Hurricanes

More About Hurricanes

The portrait of a typical North Carolina beach day is a beautiful one, with miles of shoreline, calm ocean waves and blue skies that are as clear as a bell. The majority of summer visitors don't typically see the coastal landscape during a hurricane, a far cry from the picturesque postcard scenes that most folks encounter and enjoy.

Because of its geographic location in the middle of the East Coast, with some barrier islands stretching 30 miles into the ocean, hurricanes can be a threat to the delicate North Carolina shoreline. Hurricane season runs from June 1 through November 30 each year, and particularly in the unpredictable late summer and early fall, locals' eyes are tuned to the weather, watching for an approaching storm to develop.

North Carolina is just one of the coastal states that has to keep an eye out for storms, as all of the East Coast states can potentially be in a hurricane's path, especially southern states like Florida and Georgia. The states bordering the Gulf of Mexico, where warm waters can strengthen tropical systems, also have their fair share of preparation and monitoring during each hurricane season. And, though it's rare, even a Pacific Coast state can catch a storm that forms off Mexico and Baja, California.

As evident in recent years, when notorious storms such as Katrina and Rita graced headlines across the world, a hurricane can be truly devastating, causing massive damage and flooding. North Carolina has had its own tattered history and encounters with major storms, but with every hurricane that passes through, residents and visitors learn how to prepare, how to cope with the aftermath and how to weather the storm.

Roots of a Storm

According to the National Hurricane Center, the word hurricane comes from the name Hurican, the Caribbean god of evil, though there are no hidden, mythical reasons for what a hurricane is or why it forms - it is simply science.

A hurricane has many regionally specific monikers, such as the Asian term typhoon, and these are all offshoots of the generic term, tropical cyclone. A tropical cyclone is basically a non-frontal synoptic scale low-pressure system over tropical or sub-tropical waters with organized thunderstorms and definite cyclonic surface wind circulation. Hurricanes or typhoons are tropical cyclones that have surface winds over 74 mph.

Tropical cyclones with maximum sustained surface winds of less than 39 mph are called tropical depressions. The tropical depression is typically very unorganized, and has not yet begun forming the cyclonic movement that categorizes a hurricane. Once the tropical cyclone reaches winds of at least 39 mph, it becomes a tropical storm. You can typically see the spinning cyclone movement of the storms in a tropical storm, although the eye, which is a calm center that is prominent in hurricanes, may not be formed or barely visible. The next step a tropical cyclone reaches is the hurricane, or typhoon.

Hurricanes form in tropical regions where there is warm water, at least 80 degrees Fahrenheit, moist air and converging equatorial winds. Most Atlantic hurricanes begin off the west coast of Africa near Cape Verde, starting as thunderstorms that move out over the warm, tropical ocean waters. It can take just a few hours or several days for a thunderstorm to develop into a hurricane, and although scientists are still uncovering the mysteries of what specific conditions lead to a hurricane, three weather conditions or events must occur for a hurricane formation to be possible:

1. A continuing evaporation-condensation cycle of warm, humid ocean air.
2. Specific wind patterns characterized by converging winds at the surface and strong, uniform-speed winds at higher altitudes.
3. A difference in air pressure between the surface winds and high altitude winds.

When the conditions are ripe for a hurricane, warm, moist air from the ocean surface begins to rise rapidly. As this warm air rises, its water vapor condenses to form storm clouds and droplets of rain. The condensation releases heat, called latent heat of condensation. This latent heat warms the cool air above, causing it to rise. This rising air is replaced by more warm, humid air from the ocean below. This cycle continues, with warm air continually being drawn into the storm and fed upwards, and the process creates a cyclone of moving air.

Converging winds at the surface, or winds moving in different directions, collide and push additional warm, moist air upward. This is added to the current cycle of warm air rising, and increases both the circulation and the wind speeds. During this process, strong winds blowing at uniform speeds at higher altitudes (up to 30,000 ft / 9,000 m) help to remove the rising hot air from the storm's center, maintaining a continual movement of warm air from the surface and keeping the storm organized. If the high-altitude winds do not blow at the same speed at all levels, then the storm loses organization and weakens.

High-pressure air in the upper atmosphere (above 30,000 ft / 9,000 m) over the storm's center also removes heat from the rising air, further driving the air cycle and the hurricane's growth. As high-pressure air is sucked into the low-pressure center of the storm, wind speeds increase.

Once a hurricane has formed, it is characterized by three distinctive parts: the eye, the calm, low pressure center of the circulation storm; the rain bands of thunderstorms circulating outward from the eye that are part of the evaporation/condensation process; and the eye wall that borders the eye and has the fastest, most damaging winds.

