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00:16A freakish kind of weather event...
00:19We should not be...
00:21I'm taking right now.
00:23...is now striking again and again.
00:26People were panicking, running, taking cover.
00:30Intense.
00:31Batten down the hatches for the potential
00:33for straight line wind gusts
00:35in excess of 75 miles an hour.
00:39Highly localized.
00:41That thing just collapsed right on those mountains
00:43and all that air is just exploding.
00:47And devastating.
00:51It sucked windows out.
00:53There was glass everywhere.
00:56They fall from the sky without warning.
01:02Explosions of wind and water so violent
01:05they can flatten homes in seconds.
01:09They're known as rain bombs.
01:12And they're getting stronger.
01:14The damage each year just continues to pile up and up and up.
01:19Now researchers are attempting to understand
01:21these destructive weather events.
01:24In some cases it can look like a bomb went off.
01:28Trying to predict where they'll drop and when.
01:32It's not safe to be outside.
01:34We've got about 20 minutes until this severe storm passes through.
01:39Rain bombs.
01:41Right now.
01:43On Nova.
01:44When.
01:46Bye.
01:48Beautiful.
02:00Right now.
02:01having.
02:01a roster of stripped ironowa
02:08theme.知道ing
02:13of hand would lift it. were all
02:14Out of nowhere, the skies darken.
02:19As powerful winds gust at over 80 miles per hour.
02:25Please exit the tent.
02:27Stages collapse.
02:29Very quickly, within a couple of minutes, it became probably the heaviest rain I'd ever seen.
02:34Lauren Behan was 19 when she and her friends traveled from Ireland to Belgium for the festival.
02:42You couldn't see anything, really.
02:44There was wind-blowing debris.
02:47It was very much a case of feeling like we were trapped.
02:52For it to turn from such a sunny, cloudless day to something apocalyptic in the space of 20 minutes is
02:59frightening.
03:00It's like something from a disaster movie.
03:03140 people are injured.
03:06And five festival-goers lose their lives.
03:13August 2024, a superyacht called the Basian sinks off the coast of Sicily.
03:20CCTV from the shore that night catches the vessel's mast, lights barely visible in the 100-mile-per-hour wind
03:28gusts and rain.
03:31It drags anchor, then capsizes.
03:36Divers recover seven bodies from the wreckage.
03:44July 2018.
03:47In heavy rain at Durango International Airport, Aeromexico Connect Flight 2431 is cleared for takeoff.
04:12The aircraft crashes back down to earth before it even clears the runway.
04:18Miraculously, there are no fatalities.
04:26Each of these events was caused by a mysterious weather phenomenon, recognized only in the last 50 years.
04:35Each began with a thunderstorm, but what followed was much more violent and unexpected.
04:45Highly localized, sudden and extreme rainfall, and low-altitude, high-speed winds.
04:53They're nicknamed rain bombs, but scientists call them downbursts.
04:59So what are they?
05:01And what causes them?
05:18Mike Olbinski is one of the world's foremost thunderstorm photographers.
05:24After 15 years of chasing storms, he's mastered the art of being in exactly the right spot at the right
05:30time to photograph an elusive weather phenomenon.
05:35Rain bombs exploding from the sky.
05:40His images can help scientists understand how these weather systems form and how they detonate.
05:48We have an updraft going up right to our west, and then this big storm is forming right behind it,
05:55and I can see it on the horizon.
05:57So I think we need to get a little bit more west.
06:08Growing up in Phoenix, we used to watch lightning storms, you know, outside at night.
06:15I loved them, and I've always loved them, and I traced it back to seeing a lightning bolt strike behind
06:21my house.
06:22I still have this insane, vivid memory of it happening.
06:27Mike is on the hunt for rain bombs.
06:31These intense weather events are striking with greater strength than ever.
06:36To track one down, he first needs to find a developing thunderstorm.
06:44But what is the difference between a rain bomb and a run-of-the-mill thunderstorm?
06:51In a normal thunderstorm, you get heavy rainfall, lightning, and sometimes hail, and this can happen over hours.
07:00A thunderstorm can drop rain at about two inches per hour.
07:04A rain bomb can triple that rate.
07:09And in a rain bomb, the rain and hail aren't just falling to the ground.
07:15They're being thrown down by hurricane force vertical winds.
07:20What does a rain bomb look like?
07:22It looks like a massive volume of rain and cold air coming from cloud base to the surface.
07:38Across the planet, there are 2,000 electrical storms generating thunder and lightning at any given moment.
07:47Each one of them releases more energy over its lifetime than the 15 kiloton atomic bomb dropped on Hiroshima.
07:56Every rain bomb forms from a developing thunderstorm.
08:00But to understand how, we must first understand how clouds form.
08:11When sunlight hits the earth, the surface heats up and water from oceans, lakes, soils, and plants starts to evaporate,
08:20turning into water vapor.
