St. Petersburg Times Online: News of Florida
Place an Ad Calendars Classified Forums Sports Weather
  • State tax cuts to be tougher, Bush says
  • President to visit Tampa on Monday
  • Forecasters get a better fix on fury
  • Status of air base under review
  • Judge delays trial for 8 accused in inmate death

  • From the state wire

  • Hurricane Jeanne appears on track to hit Florida's east coast
  • Rumor mill working overtime after Florida hurricanes
  • Developments associated with Hurricanes Ivan and Jeanne
  • Four killed in Panhandle plane crash were on Ivan charity mission
  • Hurricane Frances caused estimated $4.4 billion in insured damage
  • Disabled want more handicapped-accessible voting machines
  • USF forces administrators to resign over test score changes
  • Man's death at Universal Studios ruled accidental
  • State child welfare workers in Miami fail to do background checks
  • Hurricane Jeanne heads toward southeast U.S. coast
  • Hurricane Jeanne spurs more anxiety for storm-weary Floridians
  • Mistrial declared in case where teen was target of racial "joke"
  • Panhandle utility wants sewer plant moved to higher ground
  • State employee arrested on theft, bribery charges
  • Homestead house fire kills four children, one adult
  • Pierson leader tries to cut off relief to local fern cutters
  • Florida's high court rules Terri's law unconstitutional
  • Jacksonville students punished for putting stripper pole in dorm
  • FEMA handling nearly 600,000 applications for help
  • Man who killed wife, niece, self also killed mother in 1971
  • Producer sues city over lead ball fired by Miami police
  • Tourism suffers across Florida after pummeling by hurricanes
  • Key dates in the life of Terri Schiavo
  • An excerpt from the unanimous ruling in the Schiavo case
  • Four confirmed dead after small plane crash in Panhandle
  • Correction: Disney-Cruise Line story

    printer version

    Forecasters get a better fix on fury

    Scientists have a new generation of sensors to help them assess storms as season begins today.


    © St. Petersburg Times,
    published June 1, 2001

    A hurricane strike on any populated coastline is a terrible thing. But let's face it: It's a much more terrible thing if it happens here.

    So the first thing we all want to know about a hurricane is its destination, its track.

    [NOAA photo/Courtesy of University of Wisconsin Space Science and Engineering Center]
    Satellite-guided instruments - called drop sondes - can be parachuted into hurricanes such as Bret, above, to help forecasters answer a potentially lifesaving question: How dangerous is it?
    forecasters at the National Hurricane Center concentrate their resources -- satellites, aircraft, computer models and years of experience -- to answer the question foremost on everyone's mind: Where is the darn thing going?

    Until recently, however, they were less prepared to answer the next key questions: How strong is the storm? How great is the danger?

    Today begins the six-month hurricane season. From now until the Thanksgiving leftovers are gone, Floridians must keep an eye on the weather. It's expected to be an "average" season, meaning about 10 named storms, six becoming hurricanes, and two of those becoming Category 3 major storms with winds from 111 to 130 mph.

    Since the major storms have vastly more destructive potential than smaller ones, telling the difference is vital to giving proper warnings. But in determining storm intensity, forecasters have lacked good data. Satellites provide wonderful pictures of advancing storms, but they don't reveal much about the chaos inside.

    That's now changing.

    A new generation of disposable, satellite-guided instruments dropped into approaching hurricanes is giving forecasters a better-than-ever picture of the storms' chaotic, destructive center.

    The National Weather Service, which operates the National Hurricane Center in Miami, acknowledged the problem and the progress recently when it gave its highest honor, the Isaac M. Cline Award, to hurricane specialist James Franklin for improving the small instruments, called drop sondes.

    "For years there have been debates in the scientific community about how to accurately assess a hurricane's maximum surface wind speed," said weather service director Jack Kelly. "Franklin's research provides a detailed and accurate profile of the inner core of a hurricane -- the most intense and turbulent part."

    Sondes have been around for years, but the new ones are linked to the Global Positioning System satellites. As they whirl about near the core, they provide precise wind speed measurements. New sensors are more accurate, and a new transmitter design allows the sondes' signals to be received by nearby aircraft even in the tumult of thunderstorms.

    "Electrical activity made it real hard" to receive signals from the old ones, said Franklin.

    Each is a 16-inch tube of instruments attached to a small parachute. They are dropped from an aircraft -- sometimes a few, sometimes dozens -- and drift slowly downward through a storm, sending data on barometric pressure, temperature, water vapor and wind speed.

    "They allow us to detect important changes in hurricane intensity earlier than we could before," said Franklin. Two years ago, Hurricane Bret was upgraded from a Category 3 to a Category 4 storm on the basis of drop sondes in the eyewall, he said, an increase in intensity that aircraft did not detect until 12 hours later.

    Bret made landfall in a sparsely populated stretch of the Texas coastline, but if it had hit a more populous area, the additional 12 hours could have saved lives, Franklin said.

    Over the years, the problem has been that forecasters had to project the storm's strength based on readings made in the aircraft.

    "We have always known that the wind must increase with height just above the surface," said Franklin. "We just didn't know by how much. Now we do. For example, on average, the wind at the top of a 30-story building will be one . . . category higher than the surface wind.

    "The bottom line is that our intensity estimates will be more accurate than they were even just two to three years ago."

    There are two deployment strategies.

    In the first, designed to help forecast a storm's track, 25 to 50 sondes are dropped "on a more or less regular grid completely surrounding the storm in all directions out to several hundred miles," said Franklin. "The idea is to measure the storm's steering currents."

    The second, newer strategy is designed to measure intensity.

    "Here, we will drop one or two sondes during each aircraft penetration of the center," Franklin said. "After two penetrations we can have sondes in each quadrant of the eyewall."

    Sonde usage is increasing, said Franklin, "as we continue to learn about their benefits."

    At a cost of about $500 each, the hurricane center expects to spend about $100,000 on the devices this year.

    "Not a big number," said center spokesman Frank LePore, "when you consider the billions in damages caused by landfalling hurricanes."

    Back to State news

    Back to Top

    © 2006 • All Rights Reserved • Tampa Bay Times
    490 First Avenue South • St. Petersburg, FL 33701 • 727-893-8111
    Special Links
    Lucy Morgan

    From the Times state desk