NOVA follows a chase team—a group of scientists who chart deadly Tornadoes—in an effort to learn more about predicting nature's most powerful and elusive weather phenomenon.
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00:00And God said to Elijah, go forth and stand upon the mount before the Lord, and a great
00:17and strong wind rent the mountain, but the Lord was not in the wind.
00:24In the small town of Barneville, Wisconsin, survivors of a devastating tornado struggled
00:28to rebuild their lives.
00:29All I remember is like two by fours snapping, must have been as it was taking the houses
00:36behind us, just snapped like toothpicks, you know.
00:40Across the United States each year, a thousand tornadoes suddenly take shape, and those that
00:45find targets kill more than a hundred people and cause $300 million in damage.
00:50But now, modern science is fighting back, and these storm chasers in Oklahoma are pursuing
00:56the elusive tornado as never before, daring to get close enough to unravel its mystery,
01:02possibly one day accurately predict and even help prevent its wrath.
01:07Tornado next on NOVA.
01:14Major funding for NOVA is provided by this station and other public television stations
01:19nationwide.
01:21Additional funding was provided by the Johnson & Johnson family of companies, supplying health
01:25care products worldwide.
01:31And Allied Corporation, a world leader in advanced technology products for the aerospace,
01:36automotive, chemicals, and electronics industries.
01:55A slowly darkening sky, a brooding cloud drifts over the prairie.
02:10It brings welcome rain and cool wind to the dry flatland.
02:18This is a thunderstorm, common throughout the Midwest during the spring and summer.
02:24Outside is a rising column of air, in this case powerful enough to trigger an unusual
02:28chain of events.
02:31The outcome, a spiraling whirlwind, sucking up everything in its path, swelling, becoming
02:37a swirling mass of debris.
02:46For the public, tornadoes are vicious acts of nature, appearing suddenly and striking
02:51arbitrarily, leaving in their wake death, destruction, despair.
02:57March 18th, 1925, the single most destructive tornado in history brought devastation from
03:03Missouri to Indiana, 700 killed, 11,000 homeless.
03:11More recently, April 1974, the largest outbreak ever, 148 tornadoes swept across the deep
03:17south and Ohio Valley in just 16 hours.
03:22From Huntsville, Alabama to Xenia, Ohio, 335 died amid $600 million in damage.
03:30Historically, man has been at the mercy of the tornado's uncontrollable wrath.
03:35But human ingenuity is finally catching up, and a new kind of battle against the tornado
03:39has begun.
03:42May 17th, 1981, a team of scientists races into the heart of a violent storm.
03:49A camera fixed to the top of their van records this remarkable event.
04:12Occurring in the Midwest four years later, the same group of scientists has come together
04:16in the vast flatlands of Texas and Oklahoma, where visibility is good and conditions produce
04:21the most active tornado weather on earth.
04:25They're part of the National Severe Storms Lab in Norman, Oklahoma, and they call themselves
04:29storm chasers.
04:34Day after day, they work in teams.
04:37Joining them is a pair of graduate students, Lou Wicker and Lance Rothfuse.
04:43Their goal?
04:44To track down a tornado and put a portable weather station directly in its path.
04:52Built to withstand violent weather, it can sense and record what no human can approach
04:56without real danger.
05:02The Totable Tornado Observatory, affectionately nicknamed TOTO.
05:16In charge of the intercept program is Bob Davies-Jones, one of the world's leading authorities
05:21on tornadoes and their parent thunderstorms.
05:23I've been chasing since 1974 and seen about 40 tornadoes, and we spend like 200 hours
05:31out in the field looking for tornadoes.
05:33To be a chaser, it takes a lot of persistence and a lot of fascination.
05:37You've really got to be in your blood.
05:39You've really got to get a thrill from going out and watching nature perform.
05:47Also watching is veteran tornado chaser Howard Bluestine, professor of meteorology at Oklahoma
05:52University.
05:55This year, Howie and his team seek clues to how tornadoes form by releasing weather balloons
06:00into the pre-storm environment.
06:03Balloons are an old tool of meteorology, but out in the field, they're ideal for studying
06:07thunderstorms.
06:08To me, a severe thunderstorm, like a giant piece of architecture in the sky, provides
06:14me with a sense of awe and wonder.
06:16I've always been interested in severe thunderstorms and tornadoes.
06:21Most of what is known about tornadoes has come through work of this kind, going out
06:25year after year to observe and collect data in the field.
06:29The chase teams depend on their own eyes, but they are backed by an operation that makes
06:33use of the newest and most advanced weather technology, Doppler radar.
06:40The National Severe Storms Lab is testing Doppler for use in issuing tornado warnings
06:44around the country.
06:46Here is a powerful set of new eyes guiding chasers in the field.
06:51Doppler radar allows them to probe inside thunderstorms and see the spiraling wind patterns
06:56that may lead to a tornado.
07:00Working directly with chase teams is lab meteorologist Don Burgess.
07:04All of the elements must come together for our knowledge to increase at the rate we wish
07:10it.
07:11We at the Doppler need to know what the chase teams see in the clouds to give us reference
07:17to those measurements we make in the wind field.
07:19So we've learned to work very closely together to learn the most we can about the storm.
07:25And to do that, the chasers have only a short season, from April to June, when tornadoes
07:31erupt along a notorious strip of land known as Tornado Alley, stretching from Texas up
07:37to Iowa and Indiana.
07:40They look for storms along two weather boundaries.
07:44As spring turns to summer, thunderstorms commonly occur as warm, moist air rushes up from the
07:49Gulf of Mexico and collides with a front of cool, dry air from Canada.
07:55The second volatile boundary is what scientists call the dry line.
07:59It forms as dry air spills onto the plains from the Rockies, butting up against and flowing
08:04over moist air from the Gulf.
08:07The dry line is a natural laboratory for studying thunderstorms.
08:12It's very dry and warm to the west of the dry line, and usually the air clears out just
08:17to the east of the dry line.
