1999-32 FOR IMMEDIATE RELEASE: August 6, 1999
Tip Sheet: Hurricanes
Contact: Anatta
Telephone: 303-497-8604
Fax: 303-497-8610
[email protected]
BOULDER--This year may bring a bumper crop of Atlantic hurricanes, thanks to the influence of La Nina and other factors. Below is a range of Web sites, answers to frequently asked questions, and a set of hurricane experts from the National Center for Atmospheric Research (NCAR) and from member institutions of the University Corporation for Atmospheric Research (UCAR). NCAR's primary sponsor is the National Science Foundation. NCAR is managed by UCAR, a consortium of more than 60 universities offering Ph.D.s in atmospheric and related sciences.
Hurricane experts
Roger Pielke, Jr., 303-497-8111, [email protected] NCAR Environmental and Societal Impacts Group
Specialty: Hurricane impacts and related societal factors. A political scientist, Pielke has completed in-depth studies of the societal vulnerability to hurricanes of the U.S. Gulf and Atlantic coasts. In the October 1999 issue of the Bulletin of the American Meteorological Society, Pielke and colleague Christopher Landsea (see listing below) will outline the relationship of El Nino and La Nina to U.S. hurricane damage. They note that most La Nina years (17 out of 22)--but only a few El Nino years (7 out of 22)--produce a U.S. landfall causing at least $1 billion in damage. Catastrophic storms of $10 billion or more are so rare that their relationships to El Nino or La Nina are difficult to assess. The study is on line at http://www.dir.ucar.edu/esig/HP_roger/bams. Pielke and Landsea have also examined trends in population and wealth to calculate the costs of historic U.S. hurricanes in 1997 dollars. Pielke is the co-author of Hurricanes: Their Nature and Impacts on Society (Wiley, 1997) and creator of the Extreme Weather Sourcebook (see Web sites below).
Robert Gall, 303-497-8160, [email protected] NCAR Mesoscale and Microscale Meteorology Division/U.S. Weather Research Program
Specialty: Analysis of tropical systems. Through radar analysis, Gall has uncovered fine-scale bands that spiral around the centers of hurricanes. These bands could be related to small-scale wind peaks that cause some of a hurricane's worst damage. Gall and fellow NCAR scientist John Tuttle have also developed a technique that uses radar data to estimate surface winds at points that lie beyond the typical range of Doppler radar. Gall is now serving a two-year term as lead scientist of the U.S. Weather Research Program, a multiagency project to examine high-impact phenomena, including hurricane landfall.
Terry Hock, 303-497-8767, [email protected] NCAR Atmospheric Technology Division
Specialty: Measurement of winds through Global Positioning System (GPS) dropsondes. Hock led NCAR's development of the revolutionary GPS device. The dropsondes have been deployed over the past three years from hurricane- hunting aircraft. They report winds between flight level and the sea surface at 16-foot (5-meter) intervals, a precision about 100 times greater than before. The new dropsondes have gathered the first-ever wind data at high resolution from the eyewall that swirls around the calm eye of a hurricane.
Christopher Landsea, 305-361-4357, [email protected] NOAA Hurricane Research Division
Specialty: Seasonal hurricane forecasting and hurricane climatology. Landsea is a collaborator with hurricane forecaster William Gray (Colorado State University). He has studied patterns of hurricane occurrence and damage along the Gulf and Atlantic coasts over the past century and is the author of a frequently-asked-questions document on the World Wide Web (see below).
Jay Baker, 850-893-8993, [email protected] Florida State University, Department of Geography
Specialty: Human response to hurricanes, including evacuations. Through on- site visits and interviews after hurricanes, Baker has examined how people respond to warnings and evacuation orders. He also has studied how emergency managers use forecasts and other information to implement evacuation plans.
Related sites on the World Wide Web
NOAA Tropical Prediction Center (TPC) http://www.nhc.noaa.gov
This site includes official outlooks, climatology, and statistics on hurricanes, tropical storms, and tropical depressions. TPC includes the National Hurricane Center, which issues hurricane watches and warnings and calculates official projections of storm tracks.
NCAR/ESIG Extreme Weather Sourcebook >http://www.dir.ucar.edu/esig/HP_roger/sourcebook/hurricane.html
This site offers yearly totals and state-by-state comparisons for hurricane damages between 1925 and 1995. The figures are normalized to account for trends in population and wealth. Florida, Texas, and Louisiana are the leaders for hurricane damage, with Florida averaging over $2 billion per year.
CSU Tropical Meteorology Project http://tropical.atmos.colostate.edu
This site, from Colorado State University, includes -- the latest long-range hurricane outlooks from CSU professor
William Gray -- a comprehensive set of answers to frequently asked questions about hurricanes and other tropical cyclones, compiled by Chris Landsea.
