Hurricane Facts
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Defining a Hurricane
A Hurricane is a type of tropical cyclone – the general term for all
circulating weather systems (counterclockwise in the Northern Hemisphere) over
tropical waters. Tropical cyclones are classified as follows:
1. Tropical Depression -- An organized system of clouds and thunderstorms
with a defined circulation and maximum sustained winds of 38 mph (33 knots) or
less.
2. Tropical Storm -- An organized system of strong thunderstorms with a
defined circulation and maximum sustained winds of 39 to 73 mph (34-63 knots).
3. Hurricane -- An intense tropical weather system with a well-defined
circulation and maximum sustained winds of 74 mph (64 knots) or higher. In the
western Pacific, hurricanes are called “typhoons,” and similar storms in the
Indian Ocean are called “cyclones.”
Hurricanes are products of the tropical ocean and atmosphere. Powered by heat
from the sea, they are steered by the easterly trade winds and the temperate
westerlies as well as by their own ferocious energy. Around their core, winds
grow with great velocity, generating violent seas. Moving ashore, they sweep the
ocean inward while spawning tornadoes and producing torrential rains and floods.
Each year on average, ten tropical storms (of which six become hurricanes)
develop over the Atlantic Ocean, Caribbean Sea, or Gulf of Mexico. Many of these
remain over the ocean. However, about five hurricanes strike the United States
coastline every three years. Of these five, two will be major hurricanes
(category 3 or greater on the Saffir-Simpson Hurricane Scale).
Source: U.S. DEPARTMENT OF COMMERCE , NOAA, National Weather
Service
Terms to Know
By international agreement, tropical cyclone is the general term for all
cyclone circulations originating over tropical waters, classified by form and
intensity as follows:
- Tropical disturbance: A moving area of thunderstorms in the
Tropics that maintains its identity for 24 hours or more. A common
phenomenon in the tropics.
- Tropical depression: Rotary circulation at surface, highest
constant wind speed 38 miles per hour (33 knots).
- Tropical storm: Distinct rotary circulation, constant wind speed
ranges 39-73 miles per hour (34-63 knots).
- Hurricane: Pronounced rotary circulation, constant wind speed of
74 miles per hours (64 knots) or more.
- Small craft cautionary statements. When a tropical cyclone
threatens a coastal area, small craft operators are advised to remain in
port or not to venture into the open sea.
- Gale Warnings may be issued when winds of 39-54 miles an hour
(34-47 knots) are expected.
- Storm Warnings may be issued when winds of 55-73 miles an hour
(48-63 knots) are expected. If a hurricane is expected to strike a coastal
area, gale or storm warnings will not usually precede hurricane warnings.
-
- A Hurricane Watch is issued for a coastal area when there is a
threat of hurricane conditions within 24-36 hours.
- A Hurricane Warning is issued when hurricane conditions are
expected in a specified coastal area in 24 hours or less. Hurricane
conditions include winds of 74 miles an hour (64 knots) and/or dangerously
high tides and waves. Actions for protection of life and property should
begin immediately when the warning is issued.
- Flash Flood Watch means a flash flood is possible in the area;
stay alert. Flash Flood Warning means a flash flood is imminent; take
immediate action.
- Tornadoes spawned by hurricanes sometimes produce severe damage
and casualties. If a tornado is reported in your area, a warning will be
issued.
Source: U.S. DEPARTMENT OF COMMERCE , NOAA, National Weather Service
All Hurricanes are
dangerous, but some are more so than others. The way storm surge, wind and other
factors combine determines a hurricane’s destructive power.
To make comparisons easier and to make the predicted hazards of approaching
hurricanes clearer to emergency forces, National Oceanic and Atmospheric
Administration’s hurricane forecasters use a disaster-potential scale which
assigns storms to five categories. This can be used to give an estimate of the
potential property damage and flooding expected along the coast with a
hurricane.
Saffir-Simpson Hurricane Scale
|
Category
|
Definition
|
Effects
|
One
|
Winds 74-95 mph
|
No real damage to building structures. Damage primarily to
unanchored mobile homes, shrubbery, and trees. Also, some coastal road
flooding and minor pier damage
|
|
Two
|
Winds 96-110 mph
|
Some roofing material, door, and window damage to buildings.
Considerable damage to vegetation, mobile homes, and piers. Coastal and
low-lying escape routes flood 2-4 hours before arrival of center. Small
craft in unprotected anchorages break moorings.
|
|
Three
|
Winds 111-130 mph
|
Some structural damage to small residences and utility buildings
with a minor amount of curtainwall failures. Mobile homes are destroyed.
Flooding near the coast destroys smaller structures with larger
structures damaged by floating debris. Terrain continuously lower than 5
feet ASL may be flooded inland 8 miles or more.
|
|
Four
|
Winds 131-155 mph
|
More extensive curtainwall failures with some complete roof
structure failure on small residences. Major erosion of beach. Major
damage to lower floors of structures near the shore. Terrain
continuously lower than 10 feet above sea level (ASL) may be flooded
requiring massive evacuation of residential areas inland as far as 6
miles.
|
|
Five
|
Winds greater than 155 mph
|
Complete roof failure on many residences and industrial buildings.