08:24That water vapor, and the warm air around it, start to rise.
08:30As it starts to rise, it takes all of the water vapor near the surface of the earth up into
08:37the atmosphere.
08:39As it lifts that up in the air, that parcel of air cools.
08:44The colder the parcel, the less able it is to carry around that water vapor,
08:50and so it forces it out into the formation of cloud droplets.
08:56Clouds form where the water vapor condenses into tiny water droplets,
09:00so small and light that they stay aloft instead of falling as rain.
09:07The altitude where this happens is called the cloud base.
09:12You see lots of little clouds developing, and they all have the same cloud base.
09:18So the cloud bases are actually occurring at the same temperature and hence the same height.
09:29In Arizona, the summer monsoon season has arrived.
09:33It carries moist, warm air from the Gulf of California, the perfect fuel for thunderstorms and rain bombs.
09:42We can feel it in the air, that it's really humid out, there's moisture, it's warm.
09:46So we've got the environment for storms to form.
09:51We're seeing these strong cauliflower kind of shapes at the top.
09:55When you're seeing that, you've got to imagine how intense that is to go from nothing to this sharply defined
10:03cloud.
10:03And then a couple of them get a little bigger, and then you get something like this where, boom, it
10:07erupts.
10:11If the conditions are right, these simple clouds can turn into thunderstorms.
10:17When you have these puffy, fluffy clouds that you see in the sky, there's some interesting things going on inside.
10:24Condensation is happening, and heat is actually being released as water vapor is changing to water.
10:31As the water vapor cools, it condenses into droplets that form a cloud, warming the surrounding air.
10:39The now warmer air rises, creating more updraft, lifting more air higher into the cooler atmosphere, where even more water
10:48can condense, which further warms the air.
10:53If the conditions are right, with enough moisture rising into cold air above, this fuels a positive feedback loop that
11:01intensifies the cloud's growth.
11:13I see, like, a whole line of updrafts going up, so I like that.
11:18A lot of these tops today, they just look really strong.
11:24Sometimes you've got the towers going up, and they don't have the same kind of powerful look.
11:28They're bubbly like a cauliflower, but they're just a little less intense.
11:31Well, a couple of these, if you look at them, they just look like there's so many areas where it's
11:37just knuckly and explosive looking.
11:42Oh, I just saw two big bolts strike way out there on the horizon.
11:51But I think something big is going to happen here.
11:53It's a nice, large, dark area.
11:56This is probably going to turn into a really strong storm.
11:58I would expect.
11:59I would hope.
12:01I'm trying to catch some lightning right now.
12:04I'm doing two time lapses.
12:05Lightning is an indicator that the updraft is tall enough to have ice and hail.
12:15Ice and hail are key ingredients that drive the most powerful rain bombs.
12:21But how does something as solid as ice or hail form and stay aloft in the atmosphere?
12:27When water vapor condenses in clouds, it releases an extraordinary amount of energy that makes our clouds very turbulent and
12:37that lifts the air higher up in the cloud.
12:40At some point in time, that air will cross over what we call the freezing level to form things like
12:46snowflakes and hailstones.
12:49And that changing phase, of course, releases more energy.
12:55This energy, in the form of heat, drives the further growth of the cloud, expanding upward to the very top
13:02of the troposphere, up to 12 miles above ground level.
13:08Above the troposphere sits a warmer band of air called the stratosphere.
13:13This warm air acts as a lid preventing the cloud from climbing any higher, so it spreads out flat, forming
13:20a distinctive anvil shape.
13:23So we've gone from the development of a tiny little fluffy cloud to these very tall, extensive storms that are
13:31now carrying around large amounts of hailstones and snowflakes.
13:37This storm is now seriously ready to do business.
13:42Lightning bolts are a telltale sign that a cloud has developed into a thunderstorm.
13:49Raindrops get so big, they're too heavy to be held by the cloud's updraft, and so it begins to rain.
13:56Or, if conditions are right, it can go on to develop into a violent rain bomb.
14:04To understand why some thunderstorms collapse into rain bombs, it helps to know what's going on inside that rain cloud.
14:13One way to uncover that is to analyze the stuff that falls out, particularly hailstones, icy chunks of a frozen
14:23cloud.
14:32Over the summer of 2025, storm researchers teamed up on a project called Ice Chip to collect hailstones from thunderstorms
14:40striking the Great Plains.
14:44The ground teams, the teams looking at what kind of hail fell at the surface, is really what made this
14:49campaign unique.
14:50Because other campaigns, you know, would go and look at storms with mobile radars, and that's a lot of great
14:56information.
14:56But only ours also tried to really fully characterize what kind of hail was down at the surface.
15:08The Ice Chip team brings the hailstones to a cold lab in Boulder, Colorado.
