NA Not available.
1 A violent, rotating column of air descending from a cumulonimbuscloud in the form of a tubular- or funnel-shaped cloud, usually characterized by movements along a narrow path and wind speeds from 100to over 300 miles per hour. Also known as a "twister" or waterspout."
2 Source: National Hurricane Center, Coral Gables, FL, unpublished data.Tropical storms have maximum winds of 39 to 73 miles per hour; hurricanes have maximum winds of 74 miles per hour or higher.

Source: U.S. National Oceanic and Atmospheric Administration, 1966-1980, Climatological Data: National Summary, monthly withannual summary; thereafter, Storm Data, annual issue.

http://www5.ncdc.noaa.gov/pubs/publications.html#CD

*Hurricane/Typhoon:

A warm-core tropical cyclone in which the maximum sustained surface wind(using the U.S. 1-minute average) is 64 kt (74 mph or 119 km/hr) or more. Theterm hurricane is used for Northern Hemisphere cyclones east of the InternationalDateline to the Greenwich Meridian. The term typhoon is used for Pacificcyclones north of the Equator west of the International Dateline.

Hurricane Season: The portion of the year having a relatively high indidence of hurricanes. Thehurricane season in the Atlantic, Caribbean, and Gulf of Mexico runs from June 1to November 30. The hurricane season in the Eastern Pacific basin runs from May15 to November 30. The hurricane season in the Central Pacific basin runs fromJune 1 to November 30.

Tropical Storm: A tropical cyclone in which the maximum sustained surface wind speed (using theU.S. 1-minute average) ranges from 34 kt (39 mph or 63 km/hr) to 63 kt (73 mphor 118 km/hr).