08:19So one can go to the dry line, see a thunderstorm, and get in the exact position that you want
08:24to be relative to the storm.
08:28So the dry line is where the chasers focus their attention.
08:32They look for potential instability, a contrast between moist air near the ground and dry
08:37air above it.
08:39As the day wears on, the sun heats the moist air, which starts to rise, condensing and
08:44forming clouds.
08:47But it's kept down by a layer of warm, dry air above, which forms a cap.
08:53Along the dry line, colliding air masses often push the clouds through the cap and
08:57storms explode into the upper atmosphere.
09:01In severe thunderstorms, rising moist air can reach speeds of 100 miles per hour and
09:07heights of 60,000 feet.
09:10As the updraft weakens near the top, cloud material settles into the upper-level winds
09:15and spreads out into an anvil.
09:21Strong and sustained thunderstorms, known as supercells, are sometimes 20 miles wide
09:26at the base, the anvil covering half a state.
09:36A small fraction of these big storms interact with winds moving through their environment
09:41and rotate as they grow.
09:43They are called mesocyclones, the birthplace of the tornado.
09:49Trailing down rope-like from the storm, a tornado is usually destined to die as abruptly
09:54as it appears.
09:56The strongest can be a mile wide and stay on the ground for over an hour.
10:01Winds swirling into their base can exceed 250 miles per hour.
10:05No other natural phenomenon produces winds this strong.
10:10For the scientists who chase them, tornadoes are mysterious, awe-inspiring, even beautiful.
10:17On one unforgettable day in 1981, the chase team saw nine tornadoes.
10:21Oh, what's it like to see a tornado?
10:25It's an incredibly exhilarating experience.
10:28The first tornado that we saw on 22nd May 1981 formed and dissipated in the classic
10:34style.
10:35It began as a whirl of dust underneath the wall of cloud.
10:40Soon the condensation funnel began to form and then connect with the dust whirl.
10:45The tornado assumed a rather sinuous or elephant trunk type of shape as it went across wheat
10:52fields.
10:53In fact, there were times when the red dirt from the fields were sucked up all the way
10:57to cloud base and the tornado was just enshrouded in a red cylinder.
11:04It's a display of nature which is extremely rare, extremely violent, something which not
11:09too many people have seen.
11:11It's very fleeting.
11:16Getting this close to one of nature's most awesome performances is an amazing accomplishment.
11:21Over a possible range of 125,000 square miles, the chasers wound up here at precisely the
11:28right time.
11:32The morning of May 12th, 1985, the first stop for the chase team is here at the lab where
11:38weather data from many sources are pooled together.
11:41It's possible that what we'll do is we'll get an occlusion, dry line cold front occlusion
11:44down on the border or something.
11:45The graduate students, guided by Bob Davies Jones, become detectives.
11:50They piece together clues that might tell them exactly where within their 200 mile range
11:55tornadoes may appear later in the day.
11:58The Doppler system can see a tornado about 20 minutes in advance, but the chasers must
12:03gaze hours into the future so they can be there when the action takes place.
12:09I'm scared about going south.
12:12This stuff, if a wave lifts north, it's a long drive.
12:19Several miles away at Oklahoma University, Howard Blustein and his crew are making similar
12:23choices.
12:25For Howie, this is a fascinating process of weaving together the atmosphere's intricate
12:29and sometimes obscure patterns.
12:34Intercepting severe thunderstorms is partly a science and partly an art.
12:38We know we need potential instability, moisture, but these conditions often persist over broad
12:45regions.
12:46The trick, and I say trick, is to try to determine over what localized regions will the severe
12:52thunderstorms actually occur.
12:54At this point, forecasting becomes somewhat of an art.
12:58People who look at weather maps day after day after day notice that certain events seem
13:05to be correlated with the formation of severe thunderstorms.
13:08What I like to do is take some of this art, noticing that there are certain relationships
13:13in the weather map between certain features and the occurrence of severe weather, and
13:20then after the fact, going and trying to determine why these features are related to severe thunderstorm
13:26activity.
13:27Good morning.
13:29We have an interesting severe weather situation developing today.
13:32Also on May 12th, the same large-scale weather patterns are being monitored at the National
13:36Severe Storms Forecast Center in Kansas City.
13:40The strong subtropical jet runs across Texas, and the polar jet comes across Kansas and Iowa.
13:46The job of these meteorologists is to predict severe weather anywhere in the continental
13:50United States and alert the public by issuing a watch.
13:55Right now, they notice an explosive situation in Tornado Alley.
14:00In this satellite image, the red shows a sharp contrast between moist air near the ground
14:05and dry, cool air above it.
14:07The atmosphere is potentially very unstable.
14:10Tornadoes could form anywhere along a 300-mile dry line, running from Oklahoma City down
14:15to Wichita Falls and Abilene, Texas.
14:19The question for the chasers is how far south to go.
14:25The answer, in Howie's mind, not far at all.
14:28His plan is to watch for storms just south of Oklahoma City.
14:35But if storms become severe down in Texas, he wants to be in position to go after them.
14:44Leaving shortly afternoon, Lou and Lance have committed themselves to going south all the
14:48way to Texas.
14:50The entire year's research depends on data they collect in these few short weeks.
14:55But this season, tornadoes have been fewer than usual, making the race against time and
15:00distance even more critical.
15:15Storms change so quickly, the teams need to stay in contact with the land.
15:21Within 50 miles of Norman, they communicate by radio.
15:25But once out of range, they're forced to pull off the road and just use the phone.
15:28I'm a little bit worried about something happening right back just south of Norman.
15:34We're seeing a little towering queue and small seabees building up under the anvil from the
15:40Wichita Falls storm.
15:41But the echo development is still weak.
15:42I don't think that's anything to worry about.
15:43I think you should still head southwest toward the Wichita Falls storm.
15:52OK, I think that this activity here appears to be going downhill.
15:59And if anything does come up from southwest of Wichita Falls, we'll have plenty of time
16:03to get it.
16:04OK, Howie.
16:05Well, good luck.
16:06Thanks.
16:07Bye-bye.
16:08What are we doing?
16:10We're going to go west.
16:12It's still not exactly clear what's happening.
16:15Thunderstorms are breaking out southwest of Wichita Falls, and the weather service is
16:19considering putting out a watch.
16:21When Howie learns that storms have started to go up in Texas, he decides to move a little
16:26further south.
16:27The situation in Oklahoma doesn't look promising.
16:30Still, his instinct tells him, stay close to home.
16:33Yeah, go west in 29 to Marlow, and then we can drop south to Duncan, and we can be in
16:39good position for any storms that are popping up down here.
16:42But I still don't have that much faith in it.
16:45How far southwest of Wichita Falls are the thunderstorms?
16:47Archer City.
16:48That's not very far.
16:49It's off the map here, but it's about 30 miles from Wichita Falls, something like that.
16:53It's where the last picture show was filmed.
17:043.25 p.m.
17:06In Kansas City, the Severe Storms Forecast Center issues a watch for northern Texas.
17:11Yeah, it's Fort Worth.
17:12This is Kansas City.
17:13It seems that the development around Abilene is going to become severe soon, and we probably
17:18should issue a severe thunderstorm watch.
17:21And what we have indicated here is a watch that extends 60 miles east.
17:26If dangerous weather materializes, it's up to the local branch of the weather service
17:30to warn the public.
17:33Lou and Lance are heading for the watch area, hoping to get Toto there in time.
17:38They make a quick decision, gambling on a shortcut to Wichita Falls.
17:42For storm chasers driving long distances over unfamiliar roads, the risk of getting lost
17:47is ever-present.
17:50Are you looking southeast or southwest, Lou?
17:53I'm looking southeast.
17:54West.
17:55West.
17:56Southwest, Lou.
17:57No, I'm looking over there.
17:58That's southwest.
18:00No, it isn't.
18:01It's east of the road, and the road goes southwest.
18:02We're going south right now.
18:03What are you saying?
18:06That's southwest.
18:08That's southeast.
18:10This road goes southwest.
18:12This road.
18:14Hold on, Bob.
18:15I've got a direction problem here.
18:16This is 65 going south.
18:18We're not on 65 yet.
18:19Yeah, we are.
18:284.30 p.m.
18:29Howie is still in Oklahoma, about 70 miles from the lab and 50 miles from the Texas border.
18:35He spots a cloud that has broken through the cap and is widening at the base.
18:39It could be the start of a thunderstorm.
18:42We have somewhat of a dilemma right now.
18:44We're right along the back side of the deep moisture.
18:49We've been measuring the temperature dew point outside the car.
18:53You can see the edge of clouds right over here.
18:56The towering cumulus cloud went up and looked very good.
18:59It looked as if it might become a thunderstorm, but then it died.
19:02We also have a thunderstorm way off in the distance to the southwest,
19:06somewhere near Wichita Falls.
19:08And we really don't know whether that particular thunderstorm is getting the deep moisture or not.
19:13But what we really need to do right now is to get a telephone call back to the lab
19:18and find out what the storms to the southwest look like on radar.
19:23Hello, Oklahoma City.
19:24We are seeing development of severe thunderstorms across the Red River into Oklahoma now.
19:29And we think that the activity will develop towards Oklahoma City.
19:34There's now a tornado watch that includes both Oklahoma City and Wichita Falls, Texas.
19:41It's 7 p.m. Howie must commit to one of these options.
19:45New cells are forming right along here.
19:48They're just not very well organized.
19:50And I'm going to try to see whether or not any of the storms
19:53which we passed by to our west earlier are coming up.
19:59Howie learns from the lab's radar that the Oklahoma storms are still weak
20:03while the Texas storms continue to build.
20:06Let's go a little bit further. Let's get suckered a little further southwest.
20:09He has reached the point of no return.
20:11He must go south or risk seeing nothing.
20:22The TOTO team crosses into Texas and gets set for intercept.
20:26Lance, we need to get both Nestle 2 cameras out of the silver case back there.
20:36Roger, we're crossing the Red River.
20:43Howie's team is moving for the clear air at the rear of the storm,
20:47the best place to see a tornado if it forms.
20:50But to get there, they must travel through a curtain of rain and hail.
20:56Even with the uncertainties of forecasting severe weather,
20:59the teams are within minutes of the largest storm in the watch area.
21:07But there is no guarantee that it will produce a tornado.
21:13See what I'm looking at here?
21:19In the clear air behind the storm,
21:21Howie's team searches for signs of rotation,
21:24the mesocyclone that may produce a tornado.
21:27If one were to form, it would form somewhere over there about three miles away.
21:33But the right ingredients have just not materialized.
21:42Several miles away, right underneath the storm,
21:45Lou and Lance are in position to deploy TOTO.
21:49Whether or not a tornado appears,
21:51they risk encountering the greatest danger to storm chasers,
21:54deadly lightning.
21:57If it's going to do anything, which I'm not so sure it's going to,
21:59it's about 30 to 40 minutes away.
22:01So we need to position ourselves 30 to 40 minutes from now.
22:03And I would guess, it looks to me like it's almost...
22:06With the team still in Wichita Falls,
22:08radar at the lab picks up strong storms near Oklahoma City.
22:12The information is transmitted to the weather service,
22:14which issues a tornado warning.
22:16Radio and TV stations alert the public.
22:19In eastern sections of Oklahoma County,
22:21also hail, goodness gracious, would you look at that?
22:23You're looking live from our tower camera.
22:25Between 8 and 9 p.m., three tornadoes were sighted.
22:28One tore through a trailer park, but no one was killed.
22:36For the chasers, the day has been a frustrating one.
22:39But not unusual, considering they only see four or five tornadoes in an average season.
22:44It's very difficult to observe severe thunderstorms.
