ATL: TROPICAL DEPRESSION ANA (02L)

[HURAKAN]

TD 2, 2008: BERTHA



INVEST 99L, 2009



A comparison between both Cape Verde systems. The image of TD 2 was the first to announce the upgrade. I think the NHC is being conservative, which is normal and understandable since the disturbance is so far away.

[KWT]

Yep they certainly are IMO being conservative, which is a little odd given some models are tracking this over Cape Verde Islands in about 12-18hrs time.

IMO this should be code red but there ya go!

[Nimbus]

which is a little odd given some models are tracking this over Cape Verde Islands in about 12-18hrs time.

Its not strong enough yet to be much of a threat to the Cape Verde islands.
And in order to track west far enough to effect the Leewards it would almost have to revert to just an open wave. The atlantic ridging looks like it will steer west for a few days but its rare for a storm near 14N this early to make it all the way to the Caribbean without recurving into a weakness in the ridge at some point.

[KatDaddy]

No doubt this will become ANA. Looking like its a TD already. I would expect the first advisory later today.

[cycloneye]

18 UTC Best Track.

AL, 99, 2009080918, , BEST, 0, 141N, 224W, 25, 1008, DB

ftp://ftp.tpc.ncep.noaa.gov/atcf/tcweb/ ... 009.invest

[cycloneye]

WHXX01 KWBC 091839
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1839 UTC SUN AUG 9 2009

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

DISTURBANCE INVEST (AL992009) 20090809 1800 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
090809 1800 090810 0600 090810 1800 090811 0600

LAT LON LAT LON LAT LON LAT LON
BAMS 14.1N 22.4W 14.8N 25.5W 15.4N 28.6W 15.7N 31.5W
BAMD 14.1N 22.4W 14.8N 24.5W 15.8N 26.3W 17.1N 27.9W
BAMM 14.1N 22.4W 15.0N 25.1W 15.9N 27.7W 16.6N 29.9W
LBAR 14.1N 22.4W 15.0N 24.7W 16.4N 26.9W 17.7N 28.5W
SHIP 25KTS 29KTS 35KTS 40KTS
DSHP 25KTS 29KTS 35KTS 40KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
090811 1800 090812 1800 090813 1800 090814 1800

LAT LON LAT LON LAT LON LAT LON
BAMS 15.6N 34.1W 15.7N 38.1W 16.6N 42.0W 18.9N 46.5W
BAMD 18.3N 29.3W 20.8N 31.9W 22.5N 32.9W 23.2N 32.2W
BAMM 17.4N 32.1W 18.9N 36.5W 20.5N 41.0W 22.3N 44.4W
LBAR 19.2N 29.7W 23.6N 31.3W 27.3N 33.3W 29.0N 34.1W
SHIP 45KTS 52KTS 50KTS 42KTS
DSHP 45KTS 52KTS 50KTS 42KTS

...INITIAL CONDITIONS...
LATCUR = 14.1N LONCUR = 22.4W DIRCUR = 290DEG SPDCUR = 15KT
LATM12 = 12.8N LONM12 = 19.4W DIRM12 = 293DEG SPDM12 = 14KT
LATM24 = 11.9N LONM24 = 16.7W
WNDCUR = 25KT RMAXWD = 30NM WNDM12 = 25KT
CENPRS = 1008MB OUTPRS = 1010MB OUTRAD = 120NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

[RL3AO]

Its looking pretty good. Could become a TD tomorrow.

[cycloneye]

In terms of shear in the next 96 hours,its favorable.After that shear increases.

Code: Select all

      *   ATLANTIC SHIPS INTENSITY FORECAST       *
                    *      GOES DATA MISSING, PROXY USED        *
                    *      OHC  DATA AVAILABLE                  *
                    *      INVEST  AL992009  08/09/09  18 UTC   *

TIME (HR)          0     6    12    18    24    36    48    60    72    84    96   108   120
V (KT) NO LAND    25    27    29    32    35    40    45    50    52    53    50    47    42
V (KT) LAND       25    27    29    32    35    40    45    50    52    53    50    47    42
V (KT) LGE mod    25    26    27    28    30    33    36    39    41    43    45    45    43

