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Hurricanes in Louisiana

Hurricane Introduction

Hurricanes are one of the earth's most significant weather events. They are powerful storm systems described by an abundance of heavy rains and ferocious winds, making them one of the most violent and destructive natural phenomena. Hurricanes originate over warm ocean water in the tropical regions of the world. Based on their point of origin, hurricanes are identified by different names. This includes typhoons in the western North Pacific and cyclones in the Indian and South Pacific Oceans. The name “hurricane” is reserved for use in the Atlantic and Eastern Pacific Oceans. Scientists refer to this weather phenomenon as a tropical cyclone, regardless of the location of occurrence.

Hurricanes occur seasonally. Each year, there is a period within which hurricane formation in a particular ocean region is most likely. The U.S. is primarily affected by hurricanes originating in the North Atlantic Basin (including the North Atlantic Ocean, Caribbean Sea, and the Gulf of Mexico), and the Eastern Pacific basin made up of the water of the Pacific Ocean. This gives rise to two aptly named periods within which hurricanes are likely to originate from each of these ocean regions. These are the Atlantic hurricane season spanning from June 1 to November 30, and the eastern Pacific hurricane season extending from May 15 to November 30. Within these timeframes, the required conditions for hurricane formation persists in these oceans, and the mechanics for hurricane formation are likely to begin.

Hurricane Science

Hurricanes typically start when there exists an instability in the atmosphere. These instabilities most often exist in the form of a disorganized series of thunderclouds. For most hurricanes that occur in the Atlantic, these thunderclouds often originate off the west coast of Africa and move out over the ocean. At this stage, the cloud formation is referred to as a tropical disturbance. A disturbance has the potential to grow into something more if the right conditions exist.

The first condition is the presence of a large body of ocean water with a surface temperature of about 26.5 degrees Celsius (79.7 Fahrenheit). This warmth in the ocean water body drives a lot of the mechanics needed to form a hurricane, allow it to grow, and sustain it. A possible consequence of this is the presence of a high amount of water vapor in the air mass moving over the ocean as a result of evaporation. This creates a large amount of warm moist air moving over the ocean’s surface. As air warms, its density reduces and the air mass begins to rise upwards. As this occurs, an area of low pressure is created over the ocean water as there is less air available over that area. This drop in air pressure creates a pressure gradient force that manipulates wind circulation. The disorganized thunderstorms moving over the ocean tend to organize around such low-pressure areas, spinning over the area and forming clusters. The warm air masses from the ocean’s surface that rose into the air also begin to cool, and the water vapor in them starts to condense. The condensing water vapor initiates cloud formation, increasing the size of the clouds over the area while also releasing latent heat during the condensation process. The latent heat released further warms the air masses in the area. Cooler high-pressure air in the surroundings rushes in to replace the rising air mass, and subsequently, becomes warm and moist. This causes them to rise as well and repeat the cycle of cloud formation. As this process repeats, a large storm system starts to form.

The second condition for hurricane formation determines if the storm system will keep growing or dissipate before becoming very large. This condition is vertical wind shear. Vertical wind shear is the change in wind speeds with increasing height. There must exist low vertical wind shear, that is, the winds in the upper part of the atmosphere where the cloud system is forming must not be too strong. Strong winds will destroy the cloud system’s structure, causing it to dissipate and prevent further formation.

This leads to the third condition, converging winds. Winds converging on the ocean’s surface pick up heat and water from the ocean, fueling the rise of warm, moist air and strengthening the storm. These winds begin to move around the low-pressure center of the storm, spinning around it and forming rotating columns of air due to the fourth condition for formation.

The fourth condition is the sufficient presence of the Coriolis force. The Coriolis force is an inertial force that influences the motion of free-moving objects such as wind on the earth’s surface due to the earth’s rotation. The Coriolis force causes the path of such free-moving objects to curve as they move, and this is what gives a hurricane its characteristic spin. This force is also responsible for the direction of rotation of a hurricane, causing hurricanes to spin counterclockwise in the Northern Hemisphere, and clockwise in the Southern Hemisphere. The Coriolis force causes the thunderclouds formed around a low-pressure center to spin; thus, hurricanes cannot form in regions about 5 degrees away from the equator as the Coriolis force here is too weak.

At this point, the storm system will become of greater public interest as the sustained wind speeds of the organized thunderclouds system increase and reach 22 mph. Then, a tropical depression is considered to have formed. This is the second stage in the development of a hurricane.