22:48You need to go out for many years and make many observations
22:51and look at the various types of phenomena,
22:53which can actually occur in nature.
22:56So it requires an incredible amount of hard work,
22:59perseverance, and it does get very frustrating.
23:04As the chase teams face a long drive home,
23:07their real work is just beginning.
23:09Back at the lab, they'll study the conditions
23:11that produce tornadoes in Oklahoma,
23:13but fail to in Texas.
23:15We think we understand and we predict pretty well
23:17the large-scale weather, the movement of large weather systems
23:20across our country.
23:22And we understand some of the mesoscale weather,
23:25a smaller scale, the size of the watches
23:28that we issue for tornadoes,
23:30maybe part of the state of Oklahoma.
23:32We know severe storms will be in western Oklahoma today.
23:35We're able to predict that in advance,
23:37but it's very hard for us to predict
23:40where a tornado will be exactly,
23:43which square mile of ground it might affect later today.
23:48That micro-scale information,
23:50we're going to have to learn more
23:53and do a lot of development,
23:55increase our skill as scientists
23:57to understand those details.
24:00As the scientists move closer to their goal
24:03of predicting severe weather on the local scale,
24:06real-world forecasters still face a monumental problem.
24:09The Weather Service is set up not to see the details,
24:12but to monitor the enormous volume of atmosphere
24:15across our country's landscape.
24:17The weather stations they rely on are simply too far apart.
24:22At the Severe Storms Forecast Center,
24:25satellite data and new computer systems
24:27are helping to fill the gaps,
24:29and the accuracy of tornado watches,
24:31the first step in alerting the public, has improved.
24:34But there's still a long way to go.
24:42The problem of such large-scale predictions
24:45was underscored on June 8, 1984.
24:48A tornado watch was posted for all of southern Wisconsin.
24:52Most people in the small town of Barneville
24:55treated the stormy night like any other.
24:58It was really windy all day,
25:00and I remember sitting in the living room
25:03talking to Mom, watching TV,
25:05and saying that we're really going to get a storm
25:08because it's so windy.
25:11It was just windy all day.
25:13I never got out here during the night.
25:16We got about 3 quarters of the way out here,
25:19and we met a young man from out in this area,
25:22and he said, don't go out there.
25:24He said, it's all gone.
25:26And I said, what do you mean it's all gone?
25:29He said, it's all gone.
25:31I said, what about the church?
25:33He said, it's flat.
25:35Just before 1 a.m., a tornado roared through town.
25:3890% of the homes were destroyed.
25:41Nearly half the 500 residents were injured.
25:44Nine died.
25:46I had to work early the next day,
25:49so I went to bed about 9 o'clock.
25:52It was windy out then,
25:54and then Laura woke me up about 9.30
25:57and said that there was a tornado watch out
26:00until I think she said 11 or 12.
26:03So it was a big deal.
26:05Michael was already in bed with us that night,
26:09and Matthew was in his bed,
26:11and both the boys shared a room.
26:14And Matt started crying and stuff because he,
26:17I don't know, apparently they've always been afraid
26:20of the thunder and lightning,
26:22especially in the middle of the night.
26:25So I went in and got Matthew and put him in our bed
26:28and laid him down, and then I went to the bathroom,
26:31and we had a bathroom right off of our bedroom.
26:34And before I ever got done, I could hear the houses,
26:37I could hear the houses and stuff crashing behind us.
26:40I ran out and told Charlie to grab Michael
26:43and go to the basement that there was a tornado coming.
26:46And I've never been in a tornado before in my whole life.
26:49It was the loudest crash of thunder that I'd ever heard.
26:53It was kind of strange because normally in a thunderstorm,
26:56you hear the wind blowing or you hear the rain
26:59hitting against the side of the house,
27:03and all of a sudden it was just dead quiet.
27:06It was the most sobering quiet that I had ever encountered.
27:12And then the next thing you know, there's a roar,
27:15and the roar didn't give you any time to react.
27:19I thought for sure that a jet plane was going to crash.
27:22There was a real peculiar kind of a pressure.
27:25The pressure was so great, it's almost like the house expanded
27:28and then almost came back together again.
27:31The next thing, I was knocked to the floor
27:34and debris started flying.
27:36And of course at that time, as soon as that happens,
27:39you think right away, tornado.
27:41All I remember is like 2x4s snapping.
27:44It must have been as it was taking the houses behind us
27:48because I remember 2x4s snapping,
27:50just snapped like toothpicks, you know.
27:53You could hear 2x4s snapping and glass shattering.
28:01Sirens
28:06All I remember is running, running down,
28:09just running for my life is all I could do.
28:12I knew she wasn't right behind me with Matthew,
28:15and I didn't think I could turn back
28:17because I had Michael with me to go find him
28:20or we'd all be up there, you know.
28:22So I just ran down to the north wall,
28:24and Michael was kind of hanging around my neck,
28:27and I just kind of put him in front of me
28:30and it was over within a few seconds.
28:33As soon as we stepped off the main foundation of the house,
28:36that's when it hit, that's when the door hit.
28:38That's how Matthew got killed, a bolt off the doorknob
28:41went to the back of his skull right next to his brain stem
28:44and killed him instantly.
28:46How I knew that he was very seriously injured and stuff was,
28:51I was leaning forward and as soon as it was done,
28:54I leaned backwards.
28:56He kicked my legs up from underneath me
28:58and I leaned back and that's when he gasped for air.
29:02When I heard my wife screaming,
29:04I made my way over to her
29:06by exiting off the back of the foundation,
29:09and her comments to me were,
29:11I don't have any clothes to wear,
29:13and why it struck me immediately as a tornado,
29:16I don't know because I'd never been in one before,
29:19but I simply told her, I said,
29:21Barb, there's been a tornado
29:23and we've got to get over to the fire station.
29:25I got her off the foundation
29:28and we started heading toward the fire station
29:30and of course we had no shoes,
29:32and as the lightning, once again,
29:34lit the sky and guided my way,
29:36I looked at the fire station,
29:38I just thought, my God, the fire station's gone.
