HURRICANES

Hurricanes are tropical cyclones that affect North America from the Caribbean, Atlantic and Eastern Pacific Ocean.

Hurricanes that occur in the early part of the season (June and July) generally are spawned in the southern Caribbean near the Yucatan peninsula and move northward threatening the Gulf Coast and Florida. Later in the season (August through October), they are spawned off the west coast of Africa west of the Sahara Desert. As they are pushed westward by the equatorial trade winds, they gain strength and threaten the Caribbean Islands, Florida and the east coast of the U.S.

Hurricanes are categorized by the National Weather Service using the Saffir-Simpson Scale. Each jump in category indicates a doubling of the damaging effects of the winds.

Tropical storms and hurricanes are categorized as follows:

Tropical Storms: 39 to 73 mph. 39 mph is where outdoor furniture, bicycles and other toys are vulnerable to being knocked over or carried away. Trash cans can roll away and small dead branches can break. Small hail may be associated with these storms.

Category one hurricane (minimal): 74 to 95 mph. A storm surge of 4 to 5 feet above normal is expected in coastal areas and some beach erosion may occur. Structural damage is limited primarily to light, unanchored mobile homes and travel trailers, poorly constructed signs and dead limbs on trees. Expect some coastal and inland road flooding due to heavy rains and minor pier damage.

Category two hurricane (moderate): 96 to 110 mph. Storm surge is generally 6 to 8 feet above normal. Some roofing material, door and window damage is expected. Shrubbery and trees will be blown down. Expect considerable damage to mobile homes, poorly constructed signs and piers. Coastal and low-lying escape routes will flood 2 to 4 hours before the eye of the storm arrives. Small craft in unprotected anchorages will break moorings.

Category three hurricane (extensive): 111 to 130 mph. Expect a storm surge 9 to 12 feet above normal. Moderate structural damage is expected to small residences and utility buildings with minor curtainwall failures. Shrubbery is severely damaged and deciduous trees with foliage will lose limbs and become flying debris. Mobile homes will be destroyed. Low-lying escape routes are cut by rising water 3 to 5 hours before the eye arrives. Flooding near the coast destroys smaller structures. Larger structures are severely damaged by battering from floating debris. Terrain continuously lower than five feet above mean sea level may be flooded inland 8 miles or more. Evacuation of low-lying residences within several blocks of the shoreline may be required.

Category four hurricane (extreme): 131 to 155 mph. Storm surge is generally 13 to 18 feet above normal. More extensive curtainwall failures with some complete roof structure failures on small residences. Shrubs, trees and all signs are blown away. Complete destruction of mobile homes. Survival is unlikely. Extensive damage to doors and windows. Low-lying escape routes may be cut 5 hours before the arrival of the eye of the storm. Major damage to lower floors of structures within a mile of the shoreline. Terrain lower than 10 feet above mean sea level are likely to be flooded requiring massive evacuation of areas as far inland as 6 miles or more.

Category five hurricane (catastrophic): Winds greater than 155 mph. Storm surge greater than 18 feet above normal. Complete roof failure on many residences and industrial buildings. Some complete building failures with small anchored utility buildings destroyed and blown away. All shrubs, trees and signs destroyed and blown away. Complete destruction of mobile homes with survival unlikely. Severe and extensive window and door damage to all building types. Low-lying escape routes are cut by rising water at least 5 hours before the eye of the storm arriving. Major damage or complete destruction of lower floors of all structures located less than 15 feet above mean sea level and within a mile of the shoreline. Massive evacuation of area on low ground with 10 miles of the shoreline are required.

TORNADOES

Tornadoes are whirlwind storms that are generated from severe thunderstorms. They are very compact generating high winds in small spaces compared to hurricanes. These whirlwinds can be funnel clouds that do not touch the ground. Once they touch down they are officially tornadoes. The photo above appears to be a funnel cloud that is not on the ground, but a closer look reveals that there is damage being done on the ground, making it a real tornado. They can be deceptive. When over water, they are known as waterspouts. Tornadoes are classified by the National Weather Service on the Enhanced Fujita Scale.

Category EF-0 (gale tornado): 40 to 72 mph. Light damage. Some damage to chimneys can be expected. Tree branches break, shallow-rooted trees are pushed over and sign boards are damaged or broken.

Category EF-1 (moderate tornado): 73 to 112 mph. Roof surfaces are peeled off, mobile homes are pushed off foundations or overturned and moving automobiles will be pushed off roads.

Category EF-2 (significant tornado): 113 to 157 mph. Expect considerable damage to structures. Roofs will be torn off frame houses, mobile homes will be destroyed, boxcars will be derailed and pushed over and large trees will be snapped, blown over and/or uprooted generating light object missiles.

Category EF-3 (severe tornado): 158 to 206 mph. Severe damage will occur to well-constructed buildings. Roofs and walls will be torn off, trains will be derailed and overturned, most trees will be uprooted and heavy motor vehicles will be lifted off the ground and sent great distances as missiles.

Category EF-4 (devastating tornado): 207 to 260 mph. Expect devastating damage to most buildings. Survival is unlikely without appropriate shelter. Well-constructed homes will be leveled. Any structures on weak foundations will be blown off and sent some distance. Most motor vehicles will become airborne and travel as deadly missiles.

Category EF-5 (incredible tornado): 261 to 318 mph. Incredible damage of epic proportions. Most well-built structures will be severely damaged or completely destroyed with survival unlikely. Buildings destroyed will disintegrate and parts traveling great distances as missiles. All motor vehicles, including trains will likely become airborne and travel great distances as deadly missiles. Most, if not all vegetation, including trees, shrubs and grass will be uprooted and destroyed. Incredible phenomena will occur.

FACTS RELATED TO HURRICANES AND TORNADOES TOGETHER.

When local weather forecasters state that a hurricane will reach a certain area at a certain time, that is when the EYE of the hurricane will arrive. By that time, two-thirds of the damage will have been done and it will be too late to escape. The damaging effects of the storm will be felt many hours before the eye arrives depending on the forward speed of the storm.

Another common phenomenon of hurricanes that is not widely publicized, but we think is very important is that hurricanes commonly spawn tornadoes that can do more damage than the hurricane by itself.

For example, if a category two hurricane with 105 mph winds moving northward at a speed of 15 mph has an EF-2 tornado within it on its eastern side, all the effects are cumulative. That means that you need to add the 105 mph winds of the hurricane with its forward speed of 15 mph and the 140 mph average wind speed of the tornado together. That means that you could experience 260 mph winds with little or no notice, causing considerable damage.

This is what happened when Hurricane Charley hit Orlando on the evening of August 13, 2004. The area east of the eye hit the downtown area after sundown and the area from Orlando International Airport to Winter Park suffered damage from 106 mph sustained winds, but the damage was consistent with a much stronger storm. Later radar research revealed that two tornadoes touched down and damaged or destroyed homes within a narrow path from International Airport to Executive Airport west of Semoran Blvd. Where the tornadoes did not touch down, damage was less severe. When one of the twisters again touched down again in the Winter Park area, more damage was seen.