Southern Hemisphere: Invest Thread 2009/2010

[Somerset Squall]

South Indian Ocean:

Invest 98S has formed, a couple hundred miles north-northwest of Cocos Islands. Deep convection has persisted in the area over the last 24hrs, and is rotating around a broad LLC. The invest is in warm waters, low shear and is feeling the benefits of good upper level outflow. This should allow the LLC to tighten and consolidate over the next couple days. The invest still has some work to do as the LLC is still broad and winds reletively weak near the centre. I think there is a fair chance of a TC forming from 98S in the next few days if the disturbance makes good use of the environment.

South Pacific:

No invests.

[Cookie]

98S

Covers a wide area

[Cookie]

98S

[Cookie]

98S

THE

POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE

WITHIN THE NEXT 24 HOURS IS UPGRADED TO FAIR.

[Cookie]

98S

up to good chance this morning of being the first named storm of 2010

WTXS21 PGTW 020230

MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//

SUBJ/TROPICAL CYCLONE FORMATION ALERT//

RMKS/

1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN

160 NM EITHER SIDE OF A LINE FROM 9.4S 96.0E TO 11.1S 91.6E WITHIN

THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY ISSUANCE OF

NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME. WINDS IN THE AREA

ARE ESTIMATED TO BE 25 TO 30 KNOTS. METSAT IMAGERY AT 020200Z

INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 10.0S 94.7E.

THE SYSTEM IS MOVING WEST-SOUTHWESTWARD AT 06 KNOTS.

2. REMARKS:

THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 9.0S 95.0E IS NOW

LOCATED NEAR 10.0S 94.7E, APPROXIMATELY 175 NM NORTHWEST OF THE

COCOS ISLANDS. ANIMATED INFRARED SATELLITE IMAGERY DEPICTS A

CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC) WITH IMPROVED

CONVECTIVE BANDING. A 011955Z AMSU IMAGE INDICATES MULTIPLE

CONVECTIVE BANDS WRAPPING INTO THE LLCC WITH AN INTENSE CLUSTER OF

DEEP CONVECTION LOCATED WITHIN THE CONVERGENT SOUTHERN FLANK. A

011429Z PARTIAL ASCAT IMAGE SHOWS THