Hurricane* Development Stages

Stage

Sustained Wind Speed

Comments

Tropical Disturbance or Wave

£ 20 knots (23 mph)

  Thunderstorms with barely organized general circulation
Tropical Depression

20 - 34 knots (23 - 39 mph)

  Several closed isobars on surface map
Tropical Storm

35 - 64 knots (40 - 74 mph)

  Closely spaced isobars
Hurricane*

> 64 knots (74 mph)

  See Saffir-Simpson Scale for strength classification

*"Hurricane" (North Atlantic and East Pacific) = "Typhoon" (Western North Pacific) = "Cyclone" (Indian Ocean)
= "Willy Willy" (Australian term) = "Tropical Cyclone" (general international term)

Hurricane/Tropical Storm Names
(assigned when a system reaches "tropical storm" strength)

Scheme

Period

Comments/Examples

 By Saint, on or near Whose Day Storm Occurred

Early

 Hurricane Santa Ana struck Puerto Rico on July 26, 1825
 By Latitude, Longitude and Date

Early, Pre-World War II

 Cumbersome, ambiguous, designation changed as storm moved
 Alphabetical, Using Radio Code Words for Letters

WW II through 1952

 Able, Baker, Charlie, . . . .
*Alphabetical, Using Female Names

1953-1977

 Hurricane Camille, 3rd Atlantic Tropical Cyclone (TC) of 1969
*Alphabetical, Using names of Alternating Gender

1978 - present in East Pacific

 Hurricane Douglas, 4th Eastern Pacific TC of 2002

1979 - present in North Atlantic

 Hurricane Andrew, 1st Atlantic TC of 1992

    *Atlantic and Pacific name lists are independent.  With the current alternating gender scheme, the first name for the year alternates between
      male and female each year, with opposite genders starting the Atlantic and Pacific lists, e.g., in 2011 the first Atlantic storm was Arlene and
      the first Eastern Pacific storm was Adrian.  In 2012 the first named Atlantic tropical cyclone will be male (Alberto) and the first Pacific storm,
      female (Aletta).

      Name lists are recycled every six years except that the names of major (Category 3 or higher) hurricanes, causing great damage, are retired
      for at least ten years, to prevent confusion of identity.  The names of truly "great" storms, e.g., Katrina, Andrew, Hugo, Camille, etc., may
      remain permanently retired
.