The next stage of development comes with a further increase in the wind speed of the tropical depression in a process called storm intensification. The intensification of the storm starts as the storm begins to obtain greater heat energy from the ocean’s surface causing it to grow. Winds at the ocean’s surface carry heat energy and moisture from the ocean water as they move towards the center of the storm. This warm air mass spirals inwards into the center of the storm and begins to rise due to atmospheric convection. As this air mass rises through the storm’s center, it emerges at the top before diverging, cooling, and starting to fall again. This process continues with succeeding air masses until a situation exists in which the air masses leaving the top of the storm move out faster than incoming air masses can spiral in. This situation causes a decrease in the central pressure of the growing storm. The lowered central air pressure creates an emptier area that air masses spiral inward faster to fill. This increases the maximum wind speed of the storm. Consequently, as the winds move faster, more heat can be collected from the ocean’s surface to fuel the storm and grow it further. When the wind speeds increase to a minimum of 39 mph, a tropical storm has formed. This tropical storm is then assigned a name. If the storm further intensifies and wind speeds continue increasing, a hurricane is considered to have formed when the wind speeds reach 74 mph.

Hurricanes have a structure made up of 3 distinct parts: the eye, the eye wall, and the rainbands. The eye of the hurricane is a region of relative calm within the maelstrom of the raging storm. The eye forms when high-pressure air in the upper parts of the atmosphere sinks into the center of the hurricane. This produces a region with clear skies that may be as large as a few miles wide. The eyewall of the hurricane surrounds the eye, and this is the most dangerous part of the hurricane. The eyewall is formed as heated air masses spiral inwards and rise in the storm. This area contains the strongest thunderstorms, the fastest wind speeds, and the greatest quantity of rainfall. Beyond the eyewall are the concentric rainbands, which are rings of thunderstorms that spiral around the center of the hurricane and produce intense rainfalls.

After formation, hurricanes are categorized based on their maximum sustained wind speeds. The categorization is made on the Saffir-Simpson Hurricane Wind Speed Scale from a rating of 1 to 5 to estimate potential property damage.

Category Wind speed (mph)
1 74 - 95
2 96 – 110
3 111 – 129
4 130 – 156
5 157+

Hurricanes ranking in Category 3 or above are regarded as major hurricanes with catastrophic damage potential.

Hurricane Disaster Impacts

Hurricanes are extremely powerful weather events capable of destruction on a massive scale. As hurricanes move, they tend to move towards land, making landfall as they leave the ocean behind. Landfall introduces the greatest danger to human settlements due to the several hazardous conditions created when a hurricane moves away from the ocean onto land. Three primary conditions present the greatest threat to life and property. These are:

  1. Storm surges

    A storm surge is a massive rise in the sea level caused by the piling up of several wind-blown waves as a hurricane approaches. A storm surge builds up water, creating an inland movement of ocean water by raising water as high as 30 feet along coastal regions. This inflow of water, when flowing fast enough, is extremely destructive to anything in its path. And the larger the approaching hurricane, the greater the potential height of the storm surge. This is the consequence of a hurricane that presents the most danger to human lives.

  2. Heavy force winds

    The winds circulating the low-pressure center of a hurricane move at very high speeds, with the fastest wind speeds appearing at the eyewall. These high-speed winds are strong enough to destroy or damage man-made and natural structures. This includes buildings, bridges, trees, cars, and power installations. These winds can also turn loose materials into projectiles that fly around smashing into things.

  3. Torrential rainfall

    Hurricanes contain a tremendous amount of moisture, enough to easily flood an area when released as rain. Hurricanes are made up of large moisture-laden air masses that are concentrated over a small area. The rains brought on by a hurricane are so heavy to release several tens of inches of rainfall over a few days. This is particularly threatening to inland regions where the rains can reach up to 50 inches, resulting in severe flooding.

As a secondary consequence, a hurricane’s passage can spawn tornadoes which when unleashed in cities can cause even more damage. Tornadoes are funnel-shaped windstorms that have very high wind speeds. These tornadoes are most common in the thunderstorms of the rainbands, though they can also occur near the eyewall. The passage of a hurricane near a coastal area can also propagate the formation of rip currents even if the hurricane doesn't make landfall in the region. Rip currents, which are narrow streams of water that cut through the breaking waves and move out directly to the sea, are formed when winds push surface water along the shore. The piled-up water seeking an escape route back to sea flows through the easiest path available, which may be a narrow path between two sandbars or a channel. This creates a fast-moving current that flows rapidly through the channel. This poses a high risk to swimmers who may get swept out to sea and be unable to swim back.

