*Note: Tornado season goes from January 1 to December 31
As we approach the end of the year, it's hard not to look back and think about the hell most of the United States went through over the last 12 months. The immense southern drought and the resulting wildfires, the flooding in the Midwest, Hurricane Irene, and countless other disasters plagued the country (and the world) this year. In fact, as recently touted on almost every news source, 2011 broke the record for most billion dollar weather disasters since they started keeping track.
However, out of all of these disasters, 2011 will go down in the history books for its tornadoes. The SPC's preliminary count for 2011 stands at 1,884 tornadoes, which will probably be 100-200 lower once the confirmed numbers come out. If the preliminary count stands, 2011 will come out on top for the most tornadoes ever recorded in one year, beating 2004's count of 1717. In addition to the record, this put the 2011 season above the average of 1200-1300 twisters every year. What made this year stand out from all the others isn't the number of tornadoes, but the number of strong tornadoes hitting populated areas.
In addition to the number of tornadoes, the human toll was catastrophic. As of December 23, 2011, 552 people died as a direct result of injuries sustained in tornadoes. This is the second highest yearly death toll attributed to tornadoes in American history, dwarfed only by the 1925 season (which killed over 800 people).
At the end of the diary, I'll offer up some explanations for the uptick in tornadic activity, tornadic intensity, and deaths.
Jump the fold...
Tracks of confirmed tornadoes in the United States between January and July 2011.
January - March
The year began with a major tornado outbreak across parts of the south, as cold front swept through the area, firing off some nasty thunderstorms as it tracked east. Between Dec 31 2010 and Jan 1 2011, there were 36 confirmed tornadoes, 7 of which were rated EF3 on the Enhanced Fujita Scale. Of these 36 tornadoes, 7 occurred after midnight on January 1, and 2 of which were rated EF3. The outbreak resulted in 9 deaths, none of which occurred in 2011.
HPC's surface analysis for midnight on January 1, 2011.
Overall, there were 16 confirmed tornadoes in January.
There were two tornado outbreaks at the end of February, resulting in 63 confirmed tornadoes. The worst outbreak occurred on February 24, when an intense squall line tracked east from Arkansas/Missouri through the Tennessee Valley (storm reports below). Another outbreak occurred in the same general area a few days later on February 27-28, resulting in one death when an EF2 tornado destroyed a mobile home in Lynchburg, TN.
SPC storm reports for the squall line/tornado event on February 24.
Overall, there were 63 confirmed tornadoes in Feburary (second most in Feb on record) resulting in one death.
March saw a slight uptick in tornado activity as the continent started to warm up and allowed for more instability to develop. Most of the tornadoes were weak (EF0-EF1), and resulted in no deaths for the month. The largest outbreak was associated with a potent cold front that swept across the deep south on March 9. The worst of these tornadoes was an EF2 that occurred just southwest of Mobile AL, injuring 4 people. As the storm happened just a few miles away from me, I covered it here on DailyKos.
Left: HPC surface analysis from 12z March 9 showing the squall line across Alabama.
Right: A destroyed gas station in Mobile AL from the EF2 tornado on March 9.
Here's security cam footage of a hardware store that was also destroyed in the Mobile tornado, which was situated directly next to the above gas station.
Overall, there were 75 tornadoes in March causing no deaths.
April 4-5 Derecho
An enormous derecho tracked across the central and eastern United States on April 4 and April 5, causing extensive damage and 9 fatalities (one due to a tornado). The SPC received just over 1,300 reports of severe weather, which is almost a month's worth of severe weather reports in just 24 hours. Most of the tornadoes were weak, the strongest ones coming in around EF2 intensity. The one death was a person killed when their mobile home was destroyed in one of the line's embedded tornadoes. This derecho/tornado event caused over $2 billion in damages.
April 9th -- Mapleton IA EF3
Between April 9th and April 11th, a total of 38 tornadoes swept through Iowa and Wisconsin, destroying hundreds of structures and causing an estimated $2.2 billion in damage. The strongest tornado of this outbreak was an EF4 in Pocahontas IA, but the worst tornado was the EF3 that hit Mapleton IA. Even though 100 homes -- 60% of the town -- were leveled by the 3/4 mile wide tornado, there were only 16 injuries due to the 20 minute lead time between issuance of the tornado warning and the tornado striking Mapleton. I wrote a diary shortly after the tornado hit the town, which elaborates a bit more on this particular tornado.
