Tornadoes are one of nature's most
terrifying phenomena. On hot summer
days, they appear out of nowhere,
spinning themselves up to break neck
speeds before petering out into nothing,
leaving only a trail of destruction in
their wake.
But not all tornadoes are created equal.
On one humid May afternoon in 2013, the
sunny skies over central Oklahoma
darkened. Deep purple clouds the color
of a bruised plum blocked out the sky as
a huge supercell storm brewed. And
before long, it birthed the mother of
all tornadoes.
This is the story of a storm so vast it
became almost impossible to recognize
what it was. A twister that in less than
60 seconds expanded from a slender rope
to a monster more than 4 km wide. Its
chaotic winds reached record-breaking
speeds and claimed the lives of those
trying to measure it. To this day, it
remains the biggest tornado the world
has ever seen. I'm James Stewart, and
you're watching Astramm Earth. Join me
today as we dissect the anatomy of the
largest tornado ever recorded, uncover
the physics behind its erratic behavior,
and pay tribute to the scientists who
gave their lives trying to understand
it.
In many ways, Oklahoma weather in late
May could be described as quite
agreeable. Warm, sunny days, not too
hot, or too cold at night. But don't let
this deceive you. These warm and
pleasant days can all too often be
cooking something sinister.
Oklahoma sits at the heart of Tornado
Alley, a geographic corridor in the
central US where the continent's most
volatile air masses collide.
And the 31st of May 2013 was not just a
normal spring day. Less than 2 weeks
earlier, the state had seen an EF5
tornado, the strongest possible on the
EF or enhanced FIA scale used to measure
these storms, ravage the city of Moore.
Even now, that was the costliest tornado
ever to hit Oklahoma.
Now, the air was hanging heavy near the
city of El Reno, just 50 km from Moore.
The atmosphere was primed with a
volatility that any meteorologist would
recognize in a heartbeat as being
absolutely perfect for forming a
tornado, also known as a twister.
Conditions that would entice any
stormchaser worth their salt straight
there.
Let's get right down into it and break
this atmospheric powder keg down into
its ingredients. Firstly, the air was
extremely unstable. And what do I mean
by that? Well, the sun had been baking
the warm Oklahoma plains, heating the
ground and the air above it. As warm air
is less dense than cold air, it will
rise like a hot air balloon for as long
as its temperature remains warmer than
the air around it. The amount of energy
available to form these rising pockets
of air causing updrafts is called the
convective available potential energy or
cape for short. On a normal severe
weather day, Cape values might reach
between 2,000 or 3,000 jewels per
kilogram. On May the 31st, Cape values
over central Oklahoma were around 4
1/2,000 to 6,000.
In other words, there was a lot of
energy in the air, and that powder keg
was just waiting for a spark.
In addition to this large cape value,
there was plenty of lift. A cold front
was moving down from the northwest and a
dry line, the boundary separating moist
Gulf air from dry desert air was coming
in from the west. The intersection of
these boundaries is known as the triple
point and it acts a bit like a wedge
violently forcing the unstable high cape
value air upwards. These two ingredients
will together make a thunderstorm. But
you need something more to make that
storm spin up into a twister.
Wind shear or the change in wind speed
and direction with height. In Oklahoma
that day, warm moist winds were blowing
from the southeast. But a couple of
kilometers up, they shifted to the south
and higher still, the jetream was
screaming in from the west.
This turning of the winds with height
creates tubes of horizontal rotation in
the atmosphere that spin invisibly in
the clouds. When those explosive
updrafts caused by the high cape punch
through these rolling tubes, they tilt
them vertically. The tubes stand on end
and suddenly you don't just have a
storm, you have a supercell.
free by clicking the link in the description.
A Supercell is the king of
thunderstorms, a tall storm cloud with
an anvilike shape that stretches out
across the sky. These are the rarest
type of thunderstorm with a deep
persistently rotating updraft called a
misoscyclone.
Think of the misocyclone as the engine
of the storm. A dangerous carousel of
air miles wide rotating
counterclockwise.
And in the right environment, not only
can these storms last for hours, but if
the rotating winds start to drop down
from the clouds, they can form strong,
intense tornadoes.
Really big twisters are the stuff of
nightmares. They are huge spinning
vortices of air that can clock wind
speeds of 450 km per hour, tearing trees
from their roots, peeling asphalt from
the streets, and even lifting entire
houses clean off their foundations.
According to the US National Weather
Service, on average, 800 tornadoes are
reported every year in the US alone,
resulting in around 80 deaths annually.
so far so terrifying.
