77 replies to this topic

[Somerset Squall]

South Indian Ocean:

90S became Tropical Cyclone Hubert.

South Pacific:

97P, against forecasts, developed into Tropical Cyclone 19P as the environment rapidly improved.

Invest 98P has formed to the west of TC 19P, to the north of Vanuatu. Deep convection is persisting over an increasingly well defined LLC and the JTWC have issued a tropical cyclone formation alert on the system. Shear is low, sea temps warm and equatorward outflow good which supports further development. If organisational trends continue, this one could be declared a tropical cyclone later tonight or early tomorrow.

[Somerset Squall]

South Indian Ocean:

Invest 90S has formed around 6S 86E, just in the Australian region of responsibilty. At present, 90S consists of a weak region of turning within an area of disorganised, limited convection. For this reason, any further development is likely to be slow. However, conditions are favourable for further development with low shear and warm sea temperatures in the surrounding area.

South Pacific:

98P became Severe Tropical Cyclone Ului.

[cookie]

90S

[Somerset Squall]

South Indian Ocean:

90S became Tropical Cyclone Imani.

Invest 92S has formed around 7S 70E. The system is quite broad at present, with disorganised yet deep convection showing signs of weak rotation around several possible circulations. Shear is moderate to high (20-30kts), which is probably disrupting any formation of a strong LLC. Waters are very warm however, fuelling the deep convection currently present in association with 92S. If 92S can move southwards, it will find lower shear values, however, if it moves too far south, it will reach cooler waters. Unless shear eases where 92S is now, then development could be slow or not occur at all. I give this system a poor chance of becoming a TC in the next 24hrs, as there is only a small area of favourable conditions to the south of the system at present.

South Pacific:

Invest 91P has formed off the north coast of Australia, in the Arafura Sea. 91P is a disorganised monsoonal system with plenty of deep convection but only weak rotation at present. JTWC haven't picked up this system at all really, though BOM are very keen on it becoming a tropical cyclone in around 36hrs time as it moves towards the Gove coastline. Waters are very warm, and shear is low, so consolidation seems possible but whether a tropical cyclone can form out of this disorganised system within the 48hrs before landfall in Gove remains to be seen. Communuties from Maningrida eastwards to Nhulunbury need to be weary of this system even if it doesn't become a tropical cyclone, as there is likely to still be some extremely heavy rains from this system. If this system doesn't develop before landfall in around 48hrs time, then it still needs watching as it is forecast to move southeastwards where it could emerge into the Gulf Of Carpentaria, where conditions are currently favourable. It's a long way off, but Queensland also need to monitor this system because if it indeed develops in the Gulf Of Carpentaria, a continued southeasterly motion seems likely judging by model predictions, which could bring further flooding rains to areas affected by Severe TC Ului at the end of last week. A lot to keep an eye on!

[cookie]

91P

this could really be an intresting one to track.

[Somerset Squall]

South Indian Ocean:

92S dissipated.

Invest 94S has formed, at 10S 93E, around 260 miles west-northwest of the Cocos Islands. An area of deep convection has been expanding through the day near an increasingly well defined LLC. Conditions are favourable for further development as shear is low and waters are warm. JTWC give 94S a fair chance of becoming a tropical cyclone within the next 24hrs.

South Pacific:

91P became TC Paul.

Invest 95P has formed around 19S 172E. The invest is little more than scattered convection showing no real signs of rotation. The system formed yesterday and does not look as impressive as then. As the system appears to be losing organisation, the chances for TC formation are poor.

[Somerset Squall]

South Indian Ocean:

94S became TC Robyn.

Invest 99S has formed around 10S, 103E, in the eastern South Indian Ocean. Messy, limited convection is showing signs of weak rotation. Most of this system's energy is probably being stolen by a larger invest to the east. Chances for TC development are poor.

Invest 91S has formed several hundred miles north of Port Hedland, Western Australia. A large and deep area of convection is expanding over a consolidating LLC. With toasty waters, low shear and good outflow, further development is expected with a fair chance of the system becoming a TC within the next 24hrs according to JTWC.

South Pacific:

No invests.

[cookie]

about time to from the SIO

[cookie]

94P

Has formed and is looking quite organized already.

[Somerset Squall]

South Indian Ocean:

No invests.

