In a letter obtained by The Associated Press, the National Oceanic and Atmospheric Administration's chief said the failure of the QuikScat satellite could bring more uncertainty to forecasts and widen the areas that are placed under hurricane watches and warnings.
If the satellite faltered, experts estimate that the accuracy of two-day forecasts could suffer by 10 percent and three-day forecasts by 16 percent, which could translate into miles of coastline and the difference between a city being evacuated or not.
"We would go blind. It would be significantly hazardous," said Wayne Sallade, emergency manager in Charlotte County, which was hit hard by Hurricane Charley in 2004.
A NOAA spokesman disputed that, saying alternatives such as using data from other satellites would help diminish any increased uncertainty coming from the loss of QuikScat.
In the letter to a Florida congressman, NOAA Administrator Conrad Lautenbacher blamed the delays in replacing the sattelite on technical and budget problems. Scientists said if QuikScat failed, they may have to rely on less accurate satellites.
Bill Proenza, director of the National Hurricane Center in Miami, said authorities "may have to err on the side of caution" in future forecasts.
That means "more people disrupted, and more impact on the economy," Proenza said. "On the other hand, we have to err on the side of the protection of life. And that's how we would handle it."
Lautenbacher said the replacement is part of a larger program to update America's weather satellites. The AP reported last week that other cuts in the program have included scaled-back efforts to measure global warming from space.
Last year, forecasts were off an average of 111 miles two days in advance, a figure that has been cut in half over the past 15 years. But experts said that could grow 10 percent to 122 miles if the satellite is lost, causing the "cone of error" well known to coastal residents to expand.
Some scientists also complain that the technology planned for the replacement satellite is less precise for hurricane forecasting than what is currently flying.
QuikScat, launched in 1999 and designed to last two to three years, provides key data on wind speed and direction over the ocean. Weather aircraft and buoys can also obtain similar measurements near a storm, but they do not provide a constant flow of data as QuikScat does.
Last year, the satellite suffered a major setback - the failure of a transmitter used to send data to Earth about every 90 minutes. Now the satellite is limping along on a backup transmitter and has other problems.
The backup transmitter could last years, but there are no guarantees and no warnings when it is about to fail, said Robert Gaston, who works with the satellite at NASA's Jet Propulsion Laboratory.
Emergency managers like Sallade have been briefed on the satellite's problems. They said if they cannot rely on forecasts, they may have to make crucial decisions earlier, such as evacuating hospital patients or moving around emergency equipment.
Emergency managers estimate that the total costs of evacuations are up to $1 million per mile of coastline, meaning wider evacuations could be expensive.
Lautenbacher's letter was sent to Rep. Ron Klein, a Florida Democrat who requested the agency's plan should the satellite fail. Klein and other members of Congress are pushing bills that would pay for a satellite to replace QuikScat.
"I'm disappointed that this letter doesn't directly address my request for a backup plan if QuikScat fails, given that we're three weeks into a hurricane season," said Klein, who has requested a hearing on the issue.
Even if money were immediately available, a replacement satellite is estimated to take at least four years and cost approximately $400 million to build. The AP first reported those estimates in a March interview with Proenza, one of the loudest voices calling for a replacement satellite.
"When you look at QuikScat what it does is it gives us a swath of data that's 1,500 to 1,800 kilometers wide, all at one time, one moment. It covers 90 percent of the global oceans in one day," he said recently.
If the satellite fails, the options are few. Other satellites have instruments to measure wind speed and direction over water, but they are less accurate.
A European satellite called ASCAT is available, but it does not give scientists as clear a picture as QuikScat because the distance between the readings it takes is larger. Using ASCAT would be like a person who wears glasses taking them off, seeing a once-sharp world blurred, said National Hurricane Center senior hurricane specialist Rick Knabb.
A NASA and Department of Defense satellite called WINDSAT also measures wind speed and direction, but it is also beyond its expected lifespan, and scientists have had trouble using it to observe tropical weather systems.
That's a problem because NOAA intended QuikScat's replacement to be modeled on WINDSAT.
A replacement for QuikScat was originally scheduled to launch in 2009. Lautenbacher would not give a date for that flight in the letter, but other officials have said it is scheduled to launch in 2016.
The satellite's final form is still undetermined, but Knabb said the design does not currently feature technology comparable to QuikScat. He said the satellite's data will not be particularly helpful for hurricanes.
"When we need the data the most is when it's not going to perform very well - inside a tropical cyclone," Knabb said.
By Jessica Gresko