Hurricane Information

Hurricanes effecting Florida, develop over warm waters off the coast of Africa or the Gulf of Mexico and usually strike the coastal areas in the United States and the Caribbean Islands. The hurricane season runs from June 1st through November 30th. August, September and October are peak months for hurricane activity. Unlike tornadoes, hurricanes develop slowly, allowing you some time to prepare. Our greatest hurricane threats for Manatee County are early or late season storms.

 

Hurricane Formation

 

  1. A hurricane is an organized collection of thunderstorms that pumps warm air near the Earth, and exhausts it out the top.
  2. Winds near the ocean surface spiral counterclockwise as they bring humid air into the storm from all directions.
  3. The humid air rises, causing the moisture in it to condense, keeping the thunderstorms going.
  4. Air blowing out the top of the storm forms high clouds that spread for hundreds of miles.
  5. As the storm strengthens, some air begins sinking in the center forming the cloud-free “eye”.


Factors Influencing Hurricane Formation

 

  1. Organized Convection (easterly wave, tropical cyclone)
  2. Ocean Temperature (over 79° F)
  3. Weak Upper-Level Winds (promote convection, concentrate thermal energy)

Hurricane Terminology

 

  • Hurricane Watch: This advisory indicates that conditions are favorable for the formation of a hurricane within 36 hours.
  • Hurricane Warning: This advisory indicates that the hurricane will affect a specific region or immediate area within 24 hours.

Saffir/Simpson Hurricane Scale

 

Type Storm Wind Speed Surge Depth
Tropical Storm 39 to 73 MPH 2 to 4 foot Surge*
No real damage to building structures. Damage to shrubbery and trees. Minor coastal flooding.
Category 1 74 to 95 MPH 4 to 5 foot Surge*
Minor damage to building structures. Damage primarily to unanchored mobile homes, shrubbery and trees. Some coastal road flooding and pier damage.
Category 2 96 to 110 MPH 6 to 8 foot Surge*
Roofing material, door and window damage. Considerable damage to vegetation, mobile homes and piers. Coastal and low-lying escape routes flood 2 to 4 hours before arrival of hurricane center. Small craft at unprotected anchorages break moorings.
Category 3 111 to 130 MPH 9 to 12 foot Surge*
Structural damage to residences and utility buildings with some curtainwall failures. Mobile homes are destroyed. Flooding near the coast destroys small structures with larger structures damaged by floating debris. Terrain lower that 5 feet above sea level flood inland as far as 6 miles.
Category 4 131 to 155 MPH 13 to 18 foot Surge*
Extensive curtainwall failures with some complete roof failure on residences. Major erosion of beach areas. Major damage to lower floors of structures near shore. Terrain lower than 10 feet above sea level flooded requiring evacuation of residential areas inland as far as 6 miles.
Category 5 156 MPH or greater 18 to 24 foot Surge*
Complete roof failure on residences and many industrial buildings. Some complete building failures with small utility buildings blown away. Major damage to lower floors of all structures less than 15 feet above sea level. Evacuation of low-lying areas up to 10 miles of the shore line may be required.
* = Surge values vary considerably depending on coastal configurations and forward speed and direction of the hurricane.