The supercell is a highly organized thunderstorm. Although supercells are rare, they pose an inordinately high threat to life and property. Like the single cell storm, the supercell consists of one main updraft. However, the updraft in a supercell is extremely strong, reaching estimated speeds of 150-175 miles an hour. The main characteristic which sets the supercell apart from the other thunderstorms we have discussed is the element of rotation. The rotating updraft of a supercell, called a mesocyclone helps the supercell to produce extreme severe weather events, such as giant hail (more than 2 inches in diameter), strong downbursts of 80 miles an hour or more, and strong to violent tornadoes.

Recall that the supercell environment is characterized by high instability, strong winds in the mid and upper atmosphere, and veering of the wind with height in the lowest mile or so. This environment is a contributing factor to the supercell's organization. As precipitation is produced in the updraft, the strong upper level winds literally blow the precipitation downwind. Relatively little precipitation falls back down through the updraft, so the storm can survive for long periods of time with only minor variations in strength. As mentioned earlier, the veering winds with height assist the mesocyclone formation within the supercell.

Figure 12: Side view of a supercell storm. View is to the
northwest. Prominent features of the storm are indicated.

The leading edge of a supercell's precipitation area is characterized by light rain. Heavier rain falls closer to the updraft with torrential rain and/or large hail immediately north and east of the main updraft. The area near the main updraft (typically towards the rear of the storm) is the preferred area of severe weather formation. Figures 12 and 13 show diagrams of a supercell storm.

Figure 13: Overhead view of a supercell storm.
The precipitation area, gust front,
and cloud features are shown.

In the next few sections, we will examine the visual aspects of the supercell (and other severe thunderstorms) in more detail. We will also discuss the tornado and some variations in the supercell model we presented above.
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