Tornado Alley

Tornado Review A tornado is a violently rotating column of air in contact with and

extending between a Thunder Storm cloud and the surface of the earth.

Winds in most tornadoes blow at 100 mph or less, but in the most violent, and least frequent tornadoes, wind speeds can exceed 250 mph.

typically track along the ground for a few miles or less and are less than 100 yards wide, although rare monsters can remain in contact with the earth for well over 50 miles and exceed one mile in width.

Tornadoes can appear as a traditional funnel shape, or in a slender rope-like form. Some have a churning, smoky look to them. Others contain "multiple vortices" which are small, individual tornadoes rotating around a common center.

Tornadoes can be nearly invisible, with only swirling dust or debris at ground level as the only indication of the tornado's presence.

Conditions for Development Abundant low level moisture. A "trigger" such as a cold front or other low level

zone of converging winds. Rising air that becomes saturated, this air will

continue to rise to great heights and produce a thunderstorm cloud if the atmosphere is unstable.

Unstable atmosphere occurs when temperature decreases rapidly with height.

Atmospheric instability can also occur when dry air overlays moist air near the earth's surface.

oAccounts of tornadoes or tornado-like winds have been noted throughout English history back to around 1,000 AD.

oIn the present-day United States, the first sightings of tornadoes or waterspouts by English speakers date back to the late 1500s, during expeditionary adventures that would ultimately lead to colonization of the country.

oDuring the mid1800s, textbooks began to describe the phenomenon and what was believed to be behind it.

A Brief History of Tornadoes

“The motion of the air in tornadoes is spirally inward and upward, so that from each side of the track objects are drawn inward from the centre of the track, and very heavy objects are carried up in the

centre. Light objects are elevated high into the air, and are sometimes carried many miles before they are thrown out of the

vortex.”

By Elias Loomis (1811-1889)Professor of Natural Philosophy and Astronomy

Yale College, New Haven, Connecticut

The Beginning of Tornado Alley On Feb. 15, 1952, two officers of the Air Force's Severe

Weather Warning Center set up a project they called “Tornado Alley”. The purpose was to monitor twisters in an area from Lubbock, Texas, to Colorado and Nebraska.

The same officers had been responsible for making the first successful tornado forecast in 1948.

They also issued the first official tornado warning in modern history. The region was called “the incubator of nature's deadliest storms” which was mentioned in the New York Times on May 5, 1957.

Where is “Tornado Alley” If you were to be exact about tornado alley, it would really be

made up of hundreds of little strips, and never one large “alley”.

States effected North Dakota South Dakota Wyoming Colorado Nebraska Minnesota Iowa Illinois Ohio Indiana Missouri Kansas Kentucky Tennessee Arkansas Oklahoma Texas Louisiana

* Texas has more tornadoes than any other state in the USA, but Oklahoma has the most dangerous storms (F4 and F5 storms).

Formation of the Alley The warm moist air, called tropical maritime air, is swept up from the Gulf of Mexico and

the Caribbean Sea due to lack of mountain barriers.

During the spring months the Earth begins to warm, which adds to the layer of warm moist air which is close to the ground. While this is occurring, cool dry air masses, called maritime polar, often sweep in from the north or northeast.

The cool air is trapped by the Rocky Mountains and rides close to 10,000 feet above the warmer air below.

Cool air over warm air creates an unstable condition. The hot middle layer, coming from

the west often acts as a “cap” on the low-level warm, moist air.

Only the strongest areas of heating near the ground can penetrate the cap. But when they do, the bottled-up, low-level moist air feeds into the break from miles around.

The shifting winds twist theses updrafts forming supercell thunderstorms. A breaking cap, with the help of an upper level jetstream, can cause convection to grow

explosively, with storms rapidly becoming severe and tornadic.

Formation

Enhanced Fujita Tornado Scale F0: 40–72 mph winds. Damage is light and might include damage

to tree branches, chimneys, and billboards. Shallow-rooted trees may be pushed over.

F1: 73–112 mph winds. Damage is moderate; mobile homes may be pushed off foundations and moving autos pushed off the road.

