Hurricanes

What conditions lead to the development of Hurricanes?

• When warm, wet air over the sea starts to rise quickly, air, water and heat combine to make a huge, spinning system of clouds, rain and wind. Hurricanes usually last 9-12 days. They form and build strength over warmer sea water, than as they approach cooler sea water, or land they lose energy.

Where do Hurricanes occur?

• Hurricanes form over warmer ocean water. No two hurricanes ever follow the same path, but they do follow general paths in the areas where they occur. Hurricanes that strike the mainland of the United States generally form in the South Atlantic Ocean, from there the move northward. The most commonly strike Caribbean Islands, that states along the Gulf of Mexico, and the Atlantic coastal states. Hurricanelike storms in the Indian Ocean, or referred to as Tropical Cyclones.

How do water and air impact the development of Hurricanes?

• The Earth's rotation creates something known as the Coriolis effect. The Coriolis Effect also starts cyclonic rotation, but it is not the force that initiates the high speeds of rotation. Combined with pressure gradient, and friction force the Coriolis Effect causes winds to spiral upward, the more force the faster the wind can spin and pick up additional energy.

How do Meteorologists track Hurricanes?

• The Saffir-Simpson Hurricane Wind Scale is a 1-5 rating based on a hurricanes wind speed. Hurricanes that reach Category 3 or higher are considered major hurricanes because of their threat to humans, and property. Category 1 and 2 hurricanes are still dangerous, and safety precautions are still taken.

Category 1.

74-95 mphVery dangerous winds will produce some damage: Well-constructed frame homes could have damage to roof, shingles, vinyl siding and gutters. Large branches of trees will snap and shallowly rooted trees may be toppled. Extensive damage to power lines and poles likely will result in power outages that could last a few to several days.

Category 2.

96-110 mph• Extremely dangerous winds will cause extensive damage: Well-constructed frame homes could sustain major roof

and siding damage. Many shallowly rooted trees will be snapped or uprooted and block numerous roads. Near-total power loss is expected with outages that could last from several days to weeks.

Category 3. (major)

111-129 mph• Devastating damage will occur: Well-built framed homes may incur major damage or removal of roof decking and

gable ends. Many trees will be snapped or uprooted, blocking numerous roads. Electricity and water will be unavailable for several days to weeks after the storm passes.

Category 4. (major)

130-156 mph• Catastrophic damage will occur: Well-built framed homes can sustain severe damage with loss of most of the roof

structure and/or some exterior walls. Most trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last weeks to possibly months. Most of the area will be uninhabitable for weeks or months.

Category 5. (major)

157 mph or higher• Catastrophic damage will occur: A high percentage of framed homes will be destroyed, with total roof failure and

wall collapse. Fallen trees and power poles will isolate residential areas. Power outages will last for weeks to possibly months. Most of the area will be uninhabitable for weeks or months.

Hurricane KatrinaBegan: August 23, 2005Ended: September 3, 2005Highest winds: 175 mph (280 km/h)Fatalities 1,833 confirmedDamages: $108 billionAreas affected: Bahamas, South Florida, Cuba, Louisiana (especially New Orleans), Mississippi, Alabama, Florida, most of eastern North America.