15:17Here at below freezing temperatures, atmospheric scientists Anthony Bernal Ayala and Becky Adams-Seelen process and analyze each of the
15:26thousands of samples.
15:28Large hailstones are extremely valuable in understanding more about the thunderstorm they came from.
15:35Once you get the hailstones, you can actually just go ahead and cut a thin slice out of it.
15:40And you polish it up so it's an even thickness.
15:43You can get a lot of information just by looking at the slice.
15:47You can see different rings in the hail, and much like tree rings, those represent different conditions under which the
15:54hail was growing in the storm.
15:57When we look at hail stones, and we look at the cross section, one of the things that we look
16:01at is whether the layer is opaque or whether the layer is clear.
16:05When you look at that clear layer, you're looking at where there is a warmer sub-zero temperature, so it's
16:10a little bit warmer in the cloud, where liquid water freezes slowly.
16:14And because it freezes slowly, that allowed the air bubbles to escape.
16:18So it's going to be clear.
16:19There's not going to be a lot of air bubbles trapped in this layer.
16:21When you look at the opaque layer, because it's in temperatures in the cloud that are very cold, it's going
16:28to freeze very rapidly.
16:29So because it freezes very rapidly, it actually traps a lot of air bubbles in that layer, so it actually
16:35looks opaque.
16:36But why would a single hailstone have both clear and opaque layers?
16:41And what does that reveal about how the hailstone formed?
16:46The hailstone had to have been moving around in the storm to experience these different conditions and to create the
16:51different layers.
16:52We think that it's actually rotating somehow around the updraft to accumulate all those layers that we see in the
17:01cross section.
17:03These layers are evidence that the hailstones are continually rising and falling inside a developing thundercloud.
17:11This hailstone spent most of its time in very cold temperatures in the cloud, but for a very short period,
17:18it actually went through a warmer side of the cloud.
17:21Then it went back a very cold temperature.
17:23Then it went back a warmer section of the cloud, where it probably fell, and then it was collected at
17:28the surface.
17:30To grow to two inches wide, this hailstone most likely spent over half an hour being lifted and dropped inside
17:37the storm.
17:39There's updrafts, there's downdrafts, there could be hail, there could be circulations or rotations inside that cloud.
17:47These intense storms are very turbulent.
17:51They have regions where air is rising very rapidly, sometimes at speeds of 150 miles per hour.
18:00This mixing of hail and ice provides the energy necessary for the storm to produce thunder and lightning.
18:09In mature thunderstorms like the one that made Anthony's hailstone, immensely powerful updrafts can suspend over a million tons of
18:18hail miles above the ground.
18:20It's actually quite incredible that storms are able to suspend these large mass of liquid raindrops and of our ice,
18:30like hail and snowflakes, so high up in the atmosphere.
18:35What happens to this core of rain, hail and ice determines whether the storm remains a regular thunderstorm or unleashes
18:45a rain bomb.
18:52Dude, that looks freaking awesome.
18:54That's just plummeting.
18:55That's like a downburst happening.
18:57When you see that middle rain shaft area where it looks like a blob, that's usually a good telltale sign
19:04of a downburst happening.
19:07Oh man, this is stunning.
19:13In a fully developed thunderstorm cloud, what goes up must eventually come down.
19:20The cloud's updraft begins to peter out as rising air cools and sinks back toward the ground as a downdraft.
19:29This is what happens in a standard thunderstorm.
19:34But in a rain bomb, things are different, because in a rain bomb, a sudden, extremely strong downdraft overwhelms the
19:43updraft, causing the cloud's core of ice and hail to collapse all at once.
19:49Two processes drive this sudden downdraft intensification.
19:54The first is that as the rain and hail start to fall downward, they drag on the air, so they
20:00pull the air down toward the earth.
20:05When massive amounts of rain and hail begin to fall, they help generate a downward rush of air, which can
20:12act as the rain bombs trigger.
20:15But that's not all that's required to get a rain bomb started.
20:20The second, more important process that accelerates this developing downburst toward the ground is evaporation.
20:29Evaporation is a cooling process.
20:30You experience it when you step out of a swimming pool or your shower.
20:34When you've got drops of water on your skin, as these drops evaporate, your skin feels very cold.
20:41If winds blowing into the cloud are dry, they can rapidly evaporate raindrops, as well as melt ice and hail.
20:49This cools the surrounding air, making it denser and heavier.
20:55This very cold air, very dense air, has to sink.
21:00So it's going to rush toward the surface, taking all of that large mass of rain and hail.
21:07As rain and hail descend from the cloud, if they hit more dry air, the evaporation can accelerate further.
21:15As the raindrops fall below cloud base into this drier air, they will evaporate in that location, too.
21:23This, of course, is going to really intensify that cooling process.
21:27This very cold, dense air rushes toward the surface, creating these phenomenal scenarios called downbursts or rain bombs.
