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EPAC Tropical Action 2011


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Good morning Adrian. Finally NRL has updated...

I am guessing the eye starting to fill with low clouds isn't a positive sign.

Edit to add Steve's pic, new page...

06102011_1315_goes13_x_vis1km_high_01EADRIAN_120kts-948mb-152N-1072W_100pc.jpg

Starting to encounter cooler water, but still above 26.5º and I thought annular canes were somewhat more resistant to cold water.

2011160epsst.png

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Avila:

THE CLOUD PATTERN OF THE HURRICANE STILL CONSISTS OF A DISTINCT EYE

AND A CENTRAL DENSE OVERCAST BUT THE DEEP CONVECTION SURROUNDING

THE EYE HAS DIMINISHED DURING THE PAST FEW HOURS.

CONSEQUENTLY...THE DVORAK T-NUMBERS FROM BOTH TAFB AND SAB HAVE

DECREASED...YIELDING AN INITIAL INTENSITY OF 115 KNOTS. WITH NO

EYEWALL REPLACEMENT CYCLES ANTICIPATED...THE INTERACTION OF THE

CYCLONE WITH THE STRONG SST TEMPERATURE GRADIENT WILL PROBABLY BE

THE MAIN CAUSE FOR ADRIAN TO WEAKEN AS INDICATED IN THE FORECAST.

WEAKENING COULD OCCUR FASTER THAN EXPECTED AS SUGGESTED BY SOME

MODELS LIKE THE FSU SUPERENSEMBLE AND THE ECMWF.

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I'd imagine it's possible on some of the small islands in the middle of nowhere... no real land mass to disrupt the core.

Where, though? I tried to think of some places, so I'll go back through my line of reasoning to see if/where disagreements lie.

To start, a couple general assumptions about annulars:

1. Needs to be out of the deep tropics. You won't find them in 29C waters

2. Needs to also be below a certain latitude as well..different between the EPAC and the ATL, but still enough to rule out northerly locations

3. Generally moving W/WNW, equatorward of an uppper level ridge, ruling out places like Bermuda which rely upon recurvers.

Now of course, there may be some exceptions...this storm is a little weird because it seems to have gone annular a little early compared to most of the other EPAC cases I have seen.

So, given that, what options do we have?

In the EPAC, Socorro is the only real option but the environment around it is generally more deep tropical than subtropical...except for years like this one where there is a nice cold pool. I suppose theoretically this is possible, just not very likely over the lifetime of an individual.

In the Atlantic, the annular cases seem to traverse the Sargasso sea...not exactly a hotbed of islands. Maybe something could roll into the Bahamas?

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Where, though? I tried to think of some places, so I'll go back through my line of reasoning to see if/where disagreements lie.

To start, a couple general assumptions about annulars:

1. Needs to be out of the deep tropics. You won't find them in 29C waters

2. Needs to also be below a certain latitude as well..different between the EPAC and the ATL, but still enough to rule out northerly locations

3. Generally moving W/WNW, equatorward of an uppper level ridge, ruling out places like Bermuda which rely upon recurvers.

Now of course, there may be some exceptions...this storm is a little weird because it seems to have gone annular a little early compared to most of the other EPAC cases I have seen.

So, given that, what options do we have?

In the EPAC, Socorro is the only real option but the environment around it is generally more deep tropical than subtropical...except for years like this one where there is a nice cold pool. I suppose theoretically this is possible, just not very likely over the lifetime of an individual.

In the Atlantic, the annular cases seem to traverse the Sargasso sea...not exactly a hotbed of islands. Maybe something could roll into the Bahamas?

These are the exact two locations I was thinking in the western hemisphere, ya. Obviously neither is an ideal location, but annulars are rare enough that even an "ideal" location would more than likely not see one. I would think the Bahamas and Socorro could see a direct annular landfall, though.

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The cyclone is slowly weakening-- now down to 110 kt-- and that trend should continue.

I found this part of the Discussion a little interestin':

SOME OF THE MODELS...IN PARTICULAR THE GFS AND THE HURRICANE MODELS DRIVEN BY THE GFS...INDICATE A MORE VIGOROUS SHORT-WAVE TROUGH...WHICH SHOULD FORCE THE CYCLONE SHARPLY TOWARD THE NORTH-NORTHEAST DESPITE THE STRONG SHEAR AND HOSTILE THERMODYNAMICS.

You can see that sharp turn in the model runs below. Note how the SHIPS really kills this thing:

post-19-0-10875500-1307745245.gif

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From the 2 am PDT Discussion. Really sad:

ADRIAN APPEARS TO BE UNDERGOING IMPLOSIVE FILLING. A RECENT TRMM OVERPASS SHOWS THAT THE EYEWALL HAS BROKEN OPEN...WITH THE REMAINING CONVECTION IN THE EASTERN QUADRANT. THE CYCLONE ALSO HAS THE APPEARANCE OF A SHEARED SYSTEM IN INFRARED IMAGERY. THE RAPID DECAY MAKES THE INITIAL INTENSITY PROBLEMATIC. SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB WERE 90 AND 77 KT RESPECTIVELY AT 0600 UTC. HOWEVER...THE LACK OF AN EYEWALL STRUCTURE SUGGESTS THESE ESTIMATES ARE TOO HIGH. THE INITIAL INTENSITY IS DECREASED TO 75 KT...AND THIS COULD BE QUITE GENEROUS.

lolz

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I'd imagine it's possible on some of the small islands in the middle of nowhere... no real land mass to disrupt the core.

Well not a huge island but not a small one and a well known one at that-Okinawa has had documented near and actual passages of annular storms.

Steve

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Well not a huge island but not a small one and a well known one at that-Okinawa has had documented near and actual passages of annular storms.

Steve

That's interesting, Steve. I had actually hypothesized to Josh in an email this week that the WPAC would be very difficult to have annular storms due to the warm SSTs. Do you know which annular storms were near Okinawa?

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