F2: 113–157 mph winds. Damage is considerable. Roofs can be torn off houses, mobile homes demolished, and large trees uprooted. Think of Salt Lake in 2007

F3: 158–206 mph winds. Damage is severe. Even well-constructed

houses may be torn apart, trees uprooted, and cars lifted off the ground.

F4: 207–260 mph winds. Damage is devastating. Houses can be leveled and cars thrown; objects become deadly missiles.

F5: 261–318 mph winds. Damage is incredible. Structures are lifted off foundations and carried away; cars become missiles. Fewer than 2% of all tornadoes reach an intensity of this magnitude.

F6: Projected wind speed are expected to exceed 318 mph. One of the closest event to an F6 was the Tri-State Tornado of 1924

Human EffectsNum. of Events: 182People killed: 4,780Average people killed per year: 165

People affected: 12,710,204

Average people affected per year:

438,283

Economic Damage (US$ X 1,000):

31,510,661

Economic Damage per year (US$ X 1,000):

1,086,575

Tornado disasters from 1980 - 2008

Fun Facts!• In 1928, a tornado in Kansas plucked the feathers right off some chickens.

• A Tornado in Oklahoma once destroyed a whole motel. People later found the motel’s sign in Arkansas.

• You need to step on the pedal of a car past 70 miles per hour to outrun the fastest tornadoes.

• Tornadoes have been reported in every state in the US and also in every season.

Community Preparation Plan 1. Prepare Your Tornado Plan - Just as schools and

offices have specific plans in the case of a tornado, so should you for your home. The first thing you need to do is designate your "shelter room."

If your house doesn't have an underground storm shelter, you should choose the area that is the lowest, smallest and most central. Often this is a cellar or basement, or it could be a central hallway or bathroom. Make sure you are as far as possible from outside walls and windows.

2. Know the Dangers of Mobile Homes - For those living in mobile homes, your tornado plan should take you to a preselected, permanent structure.

If the warning time is not sufficient, you

should never attempt to drive when a tornado is near.

You are safer lying in a ditch or depression than driving or remaining in a mobile home.

3.Prepare Your Tornado Kit - Every household should have an emergency kit that is easily accessible when tornado conditions arrive. A tornado kit should include:

Battery-powered radio or televisionFlashlightExtra batteries for both of the above First aid kit Sturdy shoes for every member of the family Identification and cash Spare set of keys to vehicles

4. Always Stay Weather-Informed - With today's technology, media outlets often know a couple of days in advance when conditions are right for tornadoes. Keep informed on the forecast, and always watch for signs of possible tornadoes such as:

Dark, greenish sky Wall cloud Cloud rotation or strong, swirling winds Loud roar, often described as sounding like a

freight train

Technology can be a life saving resource!!!

5. Act Quickly - If your area is in a tornado warning, don't waste time.

Grab your tornado kit, pillows and blankets and get immediately to your shelter room.

Make sure everyone is wearing their sturdy shoes. Use the radio to listen to weather broadcasts, and don't leave your shelter room until the tornado danger has passed.

If a tornado strikes, use pillows and blankets, arms and hands to cover your neck and head.

6. Know Your Aftermath Plan - Your entire family should have a designated area to meet just in case you are separated during a tornado. Treat anyone who may be injured, but don't move anyone who is seriously injured unless preventing them from further injury.

7 .Give Aid – Many of your neighbor may require assistance, but stay out of damaged buildings if at all possible. Leave immediately if you smell gas or chemical fumes.

RememberStay Calm - Both before and after a tornado, it is easy and quite understandable to experience panic. However, being prepared and staying calm will increase your response time, ensure you make the right decisions and often save lives.

Never stay in a car or mobile home during a tornado. You are safer outside in the lowest area.

Never try to outrun a tornado. They can change direction at any moment.

Never take cover beneath a bridge or overpass.

Never go outside to watch a tornado. Take cover immediately.

Always know the tornado plans of any schools or office buildings in which you spend time.

We are grateful for those that sacrifice their time, energy, effort and even lives to better understand

such a natural and deadly hazard.