NOAA’s preliminary estimate is that there were 305 tornadoes during the entire outbreak from 8:00 a.m. EDT April 25 to 8:00 a.m. April 28, 2011. NWS created a table to provide clearer insight into the number of tornadoes. Each of the three categories in the table below has different levels of confidence/accuracy.
- Eyewitness Reports are the least accurate/reliable because with long-lived tornadoes like those in this outbreak tend to be reported multiple times. This artificially increases the number of tornadoes.
- NOAA’s Estimate is based on expert analysis of the Eyewitness Reports compared with the details coming out of the Tornadoes Surveyed by NWS Weather Forecast Offices (WFO). It is the statistic NWS uses in public announcements since it is the best estimate at the time. The numbers will change (typically down) as WFOs complete their storm surveys.
- Tornadoes Surveyed by WFOs is the latest confirmed number of tornadoes surveyed by the National Weather Service. When all storm surveys are complete this is the number that will go into the permanent record as the actual number.
| Preliminary Tornado Data Table | |||
| Date | Eyewitness Reports | NOAA’s Estimate | Tornadoes Surveyed by WFOs (to date) |
| 25-26 | 55 | 40 | 25 |
| 26-27 | 111 | 75 | 40 |
| 27-28 | 268 | 190 | 113 |
| Total: | 434 | 305 | 178 |
- The NWS Storm Prediction Center issued severe weather outlooks five days in advance and tornado watches hours in advance.
- NWS Weather Forecast Offices issued life-saving tornado warnings, with an average lead-time of 24 minutes. NWS issued warnings for more than 90 percent of these tornadoes.
- NWS decision support for this event has been extensive. NWS Weather Forecast Offices in the affected areas of Arkansas, Tennessee, Mississippi, Alabama and Georgia advertised the potential for severe weather in the Tuesday through Wednesday timeframe since late last week. Local offices provided direct decision support services to meet the specific needs of local emergency manager partners and the general public. NWS Weather Forecast Offices issued Hazardous Weather Outlooks up to six days in advance noting the greater threat of strong, long-track tornadoes was expected.
-
Data is preliminary and subject to revision
The largest previous number of tornadoes on record in one event occurred from April 3-4, 1974, with 148 tornadoes.
There were 340 fatalities during the 24-hour-period from 8:00 a.m. April 27 to 8:00 a.m. April 28.
- The Tuscaloosa-Birmingham tornado during the April 2011 event caused at least 65 fatalities. This tornado had a maximum width of 1.5 miles and a track 80 miles long.
- These are the most fatalities from a single tornado in the United States since May 25, 1955, when 80 people were killed in a tornado in southern Kansas with 75 of those deaths in Udall, Kansas.
- The deadliest single tornado on record in the United States was the Tri-State tornado (Mo., Ill., Ind.) on March 18, 1925, when 695 died.
Ongoing (preliminary) List of Tornadoes by EF Rating (EF3 to EF5):
- EF5: 2
- EF4: 11
- EF3: 21
Note: All numbers are based on combined NOAA and historical research records and current fatality estimates. The historical research records extend back to 1860.
That was supposed to include a link…
Regarding the tornadoes, I had moved to Madison, AL, last June. Though no stranger to adverse weather conditions, the ferocity and number of these monsters that ripped through the area was mind boggling. Fortunately, my neck of the woods only lost power, not lives and houses and businesses. Scary, because just a scant two miles away from where I live a whole community was turned to splinters.
On that note, I just wanted to say that the men and women reading the radars and live cameras did an outstanding job of reporting, and by being accurate saved a lot of lives.
Thanks for letting me rant. I’m a big fan of the site.
As an Alabamian with a child at the University of Alabama (Tuscaloosa), I truly appreciated those warnings. And once the power went out and the sirens went silent at 4:30 and until the all-clear at 8:30, I quite missed them. It was disturbing to have tornados bearing down around us yet hear no warnings whatsoever.