Some complete building failures with small utility buildings blown over
or away. Major damage to lower floors of all structures located less
than 15 feet ASL and within 500 yards of the shoreline. Massive
evacuation of residential areas on low ground within 5 to 10 miles of
the shoreline may be required.
|
Source: U.S. DEPARTMENT OF COMMERCE , NOAA, National Weather
Service
In
preparing for the 2002 Hurricane Season, make plans for action:
- Know the hurricane risks in your area. Learn the storm surge history and
elevation of your area.
- Learn safe routes inland.
- Learn the 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 of dead wood.
- Review your insurance policy.
- Determine where to move your boat in an emergency.
- Individuals with special needs or others requiring more information
should contact the Putnam County Bureau of Emergency Services.
In preparing for the
hurricane season, the first step is understanding the warnings that are issued
by the National Weather Service:
A
hurricane WATCH means that hurricane conditions MAY threaten an area within
24-36 hours. When a hurricane WATCH is issued, everyone in that area should
listen for further advisories and be prepared to act promptly.
When a
hurricane WATCH is issued, people in the affected area should:
- Frequently listen to your radio, television or NOAA Weather Radio for
official bulletins on the storm��s progress.
- Fuel and service family vehicles. Service stations may be unable to pump
fuel because of flooding or loss of electrical service.
- Moor small craft or move to safe shelter.
- Inspect and secure mobile home tie downs.
- Tape, board or shutter all window and door openings. Wedge sliding glass
doors to prevent lifting from their tracks.
- Check for batteries, flashlights and battery-operated radios.
- Check on your supply of canned food, first aid supplies, drinking water
and medications.
- Prepare to bring inside lawn furniture and other loose, lightweight
objects, such as garbage cans and garden tools.
- Have on hand an extra supply of cash.
Hurricane Warning
In
preparing for the hurricane season, the first step is understanding the warnings
that are issued by the National Weather Service:
A hurricane WARNING is issued when hurricane conditions are expected in a
specified coastal area in 24 hours or less. Hurricane conditions include winds
of 74 miles an hour (64 knots) and/or dangerously high tides and waves.
Actions for protection of life and property should begin immediately when the
warning is issued, including:
- Frequently listen to your radio, television or NOAA Weather Radio for
official bulletins on the storm’s progress.
- Complete preparation activities such as putting up storm shutters,
storing loose objects, etc. Move valuables to upper floors.
- Store drinking water in clean jugs, bottles and cooking utensils. Your
town’s water system could become contaminated or damaged by the storm.
- Check your battery‑powered equipment. Your radio may be your only link
with the outside world. Emergency cooking facilities and flashlights will
be essential if utility services are interrupted.
- Follow instructions issued by local authorities. Leave IMMEDIATELY if
told to do so.
- Leave low‑lying areas that may be swept by high tides or storm waves.
- If you plan to leave your home, leave early (if possible, in daylight)
to avoid the last-minute rush that could leave you stranded. Stay with
friends or relatives, at a low-rise inland hotel/motel, or go to a
predesignated public shelters outside a flood zone.
- In any case, leave mobile homes for more substantial shelter.
- 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.
Family
Emergency Supplies
Have these items in your residence – and ready to go if you
are forced to evacuate:
- Flashlights with extra batteries. Keep flashlights – with extra, fresh
batteries -- beside your bed and in several other locations. Do not use
matches.
- Portable radio with extra batteries. Most telephones will be out of
order or limited to emergency use. The radio -- including NOAA Weather
Radio -- will be the best source of emergency information.
- First aid kit / first aid skills. Keep your first‑aid kit well stocked
and in a central location. Take basic first‑aid and CPR courses. Keep your
skills current.
- Fire extinguisher. Your fire extinguisher should be suitable for all
types of fires and should be easily accessible. Teach all family members
how to use it.
- Food. Store a three-day supply of food for each person. Items such as
canned or dehydrated food, powdered milk and canned juices can be rotated
into your daily diet and replenished on a regular basis.
- Water. Store a 3-day supply of water (one gallon per person per day).
Store in air‑tight containers and replace them every six months. Keep a
disinfectant, such as iodine tablets or chlorine bleach, to purify water, if
necessary.
- Extra blankets and clothing may be required to keep warm. Sturdy shoes
protect feet from broken glass and debris.
- Alternate cooking source. Store barbecue, charcoal, starter and matches
in case utilities are out of service. Do not use these methods of cooking
within a confined area.
- Special items for infant, elderly, or disabled family members. Have at
least a week’s supply of medications and foods for infants and those on
special diets.
- Tools. Have a crescent or pipe wrench to turn off gas and water if
necessary and know the location of the shut‑off valves.
- Valuable papers (insurance), checkbook, cash, credit cards, ATM cards.
