Tornados
Distributed by the Disaster Team
Supercourse (www.pitt.edu/~super1)
Author R.T. Schindler
Developers
• Developed by Randall Schindler while at Steven F. Austin University
• Distributed by the Supercourse Tornado Team,
Harold Brooks, NOAA, Daniel Mccarthy, NOAA,
Schaefer, NOAA
• Eric Noji, CDC, Scott Lillianbridge, Uni. Texas,
• Francois Sauer, Supercourse, Kansas City
• Faina Linkov, Mita Lovalekar, Ronald LaPorte,
Supercourse Pittsburgh
• Doug Barrett, Janet Winterton, Fraser, Kevin
Maney, USA Today
Purpose
• At the time of a tornado teachers need to present
up-to-date information to students
• A group of Global Experts in meteorology and
prevention from academia, education, and industry
have banded together to distribute cutting edge
tornado lectures to schools for free
• As the disaster evolves, new slides will be sent
Additional Lectures by world experts
"Tornadoes" lecture by Lillibridge, Scott R
www.pitt.edu/~super1/lecture/lec14141/015.htm
"A Historical Look at Tornadoes: Damage and Death" by Harold Brooks
www.pitt.edu/~super1/lecture/lec14321/index.htm which have also three
more links to online lectures:
Development of synthetic severe thunderstorm climatologies
(http://www.nssl.noaa.gov/users/brooks/public_html/present/synworld.html)
Tornado deaths in the US and mobile homes
(http://www.nssl.noaa.gov/users/brooks/public_html/present/mobile.html)
The distribution of tornadoes by F-scale in time and space
Harold Brooks.(http://www.nssl.noaa.gov/users/brooks/public_html/present/Fujita_2K3.html)
“Tornado-Related deaths and injuries due to the May 3, 1999 by Sheryll Brown, Pam Archer,
Elizabeth Kruger and corresponding author Sue Mallonee from Injury
Prevention Service, Oklahoma State Department of Health
www.pitt.edu/~super1/lecture/lec13531/index.htm
Tornado History
• The “Tri-State Tornado” is
the most violent tornado on
record
• On March 18, 1925, the
tornado formed in Missouri
and traveled 219 miles
across Illinois into Indiana
• The funnel was up to .75
miles across and traveled as
fast as 73 mph.
• It killed approximately 635
people
First Tornado Forecast
On March, 25 1948, Major
Fawbush and Captain Miller
determined that the conditions
of the atmosphere just west of
Tinker AFB, OK were suitable
for tornado development. The
first tornado forecast ever was
issued. A few hours later, a
tornado arrived causing
significant damage to the base.
However, no deaths and only a
few injuries occurred because
many had been warned by the
tornado forecast.
Tornado
A violently rotating column of air
(vortex), hanging from a cumulonimbus
cloud, with circulation that touches the
surface of the earth
Tornado Formation
Supercell Storm
• Severe weather occurs as strong downbursts…large
hail…occasional flash floods and weak to violent
tornadoes
• Severe event almost always occur near the updraft
interface typically in the rear (southwest) storm flank.
Some of the supercells have the interface on the front of
the southeast flank
• High predictability of occurrence of severe events once a
storm is identified as a supercell
• Extremely dangerous to public
• Extremely dangerous to aviation
The Supercell
Tornado forms here
Tornado Facts
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Tornados can occur almost anywhere in the world
Duration: a few minutes
Diameter (Avg.): 0.4 km
Length of path (Avg.): 6 km
Funnel can travel from 0 mph up to ~70 mph,
usually travels at 30 mph
99% of all tornados in Northern Hemisphere rotate
counterclockwise
Texas is #1 for frequency of tornados per year
Between 1950 and 1995 Texas had 5,722 recorded
tornados
Risk of death in a tornado in Texas: 1 in 1,054,267
Texas cost per person per year for tornados: $3.94
Tornado Myths
• A highway overpass is a safe place to take
shelter under during a tornado
• Opening windows during a tornado will
help balance the pressure between the inside
and outside of the house and may prevent
destruction of the structure
• One should seek shelter in the southwest
corner of a house or basement.