But what happened in El Renault on the
31st of May 2013 would challenge our
fundamental understanding of how
tornadoes are formed.
The classic model taught in meteorology
classes was that tornadoes formed by a
rotation starting high up in the storm
and gradually stretching down to the
ground, prompted by something called a
rear flank downdraft, dragging the
rolling tubes I mentioned before down to
the surface.
Forecasters and stormchasers would watch
their radar screens, seeing the rotation
tighten up in the air and waiting for it
to descend into what's called the
dynamic pipe effect.
But this wasn't what they saw that
afternoon in El Reno. A supercell
formed, but it was no ordinary
supercell. This was a high precipitation
or HP supercell. In these storms, the
updraft is so strong and moisture so
abundant that the rain wraps all the way
around the miso cyclone. Tornadoes
forming in an HP supercell can be
shrouded in a curtain of rain and hail.
Adding to the drama was a cap, a layer
of warm air that sits a loft and acts
like a lid on a pot of boiling water.
Air parcels that rise into this layer
become cooler than the surrounding air
which stops them rising further and
producing thunderstorms.
And this suppression can be dangerous.
It allows heat and moisture to build up
underneath the cap with pressure
mounting until the lift becomes too
strong and the cap breaks. And that's
exactly what happened at around 4:30
p.m. that day. What followed was an
explosive development of the storm with
towers appearing from nowhere and
rocketing to 15,000 m into the
stratosphere within just 16 minutes. By
5:35 p.m., just an hour later, the first
tornado from this enormous cloud had
touched down in Kingfisher County, but
the main event was brewing further
south. At 6:03 p.m. CDT, a few miles
southwest of El Renault, the rotation
reached THE SURFACE.
>> TORNADO.
>> INITIALLY, it didn't look like much.
Photos from the first few minutes saw a
small, dusty whirl under a dark,
brooding wall cloud. For those living in
Tornado Alley, it would have seemed like
just a small one. I can navigate around
that, no problem. But the radar data
recorded that day tells a different
story. What the researchers found in my
book makes tornadoes more menacing than
ever.
Storm researchers Dr. Jana Howser and
Dr. Howard Bluestein were parked on a
nearby overpass with their RAX pole
rapid scan Xband polarometric mobile
research radar.
This emits pulses of microwave energy
that bounce off precipitation and
debris, allowing scientists to analyze
the intensity, rotation, and structure
of a storm. The RAX pulse scan the storm
every 2 seconds, far more regularly than
the standard National Weather Service
Next RAD radars, which take 4 to 5
minutes to complete a scan.
Hower and Bluestein's high-speed data
revealed that in the minutes before the
tornado became visible, the rotation at
20 m above the ground was already
tornadic. While the rotation at 1
kilometer up was still broad and
disorganized. In other words, this
tornado did not descend from the clouds.
No, that strong rotation existed at the
surface before it existed above. It was
building up from the ground.
So, why does this matter? Well, it
matters if you're waiting to see a
funnel cloud drop from the sky to issue
a tornado warning. Because if the danger
is already on the ground, invisibly
churning up the dust and just waiting to
connect with the cloud and unleash its
full power, that warning will come far
too late. In fact, this bottomup Genesis
could explain why the El Renault Storm
caught so many offguard. This twister
didn't just grow upwards. Within
minutes, the tornado started to
metastasize, rapidly ballooning in
width. By 6:19 p.m., just 16 minutes
after formation, the tornado crossed US
Highway 81. Now, when you normally think
of a tornado, you might imagine the
Wizard of Oz classic, a sort of slender
funnel snaking down from the clouds. But
this behemoth storm had become a wedge.
It no longer really looked like a
tornado at all. In twister terminology,
a wedge is a tornado that is wider than
it is tall. But even that description
fails here. The base of the cloud
dropped significantly until it was
almost on the ground. The entire
rotating wall cloud became the tornado.
To an observer on the ground,
specifically one to the east, the
direction the storm was moving in, it
wouldn't look like a funnel at all.
Instead, it would appear to be a dark
horizon spanning wall of fog and rain,
indistinguishable from the background
sky. And this monstrosity hiding in
plain sight was still growing.
Radar measurements confirm that at its
peak, the width of the tornadic winds
reached an extraordinary 4.2 kilometers.
