Tropical weather information

Tropical weather information

What is a tropical storm?

  • A tropical storm is a fierce storm with strong winds rotating around a center of low pressure.
  • When conditions worsen, a tropical storm can be classified as a hurricane.
  • Hurricane season is June 1 to November 30.
  • It's rare, but Atlantic hurricanes have formed as early as March or as late as December.
  • Major hurricanes (Category 3 and above) hit almost exclusively between August and October.
  • Hurricanes have sustained, maximum wind speeds of 73 miles-per-hour or greater.
  • The word "hurricane" is regional -- applying to the north Atlantic Ocean, parts of the northeast Pacific Ocean and parts of the south Pacific Ocean.
  • A typhoon is the same thing occurring in the northwest Pacific Ocean.
  • Hurricanes rotate counter-clockwise in the northern hemisphere.

What determines a storm's strength and path?

  • Generally, warmer ocean water leads to stronger storms.
  • Hurricanes are steered by ocean currents, atmospheric pressures and their own winds.
  • One expert says hurricane movement is like the path of a leaf in a stream.
  • Where do hurricanes usually hit?
  • 36 percent of all American hurricanes hit Florida.
  • 76 percent of Category 4 or higher hurricanes hit Florida or Texas.

Deadliest hurricanes in American history:

  • Galveston, 1900. A Category 4 hurricane left 8,000 people or more dead.
  • South Louisiana, 2005 Hurricane Katrina, a Category 5 storm killed more than 1,800 people
  • Southeast Florida, 1928. A Category 4 storm killed 1836 people.
  • Great Miami Hurricane, 1926. Category 4 devastated Miami, killing at least 800 people.
  • Florida Keys/Southeast Texas, 1919. Some 600 people were killed by a Category 4 storm.
  • New England, 1938. Category 3 hurricane killed about 600 people.
  • Florida Keys "Labor Day Hurricane," 1935. Category 5 storm left 408 people dead.
  • Hurricane Audrey. Southwest Louisiana/NW Texas, 1957. Category 4 storm killed 390 people.

Costliest hurricanes in American history (Adjusted for inflation):

  • Hurricane Katrina. Louisiana (especially New Orleans), 2005. Category 5 storm cost $108 billion
  • Hurricane Andrew. Southeast Florida, 1992. Category 5 storm cost about $34 billion.
  • Hurricane Hugo. South Carolina, 1989. Category 4 hurricane cost $9.7 billion.
  • Hurricane Agnes. Southeast Florida, 1972. Category 1 storm cost $8.6 billion.
  • Hurricane Betsy. Southeast Florida, 1965. Category 3 storm cost $8.5 billion.
  • Hurricane Charley. Florida Gulf Coast. 2004. Category 4 cost an estimated $7.4 billion.
  • Hurricane Camille. Mississippi/Louisiana, 1969. Category 5 cost $6.9 billion.
  • Hurricane Jeanne. Florida, 2004. Category 2 cost estimated $6 billion or more.
  • Hurricane Ivan. 2004. The strong Category 3 storm caused $7 billion in damage.
  • Hurricane Frances. Central Florida, 2004, Category 2 cost an estimated $4.4 billion.

Category 4 and 5 storms:

Since 1900, just four Category 5 storms have hit the continental US. There have been 15 Category 4 storms in that time, including Hurricane Charley.

The last time the US was hit by two hurricanes of Category 4 or above in the same year was 1915. That year a Category 4 storm hit Galveston and another one hit New Orleans.

Category 5 storms since 1900 (in order of intensity):

  1. Hurricane Katrina hit Louisiana in 2005, killing more than 1,800 people.
  2. Unnamed storm hit Florida Keys in 1935, killing 408 people.
  3. Hurricane Camille hit Mississippi in 1969.
  4. Hurricane Andrew hit southeast Florida in 1992.

Hurricane Categories:

The categories are determined by the Saffir-Simpson Scale.

CATEGORY ONE: winds 74-95 mph (64-82 kt or 119-153 km/hr).

  • Storm surge 4-5 feet above normal.
  • No real damage to buildings or structures.
  • Shrubs, loose signs and unanchored mobile homes may sustain some damage. Coastal flooding is possible.

CATEGORY TWO: winds 96-110 mph (83-95 kt or 154-177 km/hr).

  • Storm surge 6-8 feet above normal.
  • Considerable damage to shrubbery and trees as well as to mobile homes, poorly constructed signs and piers.
  • Coastal and low-lying escape routes flood 2-4 hours before arrival of the hurricane center.

CATEGORY THREE: winds 111-130 mph (96-113 kt or 178-209 km/hr).

  • Storm surge generally 9-12 ft above normal. Some damage to small residences.
  • Some large trees blown down. Some mobile homes and poorly constructed signs are destroyed.
  • Flooding near the coast destroys smaller structures.
  • Terrain lower than 5 ft above sea level may be flooded inland 8 miles (13 km) or more.

CATEGORY FOUR: winds 131-155 mph (114-135 kt or 210-249 km/hr).

  • Storm surge generally 13-18 ft above normal.
  • Roofs destroyed on many buildings and residences, Shrubs, trees, and all signs are blown down. Complete destruction of mobile homes. Extensive damage to doors and windows.
  • Terrain lower than 10 ft above sea level may be flooded.

CATEGORY FIVE: winds greater than 155 mph (135 kt or 249 km/hr).

  • Storm surge generally greater than 18 ft above normal.
  • Complete roof failure on many residences and industrial buildings. Some buildings completely destroyed. All shrubs, trees, and signs blown down. Complete destruction of mobile homes.
  • Major damage to lower floors of all structures located less than 15 ft above sea level and within 500 yards of the shoreline.
  • Massive evacuation of residential areas on low ground within 5-10 miles (8-16 km) of the shoreline may be required.