Tornados and Severe Weather

TORNADO INFORMATION

WHERE TORNADOS CAN OCCUR:

Any place in the United States at any time of the year. They happen most frequently in the Midwestern, southern, and central States from March through September. In Indiana, the northwest quadrant and southwest corner of the state are well above the state average.

HOW OFTEN DO THEY OCCUR:

Indiana averages 23 tornados, occurring on 11 days throughout the year. The greatest frequency of reported tornados is in April. Other months when tornados are most likely to occur include March, May, June and July.

HOW TO RECOGNIZE A TORNADO:

Usually a funnel shaped cloud, spinning rapidly, and extending toward the earth from the base of a thundercloud. When close by, it sounds like the roar of hundreds of airplanes. Because of the differences of air pressure (which causes tornados to form), violent winds are produced and also a sucking action which can lift automobiles and cause buildings to collapse.

TORNADO WEATHER:

Hot, sticky days with southerly winds and a threatening, ominous sky. However, many such days do occur without tornados.

CLOUDS:

Familiar thunderstorm clouds are present. An hour or two before a tornado, topsy-turvy clouds appear, sometimes bulging downward instead of up. The clouds often have a greenish-black color.

PRECIPITATION:

Rain, frequently hail, precede the tornado, with a heavy downpour after it has passed.

TIME OF DAY:

Mostly between 3p.m. and 7p.m., but tornados have occurred at all hours.

DIRECTION OF TRAVEL:

In most cases they move from a westerly direction, usually from the southwest to the northeast. Only 3% come from the north, east or south. Tornados have been known to double back and move in circles or to remain motionless.

LENGTH OF PATH:

Usually 10 to 40 miles long (the average is 13 miles), but they may move for 300 miles.

WIDTH OF PATH:

The average width is about 250 yards but they have cut swaths over a mile in width.

SPEED OF TRAVEL:

Generally 25 to 40 miles per hour, but they have varied from stationary to 68 miles per hour.

WIND SPEED:

Estimated from 100 to 300 m.p.h. within the tornado.

NATIONAL WEATHER SERVICE DEFINITIONS:

SEVERE THUNDERSTORM – Possibility of frequent lightening, damaging winds (58 m.p.h.+)accompanied by ¾ inch of rain.

SEVERE WEATHER WATCH – Possibility of tornados or severe thunderstorms.

TORNADO WATCH – Existing weather conditions are such that tornados are expected to develop.

TORNADO WARNING – A tornado has been sighted in the area or is indicated on radar.

EVERYONE should know their designated evacuation location and proceed to that location in a swift, quiet manner. Take precautions to stay away from exterior walls, windows, and flying debris. The appropriate protective posture is a crouched position covering the back of your head with your hands as illustrated below.

Usually the safest location is going to be the inner core of the building, interior rooms, and hallways; however, immediate protection may be required in the center of your floor underneath desks or other furniture.