Thunderstorms

Thunderstorms

Texas is affected by thousands of thunderstorms every single year. However, the most dangerous thunderstorms are classified as severe and occur mainly in the spring and fall.

Severe thunderstorms can produce damaging winds, large hail, and tornadoes. A thunderstorm is defined as severe when it produces winds of at least 58 mph, hail 3/4 of an inch in diameter or larger, or a tornado.

Something important to remember about thunderstorm winds is that not all damaging thunderstorm winds are tornadic. Thunderstorms are capable of producing equally destructive and life-threatening thunderstorm winds, commonly referred to as downbursts or straight line winds. Straight line winds refer to winds that are not associated with rotating winds in a tornado. Lines of thunderstorms that develop across Texas can produce downburst wind speeds in excess of 100 mph.

Two types of downbursts exist: microbursts and macrobursts. The microburst is usually short-lived and is of great concern to the aviation community. It produces strong winds in an area less than 2.5 miles in diameter. In contrast, macrobursts are longer-lived and capable of producing extensive wind damage across areas larger than 2.5 miles in diameter.

Thunderstorm winds occasionally can reach speeds in excess of 100 mph. These types of winds are intense enough to uproot trees and cause substantial damage and even outright destruction to buildings. If these winds occur in conjunction with large hail, then even more extreme damage can occur.

Hail that is penny size (3/4 inch in diameter) or larger is considered severe. Hail is defined as precipitation in the form of lumps or chunks of ice that develop in some thunderstorms. Hail can range in size from pea size (1/4 inch) to greater than softball size (4.5 inches).

Hailstones are usually oval shaped or round, but can be spiky in appearance. The largest hailstone on record in the United States fell at Aurora, Nebraska on June 22, 2003. The massive stone measured 18.75 inches in circumference and more than 7 inches in diameter.

Hail falls to earth at speeds approaching 100 mph and, as a result, can produce immense damage to buildings, automobiles, and vegetation. Annually, hailstorms cause more than one billion dollars in damage across the United States. No part of Texas is immune to the dangers of large hail and it injures several dozens of people each year. In rare cases, fatalities have resulted from hail.

There are things you can do to help protect yourself and your property from the dangers associated with damaging thunderstorm winds and hail. Keep abreast of the latest weather conditions to avoid being caught in a severe storm. Monitoring weather radio from the National Weather Service as well as television, radio, and Internet information will also help keep you informed of the approaching straight line wind or hail events in your area.

Treat straight line wind events the same as you would an approaching tornado. Seek shelter in a reinforced shelter, on the lowest floor in an interior bathroom or closet. Stay away from all windows. Cover your head to protect against the impact of flying debris that can injure. If you encounter hail while driving, turn around. You may be driving into the core of a thunderstorm where tornadoes form. Report hail or strong winds to your local law enforcement as soon as it is safe to do so and seek an alternate route.

National Weather Service Severe Weather Awareness