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NOVA - Season 53 - Episode 07: Rain Bombs
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00:16A freakish kind of weather event.
00:19We should not be.
00:21I'm taking right now.
00:23Is now striking again and again.
00:26People were panicking, running, taking cover.
00:30Intense.
00:31Batten down the hatches for the potential for 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.
01:18Now researchers are attempting to understand these 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 on NOVA.
01:44Rain bombs.
01:46Rain bombs.
02:10The
02:12The Puckle Pop Music Festival, Belgium.
02:15Out 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.
03:21CCTV 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.
04:36Each 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.
05:00So what are they? And 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.
06:15Mike's. I loved them, and I've always loved them, and I traced it back to seeing a lightning bolt strike
06:21behind my 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.
06:56And 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, and so it forces it
08:52out into the formation of cloud droplets.
08:56Clouds form where the water vapor condenses into tiny water droplets, so small and light that they stay aloft instead
09:04of 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.
09:34It 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,
10:47where even more water can condense, which further warms the air.
10:53If the conditions are right, with enough moisture rising into cold air above,
10:58this fuels a positive feedback loop that intensifies the clouds' 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, but 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.
11:46Whew!
11:51But I think something big is going to happen here.
11:53It's a nice, large, dark area.
11:55This is probably going to turn into a really strong storm.
11:58I would expect.
12:00I 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.
12:34That makes our clouds very turbulent and that 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,
13:00expanding upward to the very top of 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,
13:18so it spreads out flat, forming a distinctive anvil shape.
13:23So we've gone from the development of a tiny little fluffy cloud to these very tall, extensive storms
13:31that are now carrying around large amounts of hailstones and snowflakes.
13:37This storm is now seriously ready to do business.
13:42Lightning bolts are a tell-tale 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.
14:05To understand why some thunderstorms collapse into rain bombs,
14:08it 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.
14:19Particularly hailstones.
14:21Icy chunks of a frozen cloud.
14:32Over the summer of 2025, storm researchers teamed up on a project called Ice Chip
14:38to collect hailstones from thunderstorms striking 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
15:24process and analyze each of the thousands of samples.
15:28Large hailstones are extremely valuable in understanding more about the thunderstorm they came from.
15:35Once you get the hailstone, 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 hailstones, and we look at the cross section, one of the things that we look at
16:01is 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. There'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? And what does that reveal about how the
16:44hailstone 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.
17:02These 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, then it went back a warmer section of the cloud where it
17:26probably fell and then it was collected at the 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. They have regions where air is rising very rapidly, sometimes at speeds of 150
17:56miles 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.
18:21It'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. That's just plummeting. That's like a downburst happening.
18:58When you see that middle rain shaft area where it looks like a blob, that's usually a good tell-tale
19:04sign of a downburst happening.
19:06Wow, man. This is stunning.
19:13In a fully developed thunderstorm cloud, what goes up must eventually come down.
19:19The 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 clouds' 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. You 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 then 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 clouds' 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. There's a lot going on. There's lightning, there's hail, there's very heavy
22:31rain, 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.
22:53The rain really picks up and gets really strong. Everything turns white, and then all of a sudden I can
22:57see 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, when it took off from Durango International Airport, en route
25:44to 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 and had told them that
25:56they actually have head winds, 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 near 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.
27:07June 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
27:27U.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, how they
27:45operate, 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, but many of the airports
27:59around 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 19, 2024, they discover
28:21that before it capsized and sank, it had dragged its anchor around 400 yards in a dead straight line.
28:29The Bayesian was anchored off the north coast of Sicily. It was in a bay. It was next to another
28:38yacht.
28:38This CCTV footage from a camera on shore 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, they dragged anchor in straight
28:55lines that indicates it was a straight line wind as opposed to the kind of rotational wind you would get
29:01from a tornado.
29:02It was a very large yacht with a very tall mast and it would appear that the downburst and associated
29:10cold pool was actually able to roll it over beyond its point of stability.
29:15The yacht succumbed to the same type of extreme low altitude straight line winds that led to the crash of
29:22Flight 2431.
29:30At the Puckle Pop Festival in 2011, the hail and howling winds struck an area less than 100 yards across.
29:39This was a very narrow downburst. This is what made it so unusual.
29:44You would normally expect such power from systems that are larger where they can transport more rain and more hail
29:50and more wind to the surface.
29:52than in a 100 meter wide downburst. So a really remarkable event.
29:58These real life tragedies reveal the destructive potential of powerful rain bombs.
30:03Intense, highly localized and short lived.
