Understanding the Strength of a Hurricane

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Hurricane Dorian is slowly approaching the Florida peninsula and is expected to make landfall as a category three storm or higher.  But what does that mean?  Hurricanes are categorized by the Saffir-Simpson Hurricane Wind Scale, which rates the potential damage that may occur on a scale from one to five.  Storms rated as a three or higher are considered major hurricanes because of the potential for significant property damage and loss of life.

Below is the Saffir-Simpson scale with category descriptions as provided by the National Hurricane Center (NHC)[1]:

Category

1: Minimal Damage

Type of Damage

Very dangerous winds will produce some damage: Well-constructed frame homes could have damage to roof, shingles, vinyl siding, and gutters.  Large branches of trees will snap and shallowly rooted trees may be toppled.  Extensive damage to power lines and poles likely will result in power outages that could last a few to several days.

2: Moderate Damage

Extremely dangerous winds will cause extensive damage: Well-constructed frame homes could sustain major roof and siding damage.  Many shallowly rooted trees will be snapped or uprooted and block numerous roads.  Near-total power loss is expected with outages that could last from several days to weeks.

3: Extensive Damage

Devastating damage will occur: Well-built framed homes may incur major damage or removal of roof decking and gable ends. Many trees will be snapped or uprooted, blocking numerous roads.  Electricity and water will be unavailable for several days to weeks after the storm passes.

4. Extreme Damage

Catastrophic damage will occur: Well-built framed homes can sustain severe damage with loss of most of the roof structure and/or some exterior walls.  Most trees will be snapped or uprooted and power poles downed.  Fallen trees and power poles will isolate residential areas.  Power outages will last weeks to possibly months.  Most of the area will be uninhabitable for weeks or months.

5. Catastrophic Damage

Catastrophic damage will occur: A high percentage of framed homes will be destroyed, with total roof failure and wall collapse.  Fallen trees and power poles will isolate residential areas.  Power outages will last for weeks to possibly months.  Most of the area will be uninhabitable for weeks or months.

One factor not included in the Saffir-Simpson scale but often the greatest threat to people living along the coast is the effect of storm surge, which occurs when sea water is forced ashore by storm winds. According to the NHC, tropical storms and hurricanes can produce surges of 20 feet or more[2].  For example, in 2005, Hurricane Katrina produced a storm surge of 25 to 28 feet in New Orleans and along the Mississippi coast.

A hurricane of any category, and the additional risks posed by storm surge, flooding, and debris, can cause serious and significant damage to you and your property.  It is critical you remain updated with the latest weather alerts for your area and follow evacuation orders, especially when you are located along the coast or in a flood zone.