Thankfully, though the tornadoes that evening were intense and damaging, there were no fatalities in this tornado outbreak.
April 14-16 -- Major Southeast Outbreak #1
April 14th Severe Weather Liveblog (OK/AR/KS)
April 16th Severe Weather Liveblog (North Carolina)
A strong low pressure system tracked across the central part of the country, with a cold front tracking along the southern side of the cyclone. The result was a 2 day tornado outbreak that was the worst seen in the region in 3 years. The system spawned intense tornadoes from Arkansas to North Carolina -- 178 confirmed by the end of the event, 13 of which reached EF3 intensity.
Atoka/Tushka OK Tornado
A multiple-vortex tornado hit the towns of Atoka and Tushka in Oklahoma the evening of April 14. A school was destroyed along with several homes, resulting in 2 deaths and dozens of injuries. After storm surveys, the NWS rated the tornado an EF3.
Jackson/Clinton MS Tornado
The next day, on April 15, the tornadoes moved east to Mississippi and Alabama (tearing apart the same areas that would be devastated by an even stronger outbreak a few weeks later), and dropped a strong tornado on Jackson MS, which moved into Clinton MS. The tornado crossed the runway at the commercial airport in Jackson, and moved into Clinton. Numerous storm spotters chased this dangerous EF3 tornado as it crossed an interstate and did major damage. No fatalities were reported due to this tornado.
One of the same storms that caused damage in Mississippi trekked into western Alabama, producing an EF3 tornado in Tuscaloosa, just a few miles away from where the infamous EF4 tornado would form just a week or two later. It caused heavy damage to buildings and some injuries, but thankfully there were no deaths.
North Carolina Tornadoes
On April 16, the weather system moved farther east into eastern North Carolina. The SPC issued a rare high risk for severe weather across the area, and their fears came to fruition when Oklahoma-style supercell thunderstorms formed that afternoon. Numerous tornadoes formed in this day's outbreak, killing 36 people across North Carolina and Virginia.
One of the tornadoes that formed started in Sanford NC, destroying a Lowe's Hardware Store, and tracked northeast through downtown Raleigh. This tornado was caught on WRAL's tower cam as it entered the city.
The National Weather Service put together a handy map, showing the tracks of the 28 tornadoes that touched down in North Carolina on April 16.
April 19-24 Tornado Outbreak
A prolonged tornado outbreak gripped the central and southern part of the United States between April 19 and 24, producing 98 confirmed tornadoes during the 6 day period. Most of the tornadoes were weak, and resulted in no deaths, but there was one significant tornado: the EF4 that hit St. Louis and its northwestern suburbs.
St. Louis EF4 Tornado
April 27th Tornado Outbreak
April 25th Outbreak (TX/OK/AR)
April 26th Outbreak (TX to TN)
April 27th Outbreak Part 1 (MS, AL, GA, TN)
April 27th Outbreak Part 2 (MS, AL, GA, TN)
April 28th Recap Diary
An extremely strong weather system moved across the southern United States between April 25 and April 28, with the worst weather occurring on Wednesday April 27. The tornado outbreak of April 27th broke numerous records:
A warm, humid airmass at the surface, combined with strong lift ahead of a cold front and upper-level trough allowed massive thunderstorms to develop across much of the southeast. Add in very strong vertical wind shear, and the storms turned into supercells and began to spin like tops on steroids. The result was catastrophic. Weather models saw these ingredients coming together, and the SPC had predicted a massive tornado outbreak for Mississippi and Alabama a few days in advance of the system. By the morning of April 27th, they had issued a rare high risk area over the most unstable airmass -- stating that there was a 45% (almost unheard of) risk for significant tornadoes that day.