The disaster brought on by hurricanes is most significant in coastal areas, being enough to destroy them. These hazards can even extend far inland if the hurricane moves enough. Fortunately, the departure of a hurricane from the ocean separates the storm system from its source of energy. Over time, the hurricane will rapidly lose strength and begin to dissipate.

Louisiana Hurricane Threat Profile

The state of Louisiana lies in the southeastern region of the United States, bordered to the north by Arkansas, Texas to the west, Mississippi to the east, and the Gulf of Mexico to the south. The bordering of Louisiana’s coastline with the Gulf of Mexico designates the state as one of the five Gulf states of the U.S. alongside Alabama, Florida, Mississippi, and Texas. This positioning of the state along the U.S. coastline makes it a high-risk area for hurricanes forming off the east coast in the North Atlantic basin.

Louisiana experiences the Atlantic hurricane season with its coasts being vulnerable to hurricane activity starting from the 1st of June to the 30th of November. Within this timeframe, the highest probability of hurricane occurrence usually exists from August to the middle of October. Over the years, Louisiana has suffered from several hurricane events. The Louisiana coast has been struck by 56 hurricanes since 1851; an average of one hurricane every three years. The most severely affected parts of the state are the southern regions that adjoin the coastline.

The impact of hurricane landfall on the state of Louisiana has drawn up an extensive history of numerous fatalities and massive property damage. The worst hurricane to ever hit Louisiana – Hurricane Katrina, a Category 5 hurricane, resulted in 1,833 total deaths and over $100 billion in damages. Other powerful hurricanes rating as high as Category 4 such as Hurricane Harvey in 2017 (causing 68 deaths and $125 billion in damages), Hurricane Ida in 2021 (causing 107 deaths and $75 billion in damages), and Hurricane Laura in 2020 (causing 47 deaths and $19 billion in damages) all made landfall in Louisiana within the past five years.

Getting Ready for Hurricane in Louisiana

Hurricanes are extremely costly events to human lives and property, causing several deaths and billions in damages per year. As hurricanes are inevitable, and projected to worsen and become stronger in subsequent years due to climate change, mitigating their impact when they occur is the best means of dealing with them. This is best done by making proper hurricane preparations as early as possible

Hurricane Warnings and Alerts

Hurricane alerts are the means used by the government and its agencies to notify its citizens of hurricane activity and advise on what to do. These are issued by the National Hurricane Center (NHC) in Miami, Florida for the entire United States. There are two types of alerts issued by the NHC: warnings and watches.

A watch alert is issued to notify the public of the possibility of hurricane-related events in a particular area (called the Watch area) in the near future. These warnings are issued 48 hours before the onset of the potential situation. Watch alerts are issued to notify about potential storm surges, hurricane winds, or tropical storm winds. A warning alert, on the other hand, is issued to notify of expected hurricane-related activity in an area. These are usually issued 36 hours in advance of the impending event. Events such as storm surges, hurricane winds, tropical storm winds, and extreme winds.

Extreme wind warnings are meant to advise residents of an area to shelter in place in anticipation of extreme sustained winds (115 mph+) associated with the eyewall of a major hurricane.

Hurricane warnings and watches are broadcast on TV, radio, cellphones (using the IPAWS system), and through the National Oceanic and Atmospheric Administration (NOAA) weather radio.

Preparation for Hurricane

Individual citizens must make preparations to secure their lives and property. As hurricane preparedness actions become more difficult as a storm approaches, it is best to take action ahead of the event..

Personal Safety Considerations

Safeguarding human lives is the highest priority during a hurricane. Every person should make plans on how to protect themselves and their families when a hurricane approaches.

  • Making plans helps lessen confusion during a hurricane. Establish an evacuation plan and communicate this information to family members before the hurricane season begins.

  • Create an emergency contact information list and distribute it to family members and an out-of-town contact. The list should include the contact information of the out-of-town person, personal workplace contact information, spouse’s contact information, contact information for children, doctor’s contact information, bank/credit card contact information, and insurance company contact information.

  • Create copies of identification documents, prescriptions, a household inventory, and a recent utility bill.

  • Prepare a hurricane supply kit to last the duration of the event. The kit should include enough food and water to last for at least 7 days, a battery-powered portable radio/television, cellphone, charger, personal identification, flashlights, a first aid kit, sanitary products, a whistle, cooking utensils, matches in a sealed container, extra clothing, sleeping bags, blankets, a recent map, medication, spare visual/auditory aids, cash, toys/games for children, and cash. One supply kit should be available for each person.