- Contact your local National Weather Service office or Emergency
Management office to learn what types of disasters could occur and how you
should respond.
- Learn your community’s warning signals and evacuation plans.
- Know the Emergency Alert System radio and television stations in your
area that will carry official information. Also, monitor NOAA Weather Radio
broadcasts, if possible.
- Discuss with family members what they should do in the event of a
disaster, such as a hurricane or severe storm. Pick two places to meet: a
spot outside your home for an emergency, such as a fire, and a place away
from your neighborhood in case you can’t return home.
- Designate an out‑of‑area friend or relative whom separated family
members could call to report their whereabouts. Make certain all family
members have the phone number.
- Check your home and property for potential hazards to see what actions
need to be taken to ensure your safety and to protect your belongings.
- Install safety features in your residence such as smoke detectors and
fire extinguishers.
- Know how and when to turn off water, gas and electricity in your home.
- Know where the designated shelters are within your community and how to
get to them.
- Determine if your family has any special needs and develop a plan for
meeting those needs. For example: If you have a family member on a
life‑support system, does your electric utility know about it?
- Post emergency telephone numbers by phones.
- Teach all family members – including children – how and when to call
911.
Weathering
the Storm
If you are traveling, find safe shelter immediately.
If you are at home or at work:
- 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 large containers with water.
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 the windows.
- Lie on the floor under a table or another sturdy object.
- Remain indoors during the hurricane. Don’t be fooled by the “eye” or
the lull that occurs as the storm center moves overhead. The other side of
the hurricane “eye” has winds that will rapidly increase and will come from
the opposite direction.
- If an EVACUATION is ordered by local government officials:
- Follow the instructions and advice of local government officials. If you
are advised to evacuate, do so promptly. If you are advised to go to a
certain location, go there. Don’t go anywhere else.
- If certain travel routes are advised, use those routes rather than
trying to find short cuts. If you are told to shut off water, gas or
electrical service to your home before leaving, do so. Also, find out from
the broadcast reports where emergency housing and feeding stations are
located, in case you need to use them.
- Leave early enough to avoid being marooned on flooded roads.
- Make certain you have enough fuel for your car.
- As you travel, keep listening to the radio for additional instructions.
- Watch for washed‑out roads, earth slides, broken water or sewer mains,
loose or downed electrical wires and falling or fallen objects.
- Watch out for areas where rivers or streams may flood suddenly.
- Don’t try to cross a stream or pool of water unless you are certain that
the water will not be over your knees, or above the middle of your car’s
wheels, all the way across. Sometimes the water will hide a bridge or part
of a road that has been washed out. If you do decide it is safe to cross,
put your car in low gear and drive very slowly to avoid splashing water into
your engine and causing it to stop. Also, remember that your brakes may not
work well after the car has been in deep water. Try them out a few times
when you reach the other side.
When you
hear “hurricane,” think inland flooding:
- Learn your vulnerability to flooding by determining the elevation of
your property. Evaluate your insurance coverage; as construction grows
around areas, floodplains change. If your are in a flood area, consider
what mitigation measure you can do in advance.
- In high flood-prone areas, keep materials on hand like sandbags,
plywood, plastic sheeting, plastic garbage bags, lumber, shovels, work boots
and gloves. Call your local emergency management office to learn how to
construct proper protective measures around your home.
- Be aware of streams, drainage channels and area known to flood, so you
or your evacuation routes are not cut off.
- Monitor local radio / television broadcasts or NOAA Weather Radio.
- Avoid driving into water of unknown depth. Moving water can quickly
sweep your vehicle away.
- Restrict children from playing in flooded areas.
- Test drinking water for potability; wells should be pumped out and the
water tested before drinking.
- Do not use fresh food that has come in contact with floodwaters. Wash
canned goods that come in contact with floodwaters with soap and hot water.
- Stay away from downed power lines.
- Remain where you have taken shelter until informed by local authorities
that it is safe to leave.
- Keep the radio/television turned on for advice and instructions from
local government on where to go for medical care, emergency assistance for
housing, clothing and food, as well as other ways in which you can help your
family and community recover.
- Use the telephone to report life-threatening emergencies only.
- If possible, advise interested relatives and friends that you are safe.
- Stay out of the disaster area. Do not sightsee. Sightseeing disrupts
essential rescue work and may be dangerous.
- Obey all curfew and emergency orders which are issued.
- If you must drive, use caution. Be aware of road and bridge washouts and
storm debris on roadways.
- Avoid loose or dangling wires and report them immediately to the proper
authorities. Assume that all downed wires are alive with electricity.
- Report broken sewer or water mains and downed electrical lines.
- Take extra precautions to prevent fire. Lowered pressure in water mains
may make firefighting extremely difficult.
- Check for gas leaks. Use a flashlight to inspect for damage. Do not use
candles and other open flames indoors.
- Have your electric, gas and water connections checked by professionals
before turning them back on.
- Use your emergency supply or boil water before using until there is
official word that the water is safe.
- Check refrigerated food for spoilage if the power has been off during
the storm.