What makes a Thunderstorm severe?

What exactly makes a thunder storm “severe”? One of several things:

1. a tornado
2. winds at or above 58 mph
3. or quarter-size (one inch diameter) hail or larger.

Did you know there are different types of thunderstorms?

• Single cell thunderstorms usually occur during the summer months when the air is warm, moist, and unstable, and winds are weak. These thunderstorms, also known as pulse or airmass storms, form as unorganized clusters and have little to no movement.
• Multicell thunderstorms and squall lines are organized complexes of thunderstorms that cover large areas. These storms are more likely to produce severe weather, particularly damaging winds, since they move rapidly across an area. Tornadoes, hail and flash flooding are also possible.
• Supercell thunderstorms are the strongest and most dangerous and can produce long-lived tornadoes, winds in excess of 100 mph, and large hail. Fortunately, these storms are rare.

Bottom Line

The best defense against thunderstorms is to stay inside a building or shelter for protection from lightning, wind, hail, and heavy rain. For tornado protection you need a substantial shelter or basement, preferably far from windows. But don't think a storm is "ignorable" just because there's no tornado, damaging wind events occur 10 to 20 times more often than tornadoes. Initial storm reports often erroneously attribute significant damage to tornadoes when actually strong, straight-line winds from thunderstorms are responsible.

Fortunately, thunderstorms generally pass within an hour. When thunderstorms are expected, stay tuned to your NOAA Weather Radio All Hazards for up to date information. Postpone outdoor activities.