• Most severe weather during the warm season comes from thunderstorms.
• A typical thunderstorm is 15 miles wide and lasts an average of about 30 minutes.
• Thunderstorms can produce hail, high winds, flooding rainfall, and yes, even tornadoes.
• Every thunderstorm produces lightning.
• A SEVERE Thunderstorm must contain hail 3/4-inch or larger, and/or winds gusting to 58 miles per hour or higher; and/ or a tornado.
• 1,800 thunderstorms are in progress at any given time around the world.
• 100,000 thunderstorms occur every year in the United States.
• Only about 10 percent of all thunderstorms become "severe."

(TVS_updraft Pic here:) Thunderstorms consist of moving air. Some of the moving air heads upward. This is known as the UPDRAFT. The updraft is where warm, moist air is lifted and condensed into clouds. This warm. moist air provides the fuel for the thunderstorm in the form of clouds and rain. The strength of the updraft is directly related to the strength of the storm and the weather it will produce. For example, large hail stones need a very strong updraft to suspend them high in the sky. This allows the hold stone to grow very large. Once the weight of the hail stone cannot be supported by the updraft, the hail falls to the ground.

(need photo!) Quite often one will be able to observe cloud fragments form and lift up into the base of the updraft. Since the upward motion in the updraft can be quite strong, most of the precipitation in the storm is held aloft and will fall downwind of the updraft. This creates a rain-free base as little precipitation is able to fall back through the updraft. It’s the base of the updraft that we are most interested in observing as that is were a mesocyclone-produced tornado would be located. The updraft is usually found on the back side of the thunderstorm. If the storm is moving from the west to the east, the updraft would generally be found on the south and west side of the storm.

The downdraft is located on the "front" of the storm. The downdraft is characterized by sinking or downward motion. Falling rain and hail drag some of the air within the cloud down toward the earth's surface. As this air moves downward, it picks up speed due to gravity. If you are looking at a thunderstorm, the downdraft area is the dark portion of the storm that contains most of the rainfall and hail. The lighter or brighter portion of the storm is the updraft area. Although strong winds can occur in all parts of the storm, the downdraft area is the likely location for strong, damaging winds. If a thunderstorm is moving east, the downdread will be the first portion of the storm that passes a given point and will usually be accompanied by rain-cooled air.