Severe weather risk for April 27 2011
The storms came in two rounds. The first round happened pre-dawn on April 27, and came in the form of a squall line with some embedded weak tornadoes. The squall line was extremely intense -- its winds knocked down trees, power lines, destroyed mobile homes, and completely demolished some radio and cell phone towers. This left tens of thousands of people in northern Alabama without power, without telephones, and without cable to start the day. The early morning line of storms also knocked out numerous weather radio towers across northern Alabama, rendering weather radios useless for the bigger outbreak later in the day. Many of the deaths from the tornadoes that would form later in the afternoon came from people not knowing about the tornadoes due to power outages, phone outages, and weather radio outages. The death toll may have been lower had the early morning squall line not formed and knocked out these vital lines of communication.
Starting around mid-afternoon, instability was sufficient enough to fire off the nasty supercell thunderstorms that would produce all the death and destruction. It would be impossible to cover the hundreds of tornadoes that formed, so I'll focus on the 6 most destructive and deadly ones.
All tornado warnings issued between 7AM (ET) April 27 and 7AM (ET) April 28, 2011.
Cullman EF4 Tornado
Early in the afternoon, a supercell formed near the northern Alabama town of Cullman. Meteorologist James Spann, who works for ABC 33/40 out of Birmingham, covered the tornado live on tower cam as it formed in downtown Cullman and tracked through the city and into Arab. The EF4 tornado produced extensive damage to businesses, homes, and historic buildings in the downtown area. The tornado killed 6 people.
Tuscaloosa/Birmingham EF4 Tornado
Probably the most (in)famous tornado of the outbreak was the long track, monster tornado that tracked northeast from the southwestern suburbs of Tuscaloosa AL to the northeastern suburbs of Birmingham AL. This borderline-EF5 tornado caused extensive damage across its 88 mile-long path, and the tornado was 1.5 miles wide at times. This tornado killed 63 people and injured more than 1500. What made this tornado unique is that it was caught by literally hundreds of video cameras, and it was broadcast on live TV for almost its entire lifespan.
Here's ABC 33/40 coverage of the tornado as it tore through Tuscaloosa:
A resident of Tuscaloosa took a video of the tornado as it approached his apartment complex. He should not have done this, and if you're ever in the unfortunate position to encounter a tornado this close, do not do this.
The Weather Channel was stationed on a lookout over the city of Birmingham, and caught a terrifying view of the tornado as it tore through the suburb of Pleasant Grove. The tornado is so large and intense at this point that it's nearly impossible to tell with the naked eye where the tornado stops and the storm's mesocyclone (which descended to ground level) begins.
The radar images that came out of the storm are just as terrifying as the tornado itself. The first image below is the radar as the tornado was tearing through the heavily populated areas of Tuscaloosa. It's a textbook supercell, with the debris ball (the dark red/purple dot on the southern side of the hook in the storm) visible.
This image is a 3D analysis of the thunderstorm as it skirted north of Birmingham. The image looks at the storm from the bottom of the radar scan up through the top of the thunderstorm, with only the darkest reflectivities showing. The dark red/purple column in the middle of the image is actually the tornado full of debris, throwing it tens of thousands of feet in the air. For a few days after the outbreak, they were finding small stuff like letters, clothes, and pictures over 150 miles away from where they originated.
Smithville, MS EF5 Tornado
Smithville MS was struck by the first of four EF5 tornadoes to form that day. The tornado killed 23 people, scrubbed dozens of homes and other buildings down to their foundations, and even scoured drainage pipes out of the ground. A simple picture and caption from the NWS website is able to describe the unbelievable power of this tornado:
The remains of a Ford Explorer in Smithville MS. The tornado hurled the SUV about ½ mile, into the town's water tower (the tower is in the picture background) and continued on another 1/4 mile until impact. (Photo: Mississippi Emergency Management Agency)
Alabama/Tennessee (Hackleburg) EF5 Tornado
The second of the four EF5 tornadoes tore through parts of northwestern Alabama and southern Tennessee. The tornado tracked 133 miles that afternoon, with a maximum width of 1.25. The storm killed 72 people, and was the single deadliest tornado in Alabama history.
Here is an aerial video of the damage in Hackleburg from ABC 33/40. Caution: Some images are graphic.