Categories of a Hurricane

Anyone who has heard reports of a hurricane has heard of the different labels that scientists use to distinguish one strength of hurricane from another. This method of categorization is called the Saffir-Simpson Hurricane Scale, and it consists of a 1-5 rating, or 1-5 categories, based on the hurricane's intensity. The Saffir-Simpson Scale is based on the wind speed, and it is used to give an estimate of potential property damages and flooding that the coastal areas in the hurricane's path can expect. As a storm strengthens or weakens, it is not unusual for a single storm to be different categories throughout its lifespan.

A Category 1 hurricane has wind speeds of 74-95 mph, and storm surge generally 4-5 feet above normal in coastal areas. There is no significant damage to building structures, except for unrestrained mobile homes. There can also be some damage to shrubbery, trees and poorly constructed or mounted signs. Some coastal road flooding and minor pier damage can also be expected.

A Category 2 hurricane has winds or 96-110 mph and generally a storm surge that is 6-8 feet above normal. Some roofing material, door and window damage of buildings can be expected. There can also be considerable damage to shrubbery and trees, with some trees blown down, as well as considerable damage to mobile homes, poorly constructed signs and piers. Coastal and low-lying roads can flood 2-4 hours before arrival of the hurricane center, and small crafts in unprotected anchorages can wreak moorings.

A Category 3 hurricane has Winds of 111-130 mph and a storm surge generally 9-12 feet above normal. Some structural damage to small residences and utility buildings can be expected. There can also be damage to shrubbery and trees with foliage blown off trees and some large trees blown down. Mobile homes and poorly constructed signs can be completely destroyed. Coastal and low-lying roads are cut by rising water 3-5 hours before arrival of the center of the hurricane. Flooding near the coast can destroy smaller structures, and larger structures can be damaged from floating debris. Mainland terrain that is continuously lower than 5 feet above mean sea level may be flooded up to 8 miles inland or more. Evacuation of low-lying residences within several blocks of the shoreline may be required.

A Category 4 hurricane has winds of 131-155 mph and generally a storm surge that is 13-18 feet above normal. Expect extensive roof structure failures on small residences. Shrubs, trees and all signs are typically blown down, and mobile homes are completely destroyed. There can also be extensive damage to doors and windows, and coastal low-lying roads may be cut by rising water 3-5 hours before arrival of the center of the hurricane. Homes near the shore can expect major damage to lower floors of structures. Terrain lower than 10 feet above sea level may be flooded requiring massive evacuation of residential areas as far inland as 6 miles.

A Category 5 hurricane has winds greater than 155 mph with a storm surge generally greater than 18 feet above normal. With a Category 5 hurricane, expect complete roof failure on many residences and industrial buildings. Some complete buildings can be destroyed or severely damaged with small utility buildings blown over or away. All shrubs, trees and signs can blow down, with complete destruction of mobile homes, and severe and extensive window and door damage on coastal buildings. Low-lying coastal roads are cut by rising water 3-5 hours before arrival of the center of the hurricane. There can be major damage to lower floors of all structures located less than 15 feet above sea level and within 500 yards of the shoreline. Massive evacuation of residential areas on low ground within 5-10 miles of the shoreline may be required. Only three Category 5 hurricanes have made landfall in the United States since records began: The Labor Day Hurricane of 1935, Hurricane Camille in 1969, and Hurricane Andrew in August 1992.

The 1935 Labor Day Hurricane struck the Florida Keys with a minimum pressure of 892 mb - the lowest pressure ever observed in the United States. Hurricane Camille struck the Mississippi Gulf Coast causing a 25-foot storm surge, which inundated Pass Christian. The notorious Hurricane Katrina, a Category 5 storm over the Gulf of Mexico, was responsible for at least 81 billion dollars of property damage when it struck the U.S. Gulf Coast as a Category 3. It is by far the costliest hurricane to ever strike the United States. In addition, Hurricane Wilma, also of 2005, was a Category 5 hurricane at peak intensity and is the strongest Atlantic tropical cyclone on record with a minimum pressure of 882 mb.

The Different Causes of Damage

Despite the category, hurricanes can vary widely in their physical size. Some storms can be very compact and have only a few trailing bands of wind and rain behind them. Other storms are looser, so the bands of wind and rain spread out over hundreds or thousands of miles. Hurricane Floyd, which hit the eastern United States in September 1999, and specifically eastern North Carolina, was felt from the Caribbean Islands to New England.

While the damages can vary from just a few broken tree limbs to total destruction of an area, how a hurricane causes damage varies as well, and results from a number of aspects of the storm.