Let that sink in. That's roughly as far
as the eye can see to the horizon. 2.6
mi, nearly 14,000 ft, a tenth of a
marathon. The width of Manhattan Island
at 42nd Street. Just imagine a wind
vortex spanning across New York City
from the Hudson to the East River,
grinding everything in between. This
tornado broke the previous world record
for width held by the Hallum Nebraska
tornado of 2004 by nearly 200 m.
But size was only half the equation. The
other half was speed.
Inside this 4.2 km wide circulation,
something even more incomprehensible was
happening. The El Renault tornado had
become a multiple vortex tornado. It was
no longer just one spinning column of
air. It was a spinning wheel of multiple
smaller, more intense tornadoes all
rotating around a common center,
creating the maximum possible
devastation. And these subvortices can
be incredibly powerful. Think of a
figure skater spinning. When they pull
their arms in, they spin faster. Well,
the same thing's happening here. The
core circulation becomes unstable and
breaks down into smaller eddies. Each of
these eddies, the subvortices, pulls in
just like that figure skater, condensing
the angular momentum into tight pillars
of wind, moving fast.
Two particular mobile Doppler radars
were measuring the storm that day. Rex
pole, which I've already mentioned, and
another called the Doppler on Wheels.
They capture wind speeds that are quite
frankly hard to get your head around.
One sub vortex was clocked with a ground
relative wind speed of 54 km per hour.
For context, the strongest wind speed
ever scientifically measured on Earth
was 511 kmh in the Bridge Creek Moore
tornado of 1999.
El Renault was just shy of the all-time
world records. And arguably, given the
limitations of radar sampling, we only
see a snapshot every few seconds. It may
well have exceeded that speed in between
scans. I mean, this is already
terrifying enough, right? The biggest
tornado the world has ever seen has just
grown a bunch of extra vortices that
also make it possibly one of the fastest
tornadoes ever. But we're not stopping
yet. Oh no.
These subvortices weren't just orbiting
the center. They were moving around the
ground at varying speeds. At times the
main tornado was moving east at 50 to 65
km hour, 30 to 40 mph. But the sub
vortices rotating within it would swing
around the southern edge and shoot
forward at speeds of 270 to 290 km an
hour relative to the ground. When they
looped around the northern side, they
would fight the forward motion of the
parent storm and essentially stand still
or even loop back west in what we call
troquoidal motion.
Can you even imagine the absolute chaos
of storms within a storm of differing
forces, speeds, and directions all
clashing together in a frenzy of
devastation is madness.
The best thing I can come up with to
give you at least an idea of what was
going on here is probably a spyroraph
toy. I always wanted one of these when I
was a kid, actually. So, with a
spyroraph, the pen moves around in
circles while moving forward, creating
those curly looping lines. Yeah. Well,
that's the kind of path these
subvortices took across the Oklahoma
farmland.
This tracal motion made the El Renault
tornado incredibly deceptive.
If you were a stormchaser driving
parallel to the tornado, as stormchasers
often do, you might think you were safe.
You'd match the speed of the main funnel
at a safe distance. But not with this
monstrosity. A sub vortex is incredibly
unpredictable and could suddenly swing
out from the rain curtain, accelerating
from 0 to 160 km hour forwards in
seconds, closing the gap before you
could even shift gears.
I don't know about you, but I'm
exhausted by this already just watching.
And I'm afraid this storm had more
horrors to offer. The supercell also
produced a satellite tornado. This
wasn't a subvortex inside the main
circulation. This was a completely
separate tornado that formed to the
southeast of the main wedge and it was
anticyclonic.
In the northern hemisphere, 99% of
tornadoes spin cyclonically or
counterclockwise as they are indirectly
influenced by the corololis effect. They
usually spin in the same direction as
the supercell they are associated with.
Anticcyclonic tornadoes can exist though
and they spin clockwise. Now these are
rare, usually weak and short-lived
tornadoes. The satellite tornado that
grew alongside the main twister was a
monster in its own right. a huge
multivortex anti-cyclonic beast. It
formed along the rear flank gust front,
rotating clockwise and dancing alongside
the main cyclonic wedge for nearly 15
minutes.
So now you had a 4.2 km wide cyclonic
wedge to the west and a powerful
anticyclonic satellite to the east
grinding across the landscape in a grim
almost totally unpredictable dance.
It must have been utterly petrifying for
anyone witnessing it. It's petrifying
watching it back now.
Now, while I'm guessing most of us would
be doing everything in our power to get
as far away from all of that as we
possibly could, one man was doing the
complete opposite. On the trail of this
monster storm was one of the most
well-known stormchasers in the world,
Tim Samurass. Tim was not a thrillseker
or adrenaline junkie. He was an
engineer, a scientist, and a meticulous
researcher. In the world of
stormchasing, few names commanded as
much respect.
