ATL: INVEST 99L - Discussion

[NDG]

I really don't understand why global models don't do much with 99L, according to the SHIPS model shear & mid level moisture content will not be that problematic down the road, probably just that the low level jet across the Caribbean is not dying out just yet.

Code: Select all

 * ATLANTIC     2018 SHIPS INTENSITY FORECAST     *
                    * IR SAT DATA AVAILABLE,       OHC AVAILABLE     *
                    *  INVEST      AL992018  08/16/18  00 UTC        *

TIME (HR)          0     6    12    18    24    36    48    60    72    84    96   108   120
V (KT) NO LAND    25    28    31    35    38    44    54    64    72    77    81    85    89
V (KT) LAND       25    28    31    35    38    44    54    64    72    77    81    85    89
V (KT) LGEM       25    28    30    33    36    42    49    58    68    80    91    95    96
Storm Type      TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP

SHEAR (KT)         8    10    11    17    19    21    16    15     8    12    11    20    19
SHEAR ADJ (KT)     3     1     0    -2    -6    -5    -5    -4     0    -5    -3    -4    -4
SHEAR DIR         79    61    55    52    53    50    58    24    29   326   278   275   264
SST (C)         28.4  28.7  28.3  28.3  28.5  28.2  28.6  27.1  28.2  29.0  28.6  28.7  29.0
POT. INT. (KT)   144   149   143   143   146   141   147   127   141   154   148   150   155
ADJ. POT. INT.   152   159   151   151   155   147   152   128   144   158   152   153   158
200 MB T (C)   -55.1 -55.4 -55.5 -55.1 -55.2 -55.5 -54.8 -55.2 -54.5 -54.8 -54.3 -54.5 -54.2
200 MB VXT (C)  -0.1  -0.2  -0.2  -0.2  -0.2  -0.1  -0.1  -0.1  -0.1  -0.1   0.0   0.0   0.0
TH_E DEV (C)       8     8     7     9     8     9    10    10    11    10    12    11    14
700-500 MB RH     69    71    68    67    66    64    63    63    59    61    59    60    57
MODEL VTX (KT)     4     4     4     4     4     4     4     4     4     3  LOST  LOST  LOST
850 MB ENV VOR    11    10     9    18    13     2    18    19    26    38    28    38     9
200 MB DIV        46    67    70    78    79    39    37    14    15    19    42    35    31
700-850 TADV      -7    -7    -6    -6    -5    -5     0     1    -2     0     8    12     4
LAND (KM)        660   561   483   421   415   281    66    67   179   186   223   269   184
LAT (DEG N)      9.0   9.1   9.2   9.3   9.5   9.9  10.6  11.3  12.2  13.3  14.5  15.5  16.6
LONG(DEG W)     48.0  49.6  51.2  52.8  54.4  57.5  60.4  63.2  65.9  68.8  71.9  75.4  78.9
STM SPEED (KT)    15    16    16    16    16    15    14    14    15    15    17    18    18
HEAT CONTENT      21    25    30    30    23    18    14     2     6    34    51    70    60

  FORECAST TRACK FROM TABM      INITIAL HEADING/SPEED (DEG/KT):275/ 15      CX,CY: -14/  1
  T-12 MAX WIND:  20            PRESSURE OF STEERING LEVEL (MB):  565  (MEAN=619)
  GOES IR BRIGHTNESS TEMP. STD DEV.  50-200 KM RAD:  12.4 (MEAN=14.5)
  % GOES IR PIXELS WITH T < -20 C    50-200 KM RAD:  95.0 (MEAN=65.0)
  PRELIM RI PROB (DV .GE. 55 KT IN 48 HR):            3.5

[NotSparta]

The dreaded 99L.

Is it the MDR wave? I didn't think they'd be so interested in it so fast, if at all!

