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NEWS | June 1, 2011

Hurricane Season is here ... prepare now

By 628th Civil Engineer Squadron Readiness and Emergency Management

Today begins what can be a very intense and unpredictable six-month-long hurricane season.

It's important to know the difference between a hurricane watch and a hurricane warning. A hurricane watch is an announcement for specific coastal areas that a hurricane or a developing hurricane condition poses a possible threat within 48 hours. A hurricane warning is issued when winds of 74 mph hour or higher associated with a hurricane are expected in a specified coastal area within 36 hours. A hurricane warning can remain in effect when dangerously high water or a combination of dangerously high water and exceptionally high waves continue, even though winds may be less than hurricane force.

What Is A Hurricane?

A hurricane is a tropical storm with winds that have reached a constant speed of 74 mph or more. Hurricane winds blow in a large spiral around a relative calm center known as the "eye." The "eye" is generally 20 to 30 miles wide, and the storm may extend outward 400 miles. As a hurricane nears land, it can bring torrential rains, high winds and storm surges. A single hurricane can last for more than two weeks over open waters and can run a path across the entire length of the eastern seaboard. August through October is the peak of the hurricane season that lasts from June 1 through November 30.

Hurricanes are called "typhoons" in the western Pacific, while similar storms in the Indian Ocean are called "cyclones."

Hurricanes form in the Atlantic Ocean, Gulf of Mexico, Indian Ocean, Caribbean Sea and Pacific Ocean. Around their core, winds grow with great velocity, generating violent seas. As they move ashore, they sweep the ocean inward while spawning tornadoes and producing torrential rains and floods. The 74 to 160 mph hurricane winds can extend inland for hundreds of miles.

Hurricanes can spawn tornadoes which add to the destructiveness of the storm. Floods and flash floods generated by torrential rains also cause damage and loss of life. Following a hurricane, inland streams and rivers can flood and trigger landslides. Even more dangerous than the high winds of a hurricane is the storm surge - a dome of ocean water that can be 20 feet at its peak and 50 to 100 miles wide. The surge can devastate coastal communities as it sweeps ashore. Nine out of 10 hurricane fatalities are attributable to the storm surge.

Tropical cyclones are classified as follows:

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 (34-63 knots).

The U.S. operates off a five-tier system known as the Saffir-Simpson Scale for categorizing the severity of a storm and its potential storm surge.

Category 1 hurricane: Winds between 74 and 95 mph. This hurricane will cause minimal damage, including damaging unanchored mobile homes, vegetation and signs.

Category 2 hurricane: Winds between 96 and 110 mph. This hurricane will cause moderate damage, including damaging all mobile homes, roofs, small crafts and cause flooding.

Category 3 hurricane: Winds between 111 and 130 mph. This hurricane will cause extensive damage, including damaging small buildings and cutting off low-lying roads.

Category 4 hurricane: Winds between 131 and 155 mph. This hurricane will cause extreme damage, including destroying roofs, taking down trees, cutting roads off, destroying mobile homes and flooding beach homes.

Category 5 hurricane: Winds more than 155 mph. This hurricane will cause catastrophic damage, including destroying most buildings, destroying vegetation, cutting off major roads and flooding homes.

In addition to the hurricane scale, Joint Base Charleston uses a slightly different notification system called HURCONs or Hurricane Conditions.

Hurricane Condition 4 - Winds of 58 mph or more are expected within 72 hours

Hurricane Condition 3 - Winds of 58 mph or more are expected within 48 hours

Hurricane Condition 2 - Winds of 58 mph or more are expected within 24 hours

Hurricane Condition 1 - Winds of 58 mph or more are expected within 12 hours

Hurricane Condition Black - Severe winds have passed. All personnel remain in shelter until mission essential personnel perform initial damage assessment.

All Clear - Destructive winds have ceased. Begin recovery operations and listen to the radio or television for information regarding resumption of work schedule and recall personnel as approved by the wing commander.

Rainfall and Flooding

Heavy rains and ocean waters brought ashore by strong winds can cause flooding in excess of 20 inches during a 24-hour period. Hurricanes are capable of producing copious amounts of flash flooding rainfall. During landfall, a hurricane rainfall of 10 to 15 inches or more is common. If the storm is large and moving slowly, less than 10 mph, the rainfall amounts from a well-organized storm are likely to be even more excessive.

The next time you hear hurricane ... think inland flooding!

While storm surge has been the number one cause of hurricane related deaths in the past, more people have died from inland flooding associated with tropical systems in the last 30 years. Since the 1970's, inland flooding has been responsible for more than half of all deaths associated with tropical cyclones in the United States. Flooding from hurricanes can occur hundreds of miles from the coast placing communities, which would not normally be affected by the strongest hurricane winds, in great danger.

