Image: NASA Earth Observatory
Myth: Sandy hit the U.S. Northeast as a hurricane
Perhaps the greatest myth of all is that Sandy was a hurricane for its entire journey up the U.S. eastern seaboard. There's no doubt that the storm packed a punch, but the National Hurricane Center downgraded it from hurricane to "tropical storm" on Monday, October 29.
Why the switch? The center uses a sliding scale called Saffir–Simpson to categorize hurricanes. The scale is based solely on wind speed. So when Sandy's wind velocity decreased, the storm also lost its hurricane status.
The lesser label presents a communications problem for scientists who study storm surges and for public officials who have to make evacuation decisions for entire populations because of flooding. The demotion from hurricane to tropical storm does not make the event any less deadly, says Noah Diffenbaugh, a climate scientist at Stanford University.
"We have plenty of examples of lower category storms that cause a greater level of damage and higher category storms that cause a lower level of damage," he says.
The mismatch between a storm's status and the damage it can inflict is a consequence of a gradual increase in the size and intensity of storms overall, says Rice's Bedient. As storms grow larger and more intense, their impacts might have outgrown the Saffir–Simpson scale. "We're getting these really huge storms," he adds. "They can have enormous storm surge effects compared to what we saw back in the '50s and '60s."
The meteorological community has proposed other ways of measuring hurricanes, but some researchers stand in staunch support of Saffir–Simpson. Scientific American previously covered the debate. —Mollie Bloudoff-Indelicato
Sandy was a normal hurricane
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