Sun Sep 02 2007 10:55 PM
Re: Felix



Felix is way above the pressure wind relationship as stated above. 934mb should be in the 140mph range, and 165mph should be in the 902mb range.
Hurricanes don't read the books obviously.

Yeah, the 934mb is quite a bit higher than what you'd expect for a 165mph storm. Given that Felix is a very small storm, here's my theory as to what has happened: Able to quickly respond to changes in its environment, as Felix passed over the warm oceanic eddy south of Haiti, the surface heat drawn off of the surface rapidly increased. This helped to rapidly enhance the (secondary) circulation of the storm and increase the strength of its warm core aloft. As this happened, the (primary) circulation of the storm strengthened rapidly, resulting in a sharp increase in wind speed. Also given its small size, the pressure gradient component to describing the wind field is likely very large -- the 1 mb/1 nm Danny mentioned suggests this as well -- but the angular rotational component is also likely very large, moreso than normal.

Anyway, enough technical debate. While an eyewall cycle didn't look imminent on microwave imagery as of 8pm ET, Felix will shortly be leaving the warm eddy behind. Given that the minimum sea level pressure never really responded as much as one would expect, just leaving the eddy will likely see some reduction in the wind speeds. As an eyewall cycle occurs, perhaps starting tomorrow, the system will grow in size, likely bringing down the wind speeds further. I wouldn't be totally shocked to see a temporary weakening down to a category 4 storm again tomorrow. From there, depending on how close it comes to Honduras on its way to the Yucatan/Belize, it will have the opportunity to re-strengthen into a category 5 storm before landfall. We may had gone 15 years since the last landfalling cat. 5 storm with Dean, but we may not go much more than 2 weeks between them if Felix does the same.

Clark and gang.

There is additional positive anomalies in Felix's path, near 75W, and this extends westward

Also, may I extend an addendum to Clark's explanation. The Mean Sea Level Pressure is slightly positive anomalous surrounding Felix, as well, and this may have added to a steeping of the Pressure Gradient Force.

Lastly...for now, it is rare to get hurricanes much stronger than this while moving at these forward speeds. I have discussed this I believe earlier in this thread and elsewhere, in order for a system to become richly coupled with the oceanic heat content, you want a storm to be moving tad slower so as to tap into the integrate heat content a bit more proficiently..

Heck, if a system stays in the same place, that same process can hurt it, if given enough time. That is because turbulent upwelling starts neutralizing the heat in the top layers and the thermocline shallows.

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