Hurricanes

 

Hurricanes are products of the tropical ocean and atmosphere. Powered by heat from the sea, they are steered erratically by the easterly trade winds and the temperate westerly winds, as well as by their own energy. As they move ashore, they bring with them a storm surge of ocean water along the coastline, high winds, tornadoes, torrential rains, and flooding.

 

Each year on average, ten tropical storms develop over the Atlantic Ocean, Caribbean Sea, or Gulf of Mexico. About six of these typically strengthen enough to become hurricanes. Many of these remain over the ocean with little or no impact on the continental United States. However, about five hurricanes strike the United States coastline every three years. Of these five, two will be major hurricanes measuring a category 3 or higher (defined as having winds above 111 miles per hour) on the Saffir-Simpson Scale.  These storms can end up costing our nation millions, if not billions, of dollars in damages.

 

During a hurricane, homes, businesses, public buildings, and infrastructure may be damaged or destroyed by many different storm hazards. Debris can break windows and doors, allowing high winds and rain inside the home. In extreme storms (such as Hurricanes Hugo, Andrew and Katrina), the force of the wind alone can cause tremendous devastation, as trees and power lines topple and weak elements of homes and buildings fail. Roads and bridges can be washed away and homes saturated by flooding.  Destructive tornadoes can also be present well away from the storms center during landfall. Yet, storm surge alone poses the highest threat to life and destruction in many coastal areas throughout the United States and territories. And these threats are not limited to the coastline -- they can extend hundreds of miles inland, under the right conditions.

 

Learn more about hurrican preparedness here.

During a hurricane:

  • Listen to the radio or TV for information.
  • Have an Emergency Supply Kit and Household Disaster Plan in place.
  • Secure your home, close storm shutters, and secure outdoor objects or bring them indoors.
  • Turn off utilities if instructed to do so. Otherwise, turn the refrigerator thermostat to its coldest setting and keep its doors closed.
  • Turn off propane tanks.· Avoid using the phone, except for serious emergencies.
  • Moor your boat if time permits.
  • Ensure a supply of water for sanitary purposes such as cleaning and flushing toilets. Fill the bathtub and other large containers with water.

You should evacuate under the following conditions:

  • If you are directed by local authorities to do so. Be sure to follow their instructions.
  • If you live in a mobile home or temporary structure—such shelters are particularly hazardous during hurricanes no matter how well fastened to the ground.
  • If you live in a high-rise building—hurricane winds are stronger at higher elevations.
  • If you live on the coast, on a floodplain, near a river, or on an inland waterway.
  • If you feel you are in danger.

If you are unable to evacuate, go to your safe room. If you do not have one, follow these guidelines:

  • Stay indoors during the hurricane and away from windows and glass doors.
  • Close all interior doors—secure and brace external doors.
  • Keep curtains and blinds closed. Do not be fooled if there is a lull; it could be the eye of the storm - winds will pick up again
  • Take refuge in a small interior room, closet, or hallway on the lowest level.
  • Lie on the floor under a table or another sturdy object.

Terms

Familiarize yourself with these terms to help identify a hurricane hazard:

 

Tropical Depression
An organized system of clouds and thunderstorms with a defined surface circulation and maximum sustained winds of 38 MPH (33 knots) or less. Sustained winds are defined as one-minute average wind measured at about 33 ft (10 meters) above the surface.

 

Tropical Storm
An organized system of strong thunderstorms with a defined surface circulation and maximum sustained winds of 39–73 MPH (34–63 knots).

 

Hurricane
An intense tropical weather system of strong thunderstorms with a well-defined surface circulation and maximum sustained winds of 74 MPH (64 knots) or higher.

 

Storm Surge
A dome of water pushed onshore by hurricane and tropical storm winds. Storm surges can reach 25 feet high and be 50–1000 miles wide.

 

Storm Tide
A combination of storm surge and the normal tide (i.e., a 15-foot storm surge combined with a 2-foot normal high tide over the mean sea level created a 17-foot storm tide).

 

Hurricane/Tropical Storm Watch
Hurricane/tropical storm conditions are possible in the specified area, usually within 36 hours. Tune in to NOAA Weather Radio, commercial radio, or television for information.

 

Hurricane/Tropical Storm Warning
Hurricane/tropical storm conditions are expected in the specified area, usually within 24 hours.

 

Short Term Watches and Warnings
These warnings provide detailed information about specific hurricane threats, such as flash floods and tornadoes.

Saffir-Simpson Hurricane Scale

 Scale Number

(Category)

 Sustained Winds

(MPH)

 Damage  Storm Surge
 1  74-95  Minimal: Unanchored mobile homes, vegetation, and signs.  4-5 feet
 2  96-110  Moderate: All mobile homes, roofs, small crafts, flooding.  6-8 feet
 3  111-130  Extensive: Small buildings, low lying roofs cut off.  9-12 feet
 4  131-155  Extreme: Roofs destroyed, trees down, roads cut off, mobile homes destroyed. Beach homes flooded.  13-18 feet
 5  More than 155  Catastrophic: Most buildings destroyed. Vegetation destroyed. Major roads cut off. Homes flooded.   Greater than 18 feet