Tornadoes Author R.T. Schindler Distributed by the Disaster Team Supercourse (

Tornado Tornado A violently rotating column of air (vortex), hanging from a cumulonimbus cloud, with circulation that touches the surface of the earth A violently rotating column of air (vortex), hanging from a cumulonimbus cloud, with circulation that touches the surface of the earth

Beginning Stage: Tornado begins as a rotating wall cloud which quickly evolves into a funnel Beginning Stage: Tornado begins as a rotating wall cloud which quickly evolves into a funnel

Early Stage: Early Stage: Tornado funnel develops (may be transparent) and extends down from the cloud to the ground 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 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

Tornado Formation Click here to watch “Tornadoes 101” video

The Supercell Tornado forms here

Tornado Myths A highway overpass is a safe place to take shelter under during a tornado 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 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. 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: Tornados are reported to routinely carry objects many miles and have: sucked the frogs out of a pond and dropped them on a town 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 necktie rack with 10 ties attached 40 miles carried a flour sack 110 miles from a mill carried a flour sack 110 miles from a mill Tornados also drive objects into other objects and have: Tornados also drive objects into other objects and have: Driven splinters into an iron fire hydrant Driven splinters into an iron fire hydrant Driven straw and grass into telephone poles Driven straw and grass into telephone poles

When Tornadoes Occur Anytime of the year- usually in the spring, summer, and fall Anytime of the year- usually in the spring, summer, and fall Most tornados occur during late spring in the month of May/June Most tornados occur during late spring in the month of May/June Between the late afternoon and early evening is when most tornados are spawned Between the late afternoon and early evening is when most tornados are spawned The most dangerous time for formation during evening hours The most dangerous time for formation during evening hours A typical late afternoon tornado

Where Tornados Occur Tornado Alley covers the Great Plains states

Tornado Alley The 5 states included in tornado alley are: 1) Texas 2) Oklahoma 3) Kansas 4) Nebraska 5) South Dakota Although tornados do occur in other states as well. These states include: Louisiana, Arkansas, Missouri, Tennessee, Kentucky, Colorado, Wyoming, Illinois, Indiana, Ohio, Iowa, Minnesota, and N. Dakota Louisiana, Arkansas, Missouri, Tennessee, Kentucky, Colorado, Wyoming, Illinois, Indiana, Ohio, Iowa, Minnesota, and N. Dakota

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) 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) Click here to watch “Tornado Rips Apart House in Minnesota” video

F0 Category (Weak) winds (40-72) mph, little damage (Weak) winds (40-72) mph, little damage Damage: tree branches snapped, chimneys toppled, signs torn down Damage: tree branches snapped, chimneys toppled, signs torn down

F3 Category (Strong) winds: ( ) mph, severe damage (Strong) winds: ( ) mph, severe damage Damage: most trees uprooted, trains overturned, roofs torn off, walls demolished Damage: most trees uprooted, trains overturned, roofs torn off, walls demolished

F5 Category (Violent) winds: ( ) mph, incredible damage; rare (Violent) winds: ( ) mph, incredible damage; rare Damage: bark peeled off trees, houses lifted off foundations, vehicles travel greater than 100 m through the air Click here to watch Dallas Tornado video

Tornado Occurrence 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) 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)

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 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 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. 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. Click here to watch storm chaser video

Tornado Indicators A greenish colored sky associated with the thunderstorm (caused possibly by the scattering of light by particles in the sky) A greenish colored sky associated with the thunderstorm (caused possibly by the scattering of light by particles in the sky) Mammatus clouds (clouds that look like there are pouches hanging from under the cloud) Mammatus clouds (clouds that look like there are pouches hanging from under the cloud) A sudden drop in barometric pressure A sudden drop in barometric pressure Large hail of at least.75 in. diameter Large hail of at least.75 in. diameter Strong winds > 60 mph Strong winds > 60 mph Frequent and intense lightning Frequent and intense lightning A rotating wall cloud or a cloud that appears to hang from the sky A rotating wall cloud or a cloud that appears to hang from the sky A loud rumbling noise- seek shelter! A loud rumbling noise- seek shelter!

Mammatus clouds Mammatus clouds Green sky Green sky

Tornado Damage Tornados mainly cause damage by picking up something and throwing it through the air or hurling objects against something Tornados mainly cause damage by picking up something and throwing it through the air or hurling objects against something A 20-ton trailer blown off U.S. 30; it bounced 5 times A pick-up truck caught in the path of a tornado Click here for “Tornado Destruction” video

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. 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 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!! 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