Monday, December 20 1999

STORM GLOSSARY



Hurricane Categories

Hurricanes are ranked one to five, according to the Saffir-Simpson scale of strength:

  • CATEGORY 1 - Hurricane has central pressure of 28.94 inches or more and winds of 74 to 95 mph, is accompanied by a storm surge of 4-5 feet and causes minimal damage.

  • CATEGORY 2 - Pressure 28.50 to 28.93 inches, winds from 96 to 110 mph, storm surge 6-8 feet, damage moderate.

  • CATEGORY 3 - Pressure 27.91 to 28.49 inches, winds from 111 to 130 mph, storm surge 9-12 feet, damage extensive.

  • CATEGORY 4 - Pressure 27.17 to 27.90 inches, winds from 131 to 155 mph, storm surge 13-18 feet, damage extreme. (Hurricanes Andrew, Hugo and Hazel were Category 4 storms.)

  • CATEGORY 5 - Pressure less than 27.17 inches, winds greater than 155 mph, storm surge higher than 18 feet, damage catastrophic.


Terms

  • Tropical cyclone - The general term for all circulating weather systems over tropical waters.

  • Tropical disturbance - A moving area of thunderstorms in the tropics that lasts for 24 hours or more. A common occurrence.

  • Tropical depression - An organized system of clouds and thunderstorms with a defined circulation and maximum sustained wind speed of 38 mph (33 knots) or less.

  • Tropical storm - An organized system of strong thunderstorms with a defined circulation and maximum sustained wind speed of 39-73 mph (34-63 knots). It can develop into a hurricane quickly.

  • Hurricane - An intense tropical system with a well-defined circulation and sustained wind speed of 74 mph (64 knots) or more.

  • Storm surge - A dome of water often 50-100 miles wide and as much as 20 feet high that sweeps across the coastline where a hurricane strikes land. The surging water poses the greatest threat to life and property along the coastline.

  • Tornado - Funnel of powerful swirling wind sometimes spawned by hurricanes.




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