29:40After the house was gone,
29:42I set Michael up over the cement
29:44and we walked around and got Susan and Matt,
29:47we never, you know, all I said to her
29:49is we've got to get out of here,
29:51we don't know if it's coming again or what,
29:53we've got to get to shelter,
29:55so we just picked them up
29:57and I'm speaking about underwear.
29:59I could see Charlie and Sue
30:01and they had Matt and Mikey with them
30:03and Charlie had Matt
30:05and he said,
30:07take Matty, he's really hurt bad.
30:16There was five doctors that worked on Matt
30:19and I knew by the time he ever got into the ambulance
30:22and left that he was already dead.
30:27I remember the rain,
30:29cold, cold rain just poured,
30:31dark, it was so dark you couldn't see
30:33your hand in front of your face
30:35except for when the lightning would flash
30:37and then you could look down and you could see
30:39every house was gone,
30:41that's all you could see as we walked down the street,
30:43every house was gone, just flattened.
30:48The Bonneville tornado was a quarter mile wide,
30:51its winds swirling at an estimated
30:53250 miles per hour.
30:55Some died as their homes collapsed on them,
30:58others like two-year-old Matthew Ashelman
31:00from flying debris.
31:03When a tornado this size hits a town,
31:05it becomes a churning mass of flying wreckage.
31:10This test footage shows just what debris can do.
31:17The wind by itself is enough
31:19to tear most ordinary houses apart.
31:21It can easily lift a weakly connected roof
31:23from the house.
31:25The walls then lose their support
31:27and the entire structure collapses.
31:33But a low-cost reinforcement of the roof-to-wall connection
31:36using a simple metal clip
31:38can make all the difference.
31:40It's commonly done in hurricane regions
31:42but because of the tornado's erratic nature
31:44rarely anyplace else,
31:46even Tornado Alley.
31:50To better understand how debris
31:53reacts in tornadic winds,
31:55engineers at Texas Tech University
31:57have recreated the tornado's
31:59destructive power in the lab.
32:01With a unique kind of gun,
32:03they will fire this two-by-four
32:05at 115 miles per hour,
32:07the speed it might be hurled
32:09in the strongest tornado.
32:11Their target?
32:13Various kinds of walls,
32:15even sturdy brick ones.
32:17Three, two, one.
32:21They've learned
32:23that no economically built wall
32:25remains intact.
32:27Based on these tests,
32:29they designed an impact-resistant shelter
32:31that can be built into a closet.
32:33But the battle against the tornado
32:35involves not only protection.
32:37Alright, Dale, that's a tornado drill.
32:39Open the door, please.
32:41Everybody stand up.
32:43Public education becomes increasingly important
32:45for understanding of tornadoes
32:47and more accurate predictions.
32:49Throughout Tornado Alley,
32:51students are taught to move downward,
32:53away from glass,
32:55and no matter what, to stay indoors.
32:57Go to a basement, a closet,
32:59even a bathroom where plumbing
33:01strengthens the walls.
33:03Hit the wall.
33:07The value of public awareness
33:09was made clear in April 1979
33:11when a mile-wide tornado
33:13struck northeast Texas.
33:15Some 6,000 homes and apartments
33:17were destroyed.
33:19Yet among the many thousands
33:21who found shelter in their homes,
33:23only five died.
33:25Tragically, 26 died in their cars,
33:27many of them fleeing the storm.
33:33The Barneville tornado
33:35struck in the middle of the night,
33:37too suddenly for anyone to prepare for it.
33:39But the very fact that people
33:42survived an even larger toll
33:44of death and injury.
33:46A year later, the town has been rebuilt,
33:48but there remains a shattered
33:50sense of security.
33:52It's not one thing happened.
33:54It's not like that.
33:56It's everything happened.
33:58You know, your business is gone,
34:00your town's gone, your school's gone.
34:02Just your house is gone.
34:04Everything's gone.
34:06Part of your family's not here anymore.
34:08There used to be so many kids out here.
34:10There used to be a slug of them.
34:12Some moved out.
34:14Some moved to other towns.
34:16It's just a total change,
34:18I guess.
34:22Before, we really never
34:24even had any alarm
34:26come into our lives at all
34:28when we heard of a tornado watch.
34:30But now, of course,
34:32when we hear the word tornado,
34:34it brings up a whole array
34:36of pictures in our minds.
34:38And my dreams
34:40in the first three months
34:42were never of tornadoes,
34:44but of utter confusion.
34:46Nothing ever came out right.
34:48And I think that was what people
34:50had to live through.
34:52They had nothing under control.
34:56When it gets nasty, I get scared
34:58just like, you know, really bad
35:00when it's a lot of lightning and it's windy.
35:02And it's kind of like that night started out.
35:04And I get nervous
35:06watching the clouds.
35:10And the whole heart's going 90 miles an hour
35:12and I'm right at the top of the stairs
35:14wondering if I should go down.
35:16It's scary.
35:18I think that's the biggest thing that happened
35:20for this whole community.
35:22Their sense of well-being, of safety
35:24was blown away, literally.
35:26They're vulnerable.
35:28We found that the parents
35:30were really having as much trouble
35:32if not more than the kids were.
35:34Parents tend to express it.
35:36Parents tend to try to be strong.
35:38Parents would say,
35:40I want us all to feel fine again
35:42so let's just not talk about it.
35:44And I know from a counseling standpoint
35:46that it's important to share and talk about it
35:48and to get it out.
35:54Across America's heartland,
35:56towns like Barneville live under the shadow
35:58of sudden and unexpected disaster.
36:00To make matters worse,
36:03they're plagued with false alarms
36:05and chronic lateness.
36:07On local radar, the Barneville storm
36:09looked like any other.
36:11Only after the tornado was reported
36:13did the Weather Service issue a warning.
