cieldumort
(Moderator)
Thu Sep 04 2008 04:28 PM
Re: Hanna Moving Northwest, Category 4 Hurricane Ike Forms Moving West

Once again, Hanna has shed more tropical characteristics and taken back on more subtropical ones, in their place. This change was noted in NHC's 11AM discussion.

A lot of dry air entrainment continues to hamper redevelopment of a convective core. Maximum winds have likely expanded away from the center again, and it may even be a challenge for recon to find a persistent warm center. They're heading in there now, so we shall see. Given the convective trends around noon, Hanna may be trying to redevelop a core of convection at this time, but again, she is fighting an uphill battle.

Not mentioned in any of the Hanna discussions out of NHC I have read thus far, dry/dusty air is hugging the east coast, from about the coastline out over the Gulf Stream. It might take a while for this to wash out, and it seems reasonable to assume that Hanna may also ingest some more of this, as it exists in such abundance, until it finally mixes out of the region. Unless and until Hanna can create a very moist, protective bubble, she will remain at the mercy of this less-than-ideal environment, and at some point this week she may yet become fully subtropical, assuming she isn't already.

The implications of a largely subtropical storm Hanna vs. tropical storm Hanna suggests that she can remain more offshore, and yet possibly affect a wider area with gale-force winds and perhaps a few hurricane-force wind gusts. It also suggests that it could take her longer than forecast to become a hurricane... maybe too long.. given her likely recurvature that could take much of her circulation over land.

Implications for Ike strike me as mixed. On one hand, I doubt that Hanna has turned up the waters in any very meaningful way should Ike travel over the same area. On the other, circulation into and around Hanna has brought in lots more dry, even dusty air into the region. There's still time for this to mix out, but already Ike is feeling some of the effects of downshearing winds on Hanna's outermost periphery, and it could be just a matter of time until enough of a kink in his armor opens up and lets some of the drier/dustier air in, which could trip him up pretty good.



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