When hurricanes arrive, they bring huge amounts of rain. A big hurricane can dump dozens of inches of rain in just a day or two, much of it inland. That amount of rain can create inland flooding that can totally devastate a large area around the hurricane's center, particularly in low lying areas.

During Hurricane Floyd, many communities and small towns in eastern North Carolina found themselves afloat after Floyd's massive rainfall and the ensuing floods. Streams and waterways were already swollen from Hurricane Dennis, which struck eastern North Carolina twice just weeks before Hurricane Floyd.

It's not just the flooding that can ruin buildings. The high sustained winds that accompany hurricanes can cause structural damage to both homes and businesses. These winds can also roll cars, blow over trees and erode beaches, both by blowing sand and by blowing the waves into the beach.

In 1993, Category 3 Hurricane Emily brushed the eastern coast just 25 miles off the Outer Banks, but the high sustained winds produced massive damage in the Hatteras Island beaches, tearing apart beach homes and small businesses.

Hurricane winds often spawn tornadoes, which are smaller, more intense cyclonic storms that cause additional damage. Along the coast, sometimes these cyclones can pop up over water, either along the ocean, or more commonly over the sound. These are called "water spouts, and they can be deadly for small vessels.

The prevailing winds of a hurricane can sometimes push a wall of water, called a storm surge, towards the coastline. If the storm surge accompanies a high tide, it causes beach erosion and significant inland flooding. In 2003, Hurricane Isabel caused a wall of water to plow through Hatteras Village on the Outer Banks. The result was countless destroyed homes and businesses, some pushed all the way into the sound, and a new, temporary inlet between Hatteras Village and the rest of Hatteras Island, which took weeks for crews to fill in manually.

When it comes to damage, it also matters what side of the storm your area faces. The right side of a hurricane is more dangerous and stronger because the wind speed and the hurricane speed-of-motion are complimentary. In other words, the winds and the movement of the hurricane are going in the exact same direction, compounding the wind strength. On the left side, the hurricane's speed of motion subtracts from the wind speed, as it is going in the opposite direction.

Tracking and Naming the Storm

The good thing about hurricanes, as opposed to other disastrous weather conditions like tornadoes and flash floods, is that they can be tracked. Even though their exact strike zone may not be known until the storm is close to the coastline, hurricanes can be identified weeks in advance, and communities that could potentially be in the hurricane's path can be properly notified and warned.

The National Hurricane Center (NHC) issues tropical storm or hurricane watches and warnings to coastal areas before a hurricane is likely to hit. A Watch indicates that hurricane or tropical storm conditions are possible in the specified area, usually within 36 hours. Once your area has been issued a tropical storm or hurricane watch, tune in to NOAA Weather Radio, commercial radio or television for information. You will want to be sure you have your supplies and review your evacuation plan, depending on the storm.

A "warning" indicates that hurricane or tropical storm conditions are expected in the specified area, usually within 24 hours. Again, depending on the strength and size of the storm, you may want to either stay in the home or evacuate immediately. Local news, radio and television will advise you on the next step.

When a hurricane forms and moves across a body of water, there are several phenomenon at work to both help it form, and determine which direction it will go. Hurricanes in the Northern Hemisphere rotate counterclockwise (from west to east) and move through the ocean clockwise (from east to west.) In the Southern Hemisphere, hurricanes rotate clockwise (east to west) and move counterclockwise (west to east.) These motions, known as the Coriolis Effect, are caused by the Earth's rotation.

To further monitor and track the development and movement of a hurricane, meteorologists certainly don't rely on the doctrine of the Coriolis Effect alone. They use remote sensing by satellites, as well as data gathered by the Hurricane Hunters.

The Hurricane Hunters are members of the 53rd Weather Reconnaissance Squadron / 403rd Wing, based at Keesler Air Force Base in Biloxi, Mississippi. Since 1944, the U.S. Department of Defense, which commands the U.S. military, has been the only organization to fly airplanes into tropical storms and hurricanes to gauge conditions such as strength and wind speed.

Since 1965, the Hurricane Hunters team has used the C-130 Hercules, a very sturdy turboprop plane. Highly sensitive weather equipment is installed on the C-130 Hercules, and the team can cover up to five storm missions per day, anywhere from the mid-Atlantic to Hawaii.

In addition to the hurricane hunter team, weather satellites use a series of sensors to gather different types of information about hurricanes. The "visible" sensor gauges cloud and circulation patterns. The radar, or Doppler Radar, measures rain, wind speeds and precipitation amounts, while the Infrared sensor looks at temperature differences and cloud heights.

