Scientists are hoping that the 10th anniversary of Hurricane Andrewon August 24thwill serve as a reminder that were in danger of another big storm right now.
Because as this ScienCentral News video reports, this hurricane season looks more foreboding than the season of Andrew.
An Anniversary "present"
The 10th anniversary of the most expensive natural disaster in United States history may not be cause for big celebration, but Andrew got an anniversary present nonetheless: an upgrade from Category 4 to Category 5 on the hurricane scale.
The Saffir-Simpson hurricane scale is dictated primarily by wind speed. Category 4 hurricanes have winds between 131-155 mph, and Cat 5 storms are anything above that. The problem with the measurements for Andrew was that all the wind-measuring devices on land were destroyed by the time the storms strongest winds hit.
"So we still dont know today exactly how strong Andrew was," says Michael Black, meteorologist at the National Hurricane Center. "And it [was] a controversy."
So at the time of the storm, researchers had to estimate the maximum wind speeds based on a historic formula that says wind speeds at the surface are 80 percent of those at 10,000 feet (researchers obtain those measurements from airplanes that fly through the hurricane at that altitude).
The reason Andrew was upgraded is that researchers have learned so much more about hurricanes in the last ten years. New wind measuring devices called dropwindsondes (see our Hurricane Heralds video) are released from airplanes and send researchers precise measurements of wind speed (as well as temperature, pressure, humidity and wind direction) every half second as they fall through the eye of a hurricane. This is the first time scientists have been able to record wind speeds from the upper atmosphere all the way to the ground.
What theyve learned is that wind speeds can vary dramatically at different levels, and can spike hundreds or even thousands of feet above ground--something they never suspected could happen. In fact, winds can be one or even two categories higher a few hundred feet in the air.
Andrew was first estimated to have top wind speeds of 145 mph. Using new estimates researchers now say it was more like 165 mph, which puts it in the Category 5 range, only the third such storm in U.S. history.
Such new information about hurricanes is pertinent not just to Andrew, but to our categorization of all hurricanes in US history. And researchers at the National Hurricane Center are in the process of doing a total reanalysis of the Atlantic Hurricane Database, which dates back to 1851. According to Chris Landsea, lead researcher on the project, about 80 percent of the storms he has looked at so far have been changed in some way, and when the work is done it could have profound results on insurance rates along the coast.