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Tornado Fact Check from the North Carolina Outbreak

Apr 18, 2011; 12:54 PM ET

UPDATE TUESDAY 4/19/2011: The NWS in Raleigh has released a map showing 25 tornadoes, three more than the famous 1984 outbreak. View their website for updates and click here for stats on the entire weekend outbreak in the Southeast.

AccuWeather's Mike Smith is upset about a headline he saw in a newspaper ("Killer storm system caught N.C. by surprise"), as well he should be. As I discussed below, this outbreak was well forecast. If the forecasts were not heeded, then that is a different, but equally important story. The Capital Weather Gang agrees.

As is typical with the media during a major scientific event, there's quite a bit of misinterpreted information going out about last weekend's historic and tragic tornado outbreak, which is most notorious for the number of deaths it caused in North Carolina (over 20). Allow me to clear up some misconceptions that have been floating around.

Was the number of tornado reports a record breaker and how does that relate to the number of actual tornadoes? This is a point of contention, and it depends on who you ask. Although officially there were 240 tornado reports during the 2-day outbreak, this number will be reduced considerably when the twister paths are investigated. As storm reports are easier to file with the National Weather Service due to better technology, the number of people seeing the same twister increases greatly. You can read our news story on this for more information. It will be at least a week before we know how this outbreak compares to other major events. It's possible that this system could eclipse the worst outbreak in the states history, which took place on March 28, 1984. During that storm, 22 tornadoes killed 42 people in North Carolina. UPDATE: CNN is reporting "97 confirmed tornadoes" though I find it hard to believe that the NWS would have had time to calculate that number yet.

Was the Raleigh tornado the widest ever in U.S. history? No. This was a typo in the NWS's initial storm survey report which listed the width as "3." This was later reissued CORRECTED FOR MAXIMUM PATH WIDTH of "0.3 miles." The widest tornado on record occurred in Nebraska in 2004, and was 2.5 miles in length.

Was where the tornadoes struck remarkable, in number, time of year or location? Probably not. On average, eastern North Carolina sees 3-4 tornadoes per month between March and September, but there is not enough data to tell which month is the peak. The map below, and others like it here, show that eastern North Carolina (and even Wake & Bertie counties) are no stranger to the storms.

Why did this happen? We are working on a story on what meteorological factors led to this outbreak, in this area, this time of year. It's unlikely, in my opinion, that long-term climatological factors, such as Global Warming or Cooling, had anything to do with this event, and pending answers to the questions above, it may not have been unprecedented.

Was the outbreak well-forecast?The same day forecast was almost 100% accurate for the area to be affected, but a High Risk was not in effect until hours before the outbreak. Short-term, at least 100 Tornado Warnings went out (see image below, thanks to Matt Taylor), and the storms were very well developed on radar, so there should have been sufficient lead time. More information on the forecasts can be found in our news story.

Why were so many people killed? Because of the answer to the question above, I doubt the reason was that the twisters were not well forecast. Other reasons could include coincidental tracks with populated areas, lack of tornado sirens, or too many mobile homes. It's worth mentioning that half the North Carolina deaths occurred in Bertie County, which is very rural, with only 54 people per square mile (vs. over 1,000 in Wake County, where I used to live, home to Raleigh).

What other North Carolina records did these twisters break? Outside of the number of tornadoes (discussed above), the two EF-3 tornadoes surveyed so far by the Raleigh NWS had tracks over 60 miles long, but a twister in 1992 went much farther.

Did you see that video of a tornado forming on the interstate right in front of people? Yes, but that video was taken last April. It does, however, illustrate rural eastern North Carolina storm chasing well. Because of the tall trees and lack of hills, you won't see a twister unless it forms right in front of you!

Did you see that video of a Walgreens being destroyed filmed from inside a car? Yes, and staying in his car was a very bad idea. The reason we don't see more videos like this is that the photographers and equipment are destroyed in a manner similar to what you see in the photo above.

Jesse Ferrell

The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or AccuWeather.com

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