Tim was famous for designing the turtle,
a hardened probe that looked like a sort
of squat flying saucer.
His goal when chasing storms was to
place these probes directly in the path
of a tornado to measure wind speeds and
drops in air pressure at the surface.
data that radar beams cannot see as they
overshoot the horizon.
He had successfully deployed these
probes in front of violent tornadoes
before, including the Manchester, South
Dakota F4 storm in 2003, where he
documented a record-breaking pressure
drop of 100 mibars.
Tim was known as the safest chaser in
the business. He didn't take unnecessary
risks. He studied the data, learned
everything he could about tornado
meteorology, and always planned his
intercepts with mathematical precision.
On May 31st, 2013, Tim was leading his
research team, Twistex, Tactical Weather
Instrumented Sampling in near tornadoes
experiment. With him in his white
Chevrolet Cobalt were his son Paul
Samarass, 24 and a videographer, and
Carl Young, 45, a meteorologist and
longtime stormchase partner. They were
actually out on a different mission,
chasing unusual lightning, transient
luminous events, or TLE's in supertorrms
on the planes. Tim and his team had
missed out on the mall tornado 10 days
earlier and had seen the conditions
brewing around El Renault that day. They
were scheduled to be further north on
this occasion, but decided the potential
for a huge tornado would be too good to
miss. So, they decided to head south to
attempt to deploy pods in the path of
the El Renault storm. The aim was to
gather data on near surface winds. Data
that could help engineers build stronger
houses and potentially help save lives
in the future.
At approximately 6:20 p.m., the Twistex
team was driving east on the Reuter
Road, a gravel road south of El Renault,
running parallel to the tornado.
Ahead of them was another chaser, Dan
Robinson, in a Toyota Yaris. Dan's
rear-facing dash cam captured images of
the Twistex vehicle. They were
headlights in the rain, following the
grid road, keeping pace with the storm.
But the storm was changing. Remember the
expansion before? At 6:03 p.m. the
tornado was small, but by 6:24 p.m. it
was 2.6 mi wide. The Twist X team and
Dan Robinson ahead of them were not
driving next to the tornado anymore.
Because the tornado was wrapped in rain
and because its outer circulation had
expanded so rapidly, the edge of the
storm was much closer than it appeared
visually.
The wall of rain wasn't just rain. It
was the outer wall of the 500 km an hour
vortex. And they were driving straight
into it. We can only tell the rest of
this story because the timeline of their
final chase has been reconstructed
through GPS logs, radar analysis, and
dash cam footage from other chasers like
Skip Talbbert from Skip Talbbert
Stormchasing, who very kindly helped us
with footage and maps in this video.
Thank you so much, Skip. You can see
more tornado footage from him at the
link here.
When hunting a tornado down,
stormchasers look for what's called the
inflow notch, a clean slot of air
feeding into the tornado. This usually
signifies the leading edge of the storm.
However, as the El Renault tornado
expanded, the inflow notch began to
close up or wrap around.
The clear air they were driving in was
actually being pinched off by the
expanding circulation.
Tim Samrass, astute observer that he
was, likely realized this. He remarked
on the radio, "There's no rain here.
We're in a bad spot."
Being in a rain-free area when the storm
should be raging implied they were deep
in the inflow jet, directly in the path
of the expanding vortex rather than
safely on the periphery. Then the
tornado did the unthinkable. It turned
instead of continuing eastsoutheast
along the path any seasoned stormchaser
would expect it to take. It hooked
sharply north then curled back. But
while the center of the storm turned,
the southern flank of the tornado, the
windfield, surged outward.
Dan Robinson, still ahead of Tim,
realized something was wrong. He fled
the car and pushed through the storm.
Tim, Paul, and Carl, however, were just
20 or 30 seconds behind him. And those
20 seconds in this case would prove to
be the difference between life and
death.
As the Twistex Cobalt moved down Reiter
Road near the intersection with Radio
Road, a violent subvortex swung around
the southern edge of the parent tornado.
It didn't just hit them, it swallowed
them whole.
Radar analysis suggests the winds in
this specific subvortex were approaching
320 km per hour. The Chevy Cobalt,
weighing 1.3 tons, was lifted and thrown
nearly 800 m through the air.
When the wreckage was found, it was
unrecognizable.
The three men were killed instantly.
This was the first time in history that
stormchasers had been killed by a
tornado. It sent a shock wave through
the community that is still felt today.
