Atmosphere And Weather

Hurricane Categories according to the Saffir Simpson Scale

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During the hurricane season, the numbers 1, 2, 3, 4, and 5 become of intense importance to the public trying to understand the predicted damage a storm may do.  Originally, in the 70’s and 80’s the Saffir-Simpson Hurricane Scale was based not just on wind velocity but on central pressure and storm surge predictions.  However, after a series of hurricanes like Ike and Charlie proved that wind and size did not always correlate with the damage done, it was decided to remove all factors from the hurricane scale except wind. Thus, when we hear the number given to the hurricane strength, it refers only to wind. Storm surge and flooding are determined by the amount of moisture in the storm as well as topography plus the wind driving it. Falling trees and hurricane-spawned tornadoes can also add to the destruction. Local building codes also impact the amount of housing damage to an area. 

Each number on the Saffir-Simpson Scale is approximately four times stronger than the preceding number. Thus a Category 2 Hurricane is 4 times as powerful as a Category 1. A category 3 Hurricane is 4 times as powerful as a Category 2 and 16 times as powerful as a Category 1. Sometimes a half or plus is added to the numerical designation. 

Category One Hurricanes average winds that are 74-95 mph. Older homes, especially mobile homes, may be damaged or moved off their foundations. Roofs and porch awnings may be taken off. Flying debris can injure or kill anyone unfortunate to be caught outside. Flying debris can also smash through windows, damage roof shingles, carports, sunrooms, or other attached structures. Shallow trees are often uprooted especially if there is significant ground moisture. Electricity can be disrupted due to downed lines. 

Category Two Hurricanes will have wind velocities of 96-110 sustained. These are very dangerous winds which usually cause great damage. People and animals outside can be killed or injured by falling debris. Older frame homes and old and newer mobile homes can be leveled. Even well-constructed frame houses may suffer considerable damage to siding and attached structures. Roofs may fly off. Commercial buildings may suffer roof collapse – even unreinforced masonry walls may tumble. Broken windows from flying debris will be common and injuries from flying glass will be another hazard. Widespread electrical outages can be expected as well as failure of water filtration plants. Obviously, safe shelter and drinking water are imperative in a Category Two Hurricane. 

Category Three Hurricanes with winds of 111-130 mph are devastating. Older mobile homes will be gone. Newer ones will be severely damaged. Older frame homes will be destroyed; newer ones will experience severe structural damage. Fences, canopies, signs – all gone. Windows will be blown out of high rise buildings. Any person or animal outside can become part of the wind – look for Toto and Dorothy but without a happy ending (yes, that was a tornado but the debris carried on the wind would be similar to a Cat. 3 Hurricane). Damage will be such that electricity or water to the area for several days or weeks after the storm has ended. 

Category Four Hurricanes with sustained winds of 131-155 mph cause catastrophic damage. Anyone with a mobile home or stick built house will lose it. Even steel framed industrial buildings may collapse. Trees, power lines will all be down; fences, signs, and lightweight structures will disappear. Many residential areas may be isolated for weeks or even months without water or electricity. Add in flooding, disease, and the area becomes one of human and animal suffering. Some areas like those affected by Katrina may never fully recover. Hurricane Charley (2004) impacted the Punta Gorda coastal section of Florida with long-lasting devastation. 

Category Five Hurricanes with sustained winds greater than 155 mph are the highest grade hurricane even though there can be widespread variation due to the size and duration of the storm. The worst are those held in place by low pressure systems which keep the storm from moving through and weakening inland. No one is safe in this high grade hurricane. People can be killed in their homes as buildings simply collapse or are swept away. Without electricity or water, and with broken glass and fallen trees littering the roadways, the area may become uninhabitable for months. 

As hurricanes approach, all eyes are on the weather maps showing their possible paths. Hurricane reconnaissance planes measure barometric pressure inside the storm. Weather experts calculate possible wind velocities and tidal surges. People board up, evacuate, and pray.  As this season gears up, we’ll all be watching for those prophetic numbers: One, Two, Three, Four, and Five.

More about this author: Cynthia Wall

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