Tornado Oddities
• Tornados are reported to routinely carry
objects many miles and have:
• sucked the frogs out of a pond and dropped
them on a town
• carried a necktie rack with 10 ties attached
40 miles
• carried a flour sack 110 miles from a mill
• Tornados also drive objects into other
objects and have:
• Driven splinters into an iron fire hydrant
• Driven straw and grass into telephone poles
When Tornados Occur
• Anytime of the year- usually in
the spring, summer, and fall
• Most tornados occur during late
spring in the month of May
• Between the late afternoon and
early evening is when most
tornados are spawned
• The most dangerous time for
formation during evening hours
A typical late
afternoon tornado
Songer http://www.pitt.edu/~super1/lecture/lec0761/005.htm
Where Tornados Occur
Tornado Alley covers the Great Plains states
Tornado Wind Speed
In 1971, Dr. Fujita
developed a way of
measuring the winds
of a tornado. He
reasoned that there
was a link between
wind speed and the
damage caused by a
tornado. There are 6
categories of tornados
(F0 – F5)
F0 Category
• (Weak) winds (40-72) mph , little damage
• Damage: tree branches snapped, chimneys toppled,
signs torn down
F3 Category
• (Strong) winds: (158-206) mph, severe damage
• Damage: most trees uprooted, trains overturned,
roofs torn off, walls demolished
F5 Category
• (Violent) winds: (261- 319) mph, incredible damage; rare
Damage: bark peeled off trees, houses lifted off foundations,
vehicles travel greater than 100 m through the air
Tornado Occurrence by Category
Tornado Deaths by Category
Tornado Forecasting
Meteorologists who predict
tornado development
analyze the current
atmospheric conditions
such as: air temp.,
barometric pressure, the
locations of fronts, wind
velocities, convection, etc.
Probably the most useful
tool a meteorologist can
use to identify tornados is
radar, specifically Doppler
radar (WSR-88D)
Tornados on Radar
Doppler image of a rain-wrapped tornado
The Life cycle of a Tornado
• The “Life Cycle” of a tornado consists of four
distinct stages.
• These stages were first determined during the
Union City, OK tornado of 1973
• Most tornadic events are difficult to classify and
may not exhibit stages that are obvious to the
observer
• Sometimes events become unclear: one tornado
weakens another appears, or single event?
• Tornados do not “skip” – gaps in damage path
may indicate a temporary weakening in intensity
Beginning Stage:
Tornado begins as a
rotating wall cloud
which quickly
evolves into a funnel
Early Stage:
Tornado funnel develops
(may be transparent) and
extends down from the
cloud to the ground
Mature Stage:
Tornado funnel
reaches maximum
width as well as
maximum intensity
then begins to shrink
Decay Stage:
tornado may remain
stationary and take on a
ropelike appearance
before dissipating
The Tornado Outbreak of May 3, 1999
• Severe thunderstorms move into Ok, TX,
Ks and spawn estimated 70 tornados, most
occurred in Oklahoma
• In Oklahoma 40 people killed, 675 injured
• Damage: $1.2 billion
• Largest tornado outbreak in Oklahoma
history
• 1,780 homes completely destroyed
• 6,550 homes damaged
Satellite image taken May 3, 1999 @ 645 CDT
View from the air of a
tornado path in
Central OK
Tornado near Amber,
OK at 6:30 CDT
Microburst
Microbursts are downdrafts
from thunderstorms
consisting of a narrow
column of cool air traveling
at high speeds which can
cause damage similar to a
weak tornado over a small
area
Waterspouts
A waterspout is a tornado that forms over a body of water, or
a tornado that moves from land onto water
Storm Chasers
Storm chasers are a group made up of meteorologists and
scientists, as well as amateur observers who voluntarily put
themselves in the path of a severe thunderstorm in order to
hopefully observe a tornado and obtain photographs and
scientific data.
Tornado Indicators
• A greenish colored sky associated with the
thunderstorm (caused possibly by the
scattering of light by particles in the sky)
• Mammatus clouds
• A sudden drop in barometric pressure
• Large hail of at least .75 in. diameter
• Strong winds > 60 mph
• Frequent and intense lightning
• A rotating wall cloud or a cloud that
appears to hang from the sky
• A loud rumbling noise- seek shelter!
Mammatus clouds
Green sky
Tornado Damage
A 20-ton trailer blown off
U.S. 30; it bounced 5 times
A pick-up truck caught in the
path of a tornado
Tornados mainly cause damage by picking
up something and throwing it through the
air or hurling objects against something
Early Warning Systems
The National Storm Prediction Center constantly monitors
the weather and radars across the U.S. They are
responsible for issuing tornado watches and warnings.
• Tornado Watch: a parallelogram is drawn around a 10,000
mi.^2 s area where the atmosphere seems to possess the
conditions necessary for tornado development (severe
thunderstorm)
• Tornado warning: a county has a thunderstorm which
appears to have produced a tornado or someone has
physically spotted a tornado, apparent funnel, or observed
damage from what could be a tornado! SEEK SHELTER
IMMEDIATELY!!
Early Warning Systems
Bibliography
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http//www.photolib.noaa.gov/
http://www.nsl.noaa.gov/GoldenAnniversary
http://www.srh.noaa.gov/oun/
http://www.usatoday.com/weather
www.nsl.noaa.gov/~doswell?a_tornado/atornado.html
http://www.disastercenter.com/
http://www.tornadoproject.com/
Church C., Burgess D., Doswell C., Davies-Jones,R., ed. The
Tornado: Its Structure, Dynamics, Prediction, and Hazards.
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American Geophysical Union Press: 2000
• Liu, Henry. Calculation Of Wind Speeds Required to Damage or
Destroy Buildings. Publication within The Tornado