Geography 488Thematic Cartography

& GIS

Teressa KeenanMaster of Library and

Information Science (d-MLIS)

Dimmitt, Texas. NOAA Photo Library

May 2, 2006 Geog. 488 2

From Points to Polygons & Beyond:

Mapping the Historical Record

• Tornadoes

• F-Scale

• Physical Damage

• Tennessee Tornado Trivia

Union City OK 1973.NOAA Photo Library,

May 2, 2006 Geog. 488 3

Characteristics of Tornadoes

• Violent Windstorm• Twisting• Funnel Shaped Cloud• Cool air overrides a

layer of warm air• Derived from Spanish

verb “tomar” = to turn

Lakeview, Texas in 1977. NOAA Photo Library, NOAA Central Library

May 2, 2006 Geog. 488 4

White Deer, Texas, USA. Photo by Jimmy Deguara and David Croan

Test Your Twister IQ?

• Tornadoes can rotate clockwise as well as anti-clockwise.

• Tornadoes cause houses to explode from changes in air pressure.

• The best place to be during a tornado is generally in the southwest corner of the basement.

• TRUE! Most in the US spin counter-clockwise. Some spin clockwise & a few have been seen to change from anticyclonic to cyclonic!

• False! Homes are damaged by strong winds & flying debris not air pressure changes.

• False! Current advice is to move to a protected interior room on the lowest floor of the building.

May 2, 2006 Geog. 488 5

Fujita Scale• Tetsuya (Ted) Fujita

(1920-1998)• Introduced in 1971• Accepted by

National Weather Service 1973

• Allen Pearson – Path length & width

• Measures Intensity– Empirically derived from

structural damage– Directly derived with high

resolution Doppler radar wind speed data

• Enhanced F-Scale Feb. 1, 2007

Near Seymour, Texas in 1979. Photographer: D. Burgess NOAA Photo Library

May 2, 2006 Geog. 488 6

Tornado in Attica, Kansas, USA . Photo by Jimmy Deguara

F-Scale continued• Rank intensity

based on damage • Contrived by

connecting Beaufort wind scale with the speed of sound in 12 steps.

• Estimated strength of wind based on observed damage

Fujita, T.T. 1981. Tornadoes and downbursts in the context of generalized planetary scales. J. Atmos. Sci, 38, 1511-1534.

May 2, 2006 Geog. 488 7

•F-0: Light Damage (40-72

mph) roof shingles, tree branches etc.

•F-1: Moderate Damage (73-112

mph) overturn mobile homes, cars etc.

•F-2: Significant Damage (113-

157mph) demolish mobile homes, tear off roofs, large trees uprooted, light objects become missiles.

May 2, 2006 Geog. 488 8

•F-3: Severe Damage (158-206 mph) roof & walls of frame houses, trains overturned, most trees uprooted.

•F-4: Devastating (207-260 mph) homes leveled, blown off foundations, large missiles generated.

•F-5: Incredible Damage (261-318

mph) trees debarked, steel reinforced concrete structures damaged, cars become missiles

May 2, 2006 Geog. 488 9

Union City OK 1973 NOAA Photo Library, NOAA Central Library

Fujita - Table

May 2, 2006 Geog. 488 10

May 2, 2006 Geog. 488 11

May 2, 2006 Geog. 488 12

Sharon, Kansas, USA . Photo by Jimmy Deguara of http://austrailasevereweather.com

Tennessee Tornado Trivia

• Is ranked 23rd for frequency • Ranks 9th in the US for number of

deaths, • Ranked 11th for injuries• And 25th for cost of damages

Effgen, C. (n.d.). Tennessee tornadoes. Retrieved April 26, 2006, from http://www.disastercenter.com/tennesse/tornado.html

Union City OK 1973 NOAA Photo Library, NOAA Central Library

When compared to other states by the frequency per square mile, Tennessee ranks:•23rd for the frequency •6th for fatalities•9th for injuries per area and•26th for costs per area

28 tornadoes lashed 19 counties of Middle and Eastern Tennessee between the early afternoon of April 3 and 1:00 a.m. the following morning-in the worst single outbreak of tornadoes in the State's history. The storms left 50 people dead, 635 injured, and caused approximately $30 million damage.

It was the worst tornado outbreak in U.S. history with 148 twisters touching down in 13 states. Before it was over 16 hours later, 330 people were dead and 5,484 were injured in a damage path covering more than 2,500 miles.

Carey, C. (1974). Details of outbreak by state: Tennessee. In NOAA and the 1974 tornado outbreak. Retrieved April 26, 2006, from National Oceanic and Atmospheric Administration Web site:

http://www.publicaffairs.noaa.gov/storms/tennessee.html

May 2, 2006 Geog. 488 15

Twister IQ – part 2• By opening the

windows, you can balance the pressure inside and outside your home so a tornado will not do damage.

• A tornado is always accompanied or preceded by a funnel cloud.

• When traveling by car seek shelter under an overpass.

• False! Opening windows actually make the situation worse.

• False! Especially in the early stages, a tornado can be causing damage on the ground even though a visible funnel cloud is not present.

• False! Wind currents are concentrated as they are squeezed under the overpasses and increase in speed.  This increased speed with flying debris INCREASES the risk of injury or death.

Dimmitt, Texas. NOAA Photo Library

May 2, 2006 Geog. 488 16Wall cloud of an approaching tornado NOAA Photo Library

Questions?