21:42The downdrafts can intensify into hurricane-force vertical winds, driving the cloud's core of hail, rain, and cold air downward,
21:51slamming it into the ground.
21:54Sometimes the downburst's rain can completely evaporate before reaching the ground, creating what scientists call a dry downburst.
22:05And all of these downbursts, both wet and dry, can strike in just a few minutes, in a remarkably narrow
22:13column, as small as just a couple of hundred yards across.
22:18And as our atmosphere warms, they're becoming more and more powerful.
22:24It actually can be quite a frightening moment.
22:27There's a lot going on.
22:28There's lightning, there's hail, there's very heavy rain, and then, of course, the strong wind.
22:38Storm chaser Hank Schema has been caught under a powerful rain bomb.
22:43There was a day where I get slammed by a downburst.
22:52The rain really picks up and gets really strong.
22:55Everything turns white, and then all of a sudden I can see that I'm about to drive off the road.
23:01You can feel the winds rock in your car, and the winds are picking up sand and things in the
23:07road, and they're slamming them into their car.
23:10It's really terrifying and scary.
23:20Strong winds are a key element of downbursts.
23:25They slam cold air into the ground at high speed.
23:30And this air has to go somewhere.
23:33They can't go into the ground, so they spread out horizontally in all directions.
23:37So you see extreme surface winds.
23:40Cold air hits the ground and pushes out radially from the heart of the downburst.
23:46This outflowing air, remember it's very cold, dense air, we refer to as a cold pool, because it is a
23:54cold pool of dense air.
24:00These advancing banks of cold air can kick up dust, creating the distinctive dust storms often seen in the American
24:08Southwest.
24:09Dusty cold pools are called haboobs, and they create all sorts of severe weather, including visibility issues, road accidents, and
24:20breathing issues.
24:22The dust makes the turbulent gust front of an advancing cold pool easy to see.
24:28But even when no dust is present, this billowing front of cold air is still there.
24:35And it's these fierce straight-line winds that inflict the most damage.
24:41These winds are strongest near the surface.
24:45If you compare that to something like a hurricane, a lot of the strength in a hurricane exists higher up
24:51in the atmosphere.
24:53But for downbursts, they occur very close to the surface.
24:58Trees will just flap down to the ground, and these wind gusts are so strong that you cannot stand on
25:03your own feet anymore.
25:05In some cases, it can look like a bomb went off.
25:08Literally, that air hits the ground at low levels and spreads out in all directions.
25:14Those winds are what we call straight-line winds.
25:18They are not turning like a tornado turns.
25:21They are following straight lines away from where the downburst hits.
25:35This might explain what happened to Aeromexico Connect Flight 2431
25:40when it took off from Durango International Airport en route to Mexico City.
25:46The rain, while heavy, was not extreme.
25:49There were storms in the area, but the tower had cleared them for take-off
25:54and had told them that they actually have headwinds, which would provide them lift for take-off.
26:01Without realizing it, Flight 2431 flew through a downburst.
26:07In just seconds, the plane experienced a mere 180-degree shift in wind direction.
26:13The plane was about 30 feet off the ground at a very susceptible time on any take-off.
26:20And this tailwind, it swung from being an uplift to a sinking motion.
26:26Without the lift generated by a headwind, the plane plummeted and crashed into the runway.
26:53Luckily, everyone managed to escape before the plane was fully engulfed in flames.
27:00This wasn't the first passenger jet to crash in similar conditions.
27:06June, 1975.
27:09Eastern Airlines Flight 66 crashed on approach to JFK.
27:16August, 1985.
27:19Delta Flight 191 crashed on approach to Dallas-Fort Worth.
27:26July 1994.
27:28U.S. Air Flight 1016 crashed on approach to Charlotte-Douglas International Airport.
27:37Those tragic accidents in the 70s and 80s led to a lot of very significant research in downbursts,
27:45how they operate, and then subsequently the technology that we need to warn pilots.
27:51A lot of the airports in the U.S. are fitted with these weather radars.
27:57But there are many of the airports around the world do not have this technology.
28:01Air Mexico flight would not have taken off had they been aware of the fact that they were just about
28:07to hit a downburst.
28:11When investigators study the loss of the supposedly unsinkable Bayesian yacht, which went down on August 19th, 2024,
28:20they discover that before it capsized and sank, it had dragged its anchor around 400 yards in a dead straight
28:27line.
28:29The Bayesian was anchored off the north coast of Sicily.
28:36It was in a bay. It was next to another yacht.
28:39This CCTV footage from a camera onshore about 600 feet away reveals the boat in the distance.
28:47What ended up happening was as these really strong straight line winds hit these yachts,
28:52they dragged anchor in straight lines that indicates it was a straight line wind
28:58as opposed to the kind of rotational wind you would get from a tornado.
