Hurricanes and Tropical Storms
Tropical cyclones are circulating weather systems (counter clockwise in the northern hemisphere) over tropical waters. They bring powerful winds, rain, flooding and tornadoes. These are types of tropical cyclones that you will hear forecasters talk about:
- Tropical Depression: An organized system of clouds and thunderstorms with a defined circulation and maximum sustained winds of 38 mph (33 knots) or less.
- Tropical Storm: An organized system of strong thunderstorms with a defined circulation and maximum sustained winds of 39 to 73 mph (34 to 63 knots).
- 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 season begins in June and continues through November. Most hurricane activity occurs in late summer and early fall. Detailed information about hurricanes is available through the National Hurricane Center.
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, often spawning tornadoes and producing torrential rains and floods. They begin to die once they move over land and lose the moisture from the ocean.
Personal and Community Preparedness
Hurricanes most frequently and severely hit the Gulf Coast and southern states, but they do affect the mid-Atlantic region, mostly through flooding.
Every Baltimore County household should have basic disaster supplies and a home preparedness plan. Citizens also should understand what it means to shelter in place and to evacuate, and to be prepared to follow instructions from local emergency management officials regarding whether to stay or go. We suggest that you use www.readysetgood.org as a guide to your personal preparedness.
You may also want to get involved with Community Emergency Preparedness Training, which teaches citizens to take care of themselves and their neighbors after a disaster.
If you live in a coastal or low-lying, flood-prone area, you need to take special precautions:
- Obtain and store materials, such as plywood, necessary to properly secure your home.
- Learn safe routes inland.
- Clear loose and clogged rain gutters and downspouts.
- Learn location of official shelters.
- Keep trees and shrubbery trimmed.
- Review needs and working condition of emergency equipment, such as flashlights and battery-powered radios.
- Determine where to move your boat in an emergency.
- Review your insurance policy.
Terms You Should Know
The National Weather Service continuously broadcasts updated hurricane advisories that can be received by weather alert 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.
Listen for these terms:
- 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
During the Storm...
If you are in a "watch" area:
- 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.
- Replenish your disaster supplies, if necessary.
- 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.
Plan to evacuate if you live in a mobile home, on the coast, an offshore island, near a river or a flood plain or live in a high-rise (hurricane winds are stronger at higher elevations).
If you are in a warning area:
- Closely monitor radio, TV, or NOAA weather radio for official bulletins.
- Complete preparation activities, such as putting up storm shutters and storing loose objects.
- Follow instructions issued by local officials. Leave immediately if told to do so!
- If evacuating, leave early (if possible, in daylight).
- Notify neighbors and a family member outside of the warned area of your evacuation plans.
- Make food and water available for a pet if you cannot take it with you and have not made plans for it. Public health regulations prohibit pets in public shelters, and most hotels and motels do not allow them.
If you go to a shelter, bring the following:
- A first-aid kit and medicines
- Baby food and diapers
- Cards, games and books
- A battery-powered radio
- A flashlight with extra batteries
- Blankets or sleeping bags
- Identification, valuable papers (including insurance) and cash.
If you stay in a home:
Stay in a home if you have Not been ordered to leave. Stay inside a well-constructed building. Examine the building before the storm hits and plan what you will do if winds become strong. Strong winds can produce deadly missiles and structural failure.
- Turn the refrigerator to maximum cold and open only when necessary.
- Turn off propane tanks.
- Unplug small appliances.
- Turn off utilities if told to do so by authorities.
- Fill bathtub and large containers with water for sanitation.
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.
- Be alert for tornadoes, which often are spawned by hurricanes.
After the Storm:
- Keep listening to radio, TV, or NOAA Weather Radio.
- Wait until an area is declared safe before re-entering.
- Call 911 only for life-threatening emergencies only. The county will set up public service phone lines to handle other calls during a crisis.
- 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. Even six inches of moving water can sweep you off your feet. Standing water may be electrically charged from underground 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. Follow health officials instructions for food and water safety.
- Do not use candles and other open flames indoors. Use a flashlight to inspect for damage.
- Remember that fallen trees are the property owner's responsibility, unless they obstruct a roadway. Call 911 to report fallen trees that have become entangled with power lines.
Saffir-Simpson Hurricane Scale
Hurricanes are ranked according to the strength of their winds. However, a hurricane does not need to be a Category 4 or 5 to cause serious damage. A tropical system's heavy rains and flooding usually cause the most damage and loss of life.
In 1972, Hurricane Agnes was a weak Category 1 when it came ashore, but its heavy rains caused flooding that resulted in billions in damage and killed 129 people.
Examples (States Affected)
74 to 95
Florence (1988) (Los Angeles)
96 to 110
Kate 1985 (Florida Panhandle)
111 to 130
Alicia 1983 (N Texas)
131 to 155
Andrew 1992 (South Florida)
Camille 1969 (Los Angeles and Mississippi)
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.
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.
A 15-foot surge added to the normal two-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.
Revised May 1, 2014