If Tim Samurass, the cautious,
calculating expert, could be caught,
then no one was safe. And it wasn't just
Twistex. One of the tornado subvortices,
had just narrowly missed Mike Betts and
the Weather Channel tornado hunt crew.
Their SUV was lifted and rolled nearly
200 m into a field. They survived with
just injuries, but their vehicle was
crushed flat. Another
amateur chaser, Richard Henderson,
stopped to take a photo. He sent it to a
friend with the caption funnel. Moments
later, the tornado overtook his
position. He too was killed.
In total, eight people died in the El
Reno tornado, all of them inside
vehicles.
How do you even begin to make sense of a
tornado of that scale? How do you rate a
tornado like El Renault? Well,
traditionally the enhanced fitta or EF
scale is the industry standard for
rating tornadoes. It ranges from EF0,
which is weak, to EF5, which is
incredibly violent, often leading to
total destruction. But here's the catch.
As you can see, the EF scale is a damage
scale, not a windspeed scale. An EF5
rating requires finding specific damage
indicators. Well-built houses swept
clean off their foundations. Skyscrapers
deformed, asphalt peeled from the road.
The Elreno tornado luckily passed mostly
over open fields. It hit cow sheds,
fences, and a few structures, but it
largely missed the populated
subdivisions. The structures it did hit
were rated EF3 damage, but the mobile
radars had measured winds of 476 to 503
km per hour. Winds that fast are by
definition well into the EF5 range,
which starts at around 320 km/h. Leave a
tornado emoji below if you think El
Renault should have been an EF5.
So, the National Weather Service in
Norman, Oklahoma, faced a dilemma. Do
they rate it based on what it did, EF3
damage, or what it was, EF5 winds?
Initially, they upgraded it to EF5 based
on the radar data. It was a landmark
decision, acknowledging that technology
allows us to see the wind even if it
doesn't hit a house. But months later,
in August 2013, they reversed the
decision. The El Renault tornado was
downgraded to EF3.
The official reason NWS policy for
determining EF ratings is based on
surveys of ground damage.
Because the fastest subvortices hit
wheat fields and not buildings, the
record books will forever list the
widest and possibly strongest tornado in
history as merely an EF3.
This decision sparked fury in the
meteorological community. Critics like
Dr. Josh Worman argue that ignoring the
radar data is dangerous. It essentially
says if a tree falls in the forest and
no one is around to hear it or if a
tornado spins at 300 mph and doesn't hit
a house, it didn't make a sound. It
affects engineering standards, too. If
we assume tornadoes only reach EF3
strength in this region because that's
what the damage says, we might
underbuild critical infrastructure like
nuclear plants, hospitals, or even
schools. The El Renault tornado
highlighted a glaring flaw in our
classification system. The disconnect
between the hazard, the wind, and the
impact, the damage.
To the scientists who measured it and to
the families of those lost, there is no
doubt it was an EF5.
The Elena tornado of 2013 stands as a
grim milestone in severe weather
history. It forced a re-evaluation of
safety protocols. For one, the safe
southeast quadrant of the tornado is no
longer assumed safe when dealing with
massive erratic wedges. It also prompted
a debate about chaser convergence. That
is to say, the sheer number of people
clogging the roads, potentially blocking
escape routes, which is only growing as
amateur stormchasers by to get new
footage.
On that day, thousands of locals spooked
by the more tornado just 11 days prior
had fled their homes, jamming up the
interstates.
If the El Reno tornado had not lifted
before reaching the traffic jam on I40,
the death toll could have been in the
hundreds.
But scientifically, El Renault gave us a
lot of data to think about. We now know
tornadoes can form from the ground up.
We know they can expand to unimaginable
widths in seconds. We know that
subvortices can move at racing car
speeds inside the parent circulation.
As little comfort as this may be, Tim
Samrass and his team did not die in
vain. The data they collected and the
data collected by the radar teams around
them has advanced our understanding of
tornado genesis more in one day than in
decades of theory. They stared into the
abyss so that others wouldn't have to.
The 2013 El Renault tornado remains an
outlier, a freak of nature that pushed
the boundaries of size and speed. It's a
humbling reminder that no matter how
much we study the atmosphere, no matter
how many radars we build or how many
papers we write, there is still a
wildness to the wind that cannot be
fully tamed.
It reminds us that the line between
observer and participant is thinner than
we ever thought.
We watch the sky with a little more
caution now, a little more respect. And
I know I, for one, won't look at movies
like Twister in the same way again.