29:02It was a very large yacht with a very tall mast,
29:07and it would appear that the downburst and associated cold pool was actually able to roll it over beyond its
29:14point of stability.
29:15The yacht succumbed to the same type of extreme low-altitude straight line winds
29:20that led to the crash of Flight 2431.
29:30At the Puckle Pop Festival in 2011,
29:33the hail and howling winds struck an area less than a hundred yards across.
29:39This was a very narrow downburst.
29:42This is what made it so unusual.
29:44You would normally expect such power from systems that are larger,
29:47where they can transport more rain and more hail and more wind to the surface
29:52than in a hundred-meter-wide downburst.
29:55So a really remarkable event.
29:58These real-life tragedies revealed the destructive potential
30:01of powerful rain bombs.
30:03Intense, highly localized, and short-lived.
30:12But a storm that hits Houston in May 2024
30:15has all the hallmarks of a downburst,
30:19except that it is much bigger.
30:23It travels around 1,000 miles,
30:25and it lasts much longer than a single downburst,
30:29more than 12 hours.
30:32A line of severe thunderstorms is racing into our greater Houston area.
30:36You should batten down the hatches for the potential for straight-line wind gusts
30:40at about 70, 80 to 90 miles an hour.
30:45National Weather Service forecaster Amaryllis Cotto
30:48is on call at the Houston-Galveston office,
30:5227 miles southeast of downtown Houston,
30:55when the storm hits.
30:57The storm developed very fast in areas of west-northwest Texas
31:01at around 9 a.m., and so we could see how fast it was moving.
31:06It was already affecting the Houston metro area by around 5 to 6 p.m.
31:12It's not safe to be outside.
31:14We've got about 20 minutes to get hunkered down
31:16on the first floor, interior room of your home,
31:18away from windows.
31:20That's the safest place to be
31:21until this severe storm passes through.
31:24It was devastating, Houston.
31:26We had a lot of tree damage.
31:28We had millions of people without power.
31:31Hank and Neti Ashima are 5 miles north of downtown
31:35when the storm hits.
31:37He starts recording the storm from his car.
31:40Suddenly, it goes from daylight to darkness,
31:44and chaos hits.
31:49Here it comes.
31:52Holy ! Holy !
31:55Yep, hang on. Got it.
31:59Um, we should not be here.
32:02It's not checking right now.
32:04You can't see a block in front of you
32:06just because of the whitewash of wind and rain,
32:09and trees are swaying,
32:11and downtown Houston is raining glass
32:14as windows are failing all up in the skyscrapers.
32:19The winds associated with this system
32:22were hurricane-force winds in the lower levels.
32:24It sucked windows out.
32:26There was glass everywhere.
32:29And in addition to the sucking motion,
32:31inside the buildings,
32:32the pressure in is now higher than outside.
32:34So you get this explosive force
32:37that forces windows and glass out of the buildings.
32:44It's the signature of a rain bomb.
32:49Super-strong ground-level winds
32:51shattering any weak windows along their path.
32:55Telltale signs of straight-line wind damage
32:58are seen all over the city.
33:00They pull down power lines across Houston
33:03and plunge one million people into darkness.
33:08But the Houston storm isn't the size of the storms
33:11that hit Pucklepap or sank the Bayesian.
33:15It's over 50 miles across
33:17and leaves a path of devastation
33:20across the 10,000-square-mile Houston metro area.
33:24Rain bombs just don't grow this big on their own.
33:27They need to gang together to become this large.
33:31But how?
33:4722 miles northeast of Fort Collins, Colorado,
33:51atmospheric scientist Sue Vandenhever's 20-strong team
33:55is out in the field.
33:57I think the Polk House is keen
33:58to have some surface measurements.
34:00Okay, you'll see.
34:00They're trying to assist the moisture.
34:03Her team deploys drones
34:05engineered to withstand extreme weather.
34:08They measure the outflow winds
34:10when the cold air in a downburst
34:12crashes to Earth
34:14and races across the landscape,
34:16forming the cold pool.
34:24We've launched what we call the Flying Curtain.
34:29And we're flying a wall of six drones.
34:34We have a lower level of drones
34:35and an upper level of drones.
34:37We have a lot of instruments
34:38that can measure the temperature,
34:41the moisture of the atmosphere.
34:42We've got anemometers on there
34:44that can measure the winds.
34:46And this allows us to make measurements
34:48of the variability of the atmosphere.
34:50And as the cold pool advances on us
34:52and blows through us,
34:53we are able to make that measurement
34:54in time as well.
34:56So there's a lot that we are characterizing
34:59about these cold pools.
35:02Sue and her team are tracking a storm
35:05a safe distance away beyond the horizon.
35:09Radar shows that it has produced
35:11a downburst of intense rainfall.
