April 12, 1985

Report Outline
Spring Storm Season
Vital Statistics
Tracking Tornadoes
Special Focus

Spring Storm Season

Twisters Most Common in United States

Tornado season is upon us. The whirlwinds that rank among nature's most destructive phenomena occur most often during the spring in the United States. Violent tornadoes, huge funnels of furiously rotating air, may pack winds of 300 miles per hour, the strongest ever seen on the Earth's surface. Even a “weak” one may carry winds stronger than a hurricane. Most tornadoes last for only a few minutes, and none survives for more than several hours. But in their short lifetimes, these fearsome storms can kill people, level towns and toss automobiles—even train cars—around like toys.

The word “tornado” derives from the Spanish words “tornar” (to turn) and “tronada” (thunderstorm). The most common nicknames for tornado are “twister” and “cyclone.” More tornadoes form in the United States than anywhere else on Earth. Between 750 and 1,000 are reported each year. The country's vast expanse of flatland—particularly the Great Plains area between the Rockies and the Appalachians—is the perfect arena for clashes of cold and warm air that create severe thunderstorms which, in turn, spawn tornadoes. Many of them occur in open spaces and do not harm inhabited areas. Tornadoes are rare in the Pacific Coast and Northeast states.

Scientists have theories on how tornadoes are formed but so far have been unable to prove them. No instrument that can measure wind speed and air pressure within a storm funnel has ever survived a direct hit by a tornado. Systematic efforts by “storm-chasers” to photograph and measure tornadoes have been undertaken only since the early 1970s.

ISSUE TRACKER for Related Reports
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Jan. 12, 2018  Disaster Readiness
Sep. 22, 2017  Climate Change and National Security
Aug. 02, 2013  Preparing for Disaster
Jun. 25, 2010  Offshore Drilling
Feb. 03, 2006  Rebuilding New Orleans
Nov. 18, 2005  Disaster Preparedness Updated
Dec. 16, 1994  Earthquake Research
Oct. 15, 1993  Disaster Response
Jul. 15, 1988  Slow Progress in Earthquake Prediction
Apr. 12, 1985  Tornadoes
Jul. 16, 1976  Earthquake Forecasting
Mar. 19, 1969  Earthquakes: Causes and Consequences
Aug. 22, 1962  Government Stockpiling
Jan. 18, 1956  Disaster Insurance
Mar. 06, 1952  Mobilization for a Prolonged Emergency
Jul. 01, 1950  Stand-By Laws for War
Jan. 09, 1928  Economic Effects of the Mississippi Flood
May 19, 1927  Mississippi River Flood Relief and Control
Atmospheric Sciences
Natural Disasters