F5 tornadoes nature’s most devastating force
Editor’s note: The following is the last of a three-part series published in conjunction with Severe Weather Awareness Week.
They can level an entire community in a matter of seconds and carve a swath a mile wide leaving nothing behind but splintered debris.
Tennessee serves as a tornado alley of sorts, ranking behind only the Midwest in the number of tornado strikes in an average year. While Tennessee can expect to average 16 tornadoes annually, every state has recorded at least one tornado. Even Yellowstone National Park, at an altitude of 10,000 feet, was hit with a tornado in 1987 which cleared a path of 24 miles. The tri-state tornado of 1925, which ripped through Missouri, Illinois and Indiana, was the worst tornado on record, covering a path of 219 miles and killing 695 people.
Most tornadoes are generated by severe thunderstorms, the type that are common in the Midsouth during March, April and May and to a lesser degree in November and December. Most tornadoes occur at night, but the devastating storms have been known to strike any time during any season.
This past May, several people were killed statewide, including fatalities in neighboring Coffee County, when a string of storms dropped tornados across the state. The outbreak also caused $5 million in damage. Middle Tennessee saw 22 tornados last year. In the United States, the financial costs of tornados and hail was $3.2 billion last year.
A tornado is a violently rotating column of air extending from the base of a thunderstorm. When the rotating column comes in contact with the ground, it is considered a tornado.
Tornadoes have an average wind speed of around 100 mph. However, the strongest tornadoes have been known to pack winds of over 300 mph.
A tornado’s intensity is measured on the Fujita scale, a severity measuring formula developed by Dr. T. Fujita. The weakest tornadoes are considered F1 twisters and pack winds of 73-112 mph. Although on the bottom line of the scale, the twisters still pack enough power to overturn mobile homes and peel back roofs.
The second classification, F2 tornadoes, pack winds of 113-157 mph and can cause considerable damage, uprooting trees and total destroying mobile homes.
Tornadoes of the F3 variety can cause severe damage as the pack winds of 158-206 mph, able to overturn trains and knock over well-built homes. Many of the twisters which hit the Midstate in May last year were considered F3 variety.
An F4 twister, with winds of 207-260 mph, devastates anything in its path, leveling well-built homes and tossing cars for great distances. An F4 twister hit the Barfield community of Rutherford County in 1997, damaging 147 homes and inflicting $4.7 million in damage.
Although rare, an F5 twister is the most devastating force in nature. With winds of 261-318 mph, an F5 can disintegrate well-built homes and carry debris for miles.
Given the massive force of tornadoes, the National Weather Service in cooperation with the Tennessee Emergency Management Agency, strive to give the public early warning should conditions be right for one of the devastating storms.
When conditions are right for the formation of a tornado, a watch is issued. Watches usually include an area several thousand square miles in size.
When a tornado is indicated by Doppler radar or a twister is sighted by a storm spotter, a tornado warning is issued. Warnings are issued in the specific area where a tornado is active.
If you are in a warning area, experts say you should take immediate precautions. If you are in a house when a tornado strikes, you should go to the basement or interior room, such as a bathroom or closet on the lowest floor of the structure. You should put as many walls between you and the outside as possible.
Mobile homes should be abandoned immediately and a more sturdy structure sought for cover.
Once you have taken cover, you should get under something sturdy such as a workbench or table. You should also avoid windows. Do not take time to open the windows because it will not make much difference to the structure. Instead, by attempting to open your windows, you could be subjecting yourself to unneeded danger.
If you are in a vehicle, experts say you should not try to outrun a tornado because of the fact winds from the storm could blow your car off the road while the twister is still a good distance away. Instead, look for more suitable shelter, such as under a bridge overpass, and abandon the vehicle as soon as safely possible.