35:16The air that slammed into the ground
35:18is now spreading out across the plains
35:21in a cold pool,
35:22coming toward them.
35:25Their radar tracks the dust
35:27kicked up by the advancing bank
35:29of fast-moving cold air.
35:33So we're expecting a cold pool
35:35to come through
35:36within the next few minutes,
35:37so we're waiting
35:39to try to collect the data.
35:41The team will release weather balloons
35:43up into the cold pool
35:45to measure temperature,
35:46pressure, humidity, and moisture.
36:05This cooling of the air you can feel
36:07and the wind you feeling,
36:08that's this boundary
36:09that's actually starting to hit us.
36:11So we're going to release that balloon.
36:13Everybody ready?
36:14Four, four, one.
36:21Oh, and there's some thunder.
36:24Please release.
36:37Thirty minutes after the rain bomb dropped,
36:39that bank of cold air,
36:42here graphically rendered to be visible,
36:44has covered the 17 miles
36:46from the epicenter of the storm.
36:48and breaks over the flying curtain of drones.
37:01On the ground,
37:02the team analyzes the data.
37:05So right here,
37:06we're looking at data
37:08from the balloon that we just launched.
37:10What we're looking at is pressure,
37:12moisture, temperature,
37:14and relative humidity.
37:15And this is telling us the depth of the cold pool
37:18that just came through.
37:19So right now,
37:19based on the temperature data,
37:21we're seeing a decrease in temperature
37:23that is going about 500 meters high.
37:26The team has learned
37:28the cold pool reaches 500 meters,
37:30or about 1,600 feet high.
37:32But that's not all.
37:35These balloon observations allow the team
37:37to measure what's happening to the air
37:39above the advancing cold pool.
37:42What they've found
37:43is that the cold pool acts as a wedge,
37:46pushing up an updraft of warm air.
37:50When we have a storm
37:51forming a really strong downburst
37:53and its associated cold pool,
37:55that lifts the surrounding air
37:57up and over the edge of the cold pool
37:58and forms a new updraft.
38:00That updraft can go on
38:01to build another really strong storm.
38:03That storm can then, of course,
38:05make its own downburst,
38:07its own new cold pool,
38:08which can then form another updraft.
38:10And so we get into this cyclical process
38:13of updraft formation.
38:17Background winds can stretch
38:19downburst cold pools
38:20from circular outflows
38:22into fan-shaped fronts.
38:24If atmospheric conditions
38:26are primed for multiple thunderstorms,
38:28the cold pools can merge
38:30into one broad line
38:32of advancing cold air.
38:34The advancing boundary
38:35lifts warm air ahead of it.
38:38This rising warm air
38:39feeds a new generation of updrafts
38:42and helps build an even larger storm.
38:45It's a self-sustaining cycle
38:47of updrafts, downbursts,
38:49and cold pools
38:50that sweeps across the landscape.
38:54Meteorologists call this a derecho.
39:00One thing that distinguishes derechos
39:02from other types of wind systems
39:04is their sheer size
39:05and how long they can last.
39:07The longest one on record
39:08is some 1,300 miles.
39:11Derechos can stick together
39:12for time periods
39:13of 6 to 12 hours.
39:15So these are extensive,
39:17very dangerous wind storms.
39:21The 2024 Houston storm
39:24was a derecho,
39:26an organized system
39:28of multiple repeating downbursts
39:31that ripped across
39:321,000 miles of Gulf Coast
39:34from central Texas
39:35to the Florida panhandle.
39:46Back in Arizona,
39:48Mike has a hunch
39:49that the beginnings
39:50of a multi-storm system
39:52are brewing west
39:53along Interstate 8.
39:56Oh, man, this storm.
39:58Big towers in there.
40:00Oh, man, this is...
40:02This looks freaking great.
40:12Oh, my God.
40:14Look at this demon.
40:16Holy brain bombs.
40:18Now, that's a downburst.
40:20We have a monster rain bomb
40:23right here,
40:24a downburst
40:25that we haven't seen so far.
40:27I mean, this looks like
40:29a bomb went off.
40:31That thing just collapsed
40:32right on those mountains,
40:33and all that air
40:35is just exploding
40:35and hitting us.
40:37This is awesome.
40:39I can see the towers up there.
40:41They were probably 50,000-plus.
40:44They were kind of twisting.
40:45Even right here,
40:46I see, like, this updraft
40:47has got a little twist to it.
40:49And when that happens,
40:50it's suspending that rain
40:52because it's rotating,
40:52so it's suspending up there more.
40:54So then when it comes down,
40:55it just has so much more force.
40:57And all that air,
40:59all the stuff we're feeling,
40:59it's just blasting from that storm,
41:02and it's constant
41:02because there was probably
41:04multiple downbursts that happened.
41:06There was, like, an initial one.
