The Saffir-Simpson Scale
“There’s a storm front coming, white water running and the pressure is low, storm front coming, small craft warning on the radio”—“Storm Front” by Billy Joel
June 1st was the official start of the 2010 hurricane season, and while there have not yet been any official hurricanes, there will be at some point before it’s over. The storms will come in all sizes, and there must be a way to differentiate them. Much like the Richter Scale for earthquakes, the Saffir-Simpson scale helps categorize hurricanes.
The Saffir-Simpson Scale is used only for hurricanes in the Atlantic and Northern Pacific Oceans, particularly east of the International Date Line. In other areas of the world, the storms are called typhoons or cyclones, and are measured using different scales.
Development of the Scale
First put together in 1971 by Robert Simpson and Herbert Saffir, and updated in early 2010, the scale was first made public in 1973. It was finally put into widespread use in 1974 when the new head of the National Hurricane Center (NHC), Neil Frank, took over for Simpson.
In 2010, changes were made to the scale. The NHC tried to update the scale by eliminating the storm surge aspect, therefore making wind the only factor.
It gives a 1-5 rating to all hurricanes, based on sustained winds and storm surge. Storm surge refers to a high flood of water caused by the winds and low pressure of the hurricane. Generally speaking, each level has about four times as much damage as the previous; i.e., damage from a level 3 storm is four times worse than a level 2.
Here are the categories:
Level 1: Minimal. Damaging winds 74-95 mph. 4-5 ft storm surge
Level 2: Moderate. Sustained winds 96-110 mph. 6-8 ft storm surge
Level 3: Extensive. Severe winds 110-130mph. 9-12 ft storm surge
Level 4: Extreme. Devastating winds 131-155 mph. 13-18 ft storm surge
Level 5: Catastrophic. Complete damage to roofs and buildings. Winds over 156 mph. 19+ ft storm surge
In economic terms, Hurricane Katrina was the worst hurricane to ever hit the US, at up to $60 billion in insured losses. The day before it made landfall in Louisiana, it was a category 5 on the Saffir-Simpson scale (“Cat-5”). When it did finally come ashore, on August 29, 2005—at 7:10am—it was still a very strong Cat-3.
In the end, like Billy says in his song, when that storm front is coming, you better be ready.