Atlantic Tropical Weather Center http://banzai.neosoft.com/citylink/blake/tropical.html
This site includes a wealth of links to Web-based hurricane information. Because popular Web sites often become busy and difficult to access when a major hurricane approaches, the author includes several alternate addresses for frequently sought items, such as the latest storm intensities and projected tracks.
Background information on hurricanes
What is a hurricane? Each year a number of tropical disturbances-- centers of low pressure--move westward across the Atlantic, Pacific, and Indian Oceans. Some of these become depressions--more organized disturbances with sustained surface winds of up to 38 miles per hour (61 kilometers per hour). Should the winds become stronger, the system becomes a tropical storm and is given a name. If the winds reach 74 mph (119 km/hr), the storm is reclassified as a hurricane (other names, such as typhoon, are used outside of the Atlantic). Eventually, most of these systems either strike land and quickly weaken or recurve over the ocean, moving north and east as they become caught up in the midlatitude westerly winds and lose their tropical characteristics.
What's the difference between a hurricane and a tornado? Tornadoes are spawned by thunderstorms, while hurricanes are made up of many showers and thunderstorms (which can themselves spawn tornadoes upon landfall). Hurricanes gather energy from the warmth of the ocean. A hurricane's eye is typically 10 to 15 miles (16 to 24 km) wide, and winds around it are as strong as 150 to 200 mph (240 to 320 km/hr). The hurricane circulation can be hundreds of miles across. Even the largest tornadoes are only about a mile across, although their winds can reach 300 mph (480 km/hr). Tropical storms can survive for weeks, while most tornadoes exist for much less than an hour.
How many tropical systems occur on average each year? Globally, an average of around 85 tropical storms and 45 hurricanes/typhoons form per year. The tropical Atlantic and Gulf of Mexico--the sources of U.S. hurricanes--produce an average of nine named storms per year, with around six of those becoming hurricanes and two of those becoming intense hurricanes (ones with sustained surface winds exceeding 110 mph, or 177 km/hr). The period since 1995 has been unusually active. Even though 1997 saw few Atlantic storms, the 1995-1998 total was the largest on record for a four-year span in the Atlantic, with 53 named storms, including 32 hurricanes.
How are hurricanes predicted? Some climate factors are known to affect hurricane frequency for a given ocean or a given year. For instance, El Nino enhances upper-level winds that tend to suppress Atlantic hurricanes, while La Nina has the opposite effect. Each year, out of dozens of disturbances that cross the tropical Atlantic, only a handful encounter the right combination of light wind shear and warm ocean temperatures that allows for hurricane development. The behavior of tropical storms and hurricanes is predicted by high-resolution computer models at the NOAA Tropical Prediction Center, the federal agency that issues hurricane watches and warnings (see Web site above). Hurricane motion can be projected with some skill out to five days. Changes in storm intensity are still difficult to predict, even within a day or two, but some progress has been made with better computer models. New observing tools, such as GPS dropsondes (see Terry Hock, above) and satellite-based radars that can sense unusually deep layers of warm water, are also helping to improve forecasts by providing a better picture of current conditions.
What are the storm names for this year and upcoming years? Since 1953, Atlantic tropical storms have been named from lists originated by the National Hurricane Center and now maintained and updated by Region 4 of the World Meteorological Organization. The lists featured only women's names until 1979. Six lists are used in rotation. The names of the most severe hurricanes, such as 1998's Mitch, are retired permanently. Below are the lists for 1999-2004.
Atlantic basin hurricane names
1999 2000 2001 2002 2003 2004
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Arlene Alberto Allison Arthur Ana Alex
Bret Beryl Barry Bertha Bill Bonnie
Cindy Chris Chantal Cesar Claudette Charley
Dennis Debby Dean Dolly Danny Danielle
Emily Ernesto Erin Edouard Erika Earl
Floyd Florence Felix Fran Fabian Frances
Gert Gordon Gabrielle Gustav Grace Gaston
Harvey Helene Humberto Hortense Henri Hermine
Irene Isaac Iris Isidore Isabel Ivan
Jose Joyce Jerry Josephine Juan Jeanne
Katrina Keith Karen Kyle Kate Karl
Lenny Leslie Lorenzo Lili Larry Lisa
Maria Michael Michelle Marco Mindy Matthew
Nate Nadine Noel Nana Nicholas Nicole
Ophelia Oscar Olga Omar Odette Otto
Philippe Patty Pablo Paloma Peter Paula
Rita Rafael Rebekah Rene Rose Richard
Stan Sandy Sebastien Sally Sam Shary
Tammy Tony Tanya Teddy Teresa Tomas
Vince Valerie Van Vicky Victor Virginie
Wilma William Wendy Wilfred Wanda Walter
-The End-
UCAR and NCAR news: http://www.ucar.edu/publications/newsreleases/1999. To subscribe via e-mail send name, title, affiliation, postal address, fax, and phone # to [email protected].
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