The information on wind speed, rainfall and barometric pressures inside the storm that is gathered by the Hurricane Hunters is sent to the National Hurricane Center (NHC) in Miami, FL. From here, it is interpreted and distributed to national and local news media so that folks in the storm's path can be notified of the intensity and projected path of the storm and given an NHC-issued hurricane watch or warning, if necessary.

While hurricanes have been visiting the North Carolina coastline for hundreds of years, the new technology that allows the NHC to make these predictions of where the storm is headed and give people ample warning to evacuate and seek shelter has greatly reduced the loss of life due to a hurricane over the last 50 years.

To assist with the tracking of hurricanes and make it easier to relay the information to the public, weather officials decided to name the storms. For several hundred years prior to the modern naming method, hurricanes were often named after the particular Saint's day on which the hurricane occurred. For example, Hurricane San Felipe struck Puerto Rico on September 13, 1876. When another storm struck Puerto Rico on the exact same date 52 years later, this storm was named Hurricane San Felipe the Second.

Up until World War II, only male names were used when naming hurricanes. Then, in the early 1950s, weather services switched to just female names and started naming storms alphabetically. (i.e. the first storm to form during a given hurricane season would start with A, the second storm's name would start with B, and so on.

By the late 1970s, weather officials decided to alternate between male and female names, with many of the names on the list being international sounding in nature, such as Gustav or Cristobal. The NOAA says this is intentional, as hurricanes affect a variety of different countries. Today, all the names are selected by the World Meteorological Organization.

Pacific Ocean storms have a different set of names than Atlantic storms. In 2008, the first named storm in the Atlantic Ocean was Arthur, and the first pacific storm was Alma. Because these storms are in two entirely different regions, affecting two entirely different areas, the separation of names is necessary and makes a storm easier to identify.

The list of names is recycled every six years, for example, 2010's list will also be 2016's list. In 1996, Eastern North Carolina was brushed by Hurricane Bertha, and could have been again in 2008 or could be again in 2014.

If a hurricane has a major impact, however, and causes significant damage and loss of lives, the country or countries affected can request that the storm name be retired by the World Meteorological Organization, and the name cannot be reused for at least 10 years. This makes insurance claims and legal matters easier, and avoids public confusion with another future storm of the same name. Most important, reusing a devastating storm name can be sensitive to its original victims.

Several names have been changed since the lists were created. For example, on the 2007 list, (which will be reused in 2013,) Dorian has replaced Dean, Fernand has replaced Felix, and Nestor has replaced Noel.

The two major storms which have hit North Carolina in the last decade, Hurricane Floyd and Hurricane Isabel, have also been retired and will not be reused in the near future.

Preparing for a Storm

The best way to ensure you and your family's safety when a hurricane or tropical storm approaches is to be prepared. Start with a detailed evacuation plan. If you live along the coast, many main roads identify evacuation routes, but the important thing to remember is to head west. Identify ahead of time a motel, shelter or out-of-town friend's house where you can stay until the storm passes, and be sure to keep these phone numbers handy. Most shelters do not allow pets, so make separate arrangements for your animals, like an out-of-town kennel or plan to stay at a pet-friendly motel. Do not leave your pets behind - flooding or poor road conditions can leave your pet stranded for an indeterminable amount of time.

Listen to the radio, watch the news or check out weather and county websites for evacuation notices. An optional evacuation means that you can, and probably should, leave if you do not feel safe. A mandatory evacuation means you must leave. While it is tempting to stay behind and protect your home, it is best to heed a mandatory evacuation. Remember that during and after a hurricane, medical and emergency services will be limited, if available at all.

Have an "evacuation kit" packed and prepared with these Red Cross recommended items:

• Prescription medications and medical supplies
• Bedding and clothing, including sleeping bags and pillows
• Bottled water, battery-operated radio and extra batteries, first aid kit, flashlight
• Car keys and maps
• Documents, including driver's license, Social Security card, proof of residence, insurance policies, wills, deeds, birth and marriage certificates, tax records, etc.

If there is a possibility that you may be stuck at home during the storm, or if an evacuation is not necessary, the Red Cross recommends you have a disaster supply kit with the following items:

• First aid kit and essential medications
• Canned food and can opener
• At least three gallons of water per person
• Protective clothing, rainwear and bedding or sleeping bags
• Battery-powered radio, flashlight and extra batteries
• Special items for infants, elderly or disabled family members
• Written instructions on how to turn off electricity, gas and water if authorities advise you to do so. Remember: you will need a professional to turn them back on.

