NOAA's National Weather Service completes assessment of historic tornado outbreak

2011 tied as second deadliest tornado year in U.S. history

December 20, 2011

A massive tornado outbreak between April 25 and 28 of this year spanned five states in the southeastern United States. The deadliest day was on April 27, when 122 tornadoes killed 316 people across parts of Mississippi, Alabama, Tennessee, Virginia and Georgia. Fifteen of the reported tornadoes were deemed “violent,” meaning they ranked 4 or 5 on the Enhanced Fujita Scale. This outbreak is the third deadliest in U.S. history, and it contributed to 2011 being tied as the second deadliest tornado year on record. In addition to the death toll, more than 2,400 people were injured and the area experienced more than $4.2 billion in property loss.

Following a particularly destructive or deadly weather event, NOAA’s National Weather Service may conduct a service assessment. The goal of these assessments is to strengthen National Weather Service performance by developing a list of agency best practices during the event as well as recommendations for service improvements. Best practices are then shared with NWS offices throughout the country, and recommendations become agency action items.

An assessment from the April 27 tornado outbreak was recently completed and is now available to the public. The assessment team traveled to the impacted areas to interview weather service staff, emergency managers, the media, other government agency personnel and the public. The information they learned from these field interviews formed the basis for their evaluation and final recommendations.

Gary Woodall
Gary Woodall.

(Credit: NOAA)

Below is a Q&A with Gary Woodall, leader of the assessment team and also the meteorologist in charge at the Weather Forecast Office in Phoenix:


Q: What was unique about this weather event that made you want to lead the service assessment? Going into this project, what did you hope to accomplish?

A: For almost my entire career, I have worked in areas prone to severe weather, such as Lubbock and Fort Worth, Texas. As a result, I have served on several service assessment teams. By the late evening of April 27, I was well aware of the tragic impacts of the day’s tornadoes, and expected that an assessment team would be formed.  Given the historical significance of the event and the important task facing the team, it was a privilege to lead the effort.

Going into the assessment, our team’s goal was to document what happened as far as National Weather Service operations were concerned. We needed to determine what went well, what could be improved on for future severe weather events, and how our key partners and the public responded to our warnings.


Q: Can you give us your observations about the service assessment process?

A: Service assessments are a pretty strenuous process.  Team members had to interview a lot of people in a short period of time, then had to go through and analyze the answers to determine the best practices, possible findings, and background pieces of information. 


Q: How does social science play a role in service assessments?

A: It was pretty evident early on that NOAA’s Storm Prediction Center and the local National Weather Service offices did a fantastic job forecasting and warning for this outbreak. Given that, our attention started to turn toward societal and response questions, and that’s where the social scientists on the team really shined. We had social scientists on each of the sub-teams, and they uncovered some valuable information for us.  While a lot of their discoveries mirrored what has been seen in previous service assessments, it really drove home the point for me that we need to incorporate social scientists throughout our process, not just after something really bad happens. And I think we’re making progress in that direction.


Q: What were your general findings about the service provided by the National Weather Service during this tornado outbreak?

A: I was amazed at the effort put forth by all of the affected forecast offices. The accuracy of the outlooks, watches, and warnings by the Storm Prediction Center and the local forecast offices were about as good as we could expect. For the forecast offices, this event really began months before, with their preparedness and outreach activities. As the outbreak approached, the forecast offices engaged their key partners with conference calls, web briefings, special web page graphics, and even one-on-one phone calls. As grim as the casualty numbers are, I have no doubt that these actions helped save thousands of lives. And, we cannot forget that once the storms departed, the National Weather Service’s job wasn’t done. Staff members spent hundreds of hours conducting post-storm media interviews and surveying damage tracks, sometimes in their home communities.


Q: With such good preparation and forecasts, did your team learn why so many people still died?

A: Many members of the public our team interviewed said that, when a warning was issued, they looked for confirmation of the threat before taking action. This confirmation may have been from television or radio, from a trusted friend or family member, or in some cases, waiting to visually see the tornado. People also listened for the mention of specific towns or geographic features on which to base their action decision. With the fast speeds at which these storms were moving (typically 50+ mph), looking for secondary confirmation didn’t give folks a lot of time to get to safety. 

Even more tragically, there is evidence that some people died while doing what they thought was the right thing. Many people who did not have a storm cellar or basement took shelter in an interior room of their home. However, a lot of the homes that were impacted were of wood-frame construction, and just could not withstand the battering of the strong and violent tornadoes.

Many of the survivors stated that this was a life-changing experience for them. They understand the low-probability but very high-impact nature of tornadoes, and will take protective action despite the small chances of another hit. I think this is important information, and I hope that the National Weather Service is able to gather and use some of these testimonials in our tornado safety program.


Q: What did your team recommend to improve National Weather Service operations during tornado outbreaks?

A: We have some short-term and some longer-term recommendations. In the short-term, we should emphasize the low-probability but high-impact nature of tornadoes even more in our tornado safety campaigns. We should ensure that the databases that list locations in a warning area are as detailed as possible without becoming overwhelming. This should help the people who listen for specific geographic locations as a trigger to take action – the offices did this manually on April 27. We should aim for a more continuous flow of information between watches (which can be in effect for several hours before the storms arrive) and warnings (10-20 minutes before the storms arrive). Again, the offices did a good job of this on April 27, and we need to ensure it spreads through the rest of the agency.

In the longer term, we really need to engage the social scientists in all aspects of our warning philosophy, content, and process. By embedding the social scientists into the process, our warning messages will have a better chance of bringing about the proper response from the public.


Q: Are plans underway to make any of the changes your team recommended?

A team at National Weather Service headquarters will assign action items from our recommendations, and they will track the progress of implementing the recommendations. Some of the recommendations will of course be easier to implement than others, so they won’t all be accomplished at once, but they will be monitored and tracked.


Q: What more should people do to ensure they are prepared to protect themselves when a tornado strikes their community?

A: On potential severe weather days, keep up with the weather situation. Identify locations of safe shelters wherever you might be:  at home, at work, driving to and from. Make sure your kids know the severe weather plan at home and at their school. Have as many sources as possible to receive information, to complete the “threat confirmation” process quickly.  And when the threat is confirmed, act quickly! 


Q: You were in Norman, Oklahoma, last week at the Weather-Ready Nation Symposium. How do you see the outcomes of this service assessment report converging with the goals of the Weather-Ready Nation initiative?

A: The Weather-Ready Nation Symposium was an outstanding event. The symposium brought together experts from the National Weather Service, weather research, weather industry, social sciences, engineering, emergency management and media. Many of the topics we described in our report were discussed during the seminar. It was really exciting to see people from so many diverse backgrounds come together to attack a common problem. The recommendations that are coming from the symposium and the expertise that is now focused on these issues should help move us toward our goal of a weather-ready nation.