Timely warnings have greatly diminished hurricane fatalities in the United States. In spite of this, property damage continues to mount. There is little we can do about the hurricanes themselves. However, NOAA's National Hurricane Center and National Weather Service
field offices team up with other Federal, state, and local agencies; rescue and relief organizations; the private sector; and the news media in a huge warning and preparedness effort.
Breeding
Grounds
In
the eastern Pacific, hurricanes start forming by mid-May. In the Atlantic,
Caribbean, and Gulf of Mexico, hurricanes season starts in June. For the
United States, peak hurricane threat exists from mid-August to late October
although the official hurricane season extends through November. Over other
parts of the world, such as the western Pacific, hurricanes can occur
year-round.
Developing hurricanes gather heat and energy through contact with warm
ocean waters. The addition of moisture by evaporation from the sea surface
powers them like giant heat engines.
Storm
Structure
The
process by which a disturbance forms and subsequently strengthens into a
hurricane depends on at least three conditions. Warm waters and moisture are
mentioned above. The third condition is a wind pattern near the ocean surface
that spirals air inward. Bands of thunderstorms form, allowing the air to warm
further and rise higher into the atmosphere. If the winds at these higher levels
are relatively light, this structure can remain intact and allow for additional
strengthening.
The
center, or eye, of a hurricane is relatively calm. The most violent activity
takes place in the area immediately around the eye, called the eyewall. At the
top of the eyewall (about 50,000 feet), most of the air is propelled outward,
increasing the air's upward motion. Some of the air, however, moves inward and
sinks into the eye, creating a cloud-free area.
Storm Fury
Storm
Surge
Storm
surge is a large dome of water often 50 to 100 miles wide that sweeps across the
coastline near where a hurricane makes landfall. The surge of high water topped
by waves is devastating. The stronger the hurricane and the shallower the
offshore water, the higher the surge will be. Along the immediate coast, storm
surge is the greatest threat to life and property.
Storm Tide
If
the storm surge arrives at the same time as the high tide, the water height will
be even greater. The storm tide is the combination of the storm surge and the
normal astronomical tide.
For example as hurricane
moves ashore, a 15-foot surge added to the normal 2-foot tide creates a storm
tide of 17 feet. This mound of water, topped by battering waves, moves ashore
along an area of the coastline as much as 100 miles wide. The combination of the
storm surge, battering waves, and high winds is deadly.
Storm Tide
Facts
-
Over 6,000 people were killed in the Galveston Hurricane of
1900 most by the storm tide.
-
Hurricane Camille in 1969 produced a 25-foot storm
tide in Mississippi.
- Hurricane Hugo in 1989 generated a 20-foot storm tide
in South Carolina.
Winds
Hurricane-force winds, 74 mph or more, can destroy poorly constructed
buildings and mobile homes. Debris, such as signs, roofing material, siding, and
small items left outside, become flying missiles in hurricanes. Winds often stay
above hurricane strength well inland. Hurricane Hugo (1989) battered Charlotte,
North Carolina (which is about 175 miles inland), with gusts to near 100 mph,
downing trees and power lines and causing massive disruption.
Heavy
Rains/Floods
Widespread torrential rains often in excess of 6 inches can produce
deadly and destructive floods. This is the major threat to areas well inland.
-
Tropical Storm Claudette (1979) brought 45 inches of
rain to an area near Alvin, Texas, contributing to more than $600 million* in
damage.
-
Long after the winds of Hurricane Diane (1955)
subsided, the storm brought floods to Pennsylvania, New York, and New England
that contributed to nearly 200 deaths and $4.2 billion* in damage.
- Hurricane Agnes (1972) fused with another storm
system, producing floods in the Northeast United States which contributed to
122 deaths and $6.4 billion* in damage.
* Adjusted to 1990
dollars.
Hurricanes also produce tornadoes, which add to the hurricane's
destructive power. These tornadoes most often occur in thunderstorms embedded in
rain bands well away from the center of the hurricane. However, they can also
occur near the eyewall.
Coastal
Areas and Barrier Islands
All
Atlantic and Gulf coastal areas are subject to hurricanes or tropical storms.
Although rarely struck by hurricanes, parts of the Southwest United States and
Pacific Coast suffer heavy rains and floods each year from the remnants of
hurricanes spawned off Mexico. Islands, such as Hawaii, Guam, American Samoa,
and Puerto Rico, are also subject to hurricanes.
