Understanding Thunderstorms

There are 40,000 thunderstorms each day around the world. The United States is no exception. More thunderstorms occur in the Southeast where the warm climate and moist air from the Gulf of Mexico and the Atlantic Ocean combine to create thunderstorms. Florida has 80 to 100 thunder days every year. If you're going to be outdoors, it's a good idea to understand thunderstorms so you can stay safe.

What Causes Lightning and Thunderstorms?
Thunderstorms require moisture, instability and a lifting mechanism to form. Moisture typically comes from the ocean but can come from the atmosphere as well. Air is unstable, as warm moist air rises it cools to form water vapor in the form of a cumulonimbus cloud which leads to a downpour and thunderstorm. Thunderstorms can also occur when clouds rain to lighten their load to float over top mountains. These are common in the Rocky Mountains during the summer.

Ordinary Cell  The ordinary cell or pulse thunderstorm is typically made up of a one-time updraft and a one-time downdraft. The as the cumulus cloud rise (updraft) the water will become too heavy and will fall in raindrops (downdraft). This will be a short-lived storm. However, hail and gusty winds can occur if the conditions are correct. It can become a microburst with winds up to 70 miles per hour. Weak tornados can even form.

Multi-cell Cluster  A multi-cell cluster is made up of several ordinary cells. These clouds group together influencing each other and affecting the storm. As one cloud ends its life cycle others form creating a rainfall loop. New clouds generally from upstream of the storm. However, they can also from behind the storm, known as back-building storms. These can dump a huge amount of rain in a very short time causing flash flooding.

Squall Line  Thunderstorms can form in a line that stretches for hundreds of miles. These storms can last for hours bringing hail and high winds with them.  New cloud cells are constantly forming on the leading edge of the storm due to the updraft. Squall lines tend to travel on a straight path. They are sometimes referred to as Derechos meaning straight in Spanish. Derechos can travel for hundreds of miles causing massive damage to the area. Tornados occasionally form on the leading edge of the storm and travel in a straight line.

Supercell Thunderstorm  A supercell thunderstorm is made up of a single, powerful cell. These storms can last for hours, they are the leading cause of tornados and golf ball sized hail. They are known to cause extreme winds and flash flooding. Supercells produce winds more than 100 miles per hour. Wind rotation causes the entire cloud to turn in a circular motion.

What Does This Mean for You? If you see a cloud wall that lasts for 10 minutes with visible rotation and it appears to move in up and down motions it is a potentially severe and dangerous storm. Time to find some cover and wait until it passes. Find the closest building to shelter in place. If you can't go indoors, find a grove of trees (not a single tree) or a valley and crouch with your arms and head tucked into your body so you are the smallest object in the area).  You will undoubtedly get wet, so make sure you keep a good blanket, firestarter, and hand warmers in your survival gear so you


Photo Credit: https://www.runnersworld.com/hot-weather-running/what-runners-should-know-about-lightning

Source: http://www.weather.gov/jetstream/tstorms_intro

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