36:15And by then, rescue workers were already
36:17pulling people from their destroyed homes.
36:21If the public is to be warned of tornadoes reliably
36:23and further in advance,
36:25weather technologies will have to be updated.
36:29About the time of World War II,
36:31we decided that we could take a beam of radiation,
36:33send it out,
36:35bounce some of it off of raindrops,
36:37get it back at a receiver,
36:39and measure that power amplitude.
36:41And that's what we have with conventional radar.
36:43This system shows us
36:45how heavy the rain is.
36:47If we're going to get one inch of rain
36:49or two inches of rain from a thunderstorm.
36:51But it's hard to use that information.
36:53And this is the way we've been
36:55since about the time of World War II
36:57to say, where is a tornado going to occur?
36:59With a Doppler radar,
37:01we get the exciting new prospect
37:03of seeing the winds and maybe rotation
37:05up in the storm
37:07that might produce a tornado.
37:09This new radar
37:11is based on the Doppler effect.
37:13If the wind is moving away from
37:15or toward the radar,
37:17the signal will bounce back at a different frequency.
37:19The greater the difference,
37:21the greater the speed of the wind.
37:25When we look at the Doppler display,
37:27it's much easier to see areas of circulation.
37:29All of the red colors
37:31flow away from the radar.
37:33The green colors flow back toward the radar.
37:35And right at the center
37:37there's a very dramatic color shift.
37:39We have a little red in the green
37:41and a little green in the red.
37:43Together these colors show a signature
37:45for rotation.
37:47The tornado's signature on the Doppler screen
37:49was discovered as a result of
37:51Chaser's observations.
37:53In May 1981,
37:56a long tornado was tracked on radar
37:58and followed by chase teams near Binger, Oklahoma.
38:02On the Doppler radar
38:04analysis, there was a small anomaly.
38:06It was not known
38:08for sure that it represented a tornado,
38:10but by going back and getting
38:12the times of the chase team's observations
38:14and the places where the
38:16tornado was along its path,
38:18what would look like a glitch in the data,
38:20turned out it correlated exactly
38:22with where the tornado was.
38:24It's here, the tornado.
38:26She's bubbling. What do you have?
38:28Yes, it's firing along the edge.
38:30A year later, for the first time,
38:32the Weather Service in Oklahoma City
38:34began using Doppler radar from the Severe Storms Lab
38:36to issue warnings to the public.
38:38There is now a plan
38:40to install these advanced radars
38:42across the country.
38:44The system is called NEXRAD,
38:46Next Generation Weather Radar.
38:48It will cost about a billion dollars,
38:50but it could help reduce the huge costs
38:52exacted by severe thunderstorms and tornadoes.
38:54500 lives,
38:56and as much as a billion dollars
38:58in damage each year.
39:00Mike, Ed, we've got a warning for you.
39:06Enid OHP, Stillwater PD,
39:08this is Oklahoma City Weather.
39:10We're issuing a severe thunderstorm warning.
39:14Persons in Covington, Enid, and Breckenridge
39:16are in the path of these storms
39:18and should be prepared for large hail and high winds.
39:20All right, we're putting it on the air now.
39:22Doppler radar helps
39:24with warnings on thunderstorms in several ways.
39:26First, it increases the lead time.
39:28With our conventional system right now,
39:30without Doppler,
39:32lead time is maybe zero.
39:34The tornado is formed before the warning occurs.
39:36With Doppler, we can get
39:38an average, perhaps, of 20 minutes lead time,
39:40time for people to take shelter.
39:42Also, the warnings with Doppler
39:44are more accurate.
39:46There are many fewer false alarms,
39:48about 50% fewer false alarms.
39:50That will allow the public
39:52to have more confidence in the warning
39:54and they will be more likely to follow through
39:56and take those precautions
39:58that might save their life.
40:00Here in Boulder, Colorado,
40:02is an experimental forecast center
40:04of the future.
40:06If tornadoes are ever to be predicted
40:08more than minutes in advance,
40:10it will be at weather stations like this one.
40:14Using a network of closely spaced
40:16observation posts, meteorologists
40:18here monitor the subtle atmospheric
40:20changes that may be associated
40:22with severe weather.
40:24They employ all the newest sensing technologies,
40:26including Doppler radar.
40:28And powerful computers allow them
40:30to display and manipulate information
40:32as never before.
40:36This image from 1884 is the first photo
40:38ever taken of a tornado.
40:40Historically, the subject of endless
40:42myth and speculation,
40:44tornadoes were once thought to cook potatoes
40:46in the ground,
40:48even fuse coins in people's pockets.
40:50A recently published idea
40:52held that tornadoes drew spin
40:54from vehicles passing on highways.
40:56More credible theories
40:58have had to do with electricity,
41:00hail, even the Earth's rotation.
41:04If you have a tub of water
41:06and you let it still for
41:08maybe two days,
41:10very carefully remove the plug
41:12and let the water drain out,
41:14then it's been shown
41:16in the laboratory
41:18that you will get a vortex
41:20which has the same sense of rotation as the Earth.
41:22A tornado would require
41:24about three hours to form by this
41:26mechanism, and they seem to form
41:28much more rapidly than that.
41:30Out of systematic
41:32observations made in the past decade,
41:34a body of new theories has emerged.
41:36The mystery of the tornado
41:38is being reduced to a few key questions.
41:42...attract a sounding
41:44right along the dry line right now...
41:46One of the basic questions
41:48we ask ourselves is
41:50why don't all thunderstorms rotate
41:52and why don't all those rotations
41:54or mesocyclones produce tornadoes?
41:56We need the right ingredients
41:58in terms of moisture, buoyancy,
42:00and the wind forces
42:02together to make rotation.
42:04And then there is a very, very
42:06delicate balance to get that rotation
42:08to spin up into a tornado.
42:10We find that the environment,
42:12the near environment of the storm,
42:14makes all the difference in the world.
