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Posted on 08/29/2005 2:47:45 AM PDT by NautiNurse
"Concentric eyewall cycles" (or "eyewall replacement cycle" ) naturally occur in intense tropical cyclones , i.e. major hurricanes (winds > 50 m/s, 100 kt, 115 mph) or Catories 3, 4, and 5 on the Saffir-Simpson scale. As tropical cyclones reach this threshold of intensity, they usually - but not always - have an eyewall and radius of maximum winds that contract to a very small size, around 10 to 25 km [5 to 15 mi]. At this point, some of the outer rainbands may organize into an outer ring of thunderstorms that slowly moves inward and robs the inner eyewall of its needed moisture and momentum. During this phase, the tropical cyclone is weakening (i.e. the maximum winds die off a bit and the central pressure goes up). Eventually the outer eyewall replaces the inner one completely and the storm can be the same intensity as it was previously or, in some cases, even stronger. A concentric eyewall cycle occurred in Hurricane Andrew (1992) before landfall near Miami: a strong intensity was reached, an outer eyewall formed, this contracted in concert with a pronounced weakening of the storm, and as the outer eyewall completely replaced the original one the hurricane reintensified. Another example is Hurricane Allen (1980) which went through repeated eyewall replacement cycles -- going from Categrory 5 to Category 3 status several times. To learn more about concentric eyewall cycles, read Willoughby et al. (1982) and Willoughby (1990a).
The levees will be tested.
May be old news, but ABC just had the mayor of NO on, via telephone, and the mayor is getting word that some of the Levees at Lake Pontchartrain have been breeched.
I was in Charleston for that, at the shipyard. Yikes! Lots of stories, but scroll down on this URL http://www.cofc.edu/CGOinquiry/hurricanes.htm to check out before and after shots of the Atlantic House restaurant that was on Folly Beach.
From NOAA - Not as it's being replaced (the hurricane is acutally weakening as the formation of the new eyewall robs energy from the old one). It can, under ideal conditions, emerge at the same strength or even stronger. That's not going to happen with Katrina (at least if I'm guesstimating right based on the radar); much of it is already over land.
The way I read the radar, the north half of the eye is shrinking, while the southern half is trying to re-form at its previous size.
Posts 651-700 had a 'record number' of comments removed by administrator - what's up with that on a huricane thread ???
There's an immense amount of mythology about eyewall replacements out there, the source of which I've never been able to determine.
Anyway, I assure you I'm right about this one.
4 feet of water on Hwy 90 - Biloxi
I think Shep realizes now that this storm is still packing a punch
"It's because the field is below sea level, and might end up 20 feet under water."
I recall hearing that the entire stadium is about 25 feet ABOVE sea level - one of the reasons they named it as a refuge.
Thank God Katrina weakened overnight.
The final phase of the cycle is for the new, larger eyewall to begin to contract. As this happens, any weakening that had occurred when the inner eyewall was replaced is almost always regained as the new eyewall contracts.
disagreements, confrontations and a prophetic announcement
Just sent your post to Fox & Friends.
Shep is way behind!!!!!!!
You are wrong about this one.
Not good. An intact Superdome roof was supposed to be proof against 130mph winds, which should be sufficient since the storm is weakening as it contacts land and NO is on the left side. I'd try to find a perimeter wall...
Good Morning everyone from the Sacramento area. Prayers for all who are in harm's way of this hurricane.
Isn't that the mayor's job? - He's incompetent
I thought some of the pumps were diesel?
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