8.5°N, 42°W. Yup

Certainly you mean more like 48W

oops, sorry, my bad

[Hypercane_Kyle]

Certainly looks ominous enough, but nonexistent model support from operational/ensemble members. Not likely to be anything more than a tropical wave.

[Twisted-core]

If the upper divergence ican increase (win out ))over the convergence ,this weak invest may organise further.

[SoupBone]

Certainly looks ominous enough, but nonexistent model support from operational/ensemble members. Not likely to be anything more than a tropical wave.

I disagree with this. This is exactly the type of system that sneaks up and catches people off guard. Models, as we all know, are not infallible. I posted a pic earlier this afternoon showing what appeared to be lessening shear in the Caribbean. I know not all of the ingredients are quite there, but this one could be something to watch in the next few days. I certainly hope you're right though.

[brohavwx]

Certainly looks ominous enough, but nonexistent model support from operational/ensemble members. Not likely to be anything more than a tropical wave.

Models are yet to do well in the deep Tropics, so don't write it off based on that alone. Now if we put more Recon runs into such low latitude systems we would get more data of deep tropics cyclogenesis to plug into the models but alas they wait until they are well pass 50W to do this. Now if this was up at 20N Recon would be in there in a flash.

[TheStormExpert]

Certainly looks ominous enough, but nonexistent model support from operational/ensemble members. Not likely to be anything more than a tropical wave.

Models have been actually doing very poorly this season in regards to picking up on every Atlantic system we’ve had to date.

[Ian2401]

Correct me if im wrong, but that to me looks like some banding features on the far left

[Hypercane_Kyle]

Certainly looks ominous enough, but nonexistent model support from operational/ensemble members. Not likely to be anything more than a tropical wave.

Models are yet to do well in the deep Tropics, so don't write it off based on that alone. Now if we put more Recon runs into such low latitude systems we would get more data of deep tropics cyclogenesis to plug into the models but alas they wait until they are well pass 50W to do this. Now if this was up at 20N Recon would be in there in a flash.

I'll grant you that. Harvey was also a sleeper with little-to-no model support to begin with before it reached the Caribbean.

[Cyclenall]

I really don't understand why global models don't do much with 99L, according to the SHIPS model shear & mid level moisture content will not be that problematic down the road, probably just that the low level jet across the Caribbean is not dying out just yet.

The LLJ that causes windshear in that part of the Caribbean should be gone as this is peak time for the eastern and central Caribbean. Think of how many historic hurricanes have went through there in Sept...not many aside from a certain "I" storm in 2004.

[CyclonicFury]

00z GFS doesn't develop this.

[Hypercane_Kyle]

There also appears to be a favorable MJO phase rolling through the Atlantic... also baffled as to why the global models show zero development. There's nothing immediately obvious as being unfavorable for development, IMO. And it's a fairly impressive system. There's got to be something we're missing.

[Hurricaneman]

There also appears to be a favorable MJO phase rolling through the Atlantic... also baffled as to why the global models show zero development. There's nothing immediately obvious as being unfavorable for development, IMO. And it's a fairly impressive system. There's got to be something we're missing.

May not be us missing anything, could be like last year where the models blew chunks and missed a few systems including Harvey that’s why we need to keep a very close eye on this system

[SoupBone]

I really don't understand why global models don't do much with 99L, according to the SHIPS model shear & mid level moisture content will not be that problematic down the road, probably just that the low level jet across the Caribbean is not dying out just yet.

