Lady Christabel
Editzilla™/ThesauruSnark
- Joined
- Dec 17, 2003
- Posts
- 5,693
I've seen a few "why" questions and linuxgeek and I have fielded quite a few via PMs. Here's a quick FAQ...
What do the letters mean?
TW - Tropical Wave - minor tropical disturbance
TD - Tropical Depression - exudes formation characteristics
TS - Tropical Storm - a tropical formation with winds of 39-73mph
TC - Tropical Cyclone (hurricane/typhoon) - a tropical formation with winds of 74mph
mb - millibars - a measure of barometric pressure
mph - miles per hour - a measure of speed
kts - knots - a measure of speed
How are hurricanes rated?
TC category ratings use the Saffir-Simpson Scale measuring wind speed, barometric pressure, storm surge, and damage potential:
Cat 1: Weak
wind: 74 - 95 mph; 65 - 82 kts
pressure: 28.94" or more; 980.02 mb or more
surge: 4.0' - 5.0'; 1.2 m - 1.5 m
damage: Minimal damage to vegetation
Cat 2: Moderate
wind: 96 - 110 mph; 83 - 95 kts
pressure: 28.50" - 28.93"; 965.12 mb - 979.68 mb
surge: 6.0' - 8.0'; 1.8 m - 2.4 m
damage: Moderate damage to houses
Cat 3: Strong
wind: 111 - 130 mph;96 - 113 kts
pressure: 27.91" - 28.49"; 945.14 mb - 964.78 mb
surge: 9.0' - 12.0'; 2.7 m - 3.7 m
damage: Extensive damage to small buildings
Cat 4: Very strong
wind: 131 - 155 mph; 114 - 135 kts
pressure: 27.17" - 27.90"; 920.08 mb - 944.80 mb
surge: 13.0' - 18.0'; 3.9 m - 5.5 m
damage: Extreme structural damage
Cat 5: Devastating
wind: 156 mph or greater; 136 kts or greater
pressure: Less than 27.17" or less; 920.08 mb or less
surge: 18.0' or greater; 5.5m or greater
damage: Catastrophic building failures possible
How long does hurricane season last?
01 June to 30 November. The height of the Atlantic season is August/September.
Why do hurricanes have numbers and names?
TDs are given a number, beginning with #1 at the beginning of each storm season. Not all TDs become TSs. Once a TD becomes a TS, it gets a name. So far in 2004, TD numbers and TS names match. That is, "I" for Ivan is the 9th letter and 9th TD. That's not always true. Therefore, a storm will commonly be listed with its TD number and TC name.
Before 1950, storms were referred to by various means. Some used the number and year, some the area affected, saints names, location, but all of these identifiers had various problems with consistency. 1950-52, the government named the storms, but used military-speak, so the storms had names like Able, Baker, Charlie, Dog, East. Not only was this boring, but didn't allow for a long-term naming solution. In 1953, storms were given female names. In 1978, male names were added to the list. The letters Q, U, X, Y, and Z are not used.
Are names ever reused?
Yes. Names are often reused if the TS/TC caused little or no damage. TCs that caused major damage, like Donna (1960), Hugo (1989), Mitch (1998), are retired and not used again. Any country majorly affected by a particular storm can ask the name be retired. This year's names were first used in 1986, although that A was Andrew. When Andrew devastated South Florida in 1992, the name was retired. Six lists are now used in rotation, and are maintained by the World Meteorological Organisation.
Why do they start again with A each year?
No fuckin' clue. If the previous season ends with an L named storm, logic assumes they'd move to M and finish the alphabet. But this is the government and logic isn't exactly their forté.
If you have more questions, post them and we'll get them answered.
What do the letters mean?
TW - Tropical Wave - minor tropical disturbance
TD - Tropical Depression - exudes formation characteristics
TS - Tropical Storm - a tropical formation with winds of 39-73mph
TC - Tropical Cyclone (hurricane/typhoon) - a tropical formation with winds of 74mph
mb - millibars - a measure of barometric pressure
mph - miles per hour - a measure of speed
kts - knots - a measure of speed
How are hurricanes rated?
TC category ratings use the Saffir-Simpson Scale measuring wind speed, barometric pressure, storm surge, and damage potential:
Cat 1: Weak
wind: 74 - 95 mph; 65 - 82 kts
pressure: 28.94" or more; 980.02 mb or more
surge: 4.0' - 5.0'; 1.2 m - 1.5 m
damage: Minimal damage to vegetation
Cat 2: Moderate
wind: 96 - 110 mph; 83 - 95 kts
pressure: 28.50" - 28.93"; 965.12 mb - 979.68 mb
surge: 6.0' - 8.0'; 1.8 m - 2.4 m
damage: Moderate damage to houses
Cat 3: Strong
wind: 111 - 130 mph;96 - 113 kts
pressure: 27.91" - 28.49"; 945.14 mb - 964.78 mb
surge: 9.0' - 12.0'; 2.7 m - 3.7 m
damage: Extensive damage to small buildings
Cat 4: Very strong
wind: 131 - 155 mph; 114 - 135 kts
pressure: 27.17" - 27.90"; 920.08 mb - 944.80 mb
surge: 13.0' - 18.0'; 3.9 m - 5.5 m
damage: Extreme structural damage
Cat 5: Devastating
wind: 156 mph or greater; 136 kts or greater
pressure: Less than 27.17" or less; 920.08 mb or less
surge: 18.0' or greater; 5.5m or greater
damage: Catastrophic building failures possible
How long does hurricane season last?
01 June to 30 November. The height of the Atlantic season is August/September.
Why do hurricanes have numbers and names?
TDs are given a number, beginning with #1 at the beginning of each storm season. Not all TDs become TSs. Once a TD becomes a TS, it gets a name. So far in 2004, TD numbers and TS names match. That is, "I" for Ivan is the 9th letter and 9th TD. That's not always true. Therefore, a storm will commonly be listed with its TD number and TC name.
Before 1950, storms were referred to by various means. Some used the number and year, some the area affected, saints names, location, but all of these identifiers had various problems with consistency. 1950-52, the government named the storms, but used military-speak, so the storms had names like Able, Baker, Charlie, Dog, East. Not only was this boring, but didn't allow for a long-term naming solution. In 1953, storms were given female names. In 1978, male names were added to the list. The letters Q, U, X, Y, and Z are not used.
Are names ever reused?
Yes. Names are often reused if the TS/TC caused little or no damage. TCs that caused major damage, like Donna (1960), Hugo (1989), Mitch (1998), are retired and not used again. Any country majorly affected by a particular storm can ask the name be retired. This year's names were first used in 1986, although that A was Andrew. When Andrew devastated South Florida in 1992, the name was retired. Six lists are now used in rotation, and are maintained by the World Meteorological Organisation.
Why do they start again with A each year?
No fuckin' clue. If the previous season ends with an L named storm, logic assumes they'd move to M and finish the alphabet. But this is the government and logic isn't exactly their forté.
If you have more questions, post them and we'll get them answered.