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Major Hurricane Irma


NJwx85

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I'm reading a few studies, but I still don't know what a large diameter eye means for hurricane strength. If anyone can help me get a conceptual understanding I won't be so lost on reading. 

Example: http://onlinelibrary.wiley.com/doi/10.1029/2006GL027313/full This is a little too scientific for my understanding right now.

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I have been watching the satellite loop as it passes over Little Inagua island (unpopulated?) The satellite view is still extremely organized, with perhaps quite a bit less -75C or -70C cloud tops than a day ago. Still the -60C to -70C cloud tops are over some large areas. So the Dvorak technique should classify this as weaker than this morning or 24 hrs ago, based on critical temperature values. The recon mission #18 got about 120 kt surface and up to 149 kt at flight level. So the flight level wind is still pretty high. Flight level winds were up to 155 and higher yesterday. So it's not a lot less at flight level. Surface level winds may be realistically 110kt to possibly over 120 kt at this moment.

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9 minutes ago, Mountain_Patch said:

I'm reading a few studies, but I still don't know what a large diameter eye means for hurricane strength. If anyone can help me get a conceptual understanding I won't be so lost on reading. 

Example: http://onlinelibrary.wiley.com/doi/10.1029/2006GL027313/full This is a little too scientific for my understanding right now.

In simpliest terms and in general, a smaller eye is typically associated with a higher intensity.  Since wind speed itself is dictated by the pressure gradient over a given distance, a tighter eye generally produces a higher maximum sustained wind.  

With Irma going through an EWRC, the outer eyewall ultimately replaces the deteriorating inner one...causing a lessening of the PG, and a corresponding decrease in the MSW, as well as a larger eye.  

If conditions allow, the new larger eye will attempt to contract once again, and tighten the PG and reintensify, accordingly.   

The main concern of the larger eye resulting from the aforementioned EWRC is an expansion of the hurricane-force wind field,  and potentially an increased surge at landfall.       

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1 minute ago, ncforecaster89 said:

In simpliest terms and in general, a smaller eye is typically associated with a higher intensity.  Since wind speed itself is dictated by the pressure gradient over a given distance, a tighter eye generally produces a higher maximum sustained wind.  

With Irma going through an EWRC, the outer eyewall ultimately replaces the deteriorating inner one...causing a lessening of the PG, and a corresponding decrease in the MSW, as well as a larger eye.  

If conditions allow, the new larger eye will attempt to contract once again, and tighten the PG and reintensify, accordingly.   

The main concern of the larger eye resulting from the aforementioned EWRC is an expansion of the hurricane-force wind field,  and potentially an increased surge at landfall.       

So in other words large eyes mean nothing in a favorable environment because they'll naturally contract and restrengthen.. Appears this ERC may have come at the worst time. 

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20 minutes ago, BlunderStorm said:

Can an 8.0 generate a sizable tsunami? Mexico doesn't need this as they are already under the gun of Katia...

http://www.telegraph.co.uk/news/2017/09/08/mexico-earthquake-magnitude-8-tremor-rattles-buildings-capital/

My apologies for making a dumb mistake, not checking the date on the article I cited, and for Off Topic.

Back to Irma.

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27 minutes ago, Mountain_Patch said:

So in other words large eyes mean nothing in a favorable environment because they'll naturally contract and restrengthen.. Appears this ERC may have come at the worst time. 

Time will tell, honestly, as there is never a guarantee that an intense hurricane will ultimately regain it's previous intensity following an EWRC.   It only takes a subtle difference in either the atmospheric or oceanic environment to induce weakening.  

In the case of H Andrew, an EWRC dropped the MSW to category-four strength as it passed through the Bahamas, but Andrew rapidly reintensified to category-five intensity on approach and through landfall, after completing that EWRC.  Perfect conditions were the primary reason.  

In contrast, H Katrina weakened from a category-five to a strong category-three H following the emergence of an EWRC that combined with a less favorable environment through landfall. However,  Katrina's double-eyewall structure at landfall helped enhance a large storm surge over an immense area of the Gulf coast, as well as powerful wind gusts well inland,  than otherwise would've been the case.  

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7 minutes ago, Wow said:

GEFS ensembles have shifted back NE with more track into SC than GA after running along the FL coast. Watch that NE trough closely.

Maybe what the NAM was seeing is showing up on a few if the gefs members and pulling the mean east? Times getting short for any major changes I would think.

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This hurricane has that "skunked" post ERC look to it to me, right now......perhaps that eventually changes, but often times it doesn't once the colder cloud tops within the CDO begin to take on that shredded look.

Often times we wait the rest of its life cycle for that window when it recaptures that rigor, and it just never quite materializes-

Don't get me wrong....I'm not saying its falling apart, but I am doubting a reclassification to a cat 5, assuming it is downgraded, which it should be.

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9 minutes ago, 40/70 Benchmark said:

This hurricane has that "skunked" post ERC look to it to me, right now......perhaps that eventually changes, but often times it doesn't once the colder cloud tops within the CDO begin to take on that shredded look.

Often times we wait the rest of its life cycle for that window when it recaptures that rigor, and it just never quite materializes-

Don't get me wrong....I'm not saying its falling apart, but I am doubting a reclassification to a cat 5.

Too often people just see warm SST's as if it were the only determining factor toward intensity. If it were only that easy. 

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