From the eye to storm surge: The anatomy of a hurricane

No two tropical storms or hurricanes are exactly alike, but every system has the same basic structure that meteorologists analyze when creating life-saving forecasts for tropical systems.

Some meteorological terminology is well-known, such as the eye of a hurricane, but tropical cyclones have many moving parts that bring different dangers when they make landfall. A tropical cyclone is a broad term that encompasses tropical storms, hurricanes, typhoons and any form of tropical system around the world.

Tropical depressions, tropical storms and hurricanes are types of low pressure systems, and the air pressure in the center of a storm is an indicator of how powerful it is beyond the maximum wind speeds.

The lower the central pressure falls, the stronger the hurricane will become. Hurricane Katrina is one of the most infamous hurricanes since the turn of the millennia, and the central pressure bottomed out at 26.64 inches of mercury (902 millibars). Typhoon Tip holds the global record for the lowest pressure of a tropical system, dipping down to 25.69 inches of mercury (870 millibars) when it tracked across the western Pacific Ocean in October of 1979.

The center of a tropical system can develop a feature known as an eye. While every storm has a well-defined center, the eye may not be apparent when looking at tropical storms or weaker hurricanes on weather satellites. The eye is most prevalent in intense, long-lived hurricanes.

Winds are calm in the eye compared to other regions of the hurricane. There are also few clouds in the eye.

The eye of Hurricane Epsilon on Wednesday, Oct. 21, 2020, as seen by the Air Force Hurricane Hunters. (Hurricane Hunters)

Storm chasers and hurricane hunters that have been in the eye of powerful hurricanes have witnessed a phenomenon known as the stadium effect, as the structure of the eye resembles a large arena with grandstands towering in every direction.

The eye can vary in size and typically ranges from 20 to 40 miles across, according to NOAA, but this is not a steadfast rule. When Hurricane Wilma was near peak intensity during the 2005 Atlantic hurricane season, its eye was not even 3 miles across. Small eyes like this are often referred to as pinhole eyes by meteorologists. Typhoon Carmen, which swirled in the western Pacific Ocean in 1960, had one of the largest eyes on record, stretching more than 200 miles across.

Just outside of the eye is the eyewall, the most intense part of a hurricane where the highest winds are found.

Contrary to what is often portrayed in TV shows and movies, hurricanes do not produce much lightning, but particularly powerful hurricanes can have lightning in the eyewall. When frequent lightning is detected in this region, it is a telltale sign that the storm is rapidly intensifying.

Hurricane Ian was a prolific lightning producer as it strengthened into a Category 5 hurricane on its approach to Florida. Storm chasers along the coast of Florida even witnessed cloud-to-ground lightning, a rare occurrence for hurricanes.

Rain from a hurricane can span hundreds of miles away from the eye in the form of spiral bands. These areas of rain are also known as outer bands and rotate around the center of the storm.

Spiral bands can reach land days before large hurricanes make landfall and are a common area where tornadoes can quickly spin up. Isaias in 2020 is a recent hurricane that will be remembered more for its far-reaching rain than anything else as it tracked up the East Coast. "Widespread rainfall amounts of 4 to 8 inches, with the heaviest totals over Philadelphia's northwestern suburbs, led to record river flooding," AccuWeather Senior Meteorologist Bill Deger said.

Tropical storms and hurricanes can be broken up into four regions relative to the direction the storm is tracking.

The left front quadrant is the area of the hurricane to the left of the storm's track and in the direction in which the storm is headed. The wind flow is northeast to southwest and is where winds blow offshore after a hurricane makes landfall. There is also a lower risk of tornadoes and storm surge in this portion of a tropical system.

The strongest part of a hurricane is typically the right front quadrant, where winds blow in the same direction that the hurricane is moving, resulting in stronger winds and increased storm surge.

When a hurricane makes landfall, areas hit by the right front quadrant typically sustain the worst of the damage.

The bridge leading from Fort Myers to Pine Island, Fla., is heavily damaged in the aftermath of Hurricane Ian, Saturday, Oct. 1, 2022. Due to the damage, the island could only be reached by boat or air. (AP Photo/Gerald Herbert)

When Hurricane Ian made landfall along Florida's Gulf Coast on Sept. 28, 2022, Fort Myers, Florida, and surrounding areas were blasted by the right front quadrant and sustained catastrophic damage. Meanwhile, Sarasota and Tampa, Florida, were hit by the left front quadrant and did not sustain nearly as much damage or storm surge as the Fort Myers area.

On top of the most ferocious winds and storm surge, twisters can also be spawned within this region of a hurricane.

The winds in the right rear quadrant blow from southwest to northeast, which can exacerbate storm surge and flooding issues, especially in areas that have been hit hard by the right front quadrant.

Tornadoes can also develop in this region, adding to the destructive nature of the hurricane.

Generally, the left rear quadrant is the weakest part of a hurricane, but there can still be dangerous weather conditions.

Towns and neighborhoods hit by the left rear quadrant still face the risk of flooding rain and strong winds from the tropical storm or hurricane.

Rudy Horvath hands a piece of wood up to his wife Dawn Horvath, as their home, a boathouse in the West End section of New Orleans, takes on water a from storm surge in Lake Pontchartrain, in advance of Tropical Storm Cristobal, Sunday, June 7, 2020. (AP Photo/Gerald Herbert)

One of the deadliest aspects of any tropical system is not the powerful winds they produce but rather the storm surge generated leading up to landfall.

"The greatest storm surge will often be found at where the leading edge of the storm, and right front quadrant of the storm, move onshore," AccuWeather Hurricane Expert Dan Kottlowski said.

Storm surge is not limited to tropical systems and has been observed during powerful coastal storms, such as nor'easters.

Heavy tropical rain can also cause significant flooding far away from the coast as tropical systems track inland. Hurricane Agnes is infamous for its flooding rain when it unloaded over a foot of rain over eastern Pennsylvania in June of 1972 which triggered catastrophic flooding.

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