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1996-9 -- FOR IMMEDIATE RELEASE: May 10, 1996

Dial-an-Expert Tip Sheet: Tornadoes

May 10, 1996
BOULDER-The eastern two-thirds of the United States is home to the greatest concentration of tornadoes on earth, and spring is tornado season. To help you file stories on these devastating storms, here are the names and telephone numbers of tornado and severe-storm experts at the National Center for Atmospheric Research (NCAR), the National Oceanic and Atmospheric Administration (NOAA), or member universities of the University Corporation for Atmospheric Research (UCAR). Also included below are related sites on the World Wide Web and background information on tornadoes.

Tornado and severe-storm experts

Dan Breed, 303-497-8933, breed@ucar.edu
NCAR/Mesoscale and Microscale Meteorology Division (MMM)
Specialty: Atmospheric electricity, including cloud electrification and lightning; aircraft studies; precipitation development

Howard Bluestein, 303-497-8924 until August 15, 1996
-- and 405-325-3006, hblue@metgem.uoknor.edu
School of Meteorology, University of Oklahoma
Specialty: Observational studies of tornadoes and severe storms; synoptic and mesoscale meteorology. Note: Bluestein is on sabbatical at NCAR this spring and summer.

Harold Brooks, 405-366-0499, brooks@nssl.uoknor.edu
NOAA/National Severe Storms Laboratory
Specialty: Probabilistic forecasts of storms; short-range forecasts using ensembles of computer models

Tom Grazulis, 802-748-2505
The Tornado Project, St. Johnsbury, Vermont
Specialty: History of tornadoes; author of Significant Tornadoes 1680-1991 and producer of Tornado Video Classics (vols. I, II, III)

Morris Weisman, 303-497-8901, weisman@ucar.edu
Specialty: thunderstorm modeling and observation; mesoscale convective systems

James Wilson, 303-497-8818, jwilson@ucar.edu
NCAR/Atmospheric Technology Division
Specialty: Short-period forecasting (nowcasting) of storms, microbursts, and related phenomena, using Doppler radar

Related sites on the World Wide Web

NOAA Storm Prediction Center
This page includes official outlooks, climatology, and statistics on tornadoes and severe storms. SPC is the federal entity that issues tornado watches, formerly the Severe Local Storms unit of the National Severe Storms Forecast Center.

Tornado and Storm Research Organization
This British entity provides statistics and other information on tornadoes and severe storms in the United Kingdom and throughout Europe.

Background information on tornadoes

Frequency. As storm-spotter and Doppler-radar networks improve and public awareness increases, the number of reported tornadoes is also rising. On average, from 1953 to 1991, there have been 768 tornadoes reported per year, but since 1990 there have been over 1,000 tornadoes each year. The year 1992 produced both the yearly record of 1,293 and the monthly record of 399, reported in June. The 1995 total was 1,233.

Fatalities. Tornadoes have killed over 3,700 people since 1953. Though fatalities have been dropping in recent years, tornadoes killed 69 people in 1994, the most deaths since 1984, and 29 people in 1995.

What causes tornadoes? The strongest tornadoes occur from "supercells," long-lived thunderstorms with large-scale cyclonic circulations that can persist for hours and extend well beyond the storm itself. These strong circulations are often associated with the most violent twisters, yet only a small percentage of supercells produce tornadoes. Recent data indicate that gust fronts and other wind boundaries near the ground are important factors in a tornado's eventual formation.

Where? Tornadoes have been reported in every U.S. state, but they are most concentrated in Tornado Alley, which runs north from central Texas through Oklahoma and Kansas into eastern Nebraska, South Dakota, and Iowa. Other areas of high frequency include the Corn Belt of Illinois and Indiana and the Deep South states of Mississippi, Alabama, and Georgia.

When? Spring is tornado season, with about 50% of all reported tornadoes occurring from April through June. Most tornadoes strike between noon and sunset.

Path of destruction. The typical (median) track length is about one mile for all tornadoes and 23 miles for the strongest ones. The longest track length recorded for a single tornado is the 219-mile track of the Great Tri-State Tornado of March 18, 1925. The typical track width is only 48 yards, but it can range to more than a mile.

Direction and wind speed. Thunderstorms and their attendant tornadoes typically move northeast or east, but tornado tracks can be erratic. Tornadoes move forward at speeds ranging from nearly stationary to 60 mph or more and averaging 20 to 40 mph. Measurements from Doppler radar and estimates based on motion pictures give top speeds in the range of 250-300 mph. Most tornadic winds are below 150 mph.

UCAR manages NCAR under sponsorship of the National Science Foundation.

-The End-
David Hosansky
UCAR Communications
Boulder, CO 80307-3000
Telephone: (303)497-8611
E-mail: hosansky@ucar.edu

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The University Corporation for Atmospheric Research (UCAR) is a not-for-profit university membership consortium which carries out programs to benefit the atmospheric, oceanic, and related sciences. Among other activites, UCAR operates the National Center for Atmospheric Research with National Science Foundation sponsorship.

Julie Jargon <Julie_Jargon@qgate.ucar.edu>
Last modified: Mon 22 July 1996