Pet Considerations

Pet owners should plan for their pet's care during a hurricane period by making special provisions. Be aware that during a hurricane it may become impossible to visit stores for several days.

  • Secure sufficient amounts of pet food and water to last for at least three days. Prevent pets from consuming city water supplies during and after the hurricane as these may have become contaminated.

  • For pets that have medical conditions, always ensure that there is an emergency supply of the required medication available. These should be preferably sealed in water-proof containers.

  • Create a proof of ownership. Each pet should have a proper ID collar to identify them. Furthermore, secure photographs of pets along with their ownership paperwork by sealing them in water-proof bags and also create digital copies as back-up.

  • Ensure all pets have current vaccinations and have the necessary paperwork to prove this. Some emergency shelters or boarding facilities may refuse to admit pets if their vaccination cannot be proved.

  • Restraining a pet during the stressful events of a hurricane may become necessary. Have muzzles and leashes available to prevent the pet from becoming a danger to itself and others. Also, have a large enough pet carrier on hand to transport pets if needed.

  • Have facilities such as cat litters, pet beds, blankets, chew toys, trash bags, and clean towels available to make the animal as comfortable as possible.

Housing Considerations

Some home improvement options can greatly reduce the damage a house will suffer during a hurricane. While these might not eliminate hurricane damage, there will be significantly less to fix afterward.

To lessen force winds damage:

  • Keep trees and shrubbery trimmed back from the house as vegetation tends to sway a lot during heavy winds.

  • Unsecured roofs and roof shingles are at risk of blowing away in the storm winds. Replace old or damaged shingles with new heavy-duty ones that can withstand hurricane force winds. Roofs can be secured by binding the roof trusses to the side walls of the house using hurricane clips.

  • Reinforce garage doors with heavy-duty doors tested as being capable of withstanding hurricanes. Do the same with windows.

  • Take lawn furniture and other outdoor fixtures inside.

Very little can be done to mitigate damage from the heavy rains. The best course of action is to ensure good drainage where possible by unclogging blocked rain gutters and downspouts. Cracks should also be closed up to prevent the incursion of water into any part of the house to cause damage indoors.

The threat of storm surges should be considered when deciding to establish a home. Take note of the elevation at which the house will be sited as this determines if the area is a flood or evacuation zone.

Mobile home owners must prepare to evacuate when a storm advisory is in effect. A mobile home is highly unlikely to provide sufficient protection from the fierce winds of a hurricane, even when secured with straps or other tie-downs. When evacuation orders are issued, mobile home owners must do so immediately.

Vehicle Considerations

Hurricane winds are strong enough to flip vehicles over, and flood waters can make it difficult to access them after the storm. Plan accordingly for the protection of vehicles before the hurricane season starts to lessen/forgo the cost of repairing or replacing them afterward.

For car owners:

  • Make duplicates of car keys and give these to family members licensed to drive. This allows them to use the vehicle even if separation occurs.

  • It may be necessary to use the car to evacuate. Obtain enough fuel to fill the car’s gas tank and service the car as soon as there is a notice of a storm in the Gulf.

  • If there is no immediate need to evacuate, secure cars from high winds and water. Cars can receive adequate shelter from a significantly reinforced garage.

For boat owners:

  • Contact your local marina on policies and procedures for hurricanes.

  • If the boat can be attached to a trailer, consider moving it inland to secure it. Do this at least 48 hours before a hurricane is expected to appear.

  • If a boat is to remain in the marina, moor the boat securely enough to withstand the storm, with at least three or four anchor points.

Financial Matters

Hurricanes can cause a lot of destruction, even with the best preventative efforts. Lessening the financial burden that may appear after a hurricane is crucial to protect one’s self every hurricane season.

  • Research available insurance companies and obtain hurricane-specific insurance for items of value, including a house and cars. Fully understand what is covered under the policy taken out.

  • Store ownership and registration documents of houses and cars in water-proof containers. Make copies of each of these and store them in a safe place. Also, consider making digital copies of each.

  • Obtain pictures of insured items before the storm hits for insurance purposes. This includes houses and cars. Create digital backups and seal the original in water-proof containers. Compare these pictures to those obtained after the hurricane hit.

Hurricane Evacuation

The hazardous conditions created by a hurricane may make it impossible to remain at home during the hurricane, and maybe for a short while after. The risk of a storm surge makes it most likely for an evacuation order to be issued. Part of a hurricane preparedness plan is knowing what to do, where to go, and how to get there if it becomes necessary to evacuate.

