Tornado

Total Score=84


Definition

A violently whirling column of air extending downward from a cumulonimbus cloud (Thunderhead) and seen as a rapidly rotating, slender, funnel-shaped cloud that has a wind velocity of up to 300 miles per hour at the central core and destroys everything along its narrow ground path.

Background

Atmospheric turbulence that results from a cold front moving into a warmer area provides the ideal conditions for a thunderstorm. In extreme cases, thunderstorms can grow to altitudes of 70,000 feet and foster the development of a tornado.

The power from a tornado results from the extremely high winds and low atmospheric pressure at the central core of the funnel. This funnel cloud can touch down in one location, lift and touch down again, sometimes miles away. This characteristic is known as "skip."

Tornadoes are not limited to any particular geographical area; wherever the conditions permit, this storm phenomenon stands a reasonable chance of developing.

Tornadoes move forward at a speed of 25 to 60 miles per hour. They follow a course that is usually one mile long and 100 yards wide.

Tornadoes are classified based on the damage they produce. This classification is based on a scale called the Fujita Scale. The Fujita Scale is listed below:

F0 40-72 MPH Winds

F1 73-112 MPH Winds

F2 113-157 MPH Winds

F3 158-206 MPH Winds

F4 207-260 MPH Winds

F5 261-318 MPH Winds

History

Since 1950, Maine has experienced 88 Tornadoes. Four confirmed tornadoes occurred in Androscoggin County, occuring just north of Poland from West Minot to Turner, Maine.

There has been only one fatality due to a tornado. This occurred in Aroostook County. However, there have been 17 injuries due to tornadoes since 1950.

The strongest tornadoes on record here in Maine were classified as F2's. There have been 18 F2 Tornadoes since 1950, with a total of 2 F2's occuring in Androscoggin County.

Date

Time

Injuries

F-Scale

Damage $

Path Length

Width

July 31, 1971

1345

1

2

50K-500K

1.0-3.0 mi.

176-527 yds.

July 31, 1971

1425

0

2

50K-500K

<1 mi.

<18-55 yds.

July 14, 1975

1600

0

0

500-5000

<1 mi.

<18-55 yds

July 14, 1988

1520

0

1

500K-5 Million

<1 mi.

<18-55 yds.

Time of Year

Since tornadoes are bred from thunderstorms, June through September is the vulnerable time of year with July and August being the peak months.

Speed of Onset

Tornadoes develop rapidly. Unless a tornado is sighted or indicated by radar, adequate warning to initiate preparedness activities may not be disseminated.

Duration of Event

The destruction from natures most violent weather phenomenon occurs in the tornadoes average one-minute life span in the affected area.

Area of Impact

A tornado's impact is localized but the specific area affected cannot be determined until the tornado is sighted, indicated on radar, or reported.

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Copyright 2002, Wayne Cotterly

Revised: 10/21/2002