To me, the warnings are the signal to get to a TV or radio where the local weather teams can give us more detail about the path of the cell. I agree that it would be better if the warnings could target individual communities rather than entire counties. But until that technology is available, I will be grateful for what we have.
Joel Shore says:
Warnings should indicate imminent danger; tornadoes for instance. But it was absolutely clear from Mike Davis’ and my comments that the warnings were issued for all sorts of non-threatening weather. Moderately heavy rain? …. warning. Rain runoff will cause streams to rise? … warning. Lightning or thunder? … warning. There is no apparent difference to NWS between ‘you should carry an umbrella‘ and the more serious ‘your house may be torn apart‘. Nobody can realistically take action for all the verbal clutter pouring from weather stations.
“They [weather warnings] were continuous all week” is not hard to comprehend; while this tornado-spawning storm was a single event, predictable within hours. Kudos to the (real) meteorologists who worked this it. My complaint is over trivial warnings, perhaps bureaucratic risk-avoidance, that reduces the importance of advice of circumstances requiring immediate action.
But Shore’s attack shouldn’t detract from looking at the evidence —massive and significant evidence— that lives are saved due to computers and the internet, cell phones, citizens’ cameras and videos. Especially relevant is live media’s increasing use of citizen-journalists and viewer-supplied information; especially for weather events.
Once again (continuing on my comments of the ‘worst in forty years’ vein), the tornadoes were the worst since 1974 – a cold period. Please refer to all other weather disaster types between 1965 to 1980 and you have a simple predictive model for what to expect during the present cooling period. I essentially predicted a bad tornado season with an comment on (I believe the TX wildfires and one on spring flooding which were the worst in 40 years too).
Once again (continuing on my comments of the ‘worst in forty years’ vein), the tornadoes were the worst since 1974 – a cold period. Please refer to all other weather disaster types between 1965 to 1980 and you have a simple predictive model for what to expect during the present cooling period. I essentially predicted a bad tornado season with an comment on (I believe the TX wildfires and one on spring flooding which were the worst in 40 years too). I hate to predict an increase in hurricane ACE in this and coming years because it might blow the dust of the CAGW hibernators.
Jim Patrick says:
Well, there might be some bureaucratic risk-avoidance in it but you also have to recognize that different people face different worries or dangers. While heavy rain might not be a danger where you live, there are places where flash flooding can be deadly. And, lightning actually kills more people than tornadoes, I believe…So, while it might not be a danger if you are sitting in your office or your home, it can be quite dangerous for a farmer out in the field or someone out on the golf course.
So realistically, there is only so much filtering that the weather service can do for you. You have to do your own filtering based on what dangers are important for your own situation. Their job is to make you aware of a spectrum of dangers…and your job is to decide which ones to worry about and what action to take. You can’t expect a government agency to absolve you of all such personal responsibility.
christopher booker says:
In answer to Richard Ilfeld’s query above, this is what I posted a day or two back on another WUWT tornado thread.
May 1, 2011 at 3:4
Some of your readers may be amused by a tailpiece on this theme I put at the bottom of my column in today’s London Sunday Telegraph, as follows:
Inevitably the devastating tornadoes which have killed more than 300 people in the US prompted Newsweek to ask ‘Is global warming responsible for wild weather?’. The answer it found is ‘’yes’. Another Newsweek article cited ‘the most devastating outbreak of tornadoes ever recorded’, killing ‘more than 300 people’, as among ‘the ominous signs that the earth’s weather patterns have begun to change dramatically’. But this one was published on 28 April 1975, when Newsweek listed America’s 1974 US tornado disaster as one of the harbingers of disastrous global cooling, heralding the approach of a new ice age.
The links are as follows:
current Newsweek article, ‘Is Global Warming Responsible for Wild Weather?’
http://www.newsweek.com/2010/11/09/the-truth-behind-wild-weather-and-global-warming.html
and for 1975 Newsweek article ‘The Cooling World’
http://denisdutton.com/newsweek_coolingworld.pdf