SHEAR (KT)         9     6     6     9     4     5     4     4     8    11    18    26    32
SHEAR DIR         29   340   345   336   270   282   231   219   219   245   253   245   259
SST (C)         27.1  26.9  26.7  26.5  26.2  25.9  25.8  25.7  25.8  25.9  26.3  26.5  26.7
POT. INT. (KT)   127   124   122   120   117   113   112   111   112   113   117   118   120
ADJ. POT. INT.   127   122   119   116   112   107   106   105   105   106   108   108   108
200 MB T (C)   -52.2 -52.5 -52.9 -52.8 -52.4 -52.9 -52.6 -52.6 -52.3 -52.3 -52.2 -52.7 -53.0
TH_E DEV (C)       7     7     7     7     7     7     7     6     6     6     7     7     7
700-500 MB RH     65    61    60    58    57    57    52    53    48    48    44    46    47
GFS VTEX (KT)     11    11    12    12    12    12    12    13    12    13    10    10     9
850 MB ENV VOR    20    13    13    23    34    24    31    48    50    42    12    -8   -29
200 MB DIV        48    19    20    34    35    11     0    11     1    12    12     0     3
LAND (KM)        532   672   816   957  1099  1341  1585  1815  2050  2207  2129  2104  2110
LAT (DEG N)     14.1  14.6  15.0  15.5  15.9  16.6  17.4  18.0  18.9  19.6  20.5  21.4  22.3
LONG(DEG W)     22.4  23.8  25.1  26.4  27.7  29.9  32.1  34.2  36.5  38.7  41.0  42.8  44.4
STM SPEED (KT)    15    14    13    13    12    11    11    11    11    12    10     9     8
HEAT CONTENT       3     2     0     0     0     0     0     0     0     0     4     9    12

  FORECAST TRACK FROM BAMM      INITIAL HEADING/SPEED (DEG/KT):290/ 15      CX,CY: -13/  5
  T-12 MAX WIND:  25            PRESSURE OF STEERING LEVEL (MB):  599  (MEAN=624)
  GOES IR BRIGHTNESS TEMP. STD DEV.  50-200 KM RAD:  17.0 (MEAN=14.5)
  % GOES IR PIXELS WITH T < -20 C    50-200 KM RAD:  59.0 (MEAN=65.0)

                        INDIVIDUAL CONTRIBUTIONS TO INTENSITY CHANGE
                         6   12   18   24   36   48   60   72   84   96  108  120
                        ----------------------------------------------------------
  SAMPLE MEAN CHANGE     1.   2.   3.   4.   6.   8.   9.  11.  11.  12.  13.  13.
  SST POTENTIAL          0.   1.   1.   2.   4.   8.  13.  17.  20.  22.  23.  24.
  VERTICAL SHEAR MAG     1.   2.   4.   5.   8.  11.  12.  13.  13.  12.  10.   7.
  VERTICAL SHEAR DIR     0.   1.   1.   1.   0.  -2.  -3.  -5.  -6.  -7.  -8.  -9.
  PERSISTENCE            0.  -1.  -1.  -1.  -1.  -1.  -1.  -1.  -1.   0.   0.   0.
  200/250 MB TEMP.       0.   0.  -1.  -1.  -1.  -2.  -2.  -2.  -3.  -3.  -3.  -3.
  THETA_E EXCESS         0.  -1.  -1.  -1.  -2.  -3.  -4.  -6.  -8.  -9. -11. -12.
  700-500 MB RH          0.   0.   0.   0.   0.  -1.  -1.  -1.  -1.  -1.  -1.  -1.
  GFS VORTEX TENDENCY    0.   0.   0.   1.   0.   0.   1.   0.   0.  -2.  -2.  -3.
  850 MB ENV VORTICITY   0.   0.   0.   0.   0.   0.   0.   0.   1.   1.   0.   0.
  200 MB DIVERGENCE      0.   0.   0.   0.   0.   0.  -1.  -1.  -1.  -1.  -1.  -1.
  ZONAL STORM MOTION     0.   0.   1.   1.   2.   2.   3.   4.   4.   5.   5.   5.
  STEERING LEVEL PRES    0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.
  DAYS FROM CLIM. PEAK   0.   0.   0.   0.   0.   0.  -1.  -1.  -1.   0.   0.  -1.
  GOES PREDICTORS        0.   0.   0.   0.   0.  -1.  -1.  -2.  -2.  -2.  -2.  -1.
  OCEAN HEAT CONTENT     0.   0.   0.   0.   0.   0.  -1.  -1.  -1.  -1.   0.   0.
                        ----------------------------------------------------------
  TOTAL CHANGE           2.   4.   7.  10.  15.  20.  25.  27.  28.  25.  22.  17.