30:12But a storm that hits Houston in May 2024 has all the hallmarks of a downburst except that it is
30:21much bigger.
30:22It travels around 1,000 miles and it lasts much longer than a single downburst. More 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 at about 70, 80 to 90
30:42miles an hour.
30:45National Weather Service forecaster Amaryllis Cotto is on call at the Houston-Galveston office 27 miles southeast of downtown Houston
30:54when the storm hits.
30:57The storm developed very fast in areas of west northwest Texas at around 9 a.m.
31:04And so we can 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 on the first floor interior of your home away from windows.
31:20That's the safest place to be until this severe storm passes through.
31:23It was devastating Houston.
31:26We had a lot of tree damage.
31:29We had millions of people without power.
31:31Hank and Neti Ashima are five miles north of downtown when the storm hits.
31:37He starts recording the storm from his car.
31:40Suddenly, it goes from daylight to darkness and chaos hits.
31:49Here it comes.
31:52Holy ****!
31:54Holy ****!
31:55Yep, hang on.
31:56Got it.
31:59Um, we should not be here.
32:02It's unchecking right now.
32:04You can't see a block in front of you just because the whitewash of wind and rain
32:09and trees are swaying.
32:11And downtown Houston is raining glass as windows are failing all up in the skyscrapers.
32:19The winds associated with this system were 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, inside the buildings, the pressure in is now higher than outside.
32:34So you get this explosive force that forces windows and glass out of the buildings.
32:44It's the signature of a rain bomb.
32:49Super-strong ground-level winds shattering any weak windows along their path.
32:55Tell-tale signs of straight-line wind damage are seen all over the city.
33:00They pull down power lines across Houston and plunge one million people into darkness.
33:08But the Houston storm isn't the size of the storms that hit Puckalpump or Sanctobasian.
33:15It's over 50 miles across and leaves a path of devastation across 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 Vandenheever's 20-strong team is out in the field.
33:56I think the Polk House is keen to have some surface measurements.
34:00Okay.
34:01You're trying to fix the moisture.
34:03Her team deploys drones engineered to withstand extreme weather.
34:08They measure the outflow winds when the cold air in a downburst crashes to earth and 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 and an upper level of drones.
34:37We have a lot of instruments that can measure the temperature, the moisture of the atmosphere.
34:42We've got anemometers on there that can measure the winds.
34:46And this allows us to make measurements of the variability of the atmosphere.
34:50And as the cold pool advances on us and blows through us, we are able to make that measurement in
34:55time as well.
34:56So there's a lot that we are characterizing about these cold pools.
35:02Sue and her team are tracking a storm a safe distance away, beyond the horizon.
35:09Radar shows that it has produced a downburst of intense rainfall.
35:16The air that slammed into the ground is now spreading out across the plains in a cold pool, coming toward
35:23them.
35:25Their radar tracks the dust kicked up by the advancing bank of fast-moving cold air.
35:33So we're expecting a cold pool to come through within the next few minutes, so we're waiting to try to
35:40collect the data.
35:41The team will release weather balloons up into the cold pool to measure temperature, pressure, humidity and moisture.
36:05This cooling of the air you can feel and the wind you feeling, that's this boundary that's actually starting to
36:10hit us.
36:11So we're going to release that balloon.
36:13Everybody ready?
36:15Three, four, one.
36:20Oh, and there's some thunder.
36:24Please release.
36:3730 minutes after the rain bomb dropped, that bank of cold air, here graphically rendered to be visible, has covered
36:45the 17 miles from the epicenter of the storm and breaks over the flying curtain of drones.
37:01On the ground, the team analyzes the data.
37:05So right here, we're looking at data from the balloon that we just launched.
37:10What we're looking at is pressure, moisture, temperature and relative humidity.
37:15And this is telling us the depth of the cold pool that just came through.
37:19So right now, based on the temperature data, we're seeing a decrease in temperature that is going about 500 meters
37:24high.
37:26The team has learned the cold pool reaches 500 meters, or about 1600 feet high.
37:33But that's not all.
37:35These balloon observations allow the team to measure what's happening to the air above the advancing cold pool.
37:42What they've found is that the cold pool acts as a wedge, pushing up an updraft of warm air.
37:50When we have a storm forming a really strong downburst and its associated cold pool, that lifts the surrounding air
37:57up and over the edge of the cold pool and forms a new updraft.
38:00That updraft can go on to build another really strong storm.
38:03That storm can then, of course, make its own downburst, its own new cold pool, which can then form another
38:09updraft.
38:10And so we get into this cyclical process of updraft formation.
38:17Background winds can stretch downburst cold pools from circular outflows into fan-shaped fronts.