At the start of every hurricane season, complete the following actions to make evacuation as smooth as possible when required:

  • Identify the hurricane hazards most likely to affect the local region and plan accordingly. Coastal areas are most likely to experience storm surges, so residents of these regions should consider evacuating even before orders of mandatory evacuations. Residents of inland areas should prepare for heavy rains and high-speed winds and plan to evacuate if ordered to do so.

  • Pre-identify safe areas that will be possible to relocate to when needed. This may be an out-of-town location, American Red Cross shelters, or other public designated storm shelter locations. Find out ahead if the intended relocation space has accommodations for special conditions such as the presence of persons with special needs or pets.

  • Communicate the intended evacuation location to immediate family members, as well as to out-of-town family and friends.

  • Find out about local evacuation zip zones and obtain evacuation route maps showing how to get there. This will be invaluable when a mandatory evacuation is ordered.

  • Hurricane survival kits are necessary if choosing to hunker down or evacuate. Be sure to prepare one.

  • In the event a mandatory evacuation is ordered, follow the directions from local officials. Only leave the current place of shelter when instructed to do so. Wait until the local zip zone is called as a mandatory evacuation zone and then leave immediately.

When voluntarily evacuating, before exiting the house, unplug all small appliances, turn off propane tanks, empty refrigerators/freezers, turn off utilities if ordered, and lower swimming pool water levels by one foot.

Staying Safe During Hurricane

Protecting oneself is the highest priority when a hurricane is in the area. Persons within the hurricane impact area must seek shelter during this period and remain within the safe location until advised to come out.

Hurricane Shelters

Persons in areas being affected by a hurricane may be advised to shelter within their homes or move to a safer building. If sheltering at home, close all storm shutters and turn refrigerators/freezers to the coldest setting to preserve stored food. Be aware that energy management of such appliances may become crucial as officials may order for utilities to be turned off. Find a safe spot within the house and stay away from windows. Preferably select an interior room without windows that has good structural integrity. Keep track of hurricane updates being issued for the area via TV or radio. A hurricane supply kit provided ahead of time will serve to meet essential needs while waiting.

If advised to evacuate, there are public shelters in which temporary refuge can be sought for the duration of the hurricane. Local officials will typically notify residents of the location of available shelters and give directions on how to reach them.

Regardless of where shelter is sought, it is important not to go outside until it is declared safe to do so. The passage of the eye of the storm can create an area of relative calm that can lull unsuspecting people into a false sense of security. The eye is surrounded by the eyewall which features the highest wind speeds of the hurricane formation.

After the Hurricane

The dissipation of a hurricane begins to mark the end of the dangerous situation. It does not, however, put an immediate end to the danger. Some caution must still remain during this period to deal with post-hurricane scenarios and moving back home.

Following a hurricane, there is a high probability of the presence of damaged structures, debris, contaminated water, or breeding microorganisms in the area. If outside the area, remain there until it is declared safe to return. For persons still in the area, observe the following cautionary measures:

  • Avoid downed powerlines and do not enter damaged buildings

  • Stay off the roads unless for emergency purposes as the road may not be safe yet

  • Provide adequate ventilation if operating generators to supply power and do not use generators indoors to avoid inhalation of carbon monoxide

  • Do not drink water from the public water supply until it is declared safe to do so

  • Avoid using open flames indoors as a gas leak may exist.

A cleanup of the area will be organized by the local authority to make it habitable again. After this is completed, it should be declared safe to return. When returning, observe the following measures:

  • Check for gas leaks. If a leak is suspected, leave the home immediately without turning on the lights or using a phone inside. Place a call to the gas company outside or from a neighbor’s house.

  • Check electrical outlets. If electrical connections have come into contact with water, turn off power at the main breaker and call the electric company.

  • Avoid connecting generators to the home’s electrical circuits. This can result in a fire hazard when the power supply is restored.

  • Stay off the plumbing utilities if there is a suspicion of damaged water or sewage lines. Call the water company to turn off the water supply and call a plumber for repairs.

  • Disinfect the interior of buildings and their contents to prevent the growth of microorganisms.

After the hurricane and its secondary dangers have passed, it is time to assess the damages. Persons with hurricane insurance coverage can attempt to cover home repair expenses by submitting claims to their insurance companies. Damage claims should be submitted promptly, along with a valid means of being contacted if displacement has occurred. Obtain photographs and videos of the damage suffered as evidence. Keep a record of all further expenses incurred, such as temporary repairs, as specified in the policy agreement.

Completing all these marks the survival of one of nature’s most devastating events, and the next thing to do is to start preparing for a new one.