   ** 2009 ATLANTIC RI INDEX AL992009     INVEST 08/09/09  18 UTC **
           ( 30 KT OR MORE MAX WIND INCREASE IN NEXT 24 HR)
 
 12 HR PERSISTENCE (KT):   0.0 Range:-45.0 to  30.0 Scaled/Wgted Val:  0.6/  1.3
 850-200 MB SHEAR (KT) :   6.7 Range: 26.2 to   3.2 Scaled/Wgted Val:  0.8/  1.1
 D200 (10**7s-1)       :  31.2 Range:-21.0 to 140.0 Scaled/Wgted Val:  0.3/  0.5
 POT = MPI-VMAX (KT)   :  94.2 Range: 33.5 to 126.5 Scaled/Wgted Val:  0.7/  0.4
 850-700 MB REL HUM (%):  60.2 Range: 56.0 to  85.0 Scaled/Wgted Val:  0.1/  0.1
 % area w/pixels <-30 C: 999.0 Range: 16.0 to 100.0 Scaled/Wgted Val:999.0/999.0
 STD DEV OF IR BR TEMP : 999.0 Range: 30.6 to   3.2 Scaled/Wgted Val:999.0/999.0
 Heat content (KJ/cm2) :   1.0 Range:  0.0 to 130.0 Scaled/Wgted Val:  0.0/  0.0
 
 Prob of RI for 25 kt RI threshold=   999% is 999.0 times the sample mean(12.3%)
 Prob of RI for 30 kt RI threshold=   999% is 999.0 times the sample mean( 8.0%)
 Prob of RI for 35 kt RI threshold=   999% is 999.0 times the sample mean( 4.8%)


[jinftl]

I have seen tropical storms that don't look this good on satellite....

[Sanibel]

Interesting to see what the negative conditions will do to it. Maybe nothing. Interesting to see that formation depends on getting over the hump of whatever inhibiting factors existed. I assume this favorability will migrate west.

[jinftl]

Looks 'fishy' no matter how you slice it at this time

[KWT]

Seems to be what some of the other models may be suggesting, as they also weaken this system after 72-96hrs.

[jinftl]

What are the inhibiting factors short-term? Water is around 27C, shear is 10kts or less, SAL is to it's north.....the way it looks now, if anything, is a testament to the favorable conditions it is under

Interesting to see what the negative conditions will do to it. Maybe nothing. Interesting to see that formation depends on getting over the hump of whatever inhibiting factors existed. I assume this favorability will migrate west.

[cycloneye]

[cycloneye]

KWT,the 12z EURO develops 99L and takes it on a westnorthwest track to almost the northern Leewards.

http://www.ecmwf.int/products/forecasts ... 12!!!step/

[KWT]

Its a threat to Bermuda on that run as well, certainly needs watching!

[Sanibel]

What are the inhibiting factors short-term? Water is around 27C, shear is 10kts or less, SAL is to it's north.....the way it looks now, if anything, is a testament to the favorable conditions it is under.

Not sure. But the last wave had a fairly good look before it vaporized. Perhaps it is a simple matter of the low pressure finally being driven by seasonal latent heat to the point where it is able to puncture and overcome the surrounding prevailing high pressure regime.

In any case the best indicator is always the disturbance itself. If dry subsiding conditions are still in place it will struggle.

[jinftl]

Analysis of current environment from Dr. Jeff Masters...

The wave was designated 99L by NHC Sunday morning. Wind shear is moderate, about 10 knots, and sea surface temperatures are moderately warm, about 27 - 28°C. There is a large area of dry air to 99L's north, but this is not currently interfering with the storm's organization. This morning's QuikSCAT pass showed a nearly closed surface circulation, stretched out along two axes.

Wind shear is expected to be low, 5 - 10 knots, tonight through Tuesday. SSTs will remain relatively constant at 27°C, so conditions favor development.

The atmosphere is always in flux and clearly the hostile conditions have been replaced by more typical favorable conditions for the time of year. 99L may develop due to the conditions around it, not 'in spite of'....that is a first this season.

What are the inhibiting factors short-term? Water is around 27C, shear is 10kts or less, SAL is to it's north.....the way it looks now, if anything, is a testament to the favorable conditions it is under.

Not sure. But the last wave had a fairly good look before it vaporized. Perhaps it is a simple matter of the low pressure finally being driven by seasonal latent heat to the point where it is able to puncture and overcome the surrounding prevailing high pressure regime.

In any case the best indicator is always the disturbance itself. If dry subsiding conditions are still in place it will struggle.

[Sanibel]

The atmosphere is always in flux and clearly the hostile conditions have been replaced by more typical favorable conditions for the time of year. 99L may develop due to the conditions around it, not 'in spite of'....that is a first this season.

Whether the change of conditions is a part of the tropical "forcing" a stronger Low creates is beyond me. Either way there it is.

[jinftl]

probably a case of which came first....the strong system or the environment making development conducive

one thing to note, check out the satellite images, this is not a system being sheared apart...an argument for the environment playing a factor in 1) it sustaining itself and 2) thereby being allowed to make advantage of the warm water to help develop

this is not a sytem 'holding on for dear life', like many we have seen thus far

The atmosphere is always in flux and clearly the hostile conditions have been replaced by more typical favorable conditions for the time of year. 99L may develop due to the conditions around it, not 'in spite of'....that is a first this season.

Whether the change of conditions is a part of the tropical "forcing" a stronger Low creates is beyond me. Either way there it is.