Some of the greatest rainfall amounts associated with tropical systems occur from weaker Tropical Storms that have a slow forward speed (one to 10 mph) or stall over an area. Due to the amount of rainfall a Tropical Storm can produce, they are capable of causing as much damage as a Category 2 hurricane.

· Freshwater floods accounted for more than half of U.S. tropical cyclone deaths during the past 30 years.
· During the past 30 years, 78 percent of children killed by tropical cyclones drowned in freshwater floods.
· One cubic yard of water weighs 1,700 lbs. The average automobile weighs 3,400 lbs. Many automobiles will float in just two feet of water.
· The average person can be swept off their feet in six inches of moving water.
· The average automobile can be swept off the road in 12 inches of moving water.
· At least 23 percent of U.S. tropical cyclone deaths occur to people who drown in, or are attempting to abandon their cars.
· Rainfall is typically heavier with slower moving storms

Storm Surge

Storm surge is an abnormal increase in the ocean's level, sometimes in excess of several meters high and several miles wide. Storm surges can come ashore up to five hours before the storm and destroy low-elevation coastal areas. It is especially damaging when the storm surge occurs during high tide and consequently is often responsible for most hurricane-related deaths. 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. Storm surge can range from four to six feet for a minimal hurricane to greater than 20 feet for the stronger ones. 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, even more so than the high winds. More than 6,000 people were killed in the Galveston Hurricane of 1900, most by storm surge. Hurricane Camille produced a 25-foot storm surge in Mississippi. Hurricane Hugo generated a 20-foot storm tide in South Carolina in 1989.


Hurricanes also produce tornadoes which add to the hurricane's destructive power. Typically, the more intense a hurricane is, the greater the tornado threat. The greatest concentration of tornadoes occurs in the right front quadrant of the hurricane. Ten percent of deaths in the United States associated with hurricanes are a result of tornadoes. Most tornadoes occur within 24 hours after hurricane landfall. Most tornadoes occur within 150 miles of the coastline and occur during the morning and afternoon rather than evening or night due to the need for a tornado to have a heat source. The majority of tornadoes occur within 30 miles of the center of the cyclone, but there is a secondary maximum further away in the outer rain bands (100-150 miles away from the center). Tornado winds can reach up to 300 mph at a forward speed of 60 mph and are usually 100-300 yards wide.

Emergency Supplies

Putting together an emergency supply kit as well as a "go bag" in the event of an evacuation is a must. All household members should know where the kits are located and what the family evacuation plan is. Don't forget to include your pets in your planning. The number of items included in a disaster kit is limited only by imagination. Build your kit only as big as you can carry since you might have to walk. Some items to include are:

Prescription medications                                Required medical supplies
Maps of evacuation routes                              Non-perishable food items
Cash (ATMs may not be working)                  Battery-operated radio
First-aid kit
Bottled water                                                      Full tank of vehicle fuel
Clothing (include sturdy walking shoes)      Bedding
Playing cards                                                     Cell phone with charger
Important documents (social security cards, proof of residency and insurance policies)


For military and civilian personnel living on Joint Base Charleston, the 628th Air Base Wing commander will give the evacuation order when it is necessary for personnel to leave. Military and civilian personnel living off the installation will obey the evacuation orders of civil authorities. Personnel are authorized and will be refunded for travel up to 500 miles away from the installation. This mandatory relocation will be funded for travel and per diem in accordance with the Joint Travel Regulation or the Joint Federal Travel Regulation.

This evacuation process does not apply to hurricane ride-out team personnel who will relocate from their on-base or off-base housing into designated facilities on the base. Their dependents, if applicable, should evacuate and are entitled to fund IAW the JTR/JFTR as per the rules set forth in paragraph 1.

Individuals engaged in mandatory evacuation activities are authorized to use the Government Travel Card for travel related expenses (i.e., meals, gas charges and lodging). Individuals should keep receipts for all lodging expenses (regardless of cost) and any other expenses more than $75. If in doubt, keep all receipts.

All evacuated personnel are further ordered to notify both their unit and appropriate service branch of their evacuation location and where they may be reached. Such notification shall be made no later than 24 hours from the issue of the evacuation order.
Accountability will be a priority for commanders. Follow your commander's directives! As a minimum make sure you report in to the following:

Air Force: or 1-800-435-9941
Army: or (703) 805-1014
Coast Guard: 1-866-504-USCG
Navy: or 1-866-946-9183

The JB CHS Installation Office of Emergency Management has natural disaster handbooks and South Carolina Hurricane handbooks available for free. They can also be found on the Air Force Portal on the JB CHS Readiness and Emergency Management Community of Practice. The JB CHS Installation Office of Emergency Management is also available to conduct more in depth hurricane briefings at Commanders Calls, musters and other meetings upon request.

The Federal Emergency Management Agency has a web site dedicated to providing disaster information to the public. Visit for a full list of emergency supplies and how to make a disaster plan. More hurricane information can be found by visiting