Severe Weather: What are Thunderstorms?


I know the weather does not look like it now but we are officially headed toward spring, and that means severe weather. One type of severe weather that is common in the spring and summer are thunderstorms. A thunderstorm, according to the National Severe Storms Laboratory (NSSL), “is a rain shower during which you hear thunder. Since thunder comes from lightning, all thunderstorms have lightning.”

A thunderstorm only occurs when certain situations collide. Thunderstorms are only created with a mix of different ingredients; moisture, lift and unstable air. Ever been out on a hot day and the air is sticky? Sometimes this is called humidity but it can be considered moisture in the air. Another thing needed is unstable air. Normally in our atmosphere, cold air is on bottom and hot air is on top, and everything is fine in the world. Sometimes though, things switch and the hot air is on the bottom and cold air is on top and causes the atmosphere to get out of whack. This is where the unstable air comes into the picture. Finally, we have lift. To kick off a thunderstorm, something such as a front, sea breezes or mountains lift up a storm and start it up.

However thunderstorms are a common occurrence, with 16 million thunderstorms a year worldwide occurring. There are about 100,000 thunderstorms a year in the United States alone! Thankfully only about ten-percent of these reach severe status, according to the NSSL. Thunderstorms are more likely to occur in the spring and summer months though although they can appear year round at all hours. In the Plains states, otherwise known as the Southwest and Midwest,  thunderstorms tend to appear in the late afternoon and nighttime.

According to the NSSL:

Many hazardous weather events are associated with thunderstorms. Under the right conditions, rainfall from thunderstorms causes flash flooding, killing more people each year than hurricanes, tornadoes or lightning. Lightning is responsible for many fires around the world each year, and causes fatalities. Hail up to the size of softballs damages cars and windows, and kills livestock caught out in the open. Strong (up to more than 120 mph) straight-line winds associated with thunderstorms knock down trees, power lines and mobile homes.

The greatest of these threats mainly occur in the United States, from Texas all the way to southern Minnesota, but can occur anywhere in the United States.

There are different varieties of thunderstorms though that can form, many harmless. The first type is typically called a ‘popcorn’ or single cell storm that only lasts about an hour, and it just pops up quick. These are typically harmless. “They are typically driven by heating on a summer afternoon. Single-cell storms may produce brief heavy rain and lightning.” (NSSL)

Another type of storm is a multi-cell storm and these are basically a garden-variety storm in which updrafts are created in rain-cooled air. According to the NSSL, “Individual cells usually last 30 to 60 minutes, while the system as a whole may last for many hours. Multi-cell storms may produce hail, strong winds, brief tornadoes, and/or flooding.”

Finally there is the super-cell storm which is a long-lived storm that feeds off an updraft that is tilted and rotating, according to the NSSL.  This rotating updraft can be around for anywhere from 20 to 60 minutes before a tornado can form. These are the most dangerous storms.

According to the American Red Cross, “A thunderstorm is considered severe if it produces hail at least 1 inch in diameter or has wind gusts of at least 58 miles per hour. Every thunderstorm produces lightning, which kills more people each year than tornadoes or hurricanes. Heavy rain from thunderstorms can cause flash flooding, and high winds can damage homes and blow down trees and utility poles, causing widespread power outages.”

So in this case there are some things that you can do to know the difference in when it is time to hide in the basement or not. Sometimes news places will give out two different types of warnings on storms these are called watches and warnings.

According to the American Red Cross:

Severe Thunderstorm Watch – Severe thunderstorms are possible in and near the watch area. Stay informed and be ready to act if a severe thunderstorm warning is issued.

Severe Thunderstorm Warning – Severe weather has been reported by spotters or indicated by radar. Warnings indicate imminent danger to life and property.

“Every year people are killed or seriously injured by severe thunderstorms despite advance warning. While some did not hear the warning, others heard the warning and did not pay attention to it,” says the American Red Cross.

So when the weather is calling for a severe thunderstorm, at least now you know what to look for in case of a thunderstorm.

Author: Courtney Swessinger

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