NASA Sees Hurricane Isabel From Cradle to Grave
In 2003, a hurricane named Isabel was born out of Africa on August 22. As she moved across the warm open waters of the Atlantic Ocean, she grew up, she gained strength, and she packed her bags for the United States.
Image to right: This animation follows 2003's Hurricane Isabel from its surprising birthplace in the Ethiopian Highlands of East Africa, across the Atlantic Ocean, and to the United States. Note how Isabel gains size and speed over the warm waters of the Atlantic. Click on image to view animation (3.07 MB) Credit: NASA
When Isabel arrived in North Carolina on September 18, she made a name for herself, by packing hurricane force winds as she came ashore.
Now, after almost a year after studying information gathered by satellites, airplanes, buoys, ships and computer models gathered during Isabel's journey, scientists have a unique insight into her life.
Hurricane Isabel was a long-lived Cape Verde hurricane that reached Category 5 status on the Saffir-Simpson Hurricane Scale with maximum sustained winds of 166 mph at sea. It made landfall on North Carolina's Outer Banks as a Category 2 hurricane with sustained winds between 97-103 mph. Isabel was one of the most significant tropical cyclones to affect portions of northeastern N.C. and east-central Va. since 1954's Hurricane Hazel.
Images above: As Isabel cruises across the Atlantic and changes in intensity, the distribution of rainfall and heat inside the storm is fluctuating dramatically. The "warm core" of the hurricane (inset window) is the engine that drives the storm, allowing it to draw up energy from the ocean, gathering strength and size. Click on each image to view a different animation. (1.26 MB - animation one, 984 Kb - animation two, 792 Kb - animation three) Credit: NASA
NASA and National Oceanic and Atmospheric Administration (NOAA) satellites monitored Isabel's track, wind intensity, precipitation, and temperature inside the storm using multiple sensors on a number of earth-observing satellites simultaneously. NASA satellite data was provided to NOAA, who provided the watches and warnings to the public.
NASA's Seawinds instrument on QuikScat satellite looked at Isabel's wind speed and direction. NASA and the Japanese Meteorological Agency's Tropical Rainfall Measuring Mission (TRMM) satellite kept a close eye on Isabel's clouds and rainfall to see if she was getting stronger or weaker.
Image to left: A powerful storm churns up colder, deeper waters and leaves a trail of cool in its wake. If another storm comes along and intersects with this cold water trail, it's likely to lose significant strength due to the fact that the colder water does not contain as much potential energy as warm water. Click on image to view animation. (1.24 MB) Credit: NASA
NASA's Aqua and TRMM satellites looked through the clouds at sea surface temperatures. Sea surface waters warmer than 82 degrees (F) can make hurricanes stronger. Scientists also looked at the heights of the sea to determine Isabel's change in strength using the Jason-1 satellite.
NOAA's GOES East satellite provided images as forecasters matched where she was going both day and night to where the computer models projected she would go. The U.S. Department of Defense also provided data from the Defense Meteorological Satellite Program (DMSP) satellite.
Closer to Earth aircraft kept a closer eye on Isabel, dropping sensors into the storm to get readings on temperature, humidity and pressure. The 53rd Weather Reconnaissance Squadron of the U. S. Air Force Reserve Command, the NOAA Aircraft Operations Center, and a Canadian research aircraft all observed Isabel.
At the Earth's surface, scientists constantly gathered information from ships, land stations, and buoys.
Image to right: A recent improvement in hurricane modeling techniques is just starting to emerge from NASA, promising great strides in understanding these giant storms. In this sequence showing five days in the life of Hurricane Isabel, you can see how closely the artificial storm (in green) matches the real world observations (in yellow) as it actually happened. Click on image to view animaton. (1.65 MB) Credit: NASA
In addition to using satellites, several computer models were used. NOAA's Tropical Analysis and Forecast Branch (TAFB), NOAA's Satellite Analysis Branch (SAB) and the U. S. Air Force Weather Agency (AFWA) estimated storm intensity. At NOAA's National Hurricane Center several computer models were run and interpreted by forecasters, resulting in hurricane advisories throughout Isabel's life.
Hurricane conditions affected portions of eastern N.C, and southeastern Va. Rainfall averaged 4-7 inches over large portions of eastern N.C., east-central Va. and Md. Rainfall totals of 8-12 inches with locally higher amounts occurred in the Shenandoah Valley in northern Va.
Storm surges were 6-8 feet above normal tide levels near the point of landfall along the N.C. coast and in the upper reaches of the Chesapeake Bay near Annapolis and Baltimore, Md. Isabel was directly responsible for 16 deaths along the U.S. east coast.
Image to left: This new insight into hurricane formation and structure would not be possible without a dedicated fleet of space-based observatories. By combining the unique assets of several distinct federal agencies, scientists have been able to extract information and insight into the structure and processes of hurricane behavior that otherwise would have been impossible prior to a space faring era. Click on image to view animation. (1.43 MB) Credit: NASA
Isabel was just under one month old when she reached the end of her life. On September 20, she became "extra tropical" developing characteristics like storms outside the tropics, and moved northward into Canada. Once in Canada, Isabel was absorbed into another weather system. She left behind her a trail of property damages up to $3.37 billion in her wake through the U.S., with a minimal loss of life as a result of improved technology and forecasts.
Official National Hurricane Center report on Hurricane Isabel
Goddard Space Flight Center