Due
to the limited number of evacuation routes, barrier islands are especially
vulnerable to hurricanes. People on barrier islands and in vulnerable coastal
areas may be asked by local officials to evacuate well in advance of a hurricane
landfall. If you are asked to evacuate, do so
IMMEDIATELY!
Inland
Areas
Hurricanes affect inland areas with high winds, floods, and tornadoes.
Listen carefully to local authorities to determine what threats you can expect
and take the necessary precautions to protect yourself, your family, and your
property.
- Camille - August 14-22, 1969: 27 inches of rain in
Virginia caused severe flash flooding.
Agnes - June 14-22, 1972: Devastating floods from North
Carolina to New York produced many record-breaking river crests. The storm
generated 15 tornadoes in Florida and 2 in Georgia.
Hugo- September 10-22, 1989: Wind gusts reached nearly
100 mph as far inland as Charlotte, North Carolina. Hugo sustained
hurricane-strength winds until shortly after it passed west of Charlotte.
Andrew- August 16-28, 1992: Damage in the United States
is estimated at $25 billion, making Andrew the most expensive hurricane in
United States history. Wind gusts in south Florida were estimated to be at least
175 mph.
The US
Hurricane Problem
Population
Growth
The
United States has a significant hurricane problem. Our shorelines attract large
numbers of people. From Maine to Texas, our coastline is filled with new homes,
condominium towers, and cities built on sand waiting for the next storm to
threaten its residents and their dreams.
There
are now some 45 million permanent residents along the hurricane-prone coastline,
and the population is still growing. The most rapid growth has been in the
sunbelt from Texas through the Carolinas. Florida, where hurricanes are most
frequent, leads the nation in new residents. In addition to the permanent
residents, the holiday, weekend, and vacation populations swell in some coastal
areas 10- to 100-fold.
A
large portion of the coastal areas with high population densities are subject to
the inundation from the hurricane's storm surge that historically has caused the
greatest loss of life and extreme property damage.
Perception of
Risk
Over
the past several years, the warning system has provided adequate time for people
on the barrier islands and the immediate coastline to move inland when
hurricanes have threatened. However, it is becoming more difficult to evacuate
people from the barrier islands and other coastal areas because roads have not
kept pace with the rapid population growth. The problem is further compounded by
the fact that 80 to 90 percent of the population now living in hurricane-prone
areas have never experienced the core of a "major" hurricane. Many of these
people have been through weaker storms. The result is a false impression of a
hurricane's damage potential. This often leads to complacency and delayed
actions which could result in the loss of many lives.
Frequency
of Hurricanes
During the 70's and 80's, major hurricanes striking the United States
were less frequent than the previous three decades. With the tremendous increase
in population along the high-risk areas of our shorelines, we may not fare as
well in the future. This will be especially true when hurricane activity
inevitably returns to the frequencies experienced during the 40's through the
60's.
In
the final analysis, the only real defense against hurricanes is the informed
readiness of your community, your family, and YOU.
Surveillance and
Forecasting
Satellite
Geostationary satellites orbiting the earth at an altitude of about
22,000 miles above the equator provide imagery both day and night. The satellite
imagery helps provide estimates of the location, size, and intensity of a storm
and its surrounding environment.
Reconnaissance Aircraft
The
US Air Force Reserve provides most of the operational reconnaissance. Pilots fly
aircraft into the core of a hurricane to measure wind, pressure, temperature,
and humidity as well as to provide an accurate location of the center of the
hurricane. The National Oceanic and Atmospheric Administration also flies
aircraft into hurricanes to aid scientists in better understanding these storms
and to improve forecast capabilities. The NOAA flights also provide operational
support as required.
Radar
When
a hurricane gets close to the coast, it is monitored by land-based weather
radars. The National Weather Service is currently installing Doppler weather
radars across the country which will add new dimensions to hurricane warning
capabilities. They will provide detailed information on hurricane wind fields
and their changes. Local NWS offices will be able to provide more accurate
short-term warnings for floods, tornadoes, and inland high winds.
National
Hurricane Center Models
The
National Hurricane Center uses several different numerical computer models to
aid in forecasting the path, speed, and strength of hurricanes. Data from
weather satellite sensors, reconnaissance aircraft, and other sources are fed
into these computer models. The National Hurricane Center also has a computer
storm surge model. This model provides guidance on storm surge height and the
extent of flooding it will cause.
