Tornadoes - Dan's Wild Wild Weather Page

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Tornado Weather

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Why do some thunderstorms produce violent tornadoes while most do not? The answer is related to the wind. If the wind changes direction and gets stronger with height, it can cause a column of air to rotate. Think of a rotating column of air about 2 miles high and half a mile wide. Suddenly a thunderstorm updraft pulls this column upward. Now it's 3 miles high and a few hundred yards wide.

When this happens the air spins up. Sit in a swivel chair and hold your arms out. Now have someone spin you around. As you spin bring your hands to your lap. Be careful doing this!

The scientific term for this spinning up is conservation of angular momentum. It is this process that can take 50 mph winds and turn them into a tornado with 200 mph winds! Everything has to come together just right for a tornado to occur.

More tornadoes occur in the United States than any other place in the world. Alabama ranks 4th in the nation for the number of killer tornadoes, and the risk of tornadoes is higher in the Tennessee Valley.

Texas and Oklahoma have many more tornadoes than we do, here in the Tennessee Valley, ours tend to be more deadly. The worst tornado disaster occurred on March 21, 1932. Over 300 people were killed in the state during 2 waves of tornadoes that day.

Is That A Tornado ?

You have probably asked yourself that question at least once while watching an approaching storm. There are several important clues that will help you tell the difference between a scary looking cloud and a developing tornado.

Tornadoes form in the updraft region of a thunderstorm. The rain and hail fall out of the downdraft. If a tornadic thunderstorm is moving Northeast, then the tornado would most likely form on the Southwest end of the storm with the rain out ahead of it. If you are in the path of the storm, then you would most likely not see the tornado approaching until it was very close.
    This is Dan's favorite tornado picture, it is from the Storm Spotter's Guide Slide series.
Meteorologists who photograph tornadoes know that the safest way is to follow the storm. If a tornado develops, it will be easier to see as it moves away.

Since the tornado is forming in the updraft, there may be a low cloud slowly rotating in the Rain Free Base of the storm. This low cloud is called a Wall Cloud and is the parent cloud to a tornado. Not all Wall 

Dan was in Oklahoma a few years ago chasing and collecting video of tornadic conditions for a News piece on Severe Weather, when a Wall Cloud developed.  He is explaining the event to his videographer.

Clouds produce tornadoes, but if you see a low rotating cloud at the back edge of a storm, take no chances. Many times blue sky or sunshine will be behind the wall cloud or tornado. Hail and lightning accompany many wall clouds along with high wind. Tornadoes are wind not clouds. Until they pick-up dust or moisture, may not be visible. Many times all you can see is a large swirl of dust or debris near the ground.

Make a Tornado

National Severe Storms Laboratory  - N.S.S.L.

Storm Spotters Guide
NWS Norman, OK Storm Spotters Guide
Glossary of Terms for Storm Spotters

Tornado History & Historical Tornado Statistics

The Tornado Project - They give the subject a little different twist, with tornado myths, tornado oddities, personal experiences, tornado chasing, tornado safety, and tornadoes in the past as well as more recent tornadoes.

Severe Weather Safety

NOAA Weather Radio

USA Today's Index of Tornado Information

Airborne Radar Homepage

Huntsville Tornado

Fujita Tornado Intensity Scale &
The NEW Enhanced Fujita Scale

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