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Severe Tropical Cyclone Jack


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Posted
  • Location: Taunton, Somerset
  • Weather Preferences: Snow, thunder, strong winds
  • Location: Taunton, Somerset

A tropical low has formed near the boundary between BOM's area of responsibility (AOR) and MeteoFrance's AOR, in the Southeastern Indian Ocean. The low is becoming increasingly well organised, with deepening convection and formative banding wrapping into an increasingly well defined LLC. 16U is forecast to head westwards across 90 degrees E into the MeteoFrance's AOR where it is likely to become a named storm before reversing track and heading back into BOM's AOR this weekend. Conditions appear favourable for strengthening over the next few days.

Edited by Somerset Squall
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Posted
  • Location: Noonamah, Top End NT
  • Location: Noonamah, Top End NT

IDW10800

Australian Government Bureau of Meteorology Western Australia

Tropical Cyclone Outlook for the Western Region

Issued at 2:14 pm WST on Thursday 17 April 2014 for the period until midnight WST Sunday 20 April 2014.

Existing Cyclones in the Western Region:

Nil.

Potential Cyclones:

At 1200 WST a low pressure system [16U] was located 325 kilometres west northwest of the Cocos Islands, near 10.8S 94.2E and moving westwards at 17 kilometres an hour towards the boundary of the Western Region. The system may develop into a tropical cyclone over the weekend west of 90E and is likely to re-enter the Western Region late Sunday or during Monday. As the system is likely to be west of 90E on Sunday, the likelihood has been reduced to moderate even though this system may be a tropical cyclone.

Likelihood of this system being a tropical cyclone in the Western Region on:

Friday Low

Saturday Moderate

Sunday High

There are no other significant lows in the Western Region and none are expected to develop over the next three days.

Edited by tropicbreeze
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Posted
  • Location: Taunton, Somerset
  • Weather Preferences: Snow, thunder, strong winds
  • Location: Taunton, Somerset

Track map issued by BOM, it'll be touch and go whether it will be named by them or MeteoFrance (AOR boundary is at 90E):

 

Posted Image

Edited by Somerset Squall
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Posted
  • Location: The Netherlands
  • Location: The Netherlands

Looking very impressive this evening, bound to be upgraded soon:

 

Indeed, 16U looks very well organized for a tropical low. 16U exhibits some very well-defined banding features to the north and south, combined with a possible CDO (central dense overcast). Therefore, it should be upgraded to a tropical cyclone by the Bureau of Meteorology (BOM) and the JTWC shortly.

 

The Bureau of Meteorology has issued their first graphical forecast of 16U, showing a southwestward track followed by a recurve to the southeast in the later timeframes.

 

Posted Image

Track forecast of 16U by the Bureau of Meteorology. (as of 18-04-2014)

 

Intensity-wise, the system is forecast to become a high end-tropical storm (category 2 on the BOM-scale) upon finishing the recurve. Weakening is forecasted afterward due to increasing wind shear caused by an upper level trough.1

 

The upper level trough can be seen on the 300 hPa heights forecast from NRL-NAVY:

 

Posted Image

300 hPa heights T90 from NRL-NAVY (as of 18-04-2014)

 

The upper level low is visible by the extension of lower heights (green colour) toward the northwest around 30S 90E.

 

The US-Naval research Laboratory (further in the post abbreviated as NRL-NAVY) has also issued their graphical forecast on 16U. This forecast can be seen below:

 

Posted Image

NRL-NAVY forecast track of 16U. (as of 18-04-2014)

 
When comparing the track forecasts of both agencies, some discrepancy can be noted. The first thing that can be seen is that the NRL-NAVY forecast shows a less sharp recurve than the BOM forecast. In other words, the NRL-NAVY shows a more south-southeastward track compared to the more southeastward track of the BOM in the later timeframes.
 
Furthermore, the NRL-NAVY forecast shows a curve back toward the southwest in the end of the forecast period, while the BOM maintains a southeastward track during this timeframe.
 
Therefore, it will be interesting to see which forecast track is the closest to the mark.
 
Sources
Edited by Vorticity0123
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Posted
  • Location: Taunton, Somerset
  • Weather Preferences: Snow, thunder, strong winds
  • Location: Taunton, Somerset

JTWC have upgraded the system to Tropical Cyclone 24S, with winds of 40kts. As Vorticity has mentioned, 24S has some very well developed banding, with a forming central dense overcast feature. Shear is low, waters very warm, and outflow excellent. Based on the impressive structure of 24S and highly favourable environment, rapid intensification is likely over the next 48hrs, with JTWC indicating a peak of 80kts in 48hrs, before 24S runs into higher shear further south.

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Posted
  • Location: Taunton, Somerset
  • Weather Preferences: Snow, thunder, strong winds
  • Location: Taunton, Somerset

BOM have upgraded 16U to Tropical Cyclone Jack, with winds of 45kts. Jack should continue to strengthen, perhaps rapidly. The cyclone is heading west-southwest but should turn south then southeast in respsonse to an approaching trough. This trough will eventually shear Jack apart, but not for another 48-60hrs.

