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Atlantic Tropical Action 2012 - Part II

HurricaneJosh

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CUmet

CUmet

Posted
Posted

I agree with Phil that the circulation is very likely closed at the surface. Whether or not NHC decides to classify this or wait longer remains to be seen, but in my eyes this is probably at least a TD already.

The outflow and convective pattern right now clearly is consistent with westerly or northwesterly shear, but it doesn't appear to be negatively impacting the genesis process, at least not yet. Instead, it appears to be providing the forcing for vertical motion that is producing the convective bursts near and downshear of the LLC. As long as the convection isn't too displaced, we should see a slow organization of the system. However, the shear appears to increase at least over the next 24 hours or so from the northwest, particularly in the 850-300 mb layer since the base of the northwesterlies extends further south at the 300 mb level than the traditional 200 mb level. Based on how good the low-level circulation looks right now, I'd bet on 99L surviving the next 36 hours, but high shear cases are tough to call.

As Phil alluded to earlier, there are vast differences in the track of 99L between the GFS and ECMWF. One factor that can be important in these sheared TC cases is the possibility of the center drifting or being tugged towards the downshear convection, which can play much havoc on track forecasts (i.e. Debby earlier this year). The shear vector might have enough of a northerly component this time to prevent a large drift to the right, as shown by the ECMWF, and this seems to be supported by the current displacement of convection towards the SE, but this will have to be watched as well.

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Mencken_Fan

Mencken_Fan

Posted
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Yes, I did.

You forget the rest of my illustrious portfolio: http://icyclone.com/chases/

Outstanding work Josh, and that's across the board; site, graphics, video, and writing.

I noticed you noticed something I've noticed with these storms (odd sentence eh?) and that is the surprising backside power of hurricanes.

Before moving to North Carolina I'd always been under the impression it was the front side of a hurricane that packed all the power but boy was I wrong! The common idea "the worst is over" after the front half of a hurricane passes is just that, a myth. The backside can not only be worse, it can be significantly worse. Any doubts I ever had about that were erased with Charley (NC) in 2004.

Angle of attack, geography, the state of the storm at landfall, etc. all play a role; and being one is often without power and communications by the time the eye is overhead... it can be quite the shocker!

Hope you get a couple good ones this year,

Tim in ILM

:)

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PSUBlizzicane2007

PSUBlizzicane2007

Posted
Posted

Well the comparison between the GFS and Euro on this is certainly interesting and will be something to watch further and with future systems this year. Whereas in past years the GFS was usually to the right and the Euro to the left in these sorts of situations, it seems with the GFS's tweaking, some changes have occurred.

On the 12Z models, the GFS is fairly straight W/WNW through the middle of the Caribbean towards Central America, while the Euro so far takes it as a weak system and slams it into SW Haiti, degenerating it into a wave in the western Caribbean south of Cuba.

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Superstorm93

Superstorm93

Posted
Posted

SHIPS was coupled with the OFPI and shows a decent hurricane with a marginally conductive enviorment.