South Pacific:

So, 94P, interesting little system this. It has formed at 30S, and you can see from the imagery it is not far off the north island of New Zealand. Tropical cyclone formation is practically unheard of at this lattitude, which makes me think if this one is to develop at all it will be subtropical at very best. Waters are cool here, and it is surprising given that it's fast approaching Winter this side of the equator that this system has found shear low enough to develop. What I expect has happend (I haven't been watching this area over the last few days), is that an extratropical low has become cut off from the baroclinic zone, and these lows are found to be more resistant to shear. It will be a bit of a miracle if this one becomes a fully fledged tropical cyclone however.

[cookie]

94P

something to watch anyway. interesting little system all the same.

[Somerset Squall]

Moving south and dissipating...

Attached Thumbnails

• 

[J07]

94P was classified a ST2.5 using the Poteat Subtropical technique a few days ago. (Basically the same as Dvorak, but for subtropical cyclones). ST2.5 corresponds to DT2.5, which has a core of winds 35-40kts, aka a tropical cyclone.
Within the next 24 hours it will complete its transition to an extratropical cyclone, as cold air from near Australia pushes up its western flank.

Where did it come from in the first place? There was a pre-existing trough in the Coral Sea, about 25-30S. A weakening front transported this eastwards, where it sat stationary northwest of the North Island, deepening quite nicely. It developed some good banding over time. SSTs are approximately 23C there.

Subtropical cyclones are not too uncommon in such waters during autumn. They don't always form as this one did, sometimes a tropical cyclone will fail to make ET transition and instead become subtropical, before finally moving off to the south and developing the standard ET features of a fairly clear warm and cold front set.

[Somerset Squall]

South Indian Ocean:

Invest 95S has formed around 300 miles north-northeast of the Cocos Islands. Deep convection is persisting over a consolidating LLC. Shear is low and waters are still warm, and outflow is also good. This could support further development over the next day or so. If the invest keeps to it's current trend of organisation then there is a fair chance a tropical cyclone could form.

Invest 97S has formed near Diego Garcia. Deep convection is flaring and showing signs of broad rotation. Shear is low over the disturbance, and at a lattitude of 6S, waters are still pretty warm. The LLC is at best very broad at the moment but the conditions do support at least some slow development.

South Pacific:

94P is now fully extratropical to the southwest of New Zealand.

[Somerset Squall]

South Indian Ocean:

95S has remained in a steady state over the last few days. The invest has moved eastwards towards Indonesia. Convection has been flaring near the LLC but has lacked persistance. In addition, the LLC has weakened a bit since when I last posted. Waters are still warm and shear low to moderate, so I still think there is a fair chance this one could eventually become a tropical cyclone.

97S has been moving eastwards too and has not got any better organised than before. Like with 95S, convection has come and go over the last 48hrs and the LLC is still broad. Shear is still not too high so some slow development may still occur over the next day or so.

South Pacific:

No invests.

[Somerset Squall]

South Indian Ocean:

95S has continued to move eastwards south of Jakarta, Indonesia. The disturbance has continued to weaken partly due to land interaction but also increasing vertical wind shear. The system has become highly disorganised with substantially reduced convection which is no longer showing much rotation. It is now unlikely this system will become a tropical cyclone.

97S has changed little in organisation over the last 24hrs. Convection has become a little more persistant, but any circulation is still ill defined. Moderate to high shear has arrived today, preventing further consolidation of 97S. As the season ended at the end of April, this is hardly surprising as much of the South Indian Ocean is now characterised by high shear, typical at this time of year. Unless this shear eases, 97S won't be long for this world.

South Pacific:

No invests.

[Somerset Squall]

South Indian Ocean:

95S has dissipated.

97S has dissipated.

An off season invest, 99S, has formed almost 400 miles north-northwest of Cocos Island. 99S is located in an area of moderate shear, but shear is expected to become unseasonably low over the next day or two as 99S heads towards the island. With sea temps still around 28-29C, and a recent increase of convection near the LLC, 99S has a fair shot at becoming a tropical cyclone over the next day or two.

South Pacific:

No invests.

Edited by Somerset Squall, 08 June 2010 - 22:52 .

[Somerset Squall]

South Indian Ocean:

99S dissipated.

Another off season invest, 91S, has formed at 6S, 92.5E, northeast of Cocos Islands. Shear is currently low, and sea temps are around 27C. The invest consists of a large mass of convection which has been showing signs of rotation over the last few hours. Cooler waters and moderate shear lie to the southwest, but it's worth noting that shear is unusually low in this area at present, which may promote some slow development.

South Pacific:

No invests.