What are the hazards of a hurricane?

Posted on Apr 14, 2022 in Hurricane- FAQ

The primary hazards from a hurricane are wind; storm surge/tides and currents; and flooding from heavy rain. All of these hazards can put people and property at risk.

Wind

Tropical storm-force winds are strong enough to be dangerous to those caught in them.

Hurricane‐force winds, 74 mph or more, can destroy buildings and mobile homes. Debris, such as signs, roofing material, siding and small items left outside become flying missiles during hurricanes. Winds can stay above hurricane strength well inland.

The Saffir-Simpson Hurricane Wind Scale is a 1 to 5 rating based on a hurricane’s sustained wind speed. This scale estimates potential property damage. Hurricanes reaching Category 3 and higher are considered major hurricanes because of their potential for significant loss of life and damage. Category 1 and 2 storms are still dangerous, however, and require preventive measures.

Source: National Hurricane Center

The image displays the Saffir-Simpson Hurricane Wind Scale, from Category 1, the lowest level, to Category 5, the highest level. A Category 1 hurricane has winds of 74 to 95 miles per hour and has very dangerous winds that will produce some damage. A Category 2 hurricane has winds of 96 to 110 miles per hour and extremely dangerous winds that will cause extensive damage. A Category 3 hurricane has winds of 111 to 129 miles an hour that will cause devastating damage. A Category 4 hurricane has winds of 130 to 156 miles an hour. A Category 5 hurricane has winds of 157 miles an hour or more. Both Category 4 and 5 hurricanes will produce catastrophic damage.

The Saffir-Simpson Hurricane Wind Scale determines a hurricane’s potential to cause property damage based on sustained wind speed | Image: NOAA

 

 

 

 

 

 

 

 

Storm Surge and Storm Tide

Storm surge and large waves produced by hurricanes pose the greatest threat to life and property along the coast.

Storm Surge is an abnormal rise of water generated by a storm’s winds. Storm surge can reach heights well over 20 feet and can span hundreds of miles of coastline.

Storm Tide is the water level rise during a storm due to the combination of storm surge and the astronomical tide.

The destructive power of storm surge and large battering waves can result in loss of life, buildings destroyed, beach and dune erosion and road and bridge damage along the coast. Storm surge can travel several miles inland. In estuaries and bayous, salt water intrusion endangers public health and the environment.

Source: National Hurricane Center

The image illustrates how a storm surge and high tide can combine to produce coastal damage. A 2 foot high tide combined with a 15 foot storm surge produces a storm tide of 17 vertical feet above the usual mean sea level.

This image shows both Storm Surge and Storm Tides | Photo: NOAA

 

 

 

 

 

 

Rip Currents

The strong winds of a tropical cyclone can cause dangerous waves that pose a significant hazard to mariners and coastal residents and visitors. When the waves break along the coast, they can produce deadly rip currents – even at large distances from the storm.

Rip currents are channeled currents of water flowing away from shore, usually extending past the line of breaking waves, that can pull even the strongest swimmers away from shore.

Source: National Hurricane Center

Heavy Rainfall and Inland Flooding 

Tropical cyclones often produce widespread, torrential rains in excess of 6 inches, which may result in deadly and destructive floods. In fact, flooding is the major threat from tropical cyclones for people living inland. Flash flooding, defined as a rapid rise in water levels, can occur quickly due to intense rainfall. Longer term flooding on rivers and streams can persist for several days after the storm. When approaching water on a roadway, always remember Turn Around Don’t Drown.

Rainfall amounts are not directly related to the strength of tropical cyclones but rather to the speed and size of the storm, as well as the geography of the area. Slower moving and larger storms produce more rainfall. In addition, mountainous terrain enhances rainfall from a tropical cyclone.

Source: National Hurricane Center

The image shows an aerial view of damage caused on Maui by Hurricane Lane in 2018, including an area where flood water caused by heavy rain running down hill destroyed a large section of pavement.

Flood damage on Maui from Hurricane Lane, circa August 2018 | Photo courtesy of the Hawai’i Emergency Management Agency