2005 Hurricane Season Ties a Record
This year may go down in the record books as having the most named tropical storms since 1933. Tropical Storm Wilma formed on Saturday, October 15 in the eastern Caribbean matching the record for number of named storms in a hurricane season. She is expected to become a hurricane in the Gulf of Mexico, and forecast to move into the middle of the Gulf by Saturday, October 22.
Image right: The Tropical Rainfall Measuring Mission (TRMM) satellite took this image (click on image to expand) of what was to become Tropical
Storm Wilma at 11:02 pm EDT 16 October 2005. This image shows a top-down
view of the rain intensity within tropical depression #24 (now Wilma). Most of the
rain is on the south side of the storm with some weak banded features west of the center, indicating
that the circulation is still in the formative stages. At the time of the image, this storm had sustained
winds estimated at 35 mph by the National Hurricane Center.
"If storms were being named in 1933, that would have been the last time we hit 21 named tropical storms," according to Lixion Avila, hurricane forecaster at the National Oceanic and Atmospheric Administration's National Hurricane Center in Miami, Fla.
A tropical cyclone gets a name when it has maximum sustained winds of 39 mph or higher. When storms pack sustained winds of 74 mph or higher, they become hurricanes.
At 11 a.m. EDT on Oct. 17, Tropical Storm Wilma was located about 220 miles (355 kilometers) south-southeast of Grand Cayman. Wilma is moving toward the southwest near 5 mph, with a gradual turn to the west expected over the next 24 hours. Maximum sustained winds are 45 mph, and Wilma could strengthen into a hurricane by Tuesday, October 18.
"The 2005 Atlantic season was unusually active from the very start, with development of two Category 4 hurricanes, Dennis and Emily, in July. Warm ocean surface water in the Gulf of Mexico and weak tropical winds appear to have contributed to this exceptionally harsh season," said Dr. Jeffrey Halverson, a hurricane research scientist as NASA's Goddard Space Flight Center, Greenbelt, Md.
Image left: This image, taken at the same time as the first image, (click on image to expand) gives a 3D perspective of the system from TRMM. The isosurface shows the height of the precipitation within the storm as defined by the 10 dBZ isosurface (equivalent to very weak precipitation). The tall towers (in red) near the center of the circulation often indicate further strengthening. Credit: Hal Pierce (NASA GSFC)/Caption credit: Steve Lang, NASA GSFC
Wilma is the last name on the 2005 official list of storm names. According to the National Hurricane Center, in the event that more than 21 named tropical cyclones occur in the Atlantic basin in a season, additional storms will take names from the Greek alphabet: Alpha, Beta, Gamma, Delta and so on.
Storms were first named after women from 1953 until 1979. During 1979, the World Meteorological Organization (WMO) added men's names to the list alternating them with women's names. The WMO is an international organization that maintains the official list of names for the upcoming six years.
Absent from the lists are names that begin with the letters Q, U, X, Y and Z, because there are so few of them. Names reappear on lists on six-year cycles, unless "retired" for causing a significant loss of life or property, such as Andrew from 1992, Bob from 1991, and Charley, Frances, Ivan and Jeanne all from the 2004 season.
Of the 21 named storms that have formed since the start of the 2005 hurricane season on June 1, eleven have become hurricanes, including five major hurricanes. This number is far above the average of ten named storms, of which six are hurricanes and two major hurricanes.
For this reason, scientists and forecasters will study the 2005 season for many years to come to assess what factors contributed to its activity. However, NASA research meteorologist Dr. Marshall Shepherd of NASA GSFC says “that it is probably a bit too early to conclusively pinpoint one specific factor.”
Hurricane season ends Nov. 30.
For the latest advisories on tropical cyclones, please visit the National Hurricane Center website at:
Goddard Space Flight Center