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.
Hats off to the National Weather Service (NWS).
Great job done and it is much appreciated.
More funds still need to be move from climate science research to more, and more advanced, Dopler radars. These guys really do save lives, all of the time. Put them right up there with the firefighters.
With the increased coverage of doppler radar the tornado counts have increased – but not the number of strong tornadoes. The NOAA annual report used to show a graph each year of strong tornadoes. After Obama, since the 2009 report, NOAA reports total including F0 tornadoes instead of strong tornadoes — gives it the opposite trend.
See: http://www.appinsys.com/GlobalWarming/TornadoLies.htm
A rather rough and ready look at the incidence of tornado supr-outbreaks and the weather at the time seems to indicate a corellation between La Nina and increased tornado incidence in the US – 1974 and 1999 being the obvious examples.
This would make sense given that the tornados are generated by the temperature difference between warm moist air from the Gulf and cold dry air from the center of the N American continent. La Nina conditions increase the amount of cold air from the NW as the cold winter and late snpowfalls indicate, and the same conditions are associated with warmer moist air flowing north from the Caribean.
Is there any solid evidewnce of changes in tornado incidence linked to the state of the N American continental weather patterns ?
It was Joe D’Aleo who warned on April 9th that tornadic activity would be much higher during a La Nina year.
…
Last Monday, April 4th was one of the most active days in recent memory for the Storm Prediction Center and folks who live in the southeast with 1347 severe weather reports (1220 high wind, 89 hail and 38 tornado) from the Ohio River southeast to northern Florida. Virtually everyone in the southeastern United States felt the fury.
…
April and May should keep forecasters busy. In my first WeatherBell post, I discussed the potential for some very big severe weather days as is the case in La Nina years in a cold PDO (Pacific Decadal Oscillation). The Palm Sunday outbreak in 1965 and the Superoutbreak in 1974 were just two prime examples.
The Palm Sunday tornado outbreak on April 11, 1965 involved 47 tornadoes (15 significant, 17 violent, 21 killers) hitting the Midwest. It was the second biggest outbreak on record. In the Midwest, 271 people were killed and 1,500 injured (1,200 in Indiana). It was the deadliest tornado outbreak in Indiana history with 137 people killed. The outbreak also made that week the second most active week in history with 51 significant and 21 violent tornadoes. The tornado which hit Midway trailer park is disputed to be an F5, as 25 homes were literally and figuratively wiped off the face of the earth, with no signs of them ever found.
Alan, thanks for the link. Good stuff!
Is all that really because the Atlantic went wee bit too cold too early?
There was quite a revealing exchange on ABC World News (US) last week. Diane Sawyer turned to “Weather Editor” Sam Champion, asked him what was up with the tornado outbreak and how does it relate to global warming.
Sam just blinked for, what, two seconds, before starting with how this was a 100-year convergence of many factors. I think the absurdity forced his brain to restart.
Next night, Diane did not mention global warming when asking about the tornadoes.
NOAA is solliciting donations for bigger and better super-computers and brighter and more highly educated employees and political appointees (with bigger benefit packages) through the Red Cross, The Salvation Army, and United Way following the most recent disasters. Donations are also possible via annual, involuntary check-offs on your Form 1040, 1040A, and 1040EZ. Give till it hurts America! (SarcOff)
Living in the area I am aware the NWS advised roughly 400% of those tornadoes. It was like the “Boy Who Cried Wolf Syndrome”! I did not even lose a tree to high wind. I was advised that 5 tornadoes were headed right towards me! Four at the same time! I quit listening to the warnings!
Appropros of very little –
in the early 70’s I lived near the Ohio-Ky border. On the previous
record tornado night I lost a couple of out buildings, a neighbor lost his life.
As I recall, the news magazines the next couple of weeks were explaining that the disaster was due to global cooling and we needed to take action NOW. I read both Time and Newsweek, and can’t pinpoint the source from memory but maybe there is an archive somewhere. The delicious irony is probably that the byline can be found today on global warming articles – to understand the warmists i think we need to read Erich Hoffer (True Believer).
West Virginia must have defensive tornado shields.
OK, mountains.
Great report Alan. Murray
I live in NW Arkansas where that string of dots is from Oklahoma into NW Arkansas. They shouldnt call that multi tornados just because the tornado skipped off the ground over and over. Plus it was an F0, which shouldnt be called a tornado either!
So right there you have 5 “tornados” for 1, and one that would of been overlooked in earlier years cause it was on the ground for yards at a time and did as far as I remember no damage to anything.
I wonder which direction the numbers will go if NOAA and others get the phased array deployed. Will they go up from the increased capabilities of the radar, or down for the same reasons? Either way we all know what the true believers will say, AGW.
