NOVA

Unprecedented devastation.

By Friday morning they started using the word "catastrophic."

Three monster hurricanes in a single month.

Harvey.

Irma.

Maria.

If you're told to evacuate, get out quickly.

They strike violently... Scouring the land.

We saw winds in excess of 190 miles per hour.

The eye was right here on top of us.

Leaving devastation

and thousands stranded in their wake.

Today the focus is on rescue.

Houston, the nation's fourth largest city,

is underwater.

You know that people are facing really catastrophic situations.

They may be fighting for their lives.

Islands like Puerto Rico

and nations of the Caribbean are ravaged.

The entire country has been decimated.

I have never seen anything like this before.

The Florida Keys are in shambles.

What explains one of the most disastrous hurricane seasons

on record?

Why did the strength of these storms take so many by surprise?

Could a warming planet be driving the weather

to new extremes?

Are storms of this intensity the new "normal"?

And how will we cope?

Many organizations talk about climate refugees.

2017 Atlantic hurricane season may have ushered in that era.

For the survivors, life may never be the same.

This is unreal!

Here was the living room right here.

I couldn't believe what was happening to us.

We lost everything.

Everything!

"Rise of the Superstorms,"

right now, on "NOVA."

Major funding for "NOVA" is provided by the following...

A Houston neighborhood devastated.

State Troopers, anybody here?

The terrible aftermath of Hurricane Harvey.

State Troopers!

Anybody here?

Now, rescue workers search for trapped residents.

We're going to go here and knock on the door.

All right.

State Troopers!

In 2017

three monster hurricanes strike the U.S.

in rapid succession.

Harvey.

Houston under water, the nation's fourth largest city.

Irma.

Much of Florida,

extreme rains, storm surge flooding.

And Maria.

In Puerto Rico,

their second heaviest rainfall on record.

They bring

life-threatening destruction to millions in their path.

I've got 18 people I'm trying to get out.

It's an unprecedented onslaught that breaks records

with powerful winds

and especially water.

Water is going to be

part of our future, both on the rivers,

at the oceans.

We need to be using the best science we have

to prepare ourselves for our "Waterworld" future.

While we scramble to rebuild

following one of the most harrowing hurricane seasons

on record,

scientists,

policy makers,

and citizens are asking,

"Is this our future?

"And if so, how can we get ready

with the next season already upon us?"

It's August 2017,

midway through the Atlantic hurricane season.

So far, it's been fairly quiet.

But that's about to end.

There's a weather disturbance developing in the Atlantic,

and it's moving steadily westward.

A storm starts off in a reasonably simple way.

You need some warm surface temperatures,

and that will give the air near the surface

an initial trigger to start rising.

On August 17,

the system grows in strength, becoming a tropical storm.

It's given a name,

which will not soon be forgotten: Harvey.

Harvey loses strength and a few days later,

crosses the Yucatán Peninsula into the Gulf of Mexico.

There's the storm, it is very disorganized.

But meteorologists at the National Weather Service

predict that as the storm moves into the warm Gulf waters...

Remember, tropical systems just feed

off of that warmer water.

Harvey will strengthen

and hit Texas within a few days.

If you are just waking up and tuning in,

we're now just dealing with a tropical storm,

we'll probably be dealing with a hurricane.

A hurricane,

but only a relatively weak one, Category One.

However, it is expected to bring at least ten inches of rain

and some flooding.

On the Gulf coast of Texas,

residents prepare for a bad,

but not catastrophic storm.

Water, canned goods, some fruit,

lots of pouches for my little boy to eat,

so just trying to be prepared.

But then Harvey takes a dramatic turn.

Well, it has changed.

And it is bigger.

In just a matter of hours,

Harvey rapidly increases in strength.

Now, with the storm just 300 miles offshore,

forecasters quickly change gears.

A few hours ago, this was going to be a Category One.

Now we're looking at a Category Three.

They predict Harvey will be a dangerous major hurricane

with winds up to 125 miles an hour.

We haven't seen anything like that along this coast

for at least 47 years, this part of Texas.

A major hurricane with big flooding, surge, wind,

and a lot of damage.

As Texas officials prepare to face

this rapidly evolving monster

wind engineer Forrest Masters

recognizes a good opportunity to gather data.

We've been there for every major event that's happened,

all the major storms you can think of,

from Katrina to Sandy.

We've been in about 30 storms conducting experiments.

He immediately travels from Florida

to Texas to meet the storm.

Along with a team of engineers,

he sets up a 5,000-pound wind tower

to measure the speed and direction

of wind close to the ground...

One of the least understood components of violent storms.

We can haul these anywhere we need to

and set them up in the span of 30 minutes.

They have different levels of anemometry,

which are precision wind instruments.

They take measurements ten times per second.

Masters thinks that having better wind speed data

at ground level...

Taken during the most powerful storms...

Can help in the design of more resilient buildings.

Harvey perfectly fits the bill.

As it nears land, it reaches Category Four out of five

on the standard hurricane wind scale.

Once we get at three or above,

we're in the major hurricane territory.

That's when things get very serious,

because we see the likelihood of windborne debris happening.

And ultimately, when we work our way up to a Category Five,

we're testing the limits of the infrastructure.

On the morning of August 25,

Harvey is moving towards Corpus Christi on the coast.

Local officials issue mandatory evacuations,

ordering several thousand coastal residents

to move inland.

Many people in Corpus Christi are getting out,

taking the city up on an offer to leave town for free.

Hundreds of people boarded school buses

headed for an evacuation center in San Antonio.

About 200 miles farther up the coast is Houston.

Even though the storm is still to the south...

It's so big, it will definitely have an impact on the city.

But there's no evacuation order,

in part because of a painful experience

during a previous major hurricane.

In 2005, when Hurricane Rita was bearing down on Houston...

Officials ordered an evacuation

several days in advance of landfall.

Millions took to the highways.

In the massive traffic jams, cars ran out of gas,

stranding thousands in 100-degree heat.

In the end, more people died while attempting to flee

than while hunkering down.

That memory is still fresh.

So officials don't order a mass evacuation.

Millions of Houston residents prepare to shelter in place.

At this time,

there will be no mass evacuations called.

We'll have a lot of water,

but it's not the kind of water

that we would ask people to evacuate from.

While residents anxiously await landfall

of what is now expected to be a Category Four hurricane,

the winds suddenly intensify even further...

Reaching sustained winds of 130 miles an hour.

Our biggest concern with hurricane forecasting