Code: Select all

 * ATLANTIC     2018 SHIPS INTENSITY FORECAST     *
                    * IR SAT DATA AVAILABLE,       OHC AVAILABLE     *
                    *  INVEST      AL992018  08/16/18  00 UTC        *

TIME (HR)          0     6    12    18    24    36    48    60    72    84    96   108   120
V (KT) NO LAND    25    28    31    35    38    44    54    64    72    77    81    85    89
V (KT) LAND       25    28    31    35    38    44    54    64    72    77    81    85    89
V (KT) LGEM       25    28    30    33    36    42    49    58    68    80    91    95    96
Storm Type      TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP

SHEAR (KT)         8    10    11    17    19    21    16    15     8    12    11    20    19
SHEAR ADJ (KT)     3     1     0    -2    -6    -5    -5    -4     0    -5    -3    -4    -4
SHEAR DIR         79    61    55    52    53    50    58    24    29   326   278   275   264
SST (C)         28.4  28.7  28.3  28.3  28.5  28.2  28.6  27.1  28.2  29.0  28.6  28.7  29.0
POT. INT. (KT)   144   149   143   143   146   141   147   127   141   154   148   150   155
ADJ. POT. INT.   152   159   151   151   155   147   152   128   144   158   152   153   158
200 MB T (C)   -55.1 -55.4 -55.5 -55.1 -55.2 -55.5 -54.8 -55.2 -54.5 -54.8 -54.3 -54.5 -54.2
200 MB VXT (C)  -0.1  -0.2  -0.2  -0.2  -0.2  -0.1  -0.1  -0.1  -0.1  -0.1   0.0   0.0   0.0
TH_E DEV (C)       8     8     7     9     8     9    10    10    11    10    12    11    14
700-500 MB RH     69    71    68    67    66    64    63    63    59    61    59    60    57
MODEL VTX (KT)     4     4     4     4     4     4     4     4     4     3  LOST  LOST  LOST
850 MB ENV VOR    11    10     9    18    13     2    18    19    26    38    28    38     9
200 MB DIV        46    67    70    78    79    39    37    14    15    19    42    35    31
700-850 TADV      -7    -7    -6    -6    -5    -5     0     1    -2     0     8    12     4
LAND (KM)        660   561   483   421   415   281    66    67   179   186   223   269   184
LAT (DEG N)      9.0   9.1   9.2   9.3   9.5   9.9  10.6  11.3  12.2  13.3  14.5  15.5  16.6
LONG(DEG W)     48.0  49.6  51.2  52.8  54.4  57.5  60.4  63.2  65.9  68.8  71.9  75.4  78.9
STM SPEED (KT)    15    16    16    16    16    15    14    14    15    15    17    18    18
HEAT CONTENT      21    25    30    30    23    18    14     2     6    34    51    70    60

  FORECAST TRACK FROM TABM      INITIAL HEADING/SPEED (DEG/KT):275/ 15      CX,CY: -14/  1
  T-12 MAX WIND:  20            PRESSURE OF STEERING LEVEL (MB):  565  (MEAN=619)
  GOES IR BRIGHTNESS TEMP. STD DEV.  50-200 KM RAD:  12.4 (MEAN=14.5)
  % GOES IR PIXELS WITH T < -20 C    50-200 KM RAD:  95.0 (MEAN=65.0)
  PRELIM RI PROB (DV .GE. 55 KT IN 48 HR):            3.5

Harvey was almost a year ago, and the models stunk it up for genesis. That's what has me concerned right now.

[CyclonicFury]

I think the reason the models do not develop 99L is because its vorticity is very weak.

[Hammy]

Euro has a bit of weak development (possibly to a TD) in the next 48 hours, and notable that 48 hours ago it showed essentially nothing there now, not even the weak low that's formed.

[Chris90]

In my opinion, some of those early season storms can sometimes give you a pretty good idea of what areas are going to be favorable going into the rest of the season, so the fact that we already had Beryl at a decently low latitude indicates to me that 99L might have a fighting chance to become something, model support or not. These low latitude runners can surprise you quickly.

[Twisted-core]

https://imgur.com/L5kGMKR

[GCANE]

With the Bermuda High anchored in the forecast, if this does develop, very likely to run thru the Carib and into GOM.

[GCANE]

Forecast of upper-air conditions (shear, 355K PV) doesn't look too bad at least to mid Carib.
Downside is that it will be pushing dry air ahead of it.