Nevada County Picayune and Gurdon Times Newspaper Archive

Spring Brings Threat Of Severe Weather To Area

As spring approaches, so does the threat of severe weather.

One of the moss underrated, but dangerous parts of spring weather is thunderstorms with lightning.

The typical thunderstorm covers a 15-mile diameter and lasts about 30 minutes, though some hang around a lot longer.

In spite of their size, every thunderstorm poses the threat of danger, as each produces lightning, and lightning kills more people annually than tornadoes.

The heavy rains associated with thunderstorms can cause flash flooding, especially in low-lying areas, while strong winds, hail and tornadoes are also possible with thunderstorms.

At any moment, according to the National Oceanic and Atmospheric Administration and National Weather Service, there are nearly 1,800 thunderstorms occurring around the world. This is a total of almost 16 million annually.

Flash flooding is the single largest taker of human life from weather-related causes, killing almost 140 people a year.

Most flash floods deaths happen at night when people get trapped in their vehicles.

Lightning follows closely killing around 93 people a year and injuring another 300.

If there's a thunderstorm, there is lightning, and it causes hundreds of millions of dollars in damage to property and forests annually.

In the U.S. there will be about 100,000 thunderstorms this year alone, with around 10 percent, or 10,000, being considered severe.

The NWS considers a thunderstorm to be severe if it produces hail at least 3/4-inch in diameter and has winds of 58 mph or higher, or spawns tornadoes.

Another problem with thunderstorms is straight-line winds which can exceed 100 mph and are responsible for most damage caused by the storms.

Over water, winds of 74 mph are considered to be hurricane-force, but on land, such winds are called straight-line winds.

One type of straight-line winds is the downburst. This wind causes damage similar to a tornado and is especially dangerous to aircraft.

Large hail results in nearly $1 billion in damage annually to property and crops.

The most violent storm in nature, though, is the tornado. Tornadic winds can exceed 200 miles an hour.

Each year tornadoes cause 80 deaths and 1,500 injuries, with most fatalities occurring when people don't leave mobile homes and automobiles.

Every thunderstorm is created the same way. They need moisture available to form clouds and rain, unstable air, relatively warm so it can rise quickly and lift. Lift comes from fronts, sea breezes and mountains.

In the developing stage cumulus clouds indicate the rising air. There is usually little, if any, rain at this stage.

The development stage takes about 10 minutes, with some lightning possible.

When the storm reaches maturity, hail and heavy rain are likely, along with frequent lightning, strong winds and the potential for tornadoes.

Such storms can have a black or dark green appearance and lasts from 10 to 20 minutes, but can last longer.

As the storm spends its energy, the rainfall decreases in intensity, though strong winds can still be produced and lightning remains a danger.

It's no surprise to anyone who's lived in Arkansas any length of time that thunderstorms are most likely to happen in the spring and summer months, usually in the afternoon and evenings.

However, they can occur any time of the year and at any time of the day.

According to the NWS and NOAA, Arkansas receives from 50-70 thunderstorms annually, with only the Gulf Coast getting more.

When a thunderstorm is in progress, it's a good idea to find shelter as soon as possible.

But, if outside, avoid tall trees, water and hilltops, as lightning is more likely to strike in these areas.

Lightning is the action of air rising, meeting with descending air inside a thunderstorm. This action separates the positive and negative charges.

Lightning results from the buildup and discharge of energy between the positively and negatively charged areas, with the average flash capable of lighting a 100-watt bulb for more than three months.The majority of all lightning occurs within the storm itself, remaining in the cloud.

While lightning is a killer, the odds of being hit are roughly 1 in 600,000.

The air near a lightning strike area is heated to 50,000 degrees Fahrenheit, hotter than the surface of the sun. The rapid heating and cooling of the air near lightning causes a shock wave, resulting in thunder.

Cloud-to-ground lightning strikes begin as channels of electrically charged air moving from the clouds to the ground. When a channel gets close to an object on the ground, a surge of electricity from the ground moves up to the cloud, producing the lightning people can see.

It is possible for lightning to occur when it's not raining, as it often strikes outside heavy rain and can hit as far as 10 miles away from any rain.

Rubber-soled shoes and the rubber tires on vehicles are no protection from lightning either. But, the steel frame of a hard-top vehicle can increase protection if the driver isn't touching any metal.

Those struck by lightning carry no electrical charge and should be treated as quickly as possible.

To increase the odds of avoiding being a victim when a thunderstorm occurs, check weather forecasts before leaving for being outdoors for extended periods of time.

Watch for signs of approaching storms, and if one is spotted, find some method of getting weather information, such as a weather radio, am/fm radio or television.

If a storm is imminent, put off outside activities.

If thunder is close enough to be heard, lightning is close enough to strike.

Seek shelter in a sturdy building or vehicle, but not in small sheds, under isolated trees or in convertible cars.

Get out of boats and water.

Also telephone lines and metal pipes can conduct electricity. Unplug appliances not necessary for getting weather information and don't use the phone or electrical appliances during a thunderstorm. Phones should only be used in emergency situations.

When outside and no shelter is available, find a low spot away from trees, fences and poles and make sure it's not flooding.

If in the woods, take shelter under shorter trees.

However, if a tingling sensation is felt on the skin, or the hair stands on end, squat low to the ground on the balls of the feet placing hands on knees with your head between your knees. This will help make a person the smallest target possible and minimize contact with the ground.

The most important thing about surviving thunderstorms, though, is not to panic and to have access to information handy, such as a weather radio or a portable am/fm radio.