Hurricane_Isabel_from_ISS

Hurricane

A hurricane is an intense weather system in which the maximum average wind speed near a center or eye exceeds 74 mph or 119 km/h. The winds rotate in a counter-clockwise spiral around a region of low pressure. Hurricanes occur in the Atlantic and Eastern Pacific. A hurricane watch is issued when there is a threat of hurricane conditions within 24-36 hours. A hurricane warning is issued when hurricane conditions (winds of 74 miles per hour or greater or dangerously high water and rough seas) are expected in 24 hours or less.

Hurricanes only form over really warm ocean water of 80°F or warmer. The atmosphere (the air) must cool off very quickly the higher you go. Also, the wind must be blowing in the same direction and at the same speed to force air upward from the ocean surface. Winds flow outward above the storm allowing the air below to rise. Hurricanes typically form between 5 to 15 degrees latitude north and south of the equator. The Coriolis Force is needed to create the spin in the hurricane and it becomes too weak near the equator, so it is unlikely hurricanes will form there. (Coriolis Force- A force that deflects moving objects to one side because of the Earth’s rotation. The object is still going straight but the Earth moves underneath it, making it look like it is moving to one side. In the Northern Hemisphere, the Coriolis Force deflects objects to the right).

Hurricane Stages
Tropical Wave A low pressure trough moving generally westward with the trade winds.
Tropical Disturbance An organized area of thunderstorms that usually form in the tropics. Typically, they maintain their identity for 24 hours and are accompanied by heavy rains and gusty winds.
Tropical Cyclone A generic term for any organized low pressure that develops over tropical and sometimes sub-tropical waters. Tropical depressions, tropical storms, and hurricanes are all examples of tropical cyclones.
Tropical Depression An organized area of low pressure in which sustained winds are 38 mph or less.
Tropical Storm A tropical cyclone with maximum sustained wind speeds that range from 39 to 73 mph.
Hurricane A tropical cyclone with sustained winds of at least 74 mph.

Hurricanes begin as tropical storms over the warm moist waters of the Atlantic and Pacific Oceans near the equator. (Near the Philippines and the China Sea, hurricanes are called typhoons.) As the moisture evaporates it rises until enormous amounts of heated moist air are twisted high in the atmosphere. The winds begin to circle counterclockwise north of the equator or clockwise south of the equator. The relatively peaceful center of the hurricane is called the eye. Around this center winds move at speeds between 74 and 200 miles per hour. As long as the hurricane remains over waters of 79 degrees Fahrenheit or warmer, it continues to pull moisture from the surface and grow in size and force. When a hurricane crosses land or cooler waters, it loses its source of power, and its wind gradually slow until it is no longer of hurricane force–less than 74 miles per hour.

Effects of a hurricane

Tropical cyclones out at sea cause large waves, heavy rain, and high winds. This can result in the disruption of international shipping and shipwrecks. On land, strong winds can damage or destroy vehicles, buildings, bridges, and other outside objects, turning loose debris into deadly flying projectiles. The storm surge or the increase in sea level due to the cyclone, is typically the worst effect from land-falling tropical cyclones. Historically, storm surges are responsible for 90% of tropical cyclone deaths.

Over the past two centuries, tropical cyclones have been responsible for the deaths of about 1.9 million people worldwide. Large areas of water caused by flooding, including stagnant water, can lead to infection, as well as contribute to mosquito-borne illnesses. Crowded evacuees in shelters increase the risk of disease spreading.

Tropical cyclones significantly interrupt infrastructure, leading to power outages, bridge destruction, and the hampering of reconstruction efforts. On the other hand, these storms sometimes bring much needed rain to very dry areas.

Things to do before a hurricane

  • Keep your radio or television on and listen for the latest warnings and advisories.
  • Board up or install shutters over all windows, doors, skylights and open vents.
  • Secure all doors by bolting and wedging.
  • Lower television and radio antennae.
  • Remove loose objects from the yard and patio.
  • Prune branches from trees.
  • Tie down any large objects that cannot be brought indoors.
  • Recharge appropriate equipment (such as cell phones and rechargeable flashlights).
  • Close all outside electrical outlets and cover with duct tape.
  • Store as much drinking water as possible in clean closed containers.
  • Put personal papers and other important documents in a waterproof container and keep nearby.
  • Prepare a hurricane disaster supplies kit.
  • Keep your vehicle filled with gas, and have extra cash on hand.
  • Unless advised to evacuate, stay at home. Remain indoors in the middle of the house away from windows and doors.
  • Beware of calm conditions (a lull in the wind lasting from a few minutes to about half an hour) when the eye of the storm passes over. Stay indoors until the entire storm has passed.

Hurricane disaster supplies kit

  • Radio and flashlight with extra batteries
  • Adequate non-perishable food, canned and dry goods
  • Paper plates, cups, cutlery
  • Adequate prescription medicines
  • Sufficient drinking water
  • Personal hygiene items
  • Special infant needs, games and toys
  • First aid supplies
  • Fire extinguisher
  • Change of clothes
  • Blankets and pillow or sleeping bags
  • Games, books etc
  • Identification cards

Evacuation procedures

  • Follow the instructions and advice of local authorities.
  • Lock all windows and doors.
  • Turn off electricity at the main box.
  • Take personal papers and important documents with you in a  waterproof container.
  • Carry as much hurricane disaster supplies as you can manage.
  • Arrive at the shelter as promptly as possible and no later than the expected arrival time of tropical storm force winds.

After the storm

  • Stay tuned to a radio station issuing emergency bulletins and updates with the latest information.
  • Avoid driving unless necessary as roads may be blocked.
  • Stay away from fallen or damaged electrical wires.
  • Do not turn the power on at your home if there is flooding or water present.
  • Ensure that all electrical appliances are dry before turning on the main power switch.
  • Check your food and water supplies before using them. For cooking and drinking purposes use only safely stored water or boil your tap water.
  • To avoid overloading the system, use the phone only for emergencies.
  • Report any damage to your insurance broker as soon as possible (take pictures of damage).

Major Hurricanes in Antigua and Barbuda

  • 1670 – New town of St. John’s rebuilt after French invasion destroyed by hurricane.
  • 1795 – Violent hurricane accompanied by an earthquake.
  • 1871 – A hurricane blew down Scotch Kirk and one of the two old slave dungeons at Parson Mules and also wiped out an entire village. Thirty-five lives were lost. Antigua was so devastated people emigrated to Trinidad and Guadeloupe.
  • 1924 – Two hurricanes hit Antigua. Country pond flooded and split Nevis Street in two.
  • 1950 – Two hurricanes struck within 10 days. Most of the wattle and daub houses were destroyed. The village of Hamilton, located between the villages of Bendals and Breaknock, was blown off the map.
  • 1989 – Hurricane Hugo passed with full violence felt. Fifteen percent of the houses were damaged and electricity severely affected. Five hundred and nine (509) people were left homeless, two dead, 181 injured. Damage was estimated at $199,999,000.
  • 1995 – Hurricane Luis. Two people died and there was extensive damage estimated at $461,484,105.
  • 1998 – Hurricane Georges. Two people died. Damage was estimated at $209,999,508.
  • 1999 – Hurricanes Jose and Tropical Storm Lenny.One person died from Hurricane Jose and one also died from Tropical Storm Lenny. Estimated damage was $ 207,429,400.
  • 2008 – Hurricane Omar. Estimated damage $ 44,942,590.
  • 2010 – Hurricane Earl. Estimated damage $ 34,141,390.73.