“beng says:
May 4, 2011 at 6:36 am
West Virginia must have defensive tornado shields.
OK, mountains.”
To put a little humorous spin to it, maybe the weather gods just take pity of WVa.
Speaking of tornadoes; In 1927 a tornado killed seven members of the Ashby family
near Pleasant Hill, La. My mother, in her teens. was a first cousin living 200 yards away. Needless to say, when I was growing up, any suspicious weather sent us to a storm shelter.
I don’t think we should altogether invalidate these warnings…that’ why they’re called “warnings”…you have to consider the marginal human factor in making such weather “predictions”. It’s better to be safe than sorry…
Even with the advances in the prediction severe weather, a growing problem is the increase in population in the tornado zones of the south and midwest. This population trend is not likely to change and it will put a greater number of people in proximity of these catastrophic weather events.
As an amateur weather-spotter, owner of a weather-radio, and resident of a tornado-struck area, I cannot reiterate Mike Davis’ comment enough about the NWS and the “Boy Who Cried Wolf Syndrome”. I, and others I know, also quit listening to the warnings. They were continuous all week: warnings of heavy rain, rising small streams, possible hail, and ‘potential’ tornadoes. The 24 hours prior to the actual storm was filled with back-to-back alarms. There is a limit to preparing for a tornado, and I turned the radio off.
I submit the reason there are now less lives lost from tornado damage is due to improved personal communication; not NWS warnings. Evidence is in the thousands of cell-phone photos, videos, tweets and twitters.
It was clear from the amount of wind blowing off the Gulf of Mexico at the Texas coast over Easter weekend that a big storm was brewing up in the SE.
Here is an excellent article on the storm’s destruction and a computerized map of the track of the largest supercell:
http://blog.chron.com/sciguy/2011/05/how-destructive-were-those-late-april-tornadoes-lets-go-to-the-satellite/
@Mike Davis & Jim Patrick – I agree that the “cried wolf” issue is something that needs to be addressed. Even my favorite local meteorologist, James Spann, has said something to that effect. While I understand the NWS desire for safety, it has to be balanced with this consideration. I wonder if some of this is driven by the currently litigious The previous week or so we had several times when warnings were issued because there were “suspect couplets” on the velocity radar readings. I have no solution, just wanted to throw my hat in with Mike and Jim. But the last two weeks have proven that the wolf does show up sometimes.
With regard to the post above, WOW… just wow. That is a bunch of serious wind! The “little girl” is sure throwing quite a tantrum. Let’s hope she gets over it soon. 😉
I have to say that the NWS office here in Shreveport saved lives. An EF2 passed over my home and community near me. It was estimated to be 0.5 mi wide, however the path of destruction is twice that. We were struck by the south side of it and experienced over 5 minutes of hail at least golf ball size. The bark on trees is bruised and battered, the roof is as well, and I have a frisbee with a nice neat golf ball sized hole in it. There were dead birds everywhere!
By listening to the weather radio, I knew nearly to the minute how much time I had to get cars under shelter, move potential missiles either into sturdy buildings or at least where they wouldn’t damage valuable property when they were launched. Miraculously, we did not lose any livestock or dogs but lost somewhere around $20,000 in timber.
This particular tornado is #10 in the report from the Shreveport NWS.
I live on the west edge of a county. The sirens are linked for the entire county, so they go off when the line of cells is either already over us or imminently over us. The sirens continue until the storms leave the county toward the east side, long after the storms have passed (sometimes as long as an hour or more after). It would be better for us if we received warnings tied to the county west of us, rather than being lumped with places east. Also, due to the local topography, a line of cells will often either split or jump and reform to our east. In these cases the storms strengthen either north or east of us, occasionally prompting warnings long after any possible danger to us is gone.
I imagine that these artificial warning boundaries also exist in the South and in Tornado Alley. If so, I fear they may represent a dangerous hole in the warning system. Many times, at night or otherwise, we don’t have the TV on and are dependent on sirens for warnings. Late warnings are not good, should there actually be a tornado coming. Does anybody else have experiences that suggest there’s a problem?
I wouldn’t be in any rush to believe anything put out by the NOAA.
Mike Davis says:
Jim Patrick says:
I am not sure exactly what you guys expect? Tornadoes are very local things. They are, at most, about a mile wide and often considerably narrower and paths are typically a few miles long (although they can be tens of miles long in some cases). A tornado can destroy your neighbor’s home and not touch yours.
Given all this, do you expect the National Weather Service to be able to tell you if your home personally is going to be hit?!? Frankly, your attitude strikes me as pretty immature. If you quit listening to the warnings then you have only yourself to blame if the consequences don’t work out for you. The NWS warning system is not idiot-proof.
Here’s a front page newspaper story about the tri-state twister back in 1925
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