep up with the Storm Prediction Center for the latest on this outbreak and any future severe weather events.
If you'd like to read more about the bigger tornado events this year, I covered them extensively here on The Vane. At one point, the site featured almost nothing but tornadoes for weeks on end. Here are some of the more interesting reads.
- How Did the Rare Twin Tornadoes in Nebraska Form?
- CBS News Falls for Hoax, Reports on Nonexistent "Sideways Tornado"
- Why Is a 30% Chance of Rain Different From a 30% Risk of Tornadoes?
- Evacuate: Why a Reckless TV Weatherman Will Get Someone Killed One Day
- Meteorologists Did an Incredible Job Forecasting the April Tornado Outbreak
- Tornado Throws Door 30 Miles Away, Lands on Mississippi State University's Campus
- Gov. Andrew Cuomo Knows Nothing About Tornadoes
- Crazy Video Shows Tornado Hitting an Office Building in Italy
[Top image: AP | All maps/charts by the author]