Wilma's Rage Suggests New Hurricane Categories Needed

[tocqueville]

Ker Than
LiveScience Staff Writer
LiveScience.com
Thu Oct 20, 6:00 PM ET

In a season that has included three Category 5 hurricanes for the first time on record in the Atlantic Basin, scientists are beginning to wonder if their rating system is adequate, LiveScience has learned.

On the Saffir-Simpson hurricane scale, there is no Category 6. But Hurricane Wilma this week brushed up against where a 6 would be if the scale were logically extrapolated to include another category.

And hurricanes are getting stronger, apparently fueled by global warming. Researchers expect that trend to continue.

Kerry Emanuel, a climatologist at the Massachusetts Institute of Technology, calls the Saffir-Simpson scale irrational, in part because it deals only with wind. "I think the whole category system needs serious rethinking," Emanuel told LiveScience

http://news.yahoo.com/s/space/20051020/sc_space/wilmasragesuggestsnewhurricanecategoriesneeded

[bbinacan]

1. I think there should be a

Cat 6 at 165 mph. Damn, we just tied 1933 and may beat that year. Is the next one called Alpha?

[niyad]

2. yes, after a "w", the names go to the greek alphabet.

[TechBear_Seattle]

3. They retire names associated with devastating storms...

What will they do if Alpha or Beta is really, really bad?

[sleipnir]

9. Ahhh...a brilliant point!!

We'll see...

[jobycom]

12. Maybe Egyptian hieroglyphic names?

:shrug:

[RaleighNCDUer]

13. Maybe go to Hebrew.

Aleph, Bet...

[bbinacan]

5. I bet we get Alpha n/t

[tocqueville]

10. so after dubya, the next president will be alpha ?

[TechBear_Seattle]

14. No. It will be illegal for someone named "George" to run for President n/t

[Zynx]

4. They should go by minimum pressure reached

Katrina was probably only around a Cat 3 when it hit Mississippi, but it had a mega Cat-5 surge because of its peak strength and amount of time speant at that strength.

[jobycom]

7. I've heard competing theories on the surge

Most people have said that the size of the storm meant that there was a greater area of water being pushed forward by the winds. One meteorolist in Mississippi even predicted an unprecedented surge based only on the size.

You're saying it was because of the greater winds at sea, and I'm guessing you're saying that the water surge doesn't disipate very quickly. Is that a guess, or are you certain on that? Cause I'm just guessing from second hand knowledge.

[MarsThe Cat]

8. storm surge is based on air pressure-

the lower it is, the bigger the surge potential is.

[jobycom]

11. Old theory, but that's wrong, It's the wind.

It's based on wind. They used to claim that the pressure created the storm surge, but now they know it's a very small factor.

http://en.wikipedia.org/wiki/Storm_surge

"A storm surge is an onshore rush of water associated with a low pressure weather system, typically a tropical cyclone. Storm surge is caused primarily by high winds pushing on the ocean's surface. The wind causes the water to pile up higher than the ordinary sea level. Low pressure at the center of a weather system also has a small secondary effect, as can the bathymetry of the body of water. It is this combined effect of low pressure and persistent wind over a shallow water body which is the most common cause of storm surge flooding problems.

Storm surges are particularly damaging when they occur at the time of a high tide, combining the effects of the surge and the tide. This increases the difficulty of predicting the magnitude of a storm surge since it requires weather forecasts to be accurate to within a few hours.

The most extreme storm surge events occur as a result of extreme weather systems, such as tropical cyclones, but storm surges can also be produced by less powerful storms.

The highest storm surge ever recorded was produced by the 1899 Bathurst Bay Hurricane, which caused a 13 meters (43 feet) storm surge at Bathurst Bay, Australia. In the United States, the greatest recorded storm surge was generated by 2005's Hurricane Katrina, which produced a storm surge 9 meters (30 feet) high in the town of Biloxi, Mississippi. The worst storm surge, in terms of loss of life, was the 1970 Bhola cyclone and in general the Bay of Bengal is particularly prone to tidal surges."

[BeFree]

16. Once upon a time

In a land far far away.....

Picture a small cabin set upon piers rising from the muck of a gulf coast Florida marsh. A hurricane to the west, some 100 miles distant, blows the water to a height five feet above normal high tide, coming within inches of the floorboard of the small cabin.

Now picture yourself being there alone, with no phone, and the only way out by boat. Should you stay, or should you go? Staying, whilst the water piled up and 40 mile an hour winds slammed the stilted house, you might have experienced one of the most exhilirating nights of your life, eh?

[jobycom]

6. The current system is good, but I'd like to see meteorologists talk more

about size and speed.

I agree with Safir in the article, that the 5 point scale is simple and a good relative scale, but with Katrina it hurt. A lot of people relaxed when it fell to a 3 before landfall. Fortunately, most people had already evacuated, but there was still a letdown.

But Katrina was vicious for two reasons, both dealing with size. The winds lasted twice as long as usual, since it was twice the size, so the cumulative effect was worse than a smaller, more powerful hurricane. And the winds at sea, it has been theorized, drove the water before it for much longer, which built the storm surge higher than any other storm on record.

The speed of hurricanes also plays a role. The slower storms push larger storm surges, usually, and the faster storms can cause more tornado damage and some suggest that the speed of the storm should be added to the wind speed for total wind force. One hurricane in 1938 moved at 70 mph, and hit Long Island (this was a real freak thing). The winds were in the low 100s, but with the speed of the storm the damage was horrible. Something like 600 people died. (Plus, no one knew it was coming).

Anyway, I think they should keep the basic 5 point scale, but they could either factor size and speed into that number, or simply mention it when they report the wind speed and pressure (which is also not factored in to the Category ratings).

[Toots]

15. Oh no...Now the Bush* administration can reclassify hurricanes so

they don't appear to be getting bigger in fact much smaller. What was once a Catagory five could become a Catagory three in the new system. Problem fixed....