Tropical Cyclones Causes, Categories, Impacts, Safety Tips, and Preparedness Guide
Tropical Cyclones
Each year, starting around June 1, the Gulf and East Coast states are at extraordinary risk for tropical cyclones. While most people know that tropical cyclones can contain damaging winds, many do not realize that they also produce several other hazards, both directly and indirectly. The following information can help minimize the impact of tropical cyclones on you and your loved ones.
Storm Surge
The wind can form large waves on top of the surge. This continuing surge combines with normal tides to create the tropical cyclone storm tide, which can increase the normal water level by 15 feet (4.5 m) or more.
This rise in water level can cause serious flooding in coastal areas, especially when the storm tide coincides with normal high tides.
The destructive power of storm surge and large waves can result in:
- Loss of life
- Destroyed buildings
- Beach and dune erosion
- Road and bridge damage
- Flooding several miles inland
In estuaries and bayous, salt water intrusion threatens public health and the environment.
Much of the densely populated Atlantic and Gulf Coast shorelines lies less than 10 feet above mean sea level, making the threat from storm tides extremely serious.
Factors That Affect Storm Surge
The level of surge in a specific area is influenced by the slope of the continental shelf.
- A shallow slope allows a greater surge to flood coastal communities.
- A steeper continental shelf results in less flooding, although large breaking waves can still cause major damage.
Storm tides, waves, and currents in narrow harbors can severely damage ships, marinas, and pleasure boats.
Wind and Squalls
Hurricanes are known for their damaging winds, which are used to rate their strength. However, the category refers only to sustained wind and does not include gusts or squalls.
Wind Gusts
Gusts are short but rapid bursts of wind caused by turbulence over land.
Squalls
Squalls are longer periods of increased wind speeds associated with thunderstorm bands surrounding the cyclone.
How Wind Damages Buildings
Tropical cyclone winds damage structures in two ways.
Roof Uplift
High winds moving over a roof create lower pressure above it. Higher pressure inside the attic helps lift the roof. Once the roof is removed, walls are more likely to collapse.
Flying Debris
The wind picks up debris such as:
- Wood
- Metal siding
- Toys
- Trash cans
- Tree branches
These objects can be thrown at high speed into nearby buildings and cause significant damage.
Because of this danger, emergency managers aim to complete evacuations before tropical storm-force winds begin.
Inland Flooding
In addition to storm surge and high winds, tropical cyclones produce heavy rainfall and flooding. Even after the winds weaken, flooding can continue for several days.
From 2013 to 2022, 442 deaths were directly related to tropical systems. Of these, 251 (56.8%) were caused by inland flooding.
Most of these fatalities occur because people underestimate the power of moving water and intentionally walk or drive into flooded areas.
Turn Around, Don't Drown.
Flooding depends not only on storm strength but also on the storm's movement and track. A weaker but slow-moving storm can cause more flooding than a stronger fast-moving storm.
Examples
- Tropical Storm Allison (2001): Produced record rainfall and severe flooding in Southeast Texas.
- Hurricane Harvey (2017): Caused catastrophic flooding and became the wettest Atlantic hurricane on record in the United States.
Types of Inland Flooding
Flash Flooding
Flash floods develop rapidly, often within minutes or hours of intense rainfall. Water can rise to 30 feet (10 m) or more and destroy buildings and bridges.
Urban and Area Floods
Roads can become fast-moving rivers, and basements can quickly fill with water. Paved surfaces prevent water from soaking into the ground, increasing flood risk.
River Flooding
River floods develop more slowly as runoff reaches rivers and streams. They can begin within hours and last a week or longer.
Tornadoes
Tropical cyclones can produce tornadoes that add to the storm's destructive power.
Tornadoes are most likely to occur:
- In the right-front quadrant of the storm
- Within rainbands far from the center
Tornadoes can cause uneven damage, destroying some buildings while leaving nearby structures relatively untouched.
Important Facts About Tornadoes
- Some tropical cyclones produce no tornadoes, while others produce many.
- Hurricane Beulah (1967) produced 141 tornadoes.
- Hurricane-related tornadoes are usually weaker than Great Plains tornadoes.
- They are not usually accompanied by hail or frequent lightning.
- They can continue for days after landfall.
- They can occur during both day and night.
Rip Currents
Strong winds from tropical cyclones create dangerous waves. When these waves break along the coast, they can generate rip currents even far from the storm.
Rip currents are narrow channels of water flowing away from shore and can pull even strong swimmers out to sea.
Examples
- In 2008, Hurricane Bertha caused rip currents that killed three people and led to 1,500 lifeguard rescues in Ocean City, Maryland.
- In 2009, six people died in the United States due to large waves and rip currents caused by tropical cyclones.
Tropical Cyclone Safety
The widespread effects of tropical cyclones, including winds, storm surge, strong currents, tornadoes, and inland flooding, place millions of people at risk.
NOAA and the National Weather Service provide many resources to help people stay safe before, during, and after a storm.
These resources include information on:
- Understanding watches and warnings
- Preparing your home
- Protecting yourself and your loved ones
- Staying safe after the storm has passed
Additional materials are available in both English and Spanish to share through social media and other channels.
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According to research on Cyclones Causes, Categories, Impacts, Safety Tips, and Preparedness Guide