41:07There was one on the right,
41:09one on the left,
41:09and then just, like,
41:10the main thing went down.
41:11And now we're getting this dust
41:13that's appearing right here.
41:17The dusty outflow winds
41:19from the rain bombs
41:20are racing west,
41:22and Mike jumps in his vehicle
41:23to get ahead of the growing storm
41:25and reset in a new position.
41:36There's, you can kind of make it out,
41:38so we actually have a dust storm coming.
41:42So just overall,
41:43it's getting better
41:45as it goes west.
41:50Ooh, lightning.
41:52There's dust in there
41:53that's looking good.
41:55This dust is just food coloring
41:59in the atmosphere.
42:00Basically, the dust
42:02and this shelf structure
42:03are showing us the outflow
42:04or the cold pool
42:05where it's all consolidated and pushing.
42:07But without the dust,
42:07you don't get to see
42:08what the air is actually doing.
42:09This is gorgeous.
42:11The color,
42:11this is what you live for.
42:13But this is the result
42:15of stronger downbursts
42:16that consolidated
42:17and just formed intense outflow.
42:22This is amazing.
42:24What?
42:33Oh, it's making them disappear now.
42:44What a day.
42:45What a day.
42:54This dust storm produced winds
42:56of over 55 miles per hour.
42:59It was the result
43:01of multiple microbursts
43:02organizing into a larger system,
43:05creating a macroburst.
43:07If this dust-filled cold pool
43:09had hit Phoenix
43:10instead of the desert,
43:12it could have caused
43:13extensive damage.
43:16And if it had grown further,
43:17it could have become
43:19a derecho.
43:21Exactly what hit Houston.
43:24Downbursts and derechos
43:26are dangerous
43:27wherever they strike,
43:29but especially so
43:30when they hit built-up areas.
43:33So is there any way
43:34to protect against them?
43:47Ian Giamonco is lead meteorologist
43:50at the Insurance Institute
43:52for Business and Home Safety,
43:53the IBHS.
43:55His team investigates
43:57how a downbursts,
43:58devastating combination
43:59of wind and hail
44:00inflicts damage on property.
44:03When wind attacks a building,
44:05it's always looking
44:06for the weakest link
44:07in that chain.
44:08And a lot of times
44:09that is at the edges of roofs.
44:11Or if an opening,
44:12say a garage door,
44:13a window,
44:14a door fails
44:15and that air is allowed
44:16to rush in.
44:20They use a monster wind tunnel
44:23to test the construction standards
44:25of North American homes.
44:26An extraordinary array
44:29of 105 fans.
44:32Each fan is almost
44:33six feet in diameter
44:35and packs 350 horsepower.
44:39Together,
44:40they can produce winds
44:41topping 100 miles per hour,
44:44just like the Houston direction.
44:50Wind is a cascade of damage.
44:52It often starts
44:54with one little thing
44:55that cascades to the next,
44:57to the next,
44:57to the next.
44:58And the next thing you know,
45:00you're looking
45:01at a catastrophic failure.
45:06To reinforce homes
45:08against the destructive power
45:09of downburst winds,
45:11Ian and the team
45:12at IBHS
45:13have developed
45:14a new building standard.
45:17It's designed
45:17to help minimize
45:19the amount of damage
45:20that comes
45:20with severe wind events.
45:25The IBHS construction methods
45:28include a hail-resistant roof
45:29and also adds
45:31anchors
45:31and metal connectors
45:32to lock the roof
45:33to the walls
45:34and the walls
45:36to the foundations,
45:37transferring the wind's force
45:39down into the ground.
45:42Build a home
45:43to these standards
45:45and put it alongside
45:46a typical home
45:47and the difference
45:48is clear.
45:55As our wind speeds increase,
45:57the front door fails.
46:00That allows wind
46:01to rush into that structure
46:03and start pushing out.
46:05Fortified home, however,
46:07sitting on its right,
46:07it's structurally sound.
46:09It can take those forces,
46:10whereas the conventionally built home
46:12simply couldn't.
46:13And the next thing you know,
46:14the wall has failed
46:18and it comes apart.
46:33As our atmosphere warms,
46:35it's simply producing
46:36more fuel for thunderstorms.
46:37It's air that wants to go up.
46:39Those thunderstorms
46:40can take advantage of that.
46:41In a warming world,
46:42you can store more
46:44water vapor in the air.
46:46So as we have
46:46more of this fuel
46:47in the air
46:48that can then condensate
46:49and release heat,
46:50these thunderstorms,
46:52the ratios,
46:52can become more intense.
46:55As the world warms,
46:57there will be more moisture
46:59in the atmosphere
46:59on average.
47:01But some regions
47:02could actually dry out.
47:04Drier air has to rise farther
47:07to cool enough to condense,
47:08so cloud bases
47:10would be higher.
47:10That could have
47:12big consequences.
