What The Different Hurricane Categories Really Mean

Although the wind can be as gentle as a breeze, we’ve seen how it can be strong enough to flatten a house. It’s also strong enough to move oceans. As hurricanes traverse the seas, their high winds push ocean water ahead of their path. As the elevated deep-ocean water approaches land and passes over the continental shelf, the storm-driven water rises up in a storm surge, inundating coastal land (via National Hurricane Center).

As that water washes ashore, it can wash away beaches, permanently changing the coastline. Water weighs over 64 pounds per cubic foot, and as that weight crashes into infrastructure, buildings and roads are literally swept away. Storm surges can be as tall as 30 feet and extend inland for miles, compounding any consequences of torrential rains. The deadliest and costliest hurricane in living memory — Katrina — can credit storm surge with the majority of its carnage.

Because the root of a storm surge’s power lies in the monstrous force of hurricane winds, you would think that the Saffir-Simpson scale would be a good metric by which to predict storm surge levels. Unfortunately for meteorologists, that’s not the case. Hurricane Ike made landfall as a category 2 storm and produced a surge of 20 feet while category 4 Hurricane Charley only produced an eight-foot surge.

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