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A tropical cyclone has formed in the eastern South Indian Ocean, north of Cocos Island. The cyclone is in the TCWC Jakarta's area of responsibility, therefore it has been named by them. This is the first tropical cyclone to form in TCWC Jakarta's area of responsibility since TC Anggrek in 2010. They indicate winds are at 50kts. JTWC have issued a tropical cyclone formation alert on the system, but do not regard it as a tropical cyclone yet. Either way, Bakung is expected to strengthen over the coming days as shear is low and poleward outflow is good. Ridging to the south is expected to steer Bakung just south of due west over the next few days, keeping the cyclone over warm water. Therefore, it should strengthen decently.

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A tropical cyclone has formed in the eastern South Indian Ocean, north of Cocos Island. The cyclone is in the TCWC Jakarta's area of responsibility, therefore it has been named by them. This is the first tropical cyclone to form in TCWC Jakarta's area of responsibility since TC Anggrek in 2010. They indicate winds are at 50kts. JTWC have issued a tropical cyclone formation alert on the system, but do not regard it as a tropical cyclone yet.

 

This is quite odd, TCWC Jakarta did not mention anything about the system yesterday, and now they have upgraded it to a 50 kt tropical storm! Probably they were not aware of the system? Could it have anything to do with the lack of observations in that area?

 

Regardless of this, Bakung does look like a healthy tropical storm. Even though banding features have diminished some over the past few hours (as of 18:00 UTC), the central convection has been on the increase, both in magnitude and intensity. This can be seen in the Rainbow loop from NOAA given below:

 

post-20885-0-10961500-1418321660_thumb.g

Rainbow satellite image loop of Bakung. It can be activated by clicking on it. Note that the image does not auto-update itself.

 

The forecast from TCWC Jakarta suggests the system will intensify into a category 3 cyclone (Australian scale), with an intensity of 70 knots. This track forecast can be seen below:

 

IDJ22001.gif?1418306669424

Track forecast of Bakung.

 

If the cyclone tracks as forecasted, it may pass three basins in just three days, being Jakarta area of responsibility, Australian area of responsibility (once it moves below 10S), and in La Reunion area of responsibility (when it tracks west of 90E).

 

Sources:

http://en.wikipedia.org/wiki/Tropical_cyclone_basins

http://www.usno.navy.mil/JTWC/

http://www.bom.gov.au/wa/forecasts/nwcyclone.shtml

http://meteo.bmkg.go.id/siklon

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Bakung has weakened slightly from it's earlier peak of 50kts. JTWC assess winds of 40kts associated with Bakung. Bakung is moving westwards along the north side of a ridge to the south. This motion is expected to continue for the next few days. Bakung is then likely to reach a break in the ridge, allowing the storm to turn south. Convection is building back over the LLCC after a lull, which may be a sign Bakung is about to begin restrengthening. Shear is low to moderate, and waters warm, which should allow at least some slow intensification over the next 5 days.

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Shear rose rapidly shortly after I posted, and Bakung fell apart. Regeneration is not expected as the LLCC is now very weak and shear remains strong.

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Shear rose rapidly shortly after I posted, and Bakung fell apart. Regeneration is not expected as the LLCC is now very weak and shear remains strong.

 

That was a sudden and quick demise from this cyclone, what shear can do to such systems. This cyclone reminds me of TC Omar in 2008 (Atlantic), with which it took only 6 hours to get from a category 4 tropical cyclone to having an exposed LLCC (low level circulation center).

 

Bakung is not dead yet, though, The system keeps firing some convection, but it is also in a region of very strong shear (20-30 kt as analyzed by CIMSS, as of 10:00 UTC). However, just to the south of the cyclone, there is a pocket with almost no shear, so it takes just a little southward drift for this cyclone to find itself in a more favorable environment.

 

Looking at ASCAT imagery from yesterday afternoon, one can see that the center is not well defined. It is given below:

 

post-20885-0-51631100-1418727668_thumb.j

ASCAT pass of Bakung (15-12-2014 15UTC)

 

The center is indicated with the black cross (center position analyzed by CIMSS, assuming little movement has occurred since yesterday). What can be seen is that there is a wide line of convergence (winds blowing toward a certain area from the north as well as from the south) oriented ESE-WNW from at least the center of Bakung up to the west. This means that the center of Bakung is very elongated at best. In fact, it seems that the cyclone is entangled with the ICTZ (intertropical convergence zone).

 

The GFS is suggesting that the cyclone will develop in a few days, but it has had a positive bias for most of the lifetime of Bakung (indicating development where it did not occur).

 

Unless Bakung is able to escape the shear and the influence from a possible ICTZ, chances for development seem not very high, at least in the short term.

 

Sources:

http://en.wikipedia.org/wiki/Hurricane_Omar_%282008%29

http://www.knmi.nl/scatterometer/ascat_osi_25_prod/ascat_app.cgi?cmd=showimage&ascending=yes&day=0&flag=yes&coord.x=374&coord.y=214

http://www.acmad.net/new/?q=en/pages/itd-itcz-positions

http://www.usno.navy.mil/JTWC/

http://tropic.ssec.wisc.edu/#

http://moe.met.fsu.edu/cyclonephase/gfs/fcst/archive/14121600/13.html

Edited by Vorticity0123

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