Hurricane Life Cycle: From Formation to Dissipation

Satellite image of a tropical storm - hurricane or cyclone or typhoon. Elements of this image furnished by NASA.

Weather patterns worldwide captivate us. Weather changes are captivating, from a serene day to a sudden downpour from shifting atmospheric pressure.

Hurricanes captivate weather experts and climate enthusiasts. Their immense destructive power surpasses most natural events. This post delves into how hurricanes form, evolve, and ultimately dissipate.

Stage 1. Disturbance Formation

The birth of a hurricane begins with a simple, innocuous event known as a “disturbance.” This disturbance is typically a large mass of organized thunderstorms that persist for several days. Thunderstorms form when warm, moist air meets over the ocean, creating a good environment for storms. As the warm water evaporates, it rises until massive amounts of heated, moist air are hanging over the ocean’s surface. This process initiates the first stage in the development of a hurricane.

the atmospheric conditions necessary for disturbance formation

For these disturbances to form, certain atmospheric conditions must be present. First, the sea surface temperature should be at least 26.5 degrees Celsius (79.7 degrees Fahrenheit). This warm temperature is essential for providing the heat and moisture needed to fuel the storm.

The atmosphere needs to cool down fast as it gets higher so it can support the heat energy that makes a tropical cyclone. Third, the wind must be blowing in the same direction and at the same speed to force air upward from the ocean surface.

These winds also need to be minimal in order for the storm to start rotating. If these conditions persist long enough, they can lead to the formation of a tropical disturbance.

Stage 2. Tropical Disturbance

A tropical disturbance is a group of clouds, showers, and thunderstorms that starts in the tropics and lasts for at least 24 hours. It is the first stage on the road to a hurricane. These are essentially large weather systems, but not yet organized around a low-pressure center. A tropical disturbance is identified by a clear band of thunderstorms.

Tropical disturbances generally cover a large area and may have winds circulating around a center. However, unlike a fully formed hurricane, the wind speeds are usually not very high.

The movement of these systems is primarily governed by the larger weather systems around them. When a disturbance moves over warm waters and the atmospheric conditions are just right, it can get bigger and stronger. This sets the stage for the next phase – the tropical depression.

Stage 3. Tropical Depression

When a tropical disturbance gathers heat and energy from warm ocean waters and its core’s atmospheric pressure drops, it can become a tropical depression.

This intensification is marked by a more organized pattern of circulation and higher wind speeds. A tropical depression is declared when the wind speed is 20 to 34 knots. The system starts to look like a hurricane with a spiral shape.

the signs and symptoms of a tropical depression

A tropical depression exhibits certain signs that meteorologists can identify. These include an increase in thunderstorm activity, a noticeable circulation of wind around the storm’s center, and sustained winds of 38 mph (61 km/h) or less.

Despite the increase in organization and wind speed, a tropical depression does not yet have the full-fledged rotation and structure of a hurricane. However, it is often at this stage that weather forecasters issue alerts about potential hurricane development.

Stage 4. Tropical Storm

Super Typhoon, tropical storm, cyclone, hurricane, tornado, over ocean. Weather background. Typhoon,  storm, windstorm, superstorm, gale moves to the ground.  Elements of this image furnished by NASA.

If a tropical depression continues to intensify, it upgrades to a tropical storm. This upgrade occurs when sustained winds within the storm reach speeds between 39 mph (63 km/h) and 73 mph (118 km/h).

At this point, the storm is given a name to aid in tracking and public communication. The storm becomes more organized and begins to rotate faster, increasing the wind speed in the process.

the increased intensity and potential dangers of a tropical storm

The primary threats posed by a tropical storm are high winds, heavy rain, and rough seas. These storms can cause significant damage to buildings and infrastructure, uproot trees, and result in substantial flooding.

Another dangerous aspect of a tropical storm is the potential for it to rapidly intensify into a hurricane. As such, warnings are often issued in areas where these systems are likely to make landfall.

Stage 5. Hurricane

The final step in the evolution of this weather phenomenon is the development of a hurricane. For a tropical storm to escalate into a hurricane, its sustained wind speeds must reach at least 74 mph (119 km/h). The storm’s core becomes increasingly tight and organized, and around this core forms the ‘eye’ of the storm.

This clear, calm center is surrounded by the eye wall, the most destructive part of the hurricane with the highest wind speeds and most severe storms.

Hurricanes are characterized by their strong, rotating winds that can cause severe damage. They also bring about heavy rains which can lead to flooding, and storm surges that can cause catastrophic damage along coastlines. The size of a hurricane can vary, but they are typically about 300 miles wide.

Hurricanes can last for over a week and travel across the ocean before making landfall. Once a hurricane makes landfall, it tends to lose strength rapidly due to the loss of the warm water fuel and increased surface friction over land.

Stage 6: Dissipation

Palm trees on the seashore in windy weather. Tropical breeze.

After making landfall, a hurricane quickly starts to lose its energy source from the warm ocean waters and begins to dissipate. As it moves inland, friction with the land and a lack of moisture and heat cause the winds of the hurricane to slow down.

Eventually, the storm breaks apart, and the cloud systems will dissipate. However, even as the hurricane dissipates, it can still bring significant rainfall and cause flood damage inland.

Hurricanes can also dissipate when they move into cooler waters, which do not provide the heat energy necessary to fuel the storm. Another factor that can lead to the dissipation of a hurricane is if the hurricane encounters wind shear or a change in wind speed and direction with height.

Wind shear can tear the storm apart. It’s important to note that even in the dissipation stage, hurricanes can still pose a significant threat due to associated heavy rains, flooding, and tornadoes.

What are the 5 stages of hurricanes?

A hurricane goes through five stages: Tropical Disturbance, Tropical Depression, Tropical Storm, Hurricane, and Dissipation. Each stage represents an increase in organization and intensity, starting from a loosely organized system of thunderstorms over warm ocean waters to a powerful storm with winds exceeding 74 mph.

How long do hurricanes usually last?

Hurricanes can last for over a week, moving slowly across the ocean. The duration of a hurricane can depend on many factors, including its formation location, the prevailing atmospheric conditions, and whether it encounters land or cooler water.

What are the 3 stages before a hurricane?

The three stages before a hurricane are the Tropical Disturbance, Tropical Depression, and Tropical Storm stages. These represent the initial organization and strengthening of the storm system before it reaches hurricane intensity.

How long do hurricanes develop?

The development of a hurricane from a tropical disturbance can take anywhere from a few days to over a week. This depends on the atmospheric conditions, including wind patterns and moisture, as well as the temperature of the ocean surface.

By Anita Brown

Anita Brown is our go-to contributor to our emergency preparedness website. Anita brings a wealth of personal experience and professional expertise to the table, having weathered several awful natural disasters. Anita is currently working towards obtaining her Community Emergency Response Team (CERT) certification.