Thunderstorms that precede a cold front are generally stronger and more likely to reach severe proportions than localized thunderstorms associated with tropical air masses.
A few things must happen in the earth's atmosphere in order for a thunderstorm to become severe.
By definition, a severe thunderstorm is a thunderstorm that contains any one or more of the following three weather conditions:
Supercell thunderstorms are fierce and can sometimes discharge a number of tornadoes. They are tremendously powerful and well-organized, containing rotating columns of rising air.
- Hail that is 3/4 of an inch or greater in diameter
- Winds 58 miles per hour or greater
These storms are capable of maintaining severe thunderstorm strength for hours. They can also produce dangerous straight line winds, large hail and torrential rain. Sometimes these storms spawn particularly strong tornadoes.
Frequently,severe thunderstorms develops as part of a line along or ahead of a cold front associated with strong jet stream winds in the upper levels of the troposphere. Spurred on by the jet stream, this line of severe thunderstorms is called a squall line. Bow echoes associated with squall lines or mesoscale convective systems can produce widespread damage.
Some of the most violent aspects of thunderstorms can be seen in microbursts.
Supercell thunderstorms are tremendously powerful storms that can produce severe weather conditions for hours on end, sometimes affecting towns and cities in their paths for hundreds of miles.
Although supercell thunderstorms produce much of our severe weather, other thunderstorms can also become severe under the right conditions. The intensity of the storm is determined by conditions brewing in the atmosphere.
Check out some of data sources meteorologists use to forecast thunderstorms.