Well before the storm, and even before the start of hurricane season, you will want to install hurricane shutters or purchase precut 1/2" outdoor plywood boards for each window of your home. Install anchors and predrill holes in the plywood so that you can put it up quickly. You can also make trees more wind resistant by removing diseased and damaged limbs, then strategically removing branches so that wind can blow through.

Once a storm watch has been issued, bring in any lawn furniture, outdoor decorations or ornaments, trash cans, hanging plants and anything else that can be picked up by the wind. Store these items in the home. Cover all windows of your home with the aforementioned shutters or precut plywood. It is a myth that applying duct or masking tape to windows helps prevent them from breaking, so do not waste precious time taping windows.

It is a good idea to take photos of your home and its surroundings in case a homeowner's insurance claim is warranted after the storm is over. You should also fill your car's gas tank, check batteries and stock up on canned food, first aid supplies, drinking water and medications.

When a storm warning is issued, listen to the advice of local officials, and evacuate if necessary. Complete preparation activities and if an evacuation is not needed, stay inside and away from windows.

Be aware that the calm eye of the hurricane can be deceptive - the storm is not over. The worst part of the storm will happen once the eye passes over and the winds blow from the opposite direction. Trees, shrubs, buildings and other objects damaged by the first winds can be broken or destroyed by the second winds.

If a tornado approaches as a result of the storm, remain indoors in the center of your home, in a closet or bathroom without windows.

Remember that a storm can be very frightening, particularly for children. Having plenty of non-electrical or battery-operated toys on hand, like books, crayons, paper, and a favorite stuffed animal can go a long way in comforting and entertaining them. Break out the board games and play by flashlight, or just tell stories and sing songs. The more that your kids are distracted, the more likely they it is that they won't be so afraid and alarmed by the storm.

Once the hurricane is over, keep listening to NOAA Weather Radio or local radio or TV stations for instructions. If you have evacuated, return home when local officials tell you it is safe to do so. Remember that you will probably need a license or proof of residency to re-enter an affected area. Then, inspect your home for damage and take photos, if necessary, for the insurance company.

North Carolina's Notorious Storms:

Since tropical cyclones were first recorded in 1896, over 30 storms have made landfall on North Carolina's coast, and 90 have simply "passed through" the state. Of these, the largest was 1960's Hurricane Donna, which hit southern Florida with maximum sustained winds of 140 mph, and continued to hover at a Category 3 or Category 4 level as it drifted up the East Coast and brushed the coastal border North Carolina.

One of the most devastating and costliest hurricanes to hit North Carolina in recent years was 1999's Hurricane Floyd. This storm triggered the second largest evacuation in U.S. history (behind Hurricane Rita) when 2.6 million coastal residents of five states were ordered from their homes as Hurricane Floyd approached as a very strong Category 4 hurricane near the eastern Bahamas.

Floyd weakened to a Category 2 hurricane when it made landfall on coastal North Carolina, and its greatest impacts were not wind, and not directly on the coast. Floyd produced devastating flooding rains across inland North Carolina, in such areas as Rocky Mount, Greenville and towns along the Tar River, which had been hit by heavy rains just a few weeks earlier by Hurricane Dennis. These rains caused widespread flooding that lasted for several weeks and nearly every river basin in the eastern part of the state exceeded 500-year flood levels. In total, Floyd was responsible for 57 fatalities and $4.5 billion in damage.

While advanced warning is usually assured when it comes to hurricanes, sometimes a hurricane can seemingly pop out of nowhere. The first named storm of the 2004 season, Alex, was a small tropical storm when it made its approach towards the Outer Banks on August 1, during the height of the tourist season. Because of the storm's weakness, an evacuation was not called. As it rapidly approached however, the storm surprisingly intensified, and by the time it passed within 10 miles of the Outer Banks, Alex was a Category 2 hurricane with sustained winds of 100 mph. As a result, over 100 houses were damaged, while numerous cars were disabled from the flooding. The damage totaled about $7.5 million.

Hurricanes and tropical storms are a familiar evil to the residents and frequent visitors of North Carolina's coast, and most locals chalk up the annual threat of storms as the price for living in paradise. Luckily, the small barrier islands and coastal towns have benefitted from the technological advancements over the last century, and the hurricanes that used to cause widespread loss of life can now be identified days in advance, giving residents and visitors enough time to evacuate.

While visitors and locals enjoy abundant sunny beach days and gorgeous weather conditions, it doesn't hurt to keep a watchful eye on the weather during hurricane season and to keep provisions and plans handy, just in case. Being prepared and knowing you are ready if a storm approaches makes the North Carolina coastal experience that much more enjoyable.

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