38:24If atmospheric conditions are primed for multiple thunderstorms, the cold pools can merge into one broad line of advancing cold
38:33air.
38:33The advancing boundary lifts warm air ahead of it.
38:38This rising warm air feeds a new generation of updrafts and helps build an even larger storm.
38:45It's a self-sustaining cycle of updrafts, downbursts, and cold pools that sweeps across the landscape.
38:54Meteorologists call this a derecho.
39:00One thing that distinguishes derechos from other types of wind systems is their sheer size and how long they can
39:06last.
39:07The longest one on record is some 1,300 miles.
39:10The ratios can stick together for time periods of 6 to 12 hours.
39:15So these are extensive, very dangerous wind storms.
39:21The 2024 Houston storm was a derecho.
39:26An organized system of multiple repeating downbursts that ripped across 1,000 miles of Gulf Coast from central Texas to
39:36the Florida Panhandle.
39:46Back in Arizona, Mike has a hunch that the beginnings of a multi-storm system are brewing west along Interstate
39:558.
39:56Oh, man, this storm, big towers in there.
40:00Oh, man, this is, this looks freaking great.
40:12Oh, my God, look at this demon.
40:16Holy rain bombs.
40:18Now that's a downburst.
40:21We have a monster rain bomb right here, a downburst like that we haven't seen so far.
40:28I mean, this looks like a bomb went off.
40:31That thing just collapsed right on those mountains, and all that air is just exploding and 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 twisted.
40:45Even right here, I see, like, this updrafts got a little twist to it.
40:49And when that happens, it's suspending that rain because it's rotating.
40:52So it's suspending up there more.
40:54So then when it comes down, it just has so much more force.
40:57And all that air, all the stuff we're feeling, it's just blasting from that storm.
41:02And it's constant because there was probably multiple downbursts that happened.
41:06There was, like, an initial one.
41:07There was one on the right, one on the left, and then just, like, the main thing went down.
41:11And now we're getting this dust that's appearing right here.
41:17The dusty outflow winds from the rain bombs are racing west.
41:21And Mike jumps in his vehicle to get ahead of the growing storm and reset in a new position.
41:36There's, you can kind of make it out, so we actually have a dust storm coming.
41:42So just overall, it's getting better as it goes west.
41:50Ooh, lightning.
41:52This dust in there is looking good.
41:55This dust is just food coloring in the atmosphere.
42:00Basically, the dust and this shelf structure are showing us the outflow or the cold pool,
42:05where it's all consolidated and pushing.
42:06But without the dust, you don't get to see what the air is actually doing.
42:09This is gorgeous.
42:11The color, this is what, this is what you live for.
42:13But this is the result of stronger downbursts that consolidated and 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 of over 55 miles per hour.
42:59It was the result of multiple microbursts organizing into a larger system, creating a macroburst.
43:07If this dust-filled cold pool had hit Phoenix instead of the desert, it could have caused extensive damage.
43:15And if it had grown further, it could have become a derecho.
43:21Exactly what hit Houston.
43:24Downbursts and derechos are dangerous wherever they strike, but especially so when they hit built-up areas.
43:32So is there any way to protect against them?
43:47Ian Giamanko is lead meteorologist at the Insurance Institute for Business and Home Safety, the IBHS.
43:55His team investigates how a downburst's devastating combination of wind and hail inflicts damage on property.
44:03When wind attacks a building, it's always looking for the weakest link in that chain.
44:08And a lot of times that is at the edges of roofs.
44:11Or if an opening, say a garage door, a window, a door fails and that air is allowed to rush
44:16in.
44:20They use a monster wind tunnel to test the construction standards of North American homes.
44:27An extraordinary array of 105 fans.
44:31Each fan is almost six feet in diameter and packs 350 horsepower.
44:40Together, they can produce winds topping 100 miles per hour, just like the Houston derecho.
44:50The wind is a cascade of damage.
44:53It often starts with one little thing that cascades to the next, to the next, to the next.
44:58And the next thing you know, you're looking at a catastrophic failure.
45:06To reinforce homes against the destructive power of downburst winds, Ian and the team at IBHS have developed a new
45:15building standard.
45:17It's designed to help minimize the amount of damage that comes with severe wind events.
45:25The IBHS construction methods include a hail-resistant roof and also adds anchors and metal connectors to lock the roof
45:33to the walls and the walls to the foundations, transferring the wind's force down into the ground.
45:42Build a home to these standards and put it alongside a typical home, and the difference is clear.
45:55As our wind speeds increase, the front door fails.
