Southern Hemisphere: Invest Thread 2009

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96S

[Somerset Squall]

South Indian Ocean:

Little has changed since yesteray in regards to 96S. Deep convection is still persisting, southeast of a fairly well defined but partially exposed LLC. The invest is under moderate shear, but waters are warm beneath the system, aaiding the current large area of convection. JTWC still has the chances for TC development in the next 24hrs as fair.

99S remains very close to land and very disorganised. Scattered convection is rotaing around a weak LLC just off the Mozambique coastline. Chances remain poor for further development, mainly due to land interaction.

South Pacific:

Invest 98P has redeveloped in the central Coral Sea. A broad monsoon trough lies across the region, and an LLC has re-emerged amongst the messy convection. The LLC has gained a little more definition today, as no rotation could be seen on satellite imagery yesterday but is visable today. Shear is low and waters are warm, however, this system is struggling to organise as the mass of flaring convection along the monsoon trough is choking the LLC. The LLC needs to seperate itself from the broader trough if any development is to occur.

[Cookie]

98P

96S

THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT

TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS FAIR.

[Cookie]

98P

The probability of this system becoming a tropical cyclone over the next three

days is:

Monday: Low

Tuesday: Moderate

Wednesday: Low

[kold weather]

ECM tries to develop both 99S and 98P so needs watching...esp as the 99S is forecasted to come towards land.

98P seems to have rather displaced convection to the east of where any circulation is trying to develop and is probably under some fairly high shear looking at how displace dit is. Any development of this system is going to require this shear easing off.

99S seems like its in the process of developing a decent LLC and whilst convection does still seems rather messy and somewhat disorganised if the circulation can get going then it has low shear and high heat content to work with decent outflow channels present as well. IF it can get its act together then it has every chance of strengthening pretty rapidly as the Mozambique channel is well known for allowing systems to undertake RI.

[Cookie]

thanks for the update Kold

Australian Government Bureau of Meteorology

Queensland

Tropical Cyclone Warning Centre

Media: This message is issued daily for the information of interested parties.

Media are NOT required to broadcast this message.

TROPICAL CYCLONE OUTLOOK

for the Coral Sea West of Longitude 160 East

Issued at 2:43pm on Monday the 23rd of March 2009

The monsoon trough extends across far northern Cape York Peninsula and the

northern Coral Sea. A low with central pressure approximately 1001 hPa lies well

offshore over the Coral Sea near 14.5S 153.5E. This low is expected to deepen

slightly and drift southeast during the next few days.

The probability of this system becoming a tropical cyclone over the next 72

hours is:

0-24 hours: Low

24-48 hours: Moderate

48-72 hours: Moderate

Tropical Cyclone outlooks issued by Brisbane can be accessed through the

Bureau's Home Page http://www.bom.gov.au.

Please note that the Darwin Regional Forecasting Centre issues Tropical Cyclone

Outlooks that cover the Gulf of Carpentaria. Refer to the Northern Region and

Gulf 3 day outlook at http://www.bom.gov.au/weather/cyclone/tc-outlooks.shtml.

99S

96S

THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE

WITHIN THE NEXT 24 HOURS IS DOWNGRADED TO POOR.

[Somerset Squall]

Thanks for your input Kold.

South Indian Ocean:

Invest 96S is suffering another increase in shear today, and as a consequence, the LLC is rather exposed with the limited convection present residing to the west. The system is drifting slowly westwards, and the system will require the shear to lessen to develop any further. The disturbance has certainly been very persistant, and it has looked very well organised at times, usually when shear is at it's lowest, so it appears that shear is governing what happens to 96S. Conditions are otherwise favourable with good poleward outflow established and waters of reasonable warmth.

As Kold mentions, things have become much more interesting with 99S. The LLC has relocated south of the previous position, slap bang over the Mozambique channel. Waters are 32C at the surface and extend quite deep, which should allow some rapid development. Shear is low and outflow good, which further supports the idea of TC formation. The LLC is well defined and convection is exploding over the centre. JTWC has rightly issued a tropical cyclone formation alert on the system. Probabilty of this one forming is very good.

South Pacific:

98P is finally showing signs of organisation. Deep convection is concentrated over a better defined circulation. The convection is much better organised and the system is taking on the appearance of a developing tropical disturbance now, which is more than can be said for the last couple of days with the system having not shown much signs of development. However, shear is fairly high again so development will be slow.

Invest 90P has formed in the northern half of the Gulf Of Carpentaria, and consists of a cluster of convection along a trough. Although waters are hot, shear is high so chances of TC development are low.

[Cookie]

thanks for the updates mate,

could be an interesting few days.