47:14If you had a cloud base
47:15of this high
47:15and now you raise it
47:17to this high,
47:18you have so much dry air
47:20to put raindrops through,
47:22to put hailstones through,
47:24that it gives the storm system
47:26a lot more time
47:27to evaporate and melt.
47:30More evaporation
47:31and melting
47:31may mean there is less precipitation
47:33hitting the ground,
47:34but it also means
47:36faster falling,
47:37cold, dense air.
47:39And so there's every reason
47:41to expect
47:42the changing climate
47:43stronger downbursts.
47:45The ratios
47:45already became
47:47more powerful
47:48over the last 40 years
47:49because the air is warmer
47:51over the U.S. nowadays
47:53than it was in the 80s.
47:54So this is a race
47:56to get our building codes
47:57and get our structures
47:58ready to deal
47:59with what could be
48:00the weather of the future.
48:04Protecting homes
48:06and businesses
48:06will reduce
48:07the financial cost
48:08of future downbursts
48:10and derechos.
48:11And better forecasting
48:12is also essential.
48:15But weather forecasts
48:17face limits
48:18because of the inherently
48:19chaotic nature
48:20of the atmosphere.
48:22If you start a model
48:24with slightly different
48:26initial conditions,
48:27the end results
48:28can be very different
48:30based on some
48:31very simple differences
48:32in the initial information
48:34we put into our models.
48:36We can't actually
48:37accurately predict
48:38the weather
48:39beyond about 14 days.
48:42By updating the model
48:43every few minutes
48:44with live data,
48:45the forecast can be nudged
48:47back to reality.
48:49But data quality
48:50is crucial.
48:52And some of the best data
48:54comes from
48:55space-based instruments.
49:01French Guiana
49:10An Ariane 5 rocket
49:12delivers a 4.2-ton
49:14next-gen weather satellite
49:15into a geostationary orbit
49:18where it stays positioned
49:20above Europe
49:20and North Africa.
49:22It's one of three satellites
49:24that will be co-located
49:26in the same orbit
49:27to probe the region's
49:28atmosphere.
49:31Olivier Breeze
49:32is part of the team
49:34behind this new
49:35satellite system.
49:37The Meteosat mission
49:38is a geostationary
49:40satellite.
49:40You have a constant
49:42and stable view
49:44of the Earth.
49:46The aim is to improve
49:48the short-term
49:48naocasting
49:49and also to provide
49:51alerts on a severe
49:52weather event
49:53on a very short term
49:54within one or two hours
49:56and within
49:57a very small area
49:58on a valley
49:59or on a village
50:00or in a town.
50:05These satellites
50:06will provide
50:07a 3-D profile
50:08of the atmosphere
50:09above Europe
50:10and North Africa,
50:12including humidity,
50:13wind speed,
50:16and temperature.
50:19This real-time view
50:21will enable
50:22forecasters
50:23to spot the warning signs
50:24of an atmosphere
50:25primed to produce
50:26downbursts,
50:27rapidly cooling cloud tops
50:29or banks of dry air
50:31around developing
50:32thunderstorms,
50:34allowing forecasters
50:35to give downburst warnings.
50:40For us working
50:42on this project,
50:43we are convinced
50:43that we are in a position
50:45to save lives.
50:47So far,
50:49the U.S. has no equivalent
50:50geostationary satellite system,
50:52but there are plans
50:54for future deployment.
50:56We want to save lives
50:58around the world.
50:59We really need global observations,
51:03and so the best way
51:04to do this
51:05is to build
51:05satellite platforms.
51:07We've made progress
51:09with the forecasting
51:09of extreme downbursts
51:11and derechos,
51:12but there's still a lot
51:13of things
51:13that we don't know
51:14about them.
51:15However,
51:16our modeling systems,
51:18our observational systems,
51:19and our field campaigns
51:21have allowed us
51:21to really move forward
51:23with understanding
51:24these storms
51:25and better predicting them.
51:27Earth's atmosphere
51:28is a cauldron,
51:29mixing warm, wet air
51:32with cold air above,
51:33a mixture
51:34that generates
51:35huge thunderstorms.
51:37And as the Earth's
51:38atmosphere warms,
51:39it will hold more moisture
51:41and more energy
51:42to fuel them.
51:43As we move forward
51:44with new satellite technology,
51:46I believe that our ability
51:47to forecast these systems
51:49will be even more improved
51:51in the next 0 to 10 years.
51:53But while we wait
51:54for forecasts to catch up,
51:57more severe winds,
51:59more deadly hail,
52:00and more extreme rainfall
52:02will mean
52:03more devastating rain bombs.
52:07through thehuh
52:09and the red
52:11We'll be there.
52:35You will never
52:36need aэ.
52:36You will
53:04Transcription by CastingWords
53:13CastingWords
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