Any hurricane experts out there?

[Eddie Haskell]

It seems to me that the physics of a hurricane might be similar to an ice skater in a spin. The smaller and denser the storm (arms tucked in) the faster the spin and wind speed. I've noticed that many storms reach Cat 4 only to get larger and drop in intensity. It's not unusual to see them drop two categories as they get larger. If this is so, why wouldn't forecasters calculate that as a storm gets larger it will lose intensity ... or do they?

[Dappleganger]

1. Not an expert, but remember that an ice skater is out on the ice alone

with no other skaters...hurricanes are constantly being acted upon by other atmospheric disturbances/fronts/water temps/barometric pressure, etc.

[Eddie Haskell]

4. Yes, but all else being equal, do larger storms lose intensity?

Put another way, are small, intense storms inherently unstable?

I know conditions must be right and total energy is a big part of the equation, but given a large size and colder waters to feed from, it seems to me that the forecast should be a less intense hurricane. There must be records of storm size vs. intensity.

[sabrina 1]

2. That's a good point.

As a (former) figure skater, I agree with your analogy. It would be interesting to know if it always works out that way with hurricanes.

[Ruby the Liberal]

8. (off topic)

I so envy you! I never had to coordination to skate (even on the old 4 wheel roller skates) and have always has a fascination with those who could glide on a blade. It is a beautiful art.

[sabrina 1]

14. You can learn the coordination if you still wanted to try it.

Best way is to take a few lessons from a coach, It's amazing how having someone help you can give you confidence you didn't have before. It truly is a wonderful feeling and nothing I have done ever gave me the kind of energy spending a few hours on a rink can do.

But you don't have to be 16 to start. I have seen people in their forties and fifties learning and thoroughly enjoying themselves. They don't do jumps etc. Dance skating seems to work for older beginners.

Hope you give it a try, you might surprise yourself :-)

[uberblonde]

3. You're right.

That's usually how it works. But this one was unusual because the central pressure was extremely low, which until now has always indicated a very powerful storm.

[Eddie Haskell]

5. I'm just thinking size may become a limiting factor.

I don't know.

[amerikat]

6. Not an authority on hurricanes but

great screen name. Hi Eddie:hi: :hi: :hi:

[Ruby the Liberal]

7. There has been a lot of debate on the weather sites

about the accuracy of Saffir-Simpson given the fact that pressure and wind speed may not be the best indicators of the destructiveness of a hurricane.

One only has to look at what is happening today in Vermont, the Catskills, Connecticut and the rest of New England under massive flooding to recognize that a low rolling TS can do even more damage.

Personally, the 13mph thing of Irene freaked me more than anything. When I was living in hurricane alley, 40-50mph was more the norm. That, and the reach. Last night, Connecticut was getting the outer bands while the eye was still over North Carolina.

I survived a Cat 3 that parked over Cancun for 3 days, and can assure you - it did hella lot more damage than some Cat 4s did to inland Florida because of the land speed (or lack thereof).

[Eddie Haskell]

9. I agree, flooding is often the major contributer to damage,

and a slow moving storm is dangerous. It's rare that wind damage turns out to be the major story.

[Ruby the Liberal]

10. We are trained to focus on wind damage

because it is those videos/photos that make the best visuals.

It is hard to judge flood damage without a before/after shot, or unless you live there and can comprehend the depth of what you are seeing.

[NRaleighLiberal]

11. This storm really confounded the Raleigh NC weather experts....

they keep saying that this is something they've never seen before. Very low pressure that wasn't matched by wind intensity expected. But a huge storm diameter. Way, way too many variables for even our best computers to be able to figure this sort of thing out yet.

[izquierdista]

12. Why a hurricane is not an ice skater

An ice skater going into a spin takes a fixed amount of linear momentum and converts it into angular momentum. This angular momentum is conserved, meaning that if the skater draws the arms in, the rotation is faster. Coming out of the spin, the skater converts the angular momentum back into linear momentum, and if no more muscle movement is applied will glide to a stop (eventually).

A hurricane is an open system, using the heat of the ocean water beneath it to add to the angular momentum in the vortex of air. Higher water temperatures continue to feed energy up into the storm, unlike the skater who has no source of additional momentum once the spin is begun. A large storm may lose intensity simply because it has run out of conditions favorable to its growth, like moving over cooler water, or like this one did, sucking in a lot of dry air. Everyone can thank us down here in Georgia for that big mass of dry air that brought it down two notches as it passed our coast.

A storm can get as large as the source of energy under it will allow. Storms on Jupiter are MUCH more intense than storms on earth because of different inputs to the fluid dynamics.

[Eddie Haskell]

15. Convergence is not unlike a skaters arms.

The moisture laden air has mass and moves toward the eye before rising. As far as I can tell, this isn't limited by size. Although some models, seem to arbitrarily limit the effective radius to a fixed maximum. Apparently, the factors influencing size are not clearly understood.

On edit: http://www.npr.org/templates/story/story.php?storyId=7672274

"A hurricane is a bit like a figure skater doing a spin. Skaters revolve slowly when their arms and legs are extended. But pull in those arms and legs, and the skater becomes a spinning blur."

[Curmudgeoness]

13. Do you really think that we can ever understand all the factors

that are involved in a hurricane development and growth? We are an arrogant species.

[Eddie Haskell]

17. No, but we're getting better all the time.

The more data we get the better the forecast.

[Lex]

18. I believe scientists and researchers can figure out a hell of a lot

and HAVE figured out a hell of a lot.

[TygrBright]

16. Thousands. You're on DU, after all. n/t

[Lex]

19. Andrew was a very small, very destructive hurricane.

Much of Katrina's death and destruction and damage to NOLA was due to the levees giving way, not the hurricane itself.

[guitar man]

20. I don't know

I'm no expert but a hurricane that seems to fit that mold would be Hurricane Camille. Incredibly intense and powerful but relatively speaking, compact, not very big compared with a lot of other storms.