Kind: captions
Language: en
September 2024,
torrential rain hits North Carolina,
triggering flash floods that surge down
valleys and destroy buildings. This
isn't just a roof. This is the entire
Asheville Tea Company building.
>> It just ripped it in half.
>> The flash floods smashed through
buildings, swept away vehicles, and
destroyed roads and bridges.
In the hills, the rain triggered
landslides that buried homes and cut off
roads.
[Music]
As the search begins for the missing,
people want to know why did this happen
here and now.
Despite its mountain location far from
the coast, Asheville's geography
actually makes it vulnerable to floods.
Parts of the city run along valleys
close to the French Broad and Swanoa
rivers and the mountains around the town
help generate rain.
>> Western North Carolina, upstate South
Carolina, it's got a unique feature
called the Blue Ridge Escarment. The
terrain rises very rapidly. So you have
this air that's being lifted up against
the Blue Ridge Escarment and as the warm
air rises it condenses and it starts
raining and it just all starts routing
down from this creek to this creek to
this creek. Eventually the larger
streams start rising and this is where
they live.
Nobody in this part of the country
that's alive has ever seen anything like
this before. It was devastating.
So why was this flood so extreme low?
>> The convergence of many factors produced
a rainfall machine.
One of the factors with this particular
case was a cut off low.
>> A cutoff low can form when an area of
cold low pressure air gets cut off from
the flow of the jetream.
This high alitude rotating mass of low
pressure air can draw in moist air from
below.
The fact that they are cut off from the
main flow in the atmosphere means that
they sit in one location and pump
moisture into the same region for
several hours to days, even up to a
week. When Hurricane Helen made
landfall, the winds spiraling around the
cutoff low pulled the storm toward it.
Downgraded to a tropical storm, Helen
barreled into the Blue Ridge Mountains
and dropped even more rain onto
Asheville and the surrounding area.
In portions of the Black Mountains, we
had 7 to 10 inches of rain leading up to
Helen and then we had over a foot of
rain with Helen. And as it just keeps
raining, keeps raining, keeps raining
again, it just set up for for just a
horrific horrific event.