Hurricane Can Form New Eyewall And Change Intensity Rapidly

[phantom power]

Improving storm models with data from the epic season of 2005.

Researchers flew through Rita, Katrina and other 2005 storms trying to unlock the key to intensity changes. Now, data from Rita is providing the first documented evidence that such intensity changes can be caused by clouds outside the wall of a hurricane's eye coming together to form a new eyewall.

(...)

A hurricane's strongest winds occur in the wall of clouds surrounding the calm eye. The researchers found that as the storm swirled into a tighter spin, a band of dry air developed around the eyewall, like a moat around a castle. But while a moat protects a castle, the hurricane's moat eventually will destroy the existing eyewall, Houze said. Meanwhile, outer rainbands form a new eyewall and the moat merges with the original eye and the storm widens, so the spin is reduced and winds around the eye are slowed temporarily, something like what happens as a figure skater's arms are extended. But the storm soon intensifies again as the new eyewall takes shape.

"The exciting thing about the data from Rita is that they show that the moat is a very dynamic region that cuts off the old eye and establishes a wider eye," Houze said. "It's not just a passive region that's caught in between two eyewalls."

Hurricane forecasters in recent years have developed remarkable accuracy in figuring out hours, even days, ahead of time what path a storm is most likely to follow. But they have been unable to say with much certainty how strong the storm will be when it hits land. This work could provide the tools they need to understand when a storm is going to change intensity and how strong it will become.

http://www.sciencedaily.com/releases/2007/03/070302082814.htm

[GliderGuider]

1. Just in time for the new hurricane season.

I remember reading people like Jeff Masters talking about "eyewall replacement cycles" during the 2005 season. Now they'll be able to quantify the effects. Science marches on.

[jkshaw]

2. Thankyou, Phantom

This will be very interesting to all of us here!

[AnneD]

3. Having lived much of my life...

on the Gulf Coast-I have seen first hand the progress they have made in Hurricane tracking. The technology has helped save lives. FEMA, however, has not progressed.