Rainsville AL EF5 Tornado
The third of four EF5 tornadoes occurred in Rainsville AL, which is on the northeastern side of the state. The tornado was 1/2 mile wide at its largest, and killed 23 people. The storm that produced this tornado would go on to produce an EF4 tornado in Ringgold GA about an hour later.
On my way back to Mobile for the fall semester, we stayed at a hotel in Rainsville that was just a few hundred yards away from the path of the tornado. Even 3 months after the tornado tore through, I couldn't believe the amount of damage that thing caused. There were pieces of metal wrapped around trees and telephone poles. There were homes scrubbed to the foundation, with little more than cinder blocks laying around the empty foundation. There were massive piles of debarked trees laying on the sides of the roads, and scattered pieces of wood and insulation still in the grass, gravel and what plant life managed to survive. I never want to see that kind of damage again, let alone up close right after the storm hits.
Here's a storm survey picture from the NWS, showing what's left of a school bus, next to the Rainsville Community Center, which was also destroyed.
Ringgold GA EF4 Tornado
About an hour after the Rainsville/DeKalb County AL tornado struck, the supercell lifted off to the northeast into the northwestern part of Georgia. The storm gained its rotation back and dropped a tornado near the town of Ringgold. The tornado strengthened into an EF4 by the time it reached the town, destroying dozens of homes and businesses, and causing damage so bad that all roads going into or out of Ringgold were closed by police. The tornado tracked across 52 miles of real estate, and killed 20 people, before finally lifting and moving off to the northeast. The storm would continue to produce smaller tornadoes throughout the night.
Overall, there were 748 confirmed tornadoes in April.
May 21-26 Tornado Outbreak
May 22nd Joplin MO Tornado Diary
May 24th Tornado Outbreak (OK/KS)
May 25th Tornado Outbreak Part 1 (Midwest/OH Valley)
May 25th Tornado Outbreak Part 2 (Midwest/OH Valley)
May 25th Tornado Outbreak Part 3 (Midwest/OH Valley)
A weather system developed on May 21 in the central United States, and very slowly made its way off to the east over the next 5 days. The system produced 180 tornadoes that week -- 8 of which reached EF3 intensity, 3 of which reached EF4 intensity, and 2 of which reached EF5 intensity. 180 people were killed in this tornado outbreak.
Joplin MO EF5 Tornado -- May 22
160 of those killed in this outbreak died in this tornado alone, making it the seventh most deadly tornado in American history, and second deadliest tornado since 1950. The monster >1 mile wide tornado tore a path directly through the southern half of Joplin on the evening of May 22, 2011, destroying nearly everything in its path. The worst damage occurred in a neighborhood on the southern and southeastern side of Joplin, around the St. Johns Medical Center. The storm survey from the NWS' website sums up the horrific nature of the tornado:
The EF-5 rating (greater than 200 mph wind speeds) was mainly arrived at by the total destruction of vehicles of various sizes and weight. Some vehicles were tossed several blocks, and owners were never able to locate their vehicles. Also, parking stops weighing over 300 pounds and re-barred into asphalt were tossed from 20 to 60 yards. Other factors included was the deflection, deformed and tossing of reinforced concrete porches and slabs, and the fact the St. John’s hospital building structure and foundation were compromised and will need to be torn down, were probably caused by winds speed at or exceeding 200 mph.
By a sheer stroke of luck (or a lack thereof), a TV crew from the Weather Channel was chasing this storm a few miles behind when it struck Joplin. Meteorologist Mike Bettes and his crew arrived at the scene of some of the worst damage near St. Johns Medical Center just 10-20 minutes after the tornado, and they were overwhelmed by what they saw. Caution: This video is extremely hard to watch.
Here's some security camera footage from Joplin High School when the tornado hit and irreparably damaged the building. JHS is now held in a refurbished, abandoned mall while the school district builds a new ones. Two elementary schools and the city's middle school were also severely damaged to the point of total loss. Thankfully, since it was relatively late in the evening, the buildings were unoccupied.
