Many family travelers leave their hurricane-free home towns and travel to tropical areas during the long hurricane season from June to November. Good idea, then, to know a few basics. Such as:
What exactly does a hurricane "Category" mean?
The classification system -- called the "Saffir-Simpson Hurricane Scale" -- is based on wind intensity. A civil engineer named Herbert Saffir, (working for the UN in 1969, studying low-cost housing in areas vulnerable to hurricanes), wanted to classify a storm's strength and potential for destruction. He devised five hurricane categories based on wind speed.
Saffir passed on his system to the National Hurricane Center, where meteorolgist Bob Simpson added further factors such as storm surge and flooding. However, by May 2010, the hurricane category system changed back to a scale for wind intensity only.
Hurricane Categories 1 Through 5
To be called a hurricane, a storm must have "sustained" winds of at least 74 miles per hour (119 kilometers/hour.)
Category 1: Wind Speed of 74 to 95 mph (119-153 km/hour)
Category 2: Wind Speed of 96 to 110 mph (154-177 km/hour)
Category 3: Wind Speed of 111 to 130 mph (178-209 km/hour)
Category 4: Wind Speed of 131 to 155 mph (178-249 km/hour)
Category 5: Wind Speed over 156 mph (250 km/hour)
A Category 1 hurricane usually causes no serious structural damage to buildings. Category 2 hurricanes can lift a house; mobile homes and prefab homes fare worst.
Hurricanes that are Category 3 and higher are major. With Category 3, expect damage to residences and many other buildings, destruction of mobile homes, flooding near the coast.
Category 4 brings more damage still; and with a Category 5 hurricane, few types of structures survive even several miles inland, and flooding brings major destruction.
Radius of Impact
Even if a hurricane doesn't make landfall, its effects can be drastic. For starters: hurricane-force winds can extend many miles from the center of the storm. So even if a hurricane stays offshore, hurricane-force winds might extend outward 90 miles from the center, and tropical-storm-force winds might have a reach of 200 miles. (And then there's also "squalls", or heavy thunderstorms, which can extend out for several hundred miles....)
The giant reach of a hurricane affects timing: if a hurricane is heading to an area at a speed, say, of 20 miles per hour, and tropical-storm-force winds extend for 200 miles, the area may be impacted 10 hours before the center of the hurricane arrives.
Another point: "landfall" only officially occurs when the center of the eye
of the storm contacts land; but the strongest winds are in the "eye-wall" around
the edge of the eye, which might hit land even if the center of the
eye does not. (See more about
area of hurricane impact.)
Read more about Hurricane Category details at the National Hurricane Center site..
Of course, the damage wreaked by a hurricane depends on the terrain and conditions of human settlement where it lands.
Is There a Better Way to Classify Hurricanes?
Some scientists consider the present hurricane category system too simple -- there's no measure of rainfall, for instance-- and several replacement systems have been suggested as better ways to classify intensity, and to predict and warn about destruction. But for now, "Hurricane Category 1 through 5" is the way we talk about hurricanes.
