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Atlantic Tropical Action 2013


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We continue to have a tough time overcoming the subsidence out in the Tropical Atlantic

as the instability is falling again after a brief spike back to around normal.

 

attachicon.gifts_al_tat_THDV.gif

Yet the Western Caribbean Sea and the Gulf of Mexico are near or slightly higher than normal. Wind shear appears to decrease across the Western Caribbean. Look closer to home for tropical development. The Multi Model Ensemble TC Genesis Probabilities including the European Suite suggest the Atlantic Ridge will build back W meaning less chance of anything that does develop re curving. A weak frontal boundary will approach the Mid/Lower Mississippi, Tennessee Valley Area next week increasing potential convective activity as the monsoonal trough lift N into the Caribbean Sea and the Central US Ridge will retreat W into the Great Basin. The best chance we have for any tropical development will be just E of the Caribbean Islands on W into the Western Caribbean and Gulf. The weaker these tropical waves remain crossing the MDR, the better for those wanting to see TC development.

 

 

 

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Oh I see it, the one behind it.

GFS is really tracking that?

yep, doesn't make it more than a strong wave or weak low but the last 3 runs have started to pick up on that area, if that on can stay near 12N as it is currently or gets to around 20N as modeled then it may have a chance

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Soo... p25L has a closed circulation. The Gulfstream doing a training mission out there found 8 kt west surface winds on the south side. Although from visible it looks extremely broad, but closed!

 

Edit: There is also a strong anti-cyclone axis aloft at cruising altitude right over the wave..

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Our "surprise" invest 97L actually has a pretty decent environment according to the SHIPS. Due to what Gonzo the Global Hawk is finding and how the SHIPS is analyzing the environment, I wouldn't be shocked to see the NHC get a little more bullish @ 2pm. 

 

Avila doesn't agree:

 

SURFACE OBSERVATIONS AND DROPSONDE DATA FROM A NOAA GULFSTREAM
AIRCRAFT SHOW A BROAD AREA OF LOW PRESSURE ASSOCIATED WITH A
TROPICAL WAVE CENTERED ABOUT 400 MILES EAST OF THE LESSER ANTILLES.
CLOUDINESS AND SHOWERS ASSOCIATED WITH THIS SYSTEM HAVE INCREASED
TODAY BUT REMAIN DISORGANIZED. THIS SHOWER ACTIVITY IS EXPECTED TO
SPREAD OVER THE LESSER ANTILLES DURING THE NEXT DAY OR TWO.
ENVIRONMENTAL CONDITIONS ARE NOT CURRENTLY FAVORABLE FOR
DEVELOPMENT...BUT COULD BECOME A LITTLE MORE CONDUCIVE FOR SOME
DEVELOPMENT WHEN THE WAVE REACHES THE WESTERN CARIBBEAN SEA IN 4 OR
5 DAYS.
THIS SYSTEM HAS A LOW CHANCE...10 PERCENT...OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS...AND A LOW CHANCE...20
PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 5 DAYS.

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Our "surprise" invest 97L actually has a pretty decent environment according to the SHIPS. Due to what the Global Hawk is finding and how the SHIPS is analyzing the environment, I wouldn't be shocked to see the NHC get a little more bullish @ 2pm. 

 

 

Hurricane in 4 days...

Except for being a tad close to Hispaniola at the end, the BAMM track is happy.

 

 

TIME (HR)          0     6    12    18    24    36    48    60    72    84    96   108   120

V (KT) NO LAND    25    27    28    29    31    36    42    50    56    62    66    70    71

V (KT) LAND       25    27    28    29    31    36    42    50    56    62    66    70    60

V (KT) LGE mod    25    27    28    30    31    34    38    45    54    66    76    86    73

 

 

SHEAR (KT)        15    11    13    11     4     6     0     5     5     4     8     6    11

SHEAR ADJ (KT)    -1    -3     0    -1    -2    -1    -1    -4    -2    -2    -3     0    -2

SHEAR DIR        256   257   241   250   261   200   241   188   304   247   296   214   262

SST ©         28.2  28.4  28.5  28.6  28.6  28.8  28.9  29.0  29.1  29.1  29.1  29.1  29.1

POT. INT. (KT)   140   142   144   145   145   148   149   151   153   153   154   154   154

 

LAT (DEG N)     15.0  15.1  15.1  15.1  15.0  14.9  14.7  14.7  14.9  15.5  16.4  17.5  18.6

LONG(DEG W)     54.0  55.1  56.1  57.1  58.0  59.8  61.4  63.0  64.7  66.5  68.5  70.6  72.8

 

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Our "surprise" invest 97L actually has a pretty decent environment according to the SHIPS. Due to what the Global Hawk is finding and how the SHIPS is analyzing the environment, I wouldn't be shocked to see the NHC get a little more bullish @ 2pm. 