El Reno OK EF5 Tornado -- May 24
A part of the same outbreak that caused the Joplin tornado two days earlier, an intense EF5 tornado struck El Reno, OK the afternoon of May 24th. The tornado spanned about 63 miles across the Oklahoma landscape, killing 9 people, injuring more than 60, and doing intense damage to homes and infrastructure in the area. The NWS doesn't have a damage survey easily accessible from their site, but there is some interesting data from the tornado. Oklahoma State University has an extensive system of Mesonet weather stations set up across Oklahoma, and one of these stations is located in El Reno. The weather station happened to be in the path of this EF5 tornado, and made the following wind measurements:
The station was on the outer edge of the tornado's circulation, and measured a 151 MPH wind as the storm went by. This was the strongest wind ever recorded by the Mesonet network in Oklahoma. Furthermore, the EF5 intensity was assigned to the El Reno tornado based on "Doppler On Wheels" data collected as the radar truck chased the storm. It measured winds of over 215 MPH at the tornado's strongest.
Overall, there were 327 confirmed tornadoes in May.
June 1 New England Tornado Outbreak
Satellite image showing the damage track of the Massachusetts tornado.
There was only one significant tornado outbreak in June, and it happened (of all places) in New England. Numerous supercells formed that afternoon, producing several tornado touchdowns. The most significant of these tornadoes was an EF3 that struck Springfield, MA. Television tower cameras caught the tornado as it crossed the Connecticut River and into the town as it moved southeast. The tornado caused extensive damage along its 39 mile path, and killed 4 people.
Overall, there were 159 confirmed tornadoes in June.
July through December
|There were a few tornado outbreaks in the second half of the year, but nothing too extensive. The two most notable outbreaks were along the Gulf Coast in September, and Oklahoma in November.
Gulf Coast Outbreak -- Tropical Storm Lee, Early September
Tropical Storm Lee formed in the Gulf of Mexico in late August, and very slowly made its way towards the Louisiana coast for the first few days in September. The heaviest rains were centered over southern Alabama, southern Mississippi, and eastern Louisiana. However, since dry air got sucked into the storm, the squall lines that are typical of tropical cyclones fell apart, and individual thunderstorms developed. Each of these thunderstorms began to rotate as they reached shore, and caused numerous weak tornadoes as they crossed land. As I blogged on September 4th, Mobile AL took the brunt of these storms. We were under a tornado watch for almost 90 consecutive hours, and went under 10 tornado warnings in just over 24 hours. No fatalities were caused by the tornadoes, though 16 people died in the storm's flooding.
Tipton OK EF4 -- November 7
Several tornadoes formed from thunderstorms ahead of a dry line in western Oklahoma on the afternoon of November 7. Most of the tornadoes were weak, but the strongest was an EF4 that struck Tipton OK. No deaths occurred and some damage was reported. The determination of the tornado's EF4 status came from the fact that the Tipton OK Mesonet station took a direct hit from the tornado. The station was able to measure 86 MPH winds before an irrigation tower struck the station. Based on the damage to the station, NWS officials determined the tornado reached EF4 strength.
The destroyed Tipton OK Mesonet station.
Overall, there were:
--102 confirmed tornadoes in July
--55 confirmed tornadoes in August
--65 unconfirmed reports of tornadoes in September
--24 unconfirmed reports of tornadoes in October
--65 unconfirmed reports of tornadoes in November
--0 reports of tornadoes in December as of Dec 23
Why were there so many tornadoes this year?
We got caught in an extremely active weather pattern. The jet stream was strong enough and sagged far enough south to create strong weather system after strong weather system. These systems were able to tap into the south's warm, humid air and create big thunderstorms. These storms benefited from strong wind shear, and it led to constant tornado outbreaks. The amount of thunderstorms that developed increased the chances of some of these storms tapping into the perfect ingredients for strong tornadoes, and as we saw, they took that opportunity one too many times.
Also, it helps to look at previous years in explaining this year's pattern. Here's a totally awesome Excel chart I made, using tornado 2011-2008 tornado statistics from the SPC:
The majority of this year's tornadoes came from the increased activity in April. With other years, there is a peak in tornado activity in the spring, with a very gradual drop-off throughout the rest of the year. However, in 2011, there was a massive spike in tornado activity in April and May, with a large drop in activity through the rest of the year. Again, this can be attributed to the active weather pattern we were in this year.
Did climate change contribute to the amount/intensity of these tornadoes?