*   ATLANTIC SHIPS INTENSITY FORECAST	   *
			    * GOES AVAILABLE,	   OHC AVAILABLE	   *
			    *	  INVEST  AL992012  08/01/12  18 UTC   *
TIME (HR)		  0	 6    12    18    24    36    48    60    72    84    96   108   120
V (KT) NO LAND    30    32    33    35    37    41    46    50    54    56    59    61    64
V (KT) LAND	   30    32    33    35    37    41    46    50    54    56    59    61    64
V (KT) LGE mod    30    32    34    35    36    38    40    42    47    52    58    65    71
Storm Type	  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP
SHEAR (KT)	    11    13    14    16    13    16    13    10	 6    15	 9    15    11
SHEAR ADJ (KT)	 3	 9	 5	 2	 4	 0	 0    -1	 0	 0    -2    -4	 0
SHEAR DIR	    300   290   290   290   277   272   273   255   261   283   273   268   268
SST (C)		 27.5  27.5  27.6  27.8  28.0  28.1  28.1  28.2  28.5  28.5  28.6  28.8  28.9
POT. INT. (KT)   132   132   133   136   139   140   140   141   146   145   147   149   150
ADJ. POT. INT.   134   133   135   138   140   141   139   142   145   144   143   143   143
200 MB T (C)   -53.2 -53.3 -53.6 -53.8 -53.5 -53.5 -53.2 -53.6 -53.2 -53.3 -53.0 -52.7 -52.5
TH_E DEV (C)	   6	 7	 7	 7	 8	 9    10    10    10    10    10	 9    10
700-500 MB RH	 64    61    60    59    58    55    56    56    62    59    60    62    63
GFS VTEX (KT)	  9    10    10    10    11    12    12    12    12    12    11    11    13
850 MB ENV VOR	 0	 7	 7	 3    11    27    23    31    37    48    51    60    46
200 MB DIV		 1    20    26    14    29    49    35    31    50    41    54    43    46
700-850 TADV	 -14   -17   -12   -12   -12    -9    -5    -3	 1    -2	 2    -1	 0
LAND (KM)	    912   876   850   840   797   536   420   431   239   188    79    24    56
LAT (DEG N)	 12.0  xx.x  xx.x  xx.x  xx.x  xx.x  xx.x  xx.x  xx.x  xx.x  xx.x  xx.x  xx.x
LONG(DEG W)	 48.2 xxx.x xxx.x xxx.x xxx.x xxx.x xxx.x xxx.x xxx.x xxx.x xxx.x xxx.x xxx.x
STM SPEED (KT)    15    15    15    15    15    15    14    15    15    14    13    12    11
HEAT CONTENT	  29    21    23    27    31    55    51    53    54    63    74   109    94
 FORECAST TRACK FROM OFPI	  INITIAL HEADING/SPEED (DEG/KT):290/ 16	  CX,CY: -14/  5
 T-12 MAX WIND:  25		    PRESSURE OF STEERING LEVEL (MB):  713  (MEAN=623)
 GOES IR BRIGHTNESS TEMP. STD DEV.  50-200 KM RAD:  29.8 (MEAN=14.5)
 % GOES IR PIXELS WITH T < -20 C    50-200 KM RAD:  60.0 (MEAN=65.0)

18z Dynamic

18zatcfearlyinvest1best.gif

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PSUBlizzicane2007

PSUBlizzicane2007

Posted
Posted

It's interesting how the GFS and Euro are once again showing really different solutions. The GFS kicked the Euro's butt with Debby-- big-time-- so it'll be interesting to see what happens with this latest match-up.

Yup. I'm honestly surprised that the Euro has failed as much as it has... the upgrade for the GFS could prove significant.

Only have limited maps for the caribbean, but at hour 174, 12z euro has a storm near Cancun as well. Not sure of strength.

Looks like it is trying to form a depression after degenerating 99L into a tropical wave after Haiti.

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HurricaneJosh

HurricaneJosh

Posted
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Posted

Outstanding work Josh, and that's across the board; site, graphics, video, and writing.

I noticed you noticed something I've noticed with these storms (odd sentence eh?) and that is the surprising backside power of hurricanes.

Before moving to North Carolina I'd always been under the impression it was the front side of a hurricane that packed all the power but boy was I wrong! The common idea "the worst is over" after the front half of a hurricane passes is just that, a myth. The backside can not only be worse, it can be significantly worse. Any doubts I ever had about that were erased with Charley (NC) in 2004.

Angle of attack, geography, the state of the storm at landfall, etc. all play a role; and being one is often without power and communications by the time the eye is overhead... it can be quite the shocker!

Hope you get a couple good ones this year,

Tim in ILM

:)

Thanks for these comments! So as not to pull this convo off topic-- which I have a habit of doing!-- I responded to it in my chase thread. :)

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jconsor

jconsor

Posted
Posted

I really don't see anything in the upper pattern to pull 99L as far north as the Euro has been indicating the past 2 runs. On the other hand, with 99L getting better organized, the chances of a track that grazes the S. American coast have decreased significantly.

It's interesting how the GFS and Euro are once again showing really different solutions. The GFS kicked the Euro's butt with Debby-- big-time-- so it'll be interesting to see what happens with this latest match-up.

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am19psu

am19psu

Posted
Posted

The GFS overall has done decent with TCs since an upgrade that occurred last year before the season really started iirc. I'm talking mostly about the Atlantic basin.

It was actually 2010. Last year, the op model actually regressed, but the experimental EnKF version did a good job. Now that they've implemented the EnKF-hybrid, I suspect it should remain good this year.

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Srain

Srain

Posted
Posted

Euro has a trough starting to pick up 99L at the very end of its run with a landfall in Texas after strengthening post-Yucatan. Interesting.

We have been forecasting a weakness (inverted trough) across E Texas/Louisiana since last week somewhat similar to what we saw mid July down here, fwiw.

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