The Saffir-Simpson Hurricane Wind Scale is the means by which meteorologists classify a storm’s intensity based on sustained winds. The numerical category (1-5) assigned to the storm gives us an idea of what kind of damage the storm might cause based on how intense the winds are. The numbers have no bearings on other elements of a hurricane like the storm surge and flooding due to rains, but the category is often a good basis of estimating how severe the storm will be in these areas.
The scale was established in 1971 and is named for a civil engineer named Herbert Saffir and a meteorologist named Robert Simpson. Saffir’s goal was to develop a scale for hurricanes that was similar to the Richter Scale for earthquakes. Saffir came up with the category rating system based on wind speed and Simpson (who at the time was the director of the National Hurricane Center) added the likely effects of flooding and storm surge. In 2009, the National Hurricane Center eliminated the flooding and storm surge elements and began using the scale based solely on wind speeds.
Hurricane categories are broken down as follows:
Category 1 – Winds somewhere between 74 and 95 mph. Older mobile homes or poorly constructed homes may sustain significant damage to roofing, vinyl siding, etc. People and animals are at risk of being injured by falling trees, broken glass, or other debris.
Category 2 – Winds somewhere between 96 and 110 mph. Mobile homes (new and old alike) are at serious risk of being destroyed as well as poorly constructed frame homes. Even well constructed homes could be at risk for damage to roofing or siding. Unprotected windows are at risk of being broken by tree branches and other debris.
Category 3 – Winds somewhere between 111 and 130 mph. Almost all mobile homes at risk of complete destruction. Even well constructed frame homes are at risk for significant structural damage to both roof and exterior walls. Unprotected windows will be at risk for being blown out which will result in falling glass even once the storm has passed. Trees may be uprooted or snapped. Electricity and/or water may be unavailable for a potentially significant amount of time once the storm subsides.
Category 4 – Winds somewhere between 131 and 155 mph. Nearly all mobile homes are at risk for complete destruction, as are poorly built frame homes. Even well built frame homes are at risk of damage and/or collapse of roofing, siding, and exterior walls. Almost all non-protected windows will be blown out which will pose the potential threat of falling glass. Older buildings will be at risk of collapse. Trees may be uprooted and there will be a good deal of debris picked up by the wind. Electricity and water could be out for weeks or months.
Category 5 – Winds that are greater than 155 mph. All mobile homes and a high percentage of frame homes will be destroyed. There will be a significant amount of structural damage to commercial buildings and almost all windows will be blown out. Nearly all trees will be either snapped or uprooted. Power and water could be out for months.
The Saffir-Simpson Hurricane Wind Scale. National Hurricane Center – National Weather Service
Williams, Jack (May 17, 2005). http://www.usatoday.com/weather/hurricane/whscale.htm.