As Hurricane Jose rumbles recklessly through the Caribbean with winds expected to exceed 90 mph, forecasters will have a tough time determining how strong the storm will ultimately become. Next year however, new satellite data currently being developed may change this.
While a hurricane's force and destruction hasn't changed over time, monitoring nature's storms has improved dramatically. This is mainly due to the eyes of numerous satellites in space, along with daring hurricane hunter pilots, land-based radar and a host of other methods.
Jose, forecasters would agree, has nowhere to hide.
But even today, though meteorologists are able to make graphic projections of where Jose might go, estimating the ultimate fury of the storm remains an elusive goal. The shortcoming is significant -- some 80 percent of all hurricane damage is attributed to the mere 20 percent of hurricanes that rapidly intensify into monster strength, often just before landfall after boiling over an eddy of warm water.
New satellite data
Recently, forecasters have been toying with another space-based monitoring device that is expected to enhance their ability to predict the intensity of hurricanes. Combined with a new forecasting model announced last week, meteorologists next year may have a good handle on how strong the winds will be when a hurricane makes landfall, regardless of where it hits.
The contribution of data from space comes in the form of altimeter readings that measure minute differences in the height of the ocean. Warm water expands, physically lifting the sea surface. These readings allow researchers to spot the warm eddies of water.
Because warm water is the fuel for all tropical storm systems, the new data -- collected by the TOPEX/POSEIDON and ERS-2 Earth-orbiting satellites -- will soon be among the most useful items in a hurricane forecaster's toolbox. The technique has been developed by Gustavo Goni at NOAA's Atlantic Oceanographic and Meteorological Laboratory, along with researchers from the University of Colorado at Boulder.
These remote-sensing satellites use a technique that measures the travel time of a microwave pulse reflected off the ocean's surface. Peering through clouds, satellite altimetry allows scientists to map sea surface height, significant wave height and wind speed over all of the world's oceans in real time.
A classic example
To form, hurricanes require sea surface temperatures exceeding 26 degrees C (79 degrees F). Warm air rises off the surface of the water, creating an area of low pressure that sucks more air in from the surrounding surface.
The incoming air picks up warmth and moisture from the water, and the storm essentially feeds on itself. When a hurricane passes over eddies of warm water, the added heat typically intensifies the storm.
Researchers found that during September 1995, analyzing past data collected by the system, Hurricane Opal's winds increased from 75 mph to 145 mph in only nine hours after the hurricane crossed a warm eddy in the Gulf of Mexico. This past September, Hurricane Floyd crossed several areas of warm water, the researchers say, building up power before it slammed into North Carolina.
Data need a model
For the new satellite data to be useful, forecasters need to be able to plug their data into better computer models. Just such an improvement appeared on the scene last week.
Writing in the journal "Nature," MIT's Kerry Emanuel explained his new computer model, which simplifies the process of forecasting a storm's intensity by focusing less on its wind patterns and more on the ocean temperatures that lie ahead.
By plugging a given forecasted path into Emanuel's model, a storm's increasing intensity can be estimated more accurately than with previous computer models used by the National Hurricane Center.
A key aspect of the approach is that intensity can be estimated for various possible locations. Residents of Miami, for example, would know how strong Jose would be if it came their way, whereas residents of Charleston, S.C. would get a different estimate of strength.
"Despite many simplifications, the model produces spectacular forecasts of maximum winds for memorable storms such as Hugo (1989), Andrew (1992) and Opal (1995)," said Hugh E. Willoughby of the NOAA Atlantic Oceanographic and Meteorological Laboratory.
One significant limitation to Emanuel's model however, is its reliance on climatological data, meaning that ocean temperatures fed into the model are based on long-term averages. But, explained Willoughby, one of the most significant patches of warm water forecasters focus on turns out to be a moving target.
Forming off the coast of Cuba, the warm eddy works its way into the Gulf of Mexico every 12 to 14 months, so it may or may not be present during the course of a given hurricane. Willoughby said the eddy was the likely cause of Opal's rapid intensification in 1995, and probably contributed to the devastating 1900 hurricane in Galveston, Texas.
The new TOPEX/POSEIDON and ERS-2 projects can track this warm eddy, and Willoughby told space.com that feeding the data into a revised version of Emanuel's model could improve intensity forecasts significantly -- possibly as early as the 2000 hurricane season.
"The beauty of this model is that it's not a big software engineering undertaking," Willoughby said. "You could run it on your PC. Every emergency manager on the East Coast could be set up to run it."
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