IMPORTANT TROPICAL TERMS
- Tropical Cyclone – A general term used to describe a tropical depression, tropical storm, or hurricane.
- Tropical Disturbance – A poorly organized cluster of thunderstorms that usually has no closed surface circulation.
- Tropical Depression – A cluster of thunderstorms organized around a central circulation with surface winds of 38 mph or less.
- Tropical Storm – A cluster of thunderstorms with a substantial rotary circulation and sustained winds of 39-73 mph. It is at this stage of development that the storm is assigned a name.
- Hurricane – A severe tropical cyclone that is nature’s most powerful storm, with sustained winds of 74 mph or greater.
- Hurricane/Tropical Storm Watch – Hurricane or Tropical Storm conditions are possible in the watch area within 36 hours.
- Hurricane/Tropical Storm Warning – Hurricane or Tropical Storm conditions are expected in the warning area within 24 hours.
WHAT IS A HURRICANE?
- A hurricane is a fierce storm with strong winds rotating around a moving center of low atmospheric pressure.
- Hurricanes rotate counter-clockwise in the northern hemisphere.
- Maximum wind speeds must be 73 miles per hour or more. Once winds go below 73 miles per hour, it is a tropical storm.
- The word hurricane is regional — applying to tropical cyclones in 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.
- Hurricane season lasts June 1 through November 30. It is rare, but hurricanes have formed in the Atlantic as early as March or as late as December.
WHERE DO THEY USUALLY HIT?
- 36% of all U.S. hurricanes hit Florida.
- 76% of Category 4 or higher hurricanes hit Florida or Texas.
HOW MANY CATEGORY FOUR AND FIVE STORMS HAVE HIT?
- Since 1900, just three Category 5 storms have hit the continental U.S. There have been 15 Category 4 storms in that time, including Hurricane Charley.
- The last time the U.S. 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) Unnamed storm hit Florida Keys in 1935, killing 408 people, 2) Hurricane Camille hit Mississippi in 1969, and 3) 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.
- Example: Hurricane Bonnie hit the North Carolina coast in 1998.
CATEGORY THREE: winds 111-129 mph (96-112 kt or 178-208 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.
- Example: Hurricane Fran hit North Carolina in 1996.
CATEGORY FOUR: winds 130-156 mph (113-136 kt or 209-251 km/hr).
- Storm surge generally 13-18 ft above normal.
- Roofs destroyed on buildings and residences, Shrubs, trees, and signs blown down. Destruction of mobile homes. Extensive doors & window damage.
- Terrain lower than 10 ft above sea level may be flooded.
- Example: Hurricane Luis passed over the Leeward Islands in 1995.
CATEGORY FIVE: winds greater than 157 mph (137 kt or 252 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.
- Example: Hurricane Andrew hit Florida in 1992.
(Source: Associated Press)
Notable hurricanes that have affected Texas since 1900, with death and damage totals for Texas only. (The National Weather Service did not start naming storms until the 1950s.)
- Sept. 15, 2008: Ike, with winds of 110 mph was very unusual in that it produced a much higher storm surge – 10-15 ft above mean sea level – than would normally be expected from a category 2 hurricane. It was the storm surge that caused the most of the damage not the wind. Ike made landfall on Galveston Island, killing 34 people and causing $22 billion in damage, the third costliest hurricane in U.S. history.
- July 23, 2008: Dolly, with 85 mph sustained winds made landfall in South Padre Island, Texas. The storm caused 212,000 customers to lose power in Deep South Texas, and dropped estimated rainfall amounts of over 16 inches in isolated areas. Dolly had no direct deaths in Texas but did cause an estimated $1.05 billion in damage.
- Sept. 24, 2005: Rita, storm carrying 120 mph winds hit between Sabine Pass and Johnson’s Bayou along Texas-Louisiana line. About 100 deaths reported, many during the evacuation of Houston and coastal counties near Houston. Damages estimated at $4.7 billion.
- July 20, 2005: Emily, storm packing 125 mph winds hit near San Fernando, Mexico, a coastal town about 85 miles south of Brownsville. Minimal damage reported in South Padre and Port Isabel. No deaths or serious injuries.
- July 15, 2003: Claudette, Matagorda Bay-Victoria; two inland deaths, $180 million in damage across central Texas coast from winds peaking near 100 mph.
- Aug. 22, 1999: Bret, Kenedy County; four highway deaths in Laredo, scattered damage as storm with 140 mph winds moved into sparsely populated region.
- Sept. 16-18, 1988: Gilbert, 125 miles south of Brownsville; one dead in San Antonio; tornado and wind damage of $5 million in Brownsville, Del Rio, and San Antonio.
- Aug. 18, 1983: Alicia, Galveston-Houston; 21 dead, more than $2 billion damage; 22 tornadoes, winds 130 mph. Last major hurricane to strike Texas.
- Aug. 9, 1980: Allen, lower coast; two dead, $55 million damage; winds 185 mph.
- Sept. 3-12, 1971: Fern, middle coast; two dead, $30.2 million damage.
- Aug. 3, 1970: Celia, Corpus Christi; 11 dead, $50 million damage; wind gusts to 160 mph.
- Sept. 18-23, 1967: Beulah, Brownsville; 13 dead, $150 million damage.
- Sept. 11-13, 1961: Carla, Port O’Connor-Galveston-Houston; 34 dead, $300 million damage; wind gusts estimated at 175 mph, storm tide 18.5 feet at Port Lavaca.
- June 27, 1957: Audrey, Sabine Pass; 10 dead, $8 million damage.
- Oct. 3-4, 1949: Freeport-Houston; two dead, $6.5 million damage; wind gusts estimated at 135 mph; storm tide 11.5 feet at Freeport.
- Aug. 25-29, 1945: Port O’Connor; three dead, $20.1 million damage; wind gusts estimated at 135 mph; storm tide 15 feet at Port Lavaca.
- July 27, 1943: Galveston Bay-Houston; 19 dead, $16.6 million damage.
- Aug. 29-31, 1942: Matagorda Bay; eight dead; $26.5 million damage; winds 115 mph, storm tide 14.7 feet at Matagorda.
- Sept. 23, 1941: Texas City; four dead, $6.5 million damage.
- July 25, 1934: Seadrift; 19 dead, $4.5 million damage.
- Sept. 4-5, 1933: Brownsville; 40 dead, $16.9 million damage.
- Aug. 13-14, 1932; Velasco (Freeport); 40 dead, $7.5 million damage.
- Sept. 14, 1919: South of Corpus Christi; 284 dead, $20.3 million damage; winds 110 mph, storm tide 16 feet.
- Aug. 18-19, 1916: Corpus Christi; 20 dead, $1.6 million damage.
- Aug. 16-19, 1915: Galveston; 375 dead, damage over $56 million. Most losses ($50 million) to crops; storm tide 16.1 feet.
- July 21-22, 1909: Velasco (Freeport); 41 dead, damage at least $2 million.
- Sept. 8-10, 1900: Galveston; 6,000-12,000 dead; damage $30 million to $40 million (around $800 million in today’s dollars); Storm surge 15-20 feet, winds estimated at 120 mph; Deadliest natural disaster in U.S. history.
(Source: Associated Press)