[Somerset Squall]

South Indian Ocean:

Good outflow and warm sea temps have caused convection to deepen and become more widespread near the LLC of 96S today. However, strong easterly shear continues to displace the bulk of convection west of the centre. Significant development is not expected as long as this shear persists.

99S is now TC 24S.

South Pacific:

98P is now TC Jasper.

90P remains insignificant. There is little evidence of a LLC, and convection is scattered and not well organised. Wind shear remains high in the northern Gulf Of Carpentaria making further development unlikely for now.

[Somerset Squall]

South Indian Ocean:

96S has dissipated.

Invest 92S has formed, several hundred miles south-south east of Diego Garcia. The system has a well defined LLC, with deep convection flaring near the centre. The high shear that destroyed 96S in this area has eased significantly, so further development is possible for 92S. I think there is a fair chance of TC development over the next couple days.

South Pacific:

90P remains very disorganised. The system has moved westwards over the last day or so, and is now located north of Darwin. Convection continues to flare but there is little evidence of a defined circulation. Shear is not quite so high as it was but there is still 20kts of shear buffeting the system which is hindering any development. The system may find lower shear in the NW Australian region but it is a big if at the moment. Shear generally is unfavourable in the Northern Territories currently.

Invest 91P has formed, at 9S, 113W. This system is far eastern South Pacific, to give you an idea, this system is much closer to South America than Australia. There is not much to the system, just scattered light convection which is showing signs of rotation. Waters aren't all that warm, and I would be surprised if it formed. If it did, I think it would be the farthest east on record a TC has formed in the South Pacific!

Edited March 26, 2009 by Somerset Squall

[Somerset Squall]

South Indian Ocean:

Convection associated with 92S has decreased significantly today. In addition, the LLC has lost definition. Moderate shear is impinging on the system currently, which is disrupting the LLC. Chances for TC development in the next day or so is poor.

South Pacific:

Convection has increased with 90P today, located in the Northern Territories. Convection is starting to look slighlty better organised and is starting to show signs of rotation. Shear is still moderate to high so any further development will be slow.

91P has dissipated.

[Somerset Squall]

South Indian Ocean:

Convection has increased in assocation with 92S overnight. However, the system is still rather messy, and is rapidly moving towards colder waters on the southward track. Therefore, the chances for development remain poor.

Invest 90P has moved into the south Indian Ocean and is still located north of Darwin. Shear remains moderate to high, but could well ease a little over the coming days. The disturbance is moving northwestwestwards so poses no threat to the Australian mainland. Waters are warm, and as shear could ease, slow development is possible. However, the system still lacks a well defined LLC and convection is highly disorganised so 90P has a long way to go yet.

South Pacific:

Invest 93P has formed, in the northern Coral Sea. Waters are very warm in the area, as the moderate shear is forecast to slowly ease. However, like 90P, 93P lacks a well defined surface circulation an convection is highly disorganised. Slow development is possible over the next couple days.

Edited March 28, 2009 by Somerset Squall

[Somerset Squall]

South Indian Ocean.

92S continues to speed away southwards and is now so far south it is over waters far too cold for development. Therefore the system is no longer considered an invest because it's no longer suspect for development.

Convection has increased substantially with 90P this evening. Waters are warm and shear is easing, which may explain the better convective appearance. However, the system still lacks a well defined LLC. Slow development is possible as conditons are now fairly favourable.

Invest 94S has formed, just off the coast of northwestern Madagascar. A small, ill defined LLC has deep convection flaring around it, but with not much persistance. Land interaction could well hinder further development as 94S is very near the coast.

South Pacific:

There is very little convection near the LLC of 93P. The ill defined LLC is just about discernable on satellite imagery, and that's only because it's fully exposed. Shear is moderate, and is very high to the south of the disturbance. Significant development is not expected.

Edited March 29, 2009 by Somerset Squall

[Somerset Squall]

South Indian Ocean:

90P has become much better organised overnight, with pronounced turning noted with the system, indicative of a better defined LLC. Additionally, banding features are beginning to form which are wrapping into the circulation. Shear is practically non-existant, and waters are very warm, which has helped this system rapidly develop. Both BOM and JTWC expect this system to develop into a tropical cyclone within the next 24hrs. The only limiting factor long term for this system is land interaction with East Timor. Short term though, chances for development are good.

94S remains highly disorganised. Scattered convection and showers are noted in a broad area northwest of Madagascar, but there is little evidence of a low level centre. Chances for development in the near term at least are poor.

South Pacific:

The LLC of 93P remains exposed. Any further development will be hindered by shear. Chances for development are low.

