Nevada County Picayune and Gurdon Times Newspaper Archive

Tornado Season Arrives In Arkansas; Various Types Exist

To no one's surprise, we're heading into tornado season in Arkansas.

The state usually has 21 tornadoes touch down every year, resulting in an average of five deaths.

It was a record year for twisters in 1999, as 107 touched down, while last year the count was 37 with no deaths and only 12 injuries.

Tornadoes are spawned by thunderstorms.

Thunderstorms develop in warm, moist air in the advance of east-moving cold fronts, they often produce large hail, strong winds and tornadoes.

As the thunderstorm forms, there is a change in the direction of the wind, along with an increase in wind speed. The increasing height creates an invisible, horizontal spinning motion in the lower atmosphere.

The rising air tilts the rotating air, thereby moving the air from horizontal to vertical.

At this point, an area of rotation 2-6 miles wide now extends through the storm. This is where tornadoes form.

Next , an area of rotation called the rotating wall cloud forms. This area is nearly rain free. Shortly thereafter, a tornado develops.

Tornadoes come in three classifications, weak, strong and violent.

Of these, 69 percent of all twisters are considered to be weak. These storms cause less than 5 percent of tornado-related deaths and are short-lived, normally lasting from one to 10 minutes and bearing winds less than 110 mph.

Strong tornadoes, being 29 percent of all twisters, cause nearly 30 percent of tornado deaths, and can last more than 20 minutes. Winds in these storms are between 110 and 205 mph.

Only 2 percent of all tornadoes are classified as violent. Yet these storms are responsible for 70 percent of all tornado deaths. They can last more than an hour and have winds in excess of 205 mph.

Tornadoes are classified according to the Fujita of F-scale. This scale ranges from F0 to F5, with the storms intensity based on wind speed.

An F0 tornado has winds from 40-72 mph and does light damage. It and the F1 are considered weak tornadoes. The F1 has winds from 73-112 mph and does moderate damage.

Tornadoes classified F2 and F3 are moderate twisters. The F2 storms have winds from 113-157 mph and do considerable damage, while the F3 storms have winds from 157-206 mph and do severe damage.

The F4 and F5 tornadoes are the violent ones. An F4 twister has winds from 207-260 mph and is devastating, while the F5 brings winds from 261-318 mph and leaves a wake of incredible damage behind. Fortunately, though these storms are rare, especially the F5 level.

While tornadoes are unpredictable in the damage they do and where they'll hit, nowhere is really safe from one.

The low pressure with a tornado does not cause buildings to "explode" as many believe. Instead, the violent winds and debris slamming into buildings causes the majority of damage from twisters.

This means opening windows to "equalize the pressure" and minimize damage, won't really help. In fact, opening windows will allow the damaging winds inside.

The best idea is to find a safe place, preferably a storm shelter.

According to the National Oceanic and Atmospheric Administration (NOAA) and the National Weather Service (NWS), the prime time for tornadoes in Arkansas is March through May.

But, tornadoes can occur any time of the year.

The NWS is placing Doppler radars across the U.S. These radar can detect air movement toward and away from the radar.

Early detection of increasing rotation in a storm can allow the NWS to issue warnings before a tornado actually forms.

Fortunately, tornadoes give advance warnings before dropping down out of thunderstorms. When a thunderstorm forms, be aware of the color of the sky. Tornadoes usually form leaving a greenish-colored sky.

They also form wall clouds, accompanied by a loud roar, similar to a freight train.Often, tornadoes can be seen extending down from a thunderstorm, but there are times the storm's density obscures the twister contained inside with low-hanging clouds.

If a tornado watch or warning is issued, it would be a good idea to find shelter, such as in a basement.

But, if an underground shelter isn't available, move to an inside room or hallway on the lowest floor and get under a sturdy piece of furniture if possible.

Make sure to stay away from windows, and get out of vehicles as they offer no protection from a twister. Don't try to outrun a tornado if in a vehicle. Instead, lie flat in a ditch or depression.

For those living in mobile homes the advice is simple  leave. Mobile homes offer little in the way of protection and should be abandoned.

Those most at risk in tornadoes are those in vehicles, the elderly, very young and physically and mentally impaired, along with people who live in mobile homes, or those who don't understand the warnings because of language barriers.

It also wouldn't be a bad idea to make a disaster supply kit. These kits should include a three-day supply of water (with a gallon of water per person per day available), and food that won't spoil.

The kit should also have extra clothing and footwear, a blanket or sleeping bag for every individual, a first aid kit with prescription medicines, emergency tools including a battery operated radio, flashlight, extra batteries, extra car keys and cash.