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Posted
  • Location: Noonamah, Top End NT
  • Location: Noonamah, Top End NT

From Perth TCWC at: 0111 UTC 19/04/2014

REMARKS:

Tropical Cyclone Jack has rapidly developed over the past 24 hours and has reached tropical cyclone intensity.

The system was located using infra-red and microwave satellite imagery. 16U is over warm SSTs 29-30C. TC Heat Potential does decrease south of 14S but SST's remain above 26 degrees celcius north of about 20S.

Dvorak: Initial T1.0 was assessed at 1800 17 April. Using a curved band pattern, DTs in the range of 3.0 to 3.5 have been obtained over the past 6 hours. System intensity is set 45 knots.

CIMSS shear analysis at 1800 UTC indicated generally easterly shear between 10 and 20 knots. The shear is forecast to decrease over the next 24 to 36 hours and the system is expected to further intensify and may reach category 3 intensity on Sunday. An approaching upper level trough will assist poleward outflow late on Saturday and during Sunday. This trough will ultimately cause an increase in shear with strong upper level northwest winds, causing the system to weaken during Monday. Due to interaction with the sub tropical ridge to the south of the system, gales may persist in the southern half until Wednesday.

Copyright Commonwealth of Australia

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Posted
  • Location: Taunton, Somerset
  • Weather Preferences: Snow, thunder, strong winds
  • Location: Taunton, Somerset

Winds are up to 55kts according to JTWC. An eye feature is becoming evident in the central dense overcast. JTWC predict further rapid strengthening, with a peak of 100kts.

Edited by Somerset Squall
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Jack's looking well organised. Sea temperatures are warm, and shear is low. Central dense overcast is becoming more solid, and there isn't much that will impeed Jack from strangthening over the next 36+ hours.

 

Posted Image

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Posted
  • Location: Noonamah, Top End NT
  • Location: Noonamah, Top End NT

From Perth TCWC at: 1915 UTC 19/04/2014

REMARKS:

Tropical Cyclone Jack has continued to rapidly develop and is a category 3 cyclone.

The system was located using infra-red satellite imagery. Recent images depict a southerly track for much of the last several hours. 16U is over warm SSTs 28-30C. TC Heat Potential does decrease south of 15S but SST's remain above 26 degrees celsius north of about 20S.

Dvorak: Over the last few hours the system has been exhibiting a DT of 4.5 based on a curved band pattern with an eye developing in the last image. Intensity is set at 65 knots which is in reasonable agreement with ADT and SATCON [70 knots 1 minute mean]. EIR imagery shows recent eye development, with patches of CMG and CDG within a broad W region.

CIMSS shear analysis at 1200 UTC continues to analyse easterly shear of less than 10 knots. Low to moderate shear and thus continued development is expected until later Sunday when the shear increase and the system begins to weaken.

Due to interaction with the subtropical ridge to the south of the system, gales may persist in southern quadrants until Thursday.

Copyright Commonwealth of Australia

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Posted
  • Location: Taunton, Somerset
  • Weather Preferences: Snow, thunder, strong winds
  • Location: Taunton, Somerset

Jack has continued to strengthen, with winds now at 90kts according to JTWC, cat 2 on the SS scale. The severe cyclone continues to produce intense convection obscuring an eye feature, but the central dense overcast doesn't look as symmetrical as yesterday, with some elongation noted by JTWC, caused by the trough approaching from the west. This has happened a little sooner than originally thought, and as the trough moves closer, it will increase the shear over Jack, whilst steering the cyclone on a more south-southeasterly trajectory. As the trough seems to already be affecting Jack, the cyclone may have peaked.

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Posted
  • Location: Noonamah, Top End NT
  • Location: Noonamah, Top End NT

From Perth TCWC at: 0056 UTC 21/04/2014

REMARKS:

Severe Tropical Cyclone Jack is showing signs of weakening as it moves slowly southwards across the central Indian Ocean.

Position has been located using satellite imagery, with a good fix on ssmi microwave imagery at 2044 UTC. EIR imagery gives a DT of 5.0 based on an embedded centre pattern. FT/CI is based on MET=4.5. ADT is slightly higher at 4.8. SATCON intensity at 19 UTC was 57 knots and CIMSS AMSU was lower at 50 knots [1 minute means]. Intensity is estimated to be 65 knots [10 minute mean] based on Dvorak.

Microwave imagery shows a slight displacement of the LLCC to the north of the cold cloud and outflow has diminished in northern quadrants. Forecast is for further weakening as an approaching upper trough increases northwesterly shear across the system. This will be the main factor influencing the system's demise over the course of the next 24-36 hours.

Copyright Commonwealth of Australia

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Posted
  • Location: Taunton, Somerset
  • Weather Preferences: Snow, thunder, strong winds
  • Location: Taunton, Somerset

Jack is dissipating, as the deep convection that was being sustained by strong poleward outflow, has diminished this morning. Shear continues to increase as Jack slips south, and dry air has fully wrapped around the system. JTWC have issued their last advisory.

Edited by Somerset Squall
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