Category 6 hurricanes?

[Boomer]

Category 6 - is it possible?

Although I'm familiar with the existing Saffir-Simpson Hurricane Scale, it occured to me that I don't know whether the range was based on observed hurricane behavior or on some law of physics that restricts the top of the scale.

Category One: 74-95 mph
Category Two: 96-110
Category Three: 111-130 mph
Category Four: 131-155
Category Five: greater than 155 mph

Given the increasing frequency and intensity of hurricanes, fueled by rising water temperatures, will the scale of 1 to 5 need a new category at the upper end?

Category Five: 156-175 mph
Category Six: greater than 175 mph

Just curious.

[trumad]

1. That was Andrew type of winds...

Gusts were clocked at over 200 mph.

[Spinzonner]

2. Funny how these things seem to come during Bush presidencies ...

[Boomer]

3. Mighty stiff breezes

>> Gusts were clocked at over 200 mph.<<

Gusts, yes, but I believe the S-S scale is based on sustained wind speeds. So my guess would be that so far there have been no hurricanes that have maintained speeds greater than 175mph for significant periods of time.

But is it theoretically possible?

[Gman]

4. I think Camille had sustained winds of 200+

estimated, I believe, because the wind speed instruments broke.

[Dogmudgeon]

5. High Fives: 200+ mph storms

I don't have a complete list handy, but there have been several in the years since Camille. Most all of them have been Pacific typhoons.

A number of storms, including Andrew, have been studied in the light of better data analysis, and have been upgraded. Andrew was originally pegged as a Category 4 when it hit Florida, but recent examination of the data provided considerable evidence that it was a Category 5, and perhaps a very strong Category 5 at that.

The most intense mainland United States hurricanes, 1900-2000

The Deadliest, Costliest, and Most Intense United States Hurricanes from 1900 to 2000

(Sorry, but I haven't found corresponding information on Pacific typhoons yet.)

--bkl

[Tims]

6. Many Storms are poorly rated

Carla in 1961 was widely reported at the time to have had sustained winds near 200mph, but is now currently rated as only a class 4. The official weather reporting sight at the time was at Galveston, almost 80 miles north of where the storm actually went inland, yet the official wind gauge there failed (blew down) and was not even capable of recording anything greater than about 150mph. Carla was HUGE storm, possibly the largest on record. It was one of the first hurricanes to be imaged by a weather satellite and it covered the entire Gulf of Mexico. Hurricane force winds were reported as far south as the northern Mexico coast and as far north as western Louisiana. On the central Texas coast, hurricane force winds lasted more than 24 hours and it took almost 36 hours for the storm to pass. The storm moved inland and turned to the northeast and remained well organized all the way into northeastern Canada. Until Camille slammed into Gulfport Miss. in 1969, Carla was widely regarded as the most powerful Atlantic storm on record.

Hurricane Celia in 1970 was one of the biggest failures in storm prediction in the era of modern weather technology. The storm formed quickly in the Gulf not far from where it would eventually move inland just north of Corpus Christi, TX. It stalled off the coast and the weather service was reporting that it was weakening and that it might even be downgraded to a tropical storm before it moved inland. Radar and satellite images showed a very small storm only about 40 miles across. At the time, I was living directly in the path of the storm only a few miles inland. When the storm came ashore, it hit with tremendous power. Winds were clocked at over 180mph at a large Aluminum Factory nearby. Winds were probably even higher directly on the coast at Port Aransas (I heard unofficial reports of 190-200mph gusts with 160+ sustained). The damage I witnessed was as great as anything I've seen in reports from Andrew and other recent big storms, I've also been through five other hurricanes in my lifetime, so I have some perspective. In my town, over 90% of all homes sustained major structural damage. A larger nearby suburban community had virtually 100% damage. Aerial photos of the town resembled the damage of that of a tornado, only on a much larger scale. Wind was strong enough to rip the sides of two large oil storage tanks with enough force to cause the steel to spark and ignite the oil (these burned for several days with large explosive fireballs erupting occasionally as bubbles of gas formed and rose to the surface). Corpus Christi (a city of about 250,000) sustained widespread damage and is the main reason Celia is listed as one of the costliest storms on record. Power was out for a month in many places, yet this storm is officially only rated as a category 3 storm. Again, the official weather station of record was at the Corpus Christi airport, significantly further inland and south (weak side) of the eye of the storm. The storm was indeed small in area and little damage occurred as little as 25 miles from the center of the storm.

What this storm showed was that a storm does not need to be large in order to have extremely high winds. Because so many people where caught unprepared and few areas were evacuated, weather prediction changed dramatically after that. Tropical storms which would not even have made the local news, suddenly were being reported as potential dangers.

[fedsron2us]

7. These are excellent points.

Over the years I have noticed a definite tendency amongst meteorological organisations to downplay storms where they have failed to forecast the intensity correctly and to play up those where they have got it right. I suppose that it is just human nature.