 

Just an FYI it's not the global hawk of HS3 it's the regular NOAA Gulfstream G-IV.

 

I was bored.. so I made this.

post-741-0-95778100-1377970981_thumb.png

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Farther out, GFS brings comfort to me weenie heart, a wonderful pattern to bring storms close to Florida, and even a robust MDR storm.  I have seen mention of ensembles trending towards happier heights.

 

 

Maybe 2013 can be saved, yet. :weenie:

 

(I'm not kidding about expecting, yes, even being proud when it happens, to be nominated for WOTY)

post-138-0-56539300-1377971016_thumb.gif

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Farther out, GFS brings comfort to me weenie heart, a wonderful pattern to bring storms close to Florida, and even a robust MDR storm.  I have seen mention of ensembles trending towards happier heights.

 

 

Maybe 2013 can be saved, yet. :weenie:

 

(I'm not kidding about expecting, yes, even being proud when it happens, to be nominated for WOTY)

 

Once the seasonal ridge can move out of the west, I would assume the gulf and Carribian will become much more favorable. A troff in the west with a ridge along the east coast should be a pattern that allows the Atlantic basin to produce storms.    The Epac has had a nice pattern all season and has yet to produce any majors, so I have my doubts about this year.   And we are looking at the long range GFS and splitting hairs!

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Our in-house calib. Euro ensembles have been consistently marking AL97 with a 40-50% chance for the past couple of days, up to 60% in this mornings 00Z. This is the most bullish I've seen the Euro ensembles over the Atl thus far this season.

 

Cool.  Small ray of light here.  Hey-- if the action isn't going to kick in now, when would it?

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Wonder if the POD gets modified this afternoon to get a WC-130J to the USVI tomorrow to fly a mission Monday.  Really, a mission tomorrow would seem prudent for issuing warnings for the Lesser Antilles, but I'm not sure they can move that fast.

 

I suppose the G-IV can drop more probes, since it is already forward positioned, but I'd want a low level invest that can nail the center...

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Well, pouch 25 has picked up convection and has just been determined to have a weak closed sfc circ. with light west winds to the south per that research mission. Therefore, it has just been designated as invest 97L as noted. Although the CMC continues to develop into a cane (at least 6th run in row...these last 2 don't hit east coast but aren't too far from it; the 12Z of 8/31 gets it to 971 mb status), it still doesn't have other support. However, I did notice on the brand new Euro a subtle increase in convection and lower pressure around a weak sfc low that moves into the LA's. I'm still not betting on the CMC, but these latest developments are at least still suggesting not to completely dismiss the CMC just yet. Just to remind folks, the reason I won't ignore the CMC like I usually do when it is on its own is because of a rare quite strong MJO phase 1 developing as we speak. If Euro projections end up right, this will turn out to be among early 9/1981 and late 8/1979 as the strongest MJO phase 1's since 1975 near the climo season peak. 1979 and 1981 produced six hurricanes, including three majors, between the two of them just while the MJO was strong in phases 1-2.

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Cool.  Small ray of light here.  Hey-- if the action isn't going to kick in now, when would it?

 

If we dont' see  an active period over the Atlantic in the next two-three weeks (most favorable MJO-state), I'm not sure if we ever will this year. These next few weeks will likely be the heart of the Atlantic Hurricane Season, coincidently the same time as the climatological peak.

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Well, pouch 25 has picked up convection and has just been determined to have a weak closed sfc circ. with light west winds to the south per that research mission. Therefore, it has just been designated as invest 97L as noted. Although the CMC continues to develop into a cane (at least 6th run in row...these last 2 don't hit east coast but aren't too far from it; the 12Z of 8/31 gets it to 971 mb status), it still doesn't have other support. However, I did notice on the brand new Euro a subtle increase in convection and lower pressure around a weak sfc low that moves into the LA's. I'm still not betting on the CMC, but these latest developments are at least still suggesting not to completely dismiss the CMC just yet. Just to remind folks, the reason I won't ignore the CMC like I usually do when it is on its own is because of a rare quite strong MJO phase 1 developing as we speak. If Euro projections end up right, this will turn out to be among early 9/1981 and late 8/1979 as the strongest MJO phase 1's since 1975 near the climo season peak. 1979 and 1981 produced six hurricanes, including three majors, between the two of them just while the MJO was strong in phases 1-2.

