FASCINATING Paper on Large-Eyed (Annular) Hurricanes

[Derecho]

http://www.ssec.wisc.edu/~kossin/articl ... arhurr.pdf

(Note, this is a PDF file, you will need Adobe's free Acrobat Reader to view.)

It's a technical academic paper, but 75% will be understandable to a serious weather enthusiast that isn't a meterologist.

Basically:

1) Isabel right now meets the classic criteria of an annular hurricane in every respect, it seems

2) Isabel would seem to be the strongest annular hurricane ever recorded

3) The key aspect of annular hurricanes is they seem to take MUCH longer to weaken than a normal hurricane of the same intensity.

[Steve Cosby]

This is interesting but this statement is present regarding the identification of annular 'canes:

the hurricane has a normal-to-large-sized circular eye surrounded by a single band of deep convection containing the inner-core region and 2) the hurricane has little or no convective activity beyond this annulus of convection.

Is that the case here? Is the "inner corse" the first few kilometers or could it be the entire body of the convection. The feeder bands don't seem to be as identifiable or they don't seem to be as independent.

[calidoug]

Wow, amazing article.

Great pictures.

Isabel looks *just* like the pics of the annular hurricanes listed.

In fact, I think I remember a few days ago, before the eye got large, that it went through a similar 'cold air intrusion' which resulted in the larger eye... wish I could find a real long-term IR loop...

Doug

[Air Force Met]

Bump for later

[PTrackerLA]

Like calidoug said, Isabel looks JUST like the pictures of annular hurricanes. It's really an odd and freaky looking storm on the IR.

[calidoug]

This paper really is interesting.

One wonders if the folks at the NHC are aware?

Perhaps this is why they were surprised to find it still a CAT 5...

These annular guys maintain their intensity much longer than normal, apprently, and don't always have the super-coldest IR cloud tops even when they're still intense.

Got to love the "mixmaster 5" eddies whirling around in there today again.

[Steve Cosby]

I shot off an email to Bastardi asking "what do you think of this?" after seeing this thread last night. He responded this morning with:

it will expand and be weaker, simply because of the pattern

I think it is clear the 'cane will be weaker for a number of reasons but the expansion part is frightening. If annular hurricanes maintain intensity longer, it follows that Isabel will still be quite strong despite the weakening which is (likely correctly) forecast. Secondly, that strength will be spread out over a larger area in the end rather than the tight signature found in "classic" hurricanes.

Obviously, this is more theoretical but it will be something to watch.

Going along with wxman57's signature line (observe the pattern), note the "pattern" part of Bastardi's response.