NOAA
Weather Radio is the best means to receive warnings from the National Weather
Service
The
National Weather Service continuously broadcasts updated hurricane advisories
that can be received by NOAA Weather Radios sold in many stores. The average
range is 40 miles, depending on topography. Your National Weather Service
recommends purchasing a radio that has both a battery backup and a tone-alert
feature which automatically alerts you when a watch or warning is
issued.
- TROPICAL STORM WATCH: Tropical Storm conditions are
possible in the specified area of the Watch, usually within 36 hours.
- TROPICAL STORM WARNING: Tropical Storm conditions are
expected in the specified area of the Warning, usually within 24 hours.
- HURRICANE WATCH: Hurricane conditions are possible in
the specified area of the Watch, usually within 36 hours. During a Hurricane
Watch, prepare to take immediate action to protect your family and property in
case a Hurricane Warning is issued.
-
HURRICANE WARNING: Hurricane conditions are expected
in the specified area of the Warning, usually within 24 hours. Complete all
storm preparations and evacuate if directed by local officials.
- SHORT TERM WATCHES AND WARNINGS: These provide
detailed information on specific hurricane threats, such as tornadoes, floods,
and high winds.
Information
for Local Decision Makers
- The PUBLIC ADVISORY - issued by the National Hurricane
Center provides critical hurricane warning and forecast information.
- The MARINE ADVISORY - issued by the National Hurricane
Center provides detailed hurricane track and wind field information.
- The TROPICAL CYCLONE UPDATE - issued by the National
Hurricane Center highlights significant changes in a hurricane that occur
between advisories.
- PROBABILITIES OF HURRICANE/TROPICAL STORM CONDITIONS -
provide a measure of the forecast track accuracy. The probabilities
have no relation to tropical cyclone intensity.
- HURRICANE LOCAL STATEMENTS - issued by local National
Weather Service offices give greater detail on how the storm will impact your
area.
All of the above information must be used to make an informed
decision on your risk and what actions should be taken. Remember to listen to
your local official's recommendations and to NOAA Weather Radio for the latest
hurricane information.
Personal
and Community Preparedness
Before the
Hurricane Season
-
Know the hurricane risks in your area.
-
Learn safe routes inland.
-
Learn location of official shelters.
-
Ensure that enough non-perishable food and water supplies are on hand.
-
Obtain and store materials, such as plywood, necessary to properly
secure your home.
-
Clear loose and clogged rain gutters and downspouts.
-
Keep trees and shrubbery trimmed.
- Review your insurance policy.
Individuals with special needs or others requiring more information
should contact their local National Weather Service office, emergency management
office, or American Red Cross chapter.
During the
Storm
When in a
Watch Area...
-
Frequently listen to radio, TV, or NOAA Weather Radio for official
bulletins of the storm's progress.
-
Fuel and service family vehicles.
-
Inspect and secure mobile home tie downs.
-
Prepare to cover all window and door openings with shutters or other
shielding materials.
-
Check batteries and stock up on canned food, first aid supplies,
drinking water, and medications.
-
Prepare to bring inside lawn furniture and other loose, light-weight
objects, such as garbage cans, garden tools, etc.
-
Have on hand an extra supply of cash.
Plan to
evacuate if you...
-
Live in a mobile home. They are unsafe in high winds, no matter how
well fastened to the ground.
-
Live on the coastline, an offshore island, or near a river or a flood
plain.
-
Live in a high-rise. Hurricane winds are stronger at higher elevations.
When in a
Warning Area...
-
Closely monitor radio, TV, or NOAA Weather Radio for official
bulletins.
-
Complete preparation activities, such as putting up storm shutters,
storing loose objects, etc.
-
Follow instructions issued by local officials. Leave immediately if
told to do so!
-
If
evacuating, leave early (if possible, in daylight). Stay with friends or
relatives, at a low-rise inland hotel/motel, or go to a predesignated public
shelter outside a flood zone.
-
Leave mobile homes in any case.
-
Notify neighbors and a family member outside of the warned area of your
evacuation plans.
-
Put food and water out for a pet if you cannot take it with you. Public
health regulations do not allow pets in public shelters, nor do most
hotels/motels allow them.