 

Ugh having comp issues! To comment on MJO signature, there's a nice wave-number 1 signal in U200 at current time. Looks like peak-MJO upper-level divergence is pushing off East Africa to over the IO.

 

u.200.anom.30.5S-5N.gif

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Not sure I agree with the 18z coordinates...

 

The center is clearly at 54.8W, but whatever. It's just a weak and sheared system. 

 

AL, 97, 2013083118, , BEST, 0, 151N, 555W

 

attachicon.gifScreenHunter_53 Aug. 31 15.15.png

 

Yea thats not the correct vortex center position, but more of the mean center of the wave 97L is embedded in. While convection is still poorly organized, the better defined center does offer some interesting possibilities. If convection blossoms again tonight similar to last night, it wouldn't take too much to take this to TD intensity.

 

Note the expanding outflow occurring near the center... now that convection is beginning to develop in larger quantities as the environment moistens up, the upper level flow is being modified by increasingly anticyclonic flow from the convection combating the weak environmental westerly flow. If convection continues to become more robust, we should see the westerly flow being replaced by upper level easterlies. This is supported by the favorable MJO phase as well as being on the backside of a CCKW which typically is dominated by upper level easterlies. 

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Actually doesn't look terrible. 

 

Might see yet another weak tropical storm...

*   ATLANTIC SHIPS INTENSITY FORECAST       *
                    * GOES AVAILABLE,       OHC AVAILABLE       *
                    *      INVEST  AL972013  08/31/13  18 UTC   *

TIME (HR)          0     6    12    18    24    36    48    60    72    84    96   108   120
V (KT) NO LAND    25    27    28    30    33    37    45    52    58    62    67    69    71
V (KT) LAND       25    27    28    30    33    37    45    52    58    62    67    53    61
V (KT) LGE mod    25    27    28    30    31    35    40    48    58    69    79    65    77
Storm Type      TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP

SHEAR (KT)        12    13    12     5     3     5     2     5     3     8     4    13    12
SHEAR ADJ (KT)    -3     0    -1    -2    -3    -2    -3    -3    -2    -3    -2    -2    -3
SHEAR DIR        259   244   251   260   221   206   133   269   318   264   285   240   249
SST (C)         28.4  28.5  28.6  28.7  28.7  28.9  29.0  29.1  29.2  29.1  29.1  29.1  29.2
POT. INT. (KT)   143   144   145   146   146   149   151   153   155   154   154   154   156
ADJ. POT. INT.   140   139   139   140   140   143   144   147   150   150   150   148   147
200 MB T (C)   -54.0 -53.8 -53.8 -53.9 -53.7 -53.8 -53.6 -53.6 -53.5 -53.4 -53.4 -53.3 -53.1
TH_E DEV (C)      10    10    10    10    11    11    11    11    11    11    11    11    12
700-500 MB RH     51    50    52    54    54    56    60    60    62    62    62    62    62
GFS VTEX (KT)      8     8     8     7     8     6     6  LOST  LOST  LOST  LOST  LOST  LOST
850 MB ENV VOR    22    21    17    17    19    23    43    52    58    52    46    34    24
200 MB DIV        32    17    25    25    28    23    14     8    14    18    24    14    19
700-850 TADV      -2    -4    -2     0    -1    -2     0     0     1     4     8     6     4
LAND (KM)        763   682   609   554   512   455   444   404   311   234   118   -17    50
LAT (DEG N)     15.1  15.1  15.1  15.1  15.1  14.9  14.7  14.8  15.2  16.0  17.2  18.4  19.6
LONG(DEG W)     55.5  56.5  57.5  58.4  59.3  61.0  62.5  64.1  65.9  67.9  70.1  72.3  74.4
STM SPEED (KT)    12    10     9     9     9     8     7     8    10    11    12    12    11
HEAT CONTENT      27    29    35    43    48    24    44    56    56    40    25    98    40 
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Back when a famous Penn State meteorologist in State College was at AccuWx, I can remember him commenting in videos that 'popcorn' convection ahead of a wave was usually a sign the environment was becoming more favorable.

 

Was he, in his own way, before he became an MJO fan (don't know if he ever became a Kelvin fan) noting the MJO?  Quien sabes?

 

 

ETA

 

Staring at vis loops with lat/long turned on for reference, there is actually an extensive area with light Westerlies winds, almost monsoon trough looking.

post-138-0-37543900-1377979515_thumb.jpg

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