How and Where Hurricanes Form
Counterclockwise winds draw heat and moisture from the tropical ocean, contributing to the formation of an intense and strong tropical cyclone. Hurricane proportions are reached when winds are sustained at 74 miles per hour (mph) or more. This air revolves around a relatively calm 20- to 30-mile-wide eye, spreading outward almost 400 miles. As the storm moves forward at about 15 mph, it releases heavy rains and accelerating winds and causes the ocean to swell. Hurricanes may be preceded by a tornado in the right front quadrant. Losing some intensity as it approaches land, the storm brings severe rains, wind and storm surges that inundate coastal areas. Moving further inland, a hurricane loses strength but continues its outpouring of rain and high winds.
Hurricanes are formed in the North Atlantic, Caribbean Sea, Gulf of Mexico and the Pacific Coast of Mexico. The greatest likelihood of a hurricane striking land areas is along the Gulf Coast and the southeastern seaboard. But hurricanes also have hit central Pennsylvania and the coast of New Jersey, New York and New England.
Over land, hurricanes break up rapidly. Cut off from their oceanic source of energy and with the added effects of frictional drag from land, their circulation rapidly weakens and becomes more disorganized. Torrential rains, however, may continue even after the winds are much diminished. In the southeastern United States, about one-fourth of the annual rainfall comes from dissipating hurricanes.
The Atlantic hurricane season lasts from June through November. August and September are peak months. There is no “season” for Pacific hurricanes. Hurricanes occur north of the equator over the Atlantic and Pacific oceans. Typhoons occur in the South Pacific. Tropical cyclones occur over the Indian Ocean. All of these storms are the same phenomenon.
How to Prepare for a Hurricane
1. Know the risks of the area. If you live in an Atlantic or Gulf Coastal state within 100 miles of the shore, or on Hawaii, Puerto Rico, the U.S. Virgin Islands, Guam American Samoa or Palau, you are subject to devastating effects from hurricanes.
2. Know what a hurricane “watch” and “warning” mean.
- A Hurricane Watch means a hurricane may hit your area.
- A Hurricane Warning means a hurricane is headed for your area. You may be told to move to a shelter or evacuate the area. Do so immediately.
3. Review your family disaster plan.
- Check straps and anchors for manufactured homes, sheds and outbuildings.
- Install hurricane shutters or pre cut inch marine plywood for each window of your home. Install anchors for the plywood and pre drill holes in it so that you can put up the plywood quickly when a WATCH is issued.
- Make trees more wind resistant by strategically removing branches so that wind can blow through them. Remove diseased or damaged limbs.
Actions During a Hurricane Situation
1. During a watch (24 to 36 hours before landfall):
- Cover ALL windows of your home. If shutters are not installed, use precut plywood. If you do not have plywood, do what you can to protect windows from breaking. Tape does not work. Remove tree limbs, branches, shrubbery and other objects that can break windows.
- Recheck manufactured home tie-downs.
- Listen to the advice of local officials and leave if told to do so.
- Take in lawn furniture, outdoor decorations or ornaments, trash cans, hanging plants and anything else that can be picked up by the wind and become a missile of destruction.
2. During a warning (24 hours before landfall):
- Evacuate if you are advised to do so. See the General Family Preparedness section for steps that should be taken. Also see the Floods section if heavy rains or flooding are present.
- If you are not advised to evacuate, stay indoors and away from windows.
- Be aware of the calm “eye,” the storm is not over. The worst part of the storm will happen when the eye passes over and wind comes from the opposite direction. Trees, shrubs, buildings and other objects damaged by the first winds can be broken or destroyed by the second winds, whose force is opposite the direction of the first winds.
- Be alert for tornadoes. Tornadoes can happen during and after a hurricane passes over. Remain indoors, in the center of your home, in a closet or bathroom without windows. The section on Tornadoes offers additional information you will need if a tornado occurs.
Basic Response After a Hurricane
1. Wait until an area is declared safe before entering.
- Roads may be closed because they have been damaged or are covered by water. Barricades have been placed for your protection. If you come upon a barricade or a flooded road, go another way.
- Keep listening to the radio for news about what to do, where to go or places to avoid.
2. If you must walk or drive in areas that have been affected by the hurricane, stay on firm ground. Moving water only 6 inches deep can sweep you off your feet. Standing water may be electrically charged from underground or downed power lines.
3. Check gas, water and electrical lines and appliances for damage. Use a flashlight to inspect for damage.
If necessary, turn off main gas valves and electrical switches or fuses. Have these services restored by a professional.
4. Use the telephone to report life-threatening emergencies only.
5. If you need assistance, visit your local Red Cross service center or chapter facility. State and federal agencies often provide assistance to individuals, families and businesses after larger storms. Listen to the radio for information on how to obtain governmental assistance.