45:59That allows wind to rush into that structure and start pushing out.
46:05Fortified home, however, sitting on its right, it's structurally sound, it can take those forces, whereas the conventionally built home
46:12simply couldn't.
46:13And the next thing you know, the wall has failed, and it comes apart.
46:33As our atmosphere warms, it's simply producing more fuel for thunderstorms.
46:37If it's air that wants to go up, those thunderstorms can take advantage of that.
46:41In a warming world, you can store more water vapor in the air.
46:46So as we have more of this fuel in the air that can then condensate and release heat, these thunderstorms
46:52and the ratios can become more intense.
46:55As the world warms, there will be more moisture in the atmosphere on average.
47:01But some regions could actually dry out.
47:04Dryer air has to rise farther to cool enough to condense, so cloud bases would be higher.
47:11That could have big consequences.
47:13If you had a cloud base of this high and now you raise it to this high, you have so
47:19much dry air to put raindrops through, to put hailstones through, that it gives the storm system a lot more
47:27time to evaporate and melt.
47:30More evaporation and melting may mean there is less precipitation hitting the ground, but it also means faster falling, cold,
47:38dense air.
47:39And so there's every reason to expect a changing climate, stronger downbursts.
47:45The ratios already became more powerful over the last 40 years because the air is warmer over the U.S.
47:52nowadays than it was in the 80s.
47:54So this is a race to get our building codes and get our structures ready to deal with what could
48:00be the weather of the future.
48:04Protecting homes and businesses will reduce the financial cost of future downbursts and derechos.
48:11And better forecasting is also essential.
48:15But weather forecasts face limits because of the inherently chaotic nature of the atmosphere.
48:22If you start a model with slightly different initial conditions, the end results can be very different based on some
48:31very simple differences in the initial information we put into our models.
48:36We can't actually accurately predict the weather beyond about 14 days.
48:42By updating the model every few minutes with live data, the forecast can be nudged back to reality.
48:49But data quality is crucial.
48:52And some of the best data comes from space-based instruments.
49:01French Guiana.
49:10An Ariane 5 rocket delivers a 4.2-ton next-gen weather satellite into a geostationary orbit, where it stays
49:19positioned above Europe and North Africa.
49:22It's one of three satellites that will be co-located in the same orbit to probe the region's atmosphere.
49:31Olivier Breeze is part of the team behind this new satellite system.
49:36The Meteosat mission is a geostationary satellite.
49:40You have a constant and stable view of the Earth.
49:45The aim is to improve the short-term nano-casting and also to provide alerts on a severe weather event
49:53on a very short-term, within one or two hours,
49:56and within a very small area, on a valley or on a village or in a town.
50:05These satellites will provide a 3D profile of the atmosphere above Europe and North Africa, including humidity, wind speed, and
50:16temperature.
50:19This real-time view will enable forecasters to spot the warning signs of an atmosphere primed to produce downbursts,
50:27rapidly cooling cloud tops or banks of dry air around developing thunderstorms,
50:33allowing forecasters to give downburst warnings.
50:40For us working on this project, we are convinced that we are in a position to save lives.
50:47So far, the U.S. has no equivalent geostationary satellite system, but there are plans for future deployment.
50:56We want to save lives around the world. We really need global observations.
51:03And so the best way to do this is to build satellite platforms.
51:07We've made progress with the forecasting of extreme downbursts and derechos,
51:12but there's still a lot of things that we don't know about them.
51:15However, our modeling systems, our observational systems, and our field campaigns have allowed us to really move forward
51:23with understanding these storms and better predicting them.
51:27Earth's atmosphere is a cauldron, mixing warm, wet air with cold air above.
51:33A mixture that generates huge thunderstorms.
51:37And as the Earth's atmosphere warms, it will hold more moisture and more energy to fuel them.
51:43As we move forward with new satellite technology, I believe that our ability to forecast these systems
51:49will be even more improved in the next 0 to 10 years.
51:53But while we wait for forecasts to catch up, more severe winds, more deadly hail, and more extreme rainfall
52:03will mean more devastating rain bombs.
52:30supply and wind.
52:37Try to catch up on the next 2 weeks later.
52:37We're just going to continue walking in the next 0 to 10 years.
52:38It's our goal to expect you to attach those storms.
52:38It's going to keep an eye on it.
52:39We'll go to the next 2 weeks.
52:39We'll have the weather and county of the tide in the next 3 weeks.
52:43Enhanced over to the next 5 weeks.
52:43We'll have the weather and the weather and the weather.
52:43It's going to be OK.
52:49That's the weather.
53:16Transcription by CastingWords
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