Short answer: we don't know yet. One bad weather year isn't enough data to give a definitive yes-or-no answer. Climate change is definitely taking place, but even the NRDC concedes in its 2011 extreme weather wrapup that we can't be sure yet:
There were also another 7 extreme tornado events in 2011 with greater than $1 billion in damages each not shown on the map. We don't know yet whether climate change will worsen tornadoes – additional studies are needed.
Some years are extremely bad, some years are dead quiet. If this year's tornadic activity persists over the next decade, something is definitely up. My guess, though, is that the activity this year was a once-in-a-generation type event, like 1925 or 1974. Hopefully that's not proven wrong.
Why were this year's tornadoes so intense?
One thing to keep in mind is that tornado intensity is measured with the Enhanced Fujita Scale, which measures tornado intensity based off of damages caused by the tornado. Trained meteorologists estimate the wind speeds based off of the severity of the damage caused. Roof tiles missing indicate an EF0 tornado, while a well-built home completely wiped off its foundation signals an EF5 tornado.
The tricky thing about tornado intensity is that the strongest part of a tornado has to hit a populated area for us to know truly how strong the tornado was. A tornado of EF5 intensity (200+ MPH winds) could go through an open field and not touch a structure, and it's automatically classified an EF0. The rating/intensity is based off damage. As people in our country continue to build and expand, more tornadoes are hitting populated areas, causing major damage and more opportunities to rate tornadoes somewhat accurately.
Aside from the technicalities of tornado measurement, the storms this year were pretty intense. I attribute this to the uptick in activity this year. More storms forming allows for greater chances of storms tapping into the perfect ingredients needed to spawn major tornadoes.
Every year on average, 80 people die in tornadoes. Why was the 2011 death toll nearly seven times the yearly average?
It can be attributed to 6 things:
1) While we have pretty good lead times on tornadoes (20+ minutes most of the time), most of these storms were moving at 50 or 60 MPH. That doesn't leave much time for hesitation when a warning is issued. Also, you have to keep in mind that people are people. Some of those who died ignored the warnings. Some didn't take them seriously. Some took them seriously and went outside to look, only to be killed before they could reach shelter. And unfortunately, some people just didn't have time to make it to shelter after receiving a warning.
2) To be frank, many of the tornadoes that hit populated areas were simply not survivable unless one was underground. Look at damage pictures from Tuscaloosa, Birmingham, Joplin, Cullman, Rainsville, El Reno, Hackleburg, and many other cities that were hit by EF4 and EF5 tornadoes. Simply taking cover in an interior bathroom or closet wasn't adequate enough to survive such intense tornadoes.
3) In the instance of the Alabama tornado outbreak on April 27, a nasty line of storms that formed hours before the tornado outbreak knocked out power to tens of thousands, destroyed NOAA weather radio towers, and seriously damaged telephone/cell phone systems. This hampered efforts to get out crucial tornado warnings to the public in parts of Alabama that were leveled.
4) In the case of the Joplin tornado, the sirens went off numerous times warning of the storm, and residents were somewhat numb to the effect of the warnings. This "Crying Wolf" effect is also a major factor in other tornado deaths, as one becomes complacent after hearing tornado warnings that don't come to fruition.
5) The tornadoes hit populated areas. Tornadoes usually stay over relatively unpopulated areas of the midwest, but this year's tornadoes were farther south, allowing them to strike more populated areas. As I said above, as people continue to expand and build in areas that were previously open fields, the chance of a tornado to hit homes and businesses rises.
6) Urban legends prove to be killers sometimes. NOAA interviewed (though I can't find the links anymore) people from across the south after these outbreaks, and found that the typical urban legends are more prevalent than once thought. The classic widely-believed myth is that "tornadoes can't cross mountains, bodies of water, or cities." This has proven fatal, and this complacency was the cause of a few of this year's deaths.
Meteorologists are constantly working on ways to improve and update warning systems, but sometimes these efforts just aren't enough when faced with strong tornadoes hitting populated areas. This year was proof of that.
10:55 AM PT: As Sandy on Signal pointed out in the comments, GET A WEATHER RADIO. It's essentially a smoke detector for bad weather. Having one could save your life and the lives of those you know and love.