According to the Glossary of Meteorology (AMS 2000), a tornado is "a violently rotating column of air, pendant from a cumuliform cloud or underneath a cumuliform cloud, and often (but not always) visible as a funnel cloud."

Twisters (or Tornadoes) have a long history in Wisconsin, capable of causing severe damage to land, buildings as well as the taking of human and other life. Annually, in Wisconsin, an average of 21 tornadoes occur and an average of 1.8 human lives are taken.

The photos below are not pictures of the biggest and most destructive of twisters, but they have the added value of showing the actual emergence and formation of a twister from storm clouds.

Peak tornado season is May through August, but tornadoes have occurred in every month but February. Most tornadoes occur between noon and 9 PM.. with 5 PM a favored time. Most Wisconsin tornadoes travel southwest to northeast or west to east, travel at speeds of 20 to 40 mph, and persist for less than 10 minutes with a path length of less 5 miles.

Roughly 80% of Wisconsin's tornadoes are weak with wind speeds of 50 to 110 mph. About 19% are rated as strong with wind speeds of 110 to 205 mph. Luckily, only 1% are violent with wind speeds over 205 mph.

Most tornadoes are found in, or very near a rotating "wall cloud", on the south or southwest side of a thunderstorm. The wall cloud is a distinct lowering of the rain-free (or almost rain-free) base of a thunderstorm. The rain-free base is found in the updraft (inflow) portion of a thunderstorm. Tornadic thunderstorms possess a rotating updraft. If you can locate the inflow region of a thunderstorm, you've located the potential "hot spot", should a tornado develop.

A tornado warning means a tornado is highly imminent, or is already on the ground. Stay away from windows! Go into a basement and get under a heavy desk/table, covering your head with your arms, a mattress, or heavy blanket. If there is no basement, go to the lowest level, or an interior hall or closet. A bathtub can also be used as a last resort. Get out of large auditoriums or large warehouses. If caught outdoors or in a motor vehicle, lie flat in a roadside ditch, ravine, or culvert, and cover your head with your arms.

Our sincere thanks to nature photographer and computer technician Neil Davey of Tech Medics for these photos (and the courage to take them!) Also thanks to the National Weather Service website for information for this feature.