Meteorologists at the National Oceanic and Atmospheric Administration expect that unusually warm water and other factors will produce as many as six major hurricanes during a busy 2013 Atlantic hurricane season, they announced today.
"There are no mitigating factors that could suppress hurricane activity," said Gerry Bell, NOAA's lead hurricane forecaster, in a conference call with reporters. "It will be active or very active."
Bell noted that water temperatures in the Atlantic are eight-tenths of a degree Fahrenheit above normal for this time of year. "That might not sound like much, but it's quite a bit," he said. (Read "Weather Gone Wild" in National Geographic magazine.)
Hurricanes draw their fierce power from warm water, and can intensify when there are no upper-level winds—known as wind shear—to disrupt their momentum.
NOAA forecasters predict that 13 to 20 named tropical storms with winds of at least 35 miles per hour (56 kilometers per hour) will form between June 1 and November 30. Seven to 11 of those could evolve into hurricanes with winds of at least 74 miles per hour (119 kilometers per hour).
And three to six of those hurricanes could intensify into major storms with winds exceeding 110 miles per hour (177 kilometers per hour), NOAA officials said.
An average hurricane season sees about 12 named storms and six hurricanes, with only one or two becoming major storms.
Building a Better Forecast
Even as NOAA forecasters are predicting a busy hurricane season, they also think that significant improvements in forecasting technology will allow them to provide better warnings to coastal residents during the summer and fall.
NOAA is in the fourth year of a ten-year plan to improve forecasting of hurricanes' paths and their likelihood to intensify, and the program already is showing results. Meteorologists got a preview of the improved forecasting last October during Superstorm Sandy, a late-season storm that morphed into a so-called superstorm when it merged with a cold front sweeping down from Canada.
Sandy devastated much of the U.S. Atlantic coast from Florida to New England, causing $71 billion in damage. The storm killed 147 during its trek from the Caribbean to the North Atlantic, including 72 deaths in the U.S. (Related: "A Tale of Two Ponds: NYC Park After the Storm.")
Still, NOAA meteorologist Frank Marks says the predictions of Sandy's path were "phenomenal" and probably saved lives. As Sandy pounded its way up the East Coast toward an eventual landfall in New Jersey on October 29, forecasts for the storm's path were extremely accurate, including the point at which the storm would merge with the cold front after it passed North Carolina.
Such forecasting was the fruit of a new computer program that NOAA is developing for hurricane forecasting, known as the Hurricane Weather Research and Forecast System, or HWRF.
Meteorologists have been using computers for hurricane forecasting for decades. But as data-gathering technology improved, earlier computer forecasting models weren't able to quickly incorporate the flood of newly available information.
"Factors that could affect a storm's track and intensification are not static," Marks said. "They are constantly changing, so that a weather system over Siberia today could affect a hurricane five days later."
The HWRF model, for its part, can track the constantly shifting, moment-to-moment weather conditions that affect a hurricane's path, as well as conditions that are distant at the moment but could influence the storm's path days later.
Real-time data for the model comes from many sources, including weather satellites, buoys, and NOAA's hurricane-hunting aircraft. As a storm progresses, each change that it encounters is immediately folded into the HWRF forecast.
The result is a forecast that is "higher resolution" in much the same way that high-definition video uses more color pixels to produce a sharper video image.
NOAA scientists think HWRF eventually will allow them to extend their long-range forecasting of a hurricane's path to seven days, and to narrow the range of uncertainty about where a hurricane is likely to come ashore.
Some emergency management professionals, meanwhile, wonder if extending the long-range warning is a good idea.
But issuing seven-day warnings for hurricane landfalls could create a longer period of intense media focus on the storm and "desensitize" coastal residents to hurricane warnings, said William Wagner III, who leads an emergency management consulting business.
"The media hypes [hurricane warnings] pretty well," said Wagner, president of Early Alert of Palm City, Florida. "Awareness [of a hurricane] is good. Hype isn't."
But Marks says the extended warning time will save lives and allow emergency managers to better prepare for the aftermath of a hurricane landfall.
"We spend taxpayers' money to pre-position stuff—fuel, power, supplies," Marks said. "The better able we are to pre-position this, the more money that can be saved."
Improvements in forecasting hurricane intensification are coming a little more slowly, Marks said.
The most dangerous and potentially deadly hurricanes are those that experience rapid intensification, mushrooming from a minimal hurricane into a city-leveling monster in the space of a day or two. Such intensification usually happens when a hurricane encounters very deep, very warm water and no wind shear.
One of the most infamous examples of this was Hurricane Andrew in August 1992. That storm was a minimal hurricane until it approached the southeast Florida coast, where its maximum winds accelerated to 175 miles per hour (282 kilometers per hour) as it approached landfall.
The key to improved intensification forecasting is a better understanding of what hurricanes do when they undergo this phenomenon. "It's like the common cold," Marks said. "We know the symptoms, but not the cause."