[Cookie]

90P

[Somerset Squall]

South Indian Ocean:

90P has fallen apart today. Convection has diminished and the LLC is now very hard to pick out on satellite imagery due to it being so ill defined. Thus, JTWC have cancelled the tropical cyclone formation alert and downgraded the chances of development to poor. The rapid deterioration of 90P can be blamed on the dry environment, reducing convection, and increasing shear, disrupting the LLC. Further development is unlikely.

94S has dissipated.

South Pacific:

The LLC of 93P remains almost entirely exposed, located near New Caledonia. Shear continues to be high, preventing any convection persisting near the centre. Therefore, further development seems unlikely.

[Cookie]

thanks for the update mate,

mainly over land this one for rest of its life

[Somerset Squall]

South Indian Ocean:

Invest 90P has changed little in organisation today. Convection remains limited due to the dry environment, and moderate shear. 90P is practically stationary, located just east of Timor. Chances for TC development are poor.

Invest 95S has formed, 385 miles south-southwest of Diego Garcia. This area around Diego Garcia has been a hotspot for invests of late, all of which have failed to develop. However, the environment is more conducive for development than last week. Shear is lower, and waters are warm. Additionally, 95S is benifitting from good outflow, which is fuelling convection over the consolidating LLC. Further development is possible as the favourable conditions persist.

South Pacific:

Convection remains limited in relation to 93P, located near New Caledonia. Significant development remains unlikely.

Edited March 31, 2009 by Somerset Squall

[Somerset Squall]

South Indian Ocean:

90P has dissipated.

95S continues to look fairly impressive on satellite imagery. Convection is quite deep in assocation with the disturbance and the LLC is becoming better defined. Shear is low to moderate, waters remain warm and outflow good. I think there is a fair chance of this one developing into a TC over the next day or so.

South Pacific:

93P has become much better organised over the past day, with convection forming around the previously exposed LLC. The LLC is not very well defined but lower shear, warm sea temps and very good outflow is now sustaining convection over the centre. The system has been moving briskly northeastwards and is now just north of Fiji, where it is providing some heavy rainfall. I think there is a fair chance of this one developing into a TC aswell.

Edited April 2, 2009 by Somerset Squall

[Somerset Squall]

South Indian Ocean:

95S continues to slowly organise. Deep, convective banding is wrapping around the LLC, indicating a developing system. 95S is moving westwards towards northern Madagascar, in warm waters and low shear. In addition, 95S is developing dual outflow channels which is tightening the LLC and sustaining deep convection. I think there is a good chance of TC development over the next day or so.

South Pacific:

After a lull in organisation, the satellite appearance of 93P has rapidly improved over the last 6hrs. Some very deep convection is persisting over a well defined LLC. 93P is in an environment of low shear, warm sea temperatures and favourable outflow. JTWC assess the chances of development in the next 24hrs as fair. Beyond this, shear could well increase dramatically so if 93P wants to develop then it will need to be sooner rather than later.

[Somerset Squall]

South Indian Ocean:

95S is now TC Jade.

No other invests.

South Pacific:

93P became TC Lin.

Invest 98P has formed, east-northeast of the Solomon Islands. Convection is flaring around a tightening LLC. Shear is low, and waters are still warm this far north. In addition, the LLC is beniffiting from good outflow, enhancing the convection. JTWC assess the chances for development in the next 24hrs as fair based on the favourable environment and increasing organisation.

[Somerset Squall]

South Indian Ocean:

Invest 99S has formed, in the central indian ocean around 8S, 77E. Deep convection is flaring over an increasingly well defined LLC. The disturbance is located in an area of low shear and good upper level divergence, which is fuelling convection. Waters are still fairly warm and can support tropical cyclone formation. Futher development is possible in the generally favourable conditions.

South Pacific:

98P has, for reasons unknown to me, has entirely collapsed this morning. Deep convection has vanished, and there is little evidence of a well defined LLC. In fact, JTWC report that there are mulitiple ill defined centres associated with the disturbance, and it can be specualted that perhaps this has caused a collapse of the disturbance. In addition, lower level convergence and upper level divergence is poor to fair which may explain the lack of convection this morning as instead of rising, moist, unstable air within the system, we probably have subsiding, dry, stable air instead. With the existence of multiple centres, chances of development is downgraded to poor by JTWC.

Edited April 8, 2009 by Somerset Squall

[Cookie]

its amazing how things can change so fast with these systems.

[Somerset Squall]

Indeed Cookie.

South Indian Ocean:

99S has dissipated.

South Pacific:

98P is now located almost slap bang over the Solomon Islands. Convection continues to flare around a poorly defined LLC which is only showing weak rotation at best. Development, if any, will be slow due to the disorganised nature of the system.

[Cookie]

98P

a few hours old but you can see the mess its in