What to bring to a shelter: first-aid kit; medicine; baby food and
diapers; cards, games, books; toiletries; battery-powered radio; flashlight (one
per person); extra batteries; blankets or sleeping bags; identification,
valuable papers (insurance), and cash.
If you ARE told to leave, do so
immediately!
If Staying
in a Home...
Only
stay in a home if you have NOT been ordered to leave. Stay
inside a well constructed building. In structures, such as a home, examine the
building and plan in advance what you will do if winds become strong. Strong
winds can produce deadly missiles and structural failure.
-
Turn refrigerator to maximum cold and open only when necessary.
-
Turn off utilities if told to do so by authorities.
-
Turn off propane tanks.
-
Unplug small appliances.
- Fill bathtub and large containers with water for sanitary
purposes.
If winds
become strong...
-
Stay away from windows and doors even if they are covered. Take refuge
in a small interior room, closet, or hallway.
-
Close all interior doors. Secure and brace external doors.
-
If
you are in a two-story house, go to an interior first-floor room, such as a
bathroom or closet.
-
If
you are in a multiple-story building and away from the water, go to the first
or second floors and take refuge in the halls or other interior rooms away
from windows.
-
Lie on the floor under a table or another sturdy object.
-
TORNADOES
which often are spawned by hurricanes.
- The calm "EYE" of the storm. After the eye passes, the
winds will change direction and quickly return to hurricane force.
After the
Storm
-
Keep listening to radio, TV, or NOAA Weather Radio.
-
Wait until an area is declared safe before entering.
-
Roads may be closed for your protection. If you come upon a barricade
or a flooded road, turn around and go another way!
-
Avoid weakened bridges and washed out roads. Do not drive into flooded
areas.
-
Stay on firm ground. Moving water only 6 inches deep can sweep you off
your feet. Standing water may be electrically charged from under-ground or
downed power lines.
-
Check gas, water, and electrical lines and appliances for damage.
-
Do
not drink or prepare food with tap water until you are certain it is not
contaminated.
-
Avoid using candles and other open flames indoors. Use a flashlight to
inspect for damage.
-
Use the telephone to report life-threatening emergencies only.
-
Be
especially cautious if using a chainsaw to cut fallen trees.
Community
Preparedness Plans
Each
community subject to a hurricane threat should develop its own hurricane safety
plan. After you have developed a personal/family safety plan, you may want to
find out about your community safety plan. Your local officials should have the
most detailed information for your immediate area. Please listen to and follow
their recommendations both before, during, and after the storm.
FAMILY
DISASTER PLAN
Families should be prepared for all hazards that could affect their area.
NOAA's National Weather Service, the Federal Emergency Management Agency, and
the American Red Cross urge every family to develop a family disaster
plan.
Where
will your family be when disaster strikes? They could be anywhere at work, at
school, or in the car. How will you find each other? Will you know if your
children are safe? Disaster may force you to evacuate your neighborhood or
confine you to your home. What would you do if basic services water, gas,
electricity or telephones were cut off?
Follow
these basic steps to develop a family disaster plan...
I. Gather information about hazards. Contact your
local National Weather Service office, emergency management office, and
American Red Cross chapter. Find out what type of disasters could occur and
how you should respond. Learn your community's warning signals and evacuation
plans.
II. Meet with your family to create a plan.
Discuss the information you have gathered. Pick two places to meet: a spot
outside your home for an emergency, such as fire, and a place away from your
neighborhood in case you can't return home. Choose an out-of-state friend as
your "family check-in contact" for everyone to call if the family gets
separated. Discuss what you would do if advised to
evacuate.
III. Implement your plan.
(1) Post emergency telephone numbers by phones; (2) Install safety
features in your house, such as smoke detectors and fire
extinguishers; (3) Inspect your home for potential hazards (such as items
that can move, fall, break, or catch fire) and correct them; (4) Have
your family learn basic safety measures, such as CPR and first aid; how to
use a fire extinguisher; and how and when to turn off water, gas, and
electricity in your home; (5) Teach children how and when to call 911 or
your local Emergency Medical Services number; (6) Keep enough supplies
in your home to meet your needs for at least three days. Assemble a disaster
supplies kit with items you may need in case of an evacuation. Store these
supplies in sturdy, easy-to-carry containers, such as backpacks or duffle
bags. Keep important family documents in a waterproof container. Keep a
smaller disaster supplies kit in the trunk of your car.
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