42:16Scientists now understand
42:18that thunderstorms gain rotation
42:20from a special combination of winds
42:22moving through their environment.
42:24Describing how these winds
42:26are organized is one of Howard Blustein's
42:28goals in a unique set of
42:30experiments along the dry line.
42:32What's the temperature?
42:34Temperature looks to be
42:36about 33...
42:39His team releases
42:41a weather balloon.
42:43While it radios back information
42:45to a small computer,
42:47chasers track it to determine
42:49wind profiles.
42:51How's the signal?
42:53The signal looks just fine.
42:55A little windy out here.
42:57In particular, they look for wind shear,
42:59a condition in which the winds
43:01increase with height.
43:03Surface winds are slowed
43:05because of friction with the earth,
43:07but the wind moves faster
43:09along a narrow high-speed river of winds,
43:11the jet stream.
43:13Now imagine that you have a wind
43:15which is coming from this direction down here
43:17and a wind coming from this direction up here.
43:19The wind's coming much,
43:21much faster up here than down here.
43:23Imagine what would happen
43:25if you put a paddle wheel in the air.
43:27It would start to rotate like this.
43:29Strong wind here, weak wind here.
43:31It would begin to rotate.
43:33Now meteorologists call
43:35this measure of rotation vorticity.
43:37When wind shear is present,
43:39rotation pervades the atmosphere
43:41like countless rolling tubes of air.
43:43The growing thunderstorm
43:45tilts the spinning air upright,
43:47creating two vertical vortices,
43:49one on either side of it.
43:51The storm builds into the area
43:53of the counterclockwise
43:55or cyclonically spinning vortex
43:57and starts to rotate.
43:59What happens now
44:01is that air will rise
44:03into the cyclonic part
44:05of the couplet
44:07and the vortex tube,
44:09if you will, becomes stretched.
44:11It's stretched vertically
44:13and it shrinks in scale horizontally,
44:15very much like a skater
44:17who's spinning around.
44:19The skater brings their arms in
44:21and they spin up.
44:23That by itself is still not enough
44:25to produce a tornado.
44:27This can produce what's called
44:29the mesocyclone,
44:31which is like a tornado
44:33but in a thunderstorm.
44:35At this stage,
44:37as the mesocyclone narrows,
44:39the cloud base lowers
44:41into a beautiful and imposing form,
44:43the wall cloud.
44:45But here the mystery deepens.
44:47Out of the rotating wall cloud,
44:49the tornado seems to form
44:51suddenly without warning.
44:53What unseen events
44:55trigger the tornado?
44:57Some of the answers are
44:59answered by a computer
45:01at the National Center
45:03for Atmospheric Research
45:05in Boulder, Colorado.
45:07Scientists here simulate
45:09mesocyclones to see how
45:11and under what conditions
45:13they may produce tornadoes.
45:15As the radar scan the storms
45:17and the chase teams are
45:19taking observations
45:21underneath these storms,
45:23they are obtaining
45:25extremely interesting observations.
45:27Comparisons with those observations
45:29show that we're simulating
45:31realistic storm features.
45:33Then we can use that data
45:35to further understand the important
45:37mechanisms within these storms.
45:39After it reaches maturity,
45:41the computer storm produces
45:43features seen by chase teams,
45:45a wall cloud, and nearby
45:47a clear area where downdrafts
45:49break through the cloud base.
45:51This is the same computer storm
45:53in horizontal cross sections
45:55five miles, two and a half miles,
45:57and 800 feet above the ground.
45:59Downdrafts occur when
46:01dry air flowing around the storm
46:03at mid-levels is cooled by falling rain.
46:05The airflow patterns
46:07here suggest that downdrafts
46:09help create a new source of rotation
46:11that ultimately leads to the tornado.
46:13Here we see the moist
46:15inflow approaching
46:17from the east and the
46:19downdraft outflow
46:21spreading out behind the storm.
46:23Where these two
46:25airstreams collide,
46:27we see a strong convergence line
46:29which separates these
46:31two very different air masses.
46:33This produces very strong
46:35rotation about a horizontal axis
46:37which is then tilted into
46:39the vertical and strongly intensified
46:41in this low-level updraft
46:43which we believe is responsible
46:45for the strong rotation
46:47which ultimately produces the tornado
46:49within the storm.
46:51The mesocyclone
46:53continues to rotate,
46:55but within it, this new rotation
46:57causes rising air to move faster
46:59around a tighter spiral.
47:01In a matter of moments, it turns into a funnel
47:03building down from the wall cloud
47:05toward the ground.
47:09The storm is now sucking
47:11in large quantities of air through the
47:13tornado's base, causing fierce
47:15ground-level winds.
47:18In most tornadoes,
47:20the updraft is constrained to the
47:22single funnel. In a strong
47:24tornado, the airflow may become so
47:26unstable that the funnel breaks down
47:28into a series of smaller vortices.
47:34For storm chasers,
47:36the computer model has created
47:38a lot of excitement, for it gives them
47:40a new way to test out their ideas
47:42and observations.
47:47For example, downdrafts were first
47:49noticed in the field, and the computer
47:51helped make sense of them.
47:53This is a spectacular wall cloud.
47:55Look at the striations,
47:57the multiple striations in this.
47:59And if there's any large hail...
48:01Near the end of the 1985 season,
48:03Howie sees a kind of storm
48:05that seems to produce tornadoes
48:07without a strong downdraft,
48:09indicating that there are probably
48:11other mechanisms at work.
48:13We'll just have to do our best.
48:15It's going to move right by us.
48:17So far I've been very impressed
48:19at how many storms,
48:21which look nearly identical to the one
48:23we saw yesterday, actually occur in nature
48:25but aren't documented.
48:27Secondly, we would like
48:29to get soundings up near these
48:31storms so that
48:33we can simulate
48:35these types of storms using the numerical
48:37model, given the environment
48:39that was measured by
48:41our balloon.
48:45...
48:49Okay, release.
48:51Okay, 19, 10,
48:5330.
48:55Good, no problem.
48:57We're right up into it.
48:59Absolutely excellent.
49:01Five seconds to go.
49:03The balloon is going perfectly.
49:07Tornadoes present the greatest
49:09challenge to severe storms forecasting.
49:11Many scientists believe
49:13that accurate predictions will eventually
49:15be made an hour or more in advance.
49:17Tornado, tornado.
49:19I think we have a tornado.
49:21I don't know.
49:23But they also realize that understanding
49:25the tornado fully will come only at the end
49:27of a long, hard battle.
49:29There's a strong outflow in that region,
49:31but there's a vortex tube
49:33along the gust front.
49:37That is the weirdest thing
49:39I've ever seen.
49:41...
49:43We're not going to deploy.
49:45For scientists, getting even the most basic
49:47temperature, pressure, and wind data
49:49can be highly dangerous.
49:51This year, when TOTA was deployed
49:53in a tornado's damage path,
49:55it was the first time that direct measurements
49:57of this kind were ever recorded.
49:59...
50:01And we deploy back down.
50:03We leave everybody here, except the crews.
50:05Let's deploy back down the road.
50:07Let's move it. Let's go.
50:11Moving west.
50:13Deploy TOTA. Right here, Steve.
50:15Somewhere in here. Somewhere in here.
50:17TOTA's about to be deployed.
50:19Time is 19.02.
50:21A little farther, Steve.
50:23A little farther. Peek the hill. Peek the hill.
50:25...
50:27...
50:29...
50:31...
50:33...
50:35...
50:37...
50:39...
50:41...
50:43...
50:45...
50:47...
50:49Let's go. Let's go. Let's go.
50:51Get out of here, guys.
50:53...
50:55...
50:57...
50:59Hopefully, the effort of these scientists
51:01will unravel the mystery of the tornado
51:03and help prevent the death and destruction
51:05that so often follow in its wake.
51:07...
51:09...
51:11...
51:13...
51:15...
51:17In Barnavel, the one-year mark
51:19approaches. A single house
51:21remains to be torn down.
51:23...
51:25...
51:27...
51:29Most people have rebuilt their homes.
51:31New trees have been planted.
51:33And businesses are starting to return.
51:35It's hard to know
51:37how much is going to happen
51:39in a normal year
51:41and how much is special
51:43because this year, this community
51:45was almost totally destroyed.
51:47One of the things we've seen
51:49was an unusual amount of depression,
51:51of sleep disturbances,
51:53of several instances
51:55of people being suicidal,
51:57several instances of people
51:59being so stressed
52:01that they were hospitalized.
52:03However, in looking back
52:05on the crises of the past year,
52:07I believe that now people
52:09are pulling together again.
52:11The depressions are lightening up.
52:13People are sleeping through the night
52:15a little better. The wind doesn't
52:17scare them quite as much.
52:19They're piecing it back together.
52:21All you can do is just
52:23forget about what happened
52:25and try to go on, you know.
52:27No matter what you do,
52:29it isn't going to change anything.
52:31Basically, that's all you can do,
52:33you know,
52:35try to forget what happened
52:37and start over again.
52:39Everything I lost
52:41could be replaced,
52:43and there were families in town
52:45that lost members and that
52:47they can't be replaced.
52:49So I'm very fortunate in the fact
52:51that my insurance company
52:53was very good, and now I have
52:55a new home and new furniture
52:57and got all my kids with me
52:59and now realistically I'll say
53:01I'll rebuild my home.
53:03I guess there are some emotional
53:05reasons why I shouldn't rebuild.
53:07The pessimism comes from
53:09do I want to be here?
53:11I can look to as many people
53:13as I want, but the answer
53:15has to come from within.
53:17I don't know if I have
53:19the spirit to rebuild.
53:21Jim Kennard finally did summon
53:23his spirits, and he began
53:25to rebuild his home and business.
53:27I don't know how to answer that.
53:29Start over again.
53:31Try not to forget
53:33what happened, but try to put it
53:35in the back of your mind and keep
53:37stumbling ahead, that's all you can do.
53:39Is there something that the rest of the country
53:41could learn from what's happened here?
53:43Don't give up.
53:47Thanks very much. Your last name is spelled
53:49A... A-S-C-H-L-I-M-N.
53:51I'm sorry, could I just hear
53:53that again, just so we make sure
53:55it's spelling right? A-S-C-H-L-I-M-N.
53:57Thank you very much. You're welcome.
53:59I'm sorry to bother you.
54:01Later in the summer,
54:03Sue Ashelman gave birth to a baby boy.
54:07The wounds here
54:09are healing. Some of these people
54:11are even going to help others,
54:13victims of a violent tornado in Pennsylvania.
54:15Most people in this
54:17village are just happy to be alive.
54:25Of a wet
54:27garden
54:29springing
54:31from weakness
54:33where
54:35it may pass.
54:39And God said
54:41to Elijah, Go forth and
54:43stand upon the mount before the Lord.
54:45And behold,
54:47the Lord passed by, and a great
54:49and strong wind
54:51rent the mountains, and
54:53broke in pieces the rocks
54:55before the Lord. But the
54:57Lord was not in the
54:59wind.
55:01God is not
55:03in the earthquakes,
55:05in the fires, in the winds
55:07of this earth.
55:09For those forces seek to destroy.
55:11What more do we
55:13need to know?
55:15Amen.
55:17We raise our voices
55:19in thanksgiving.
55:21We are thankful
55:23to be alive.
55:25For our faith,
55:27our sense of community,
55:29and belonging.
55:31For our persistent, patient,
55:33and passionate God.
55:35And we remember
55:37Matthew Eshelman,
55:41Rick Hamerly,
55:45Kirk Holland,
55:47Bruce and Jill
55:49Bruce and Jill
55:51and Cassie Simon,
55:53James Lewis
55:57and the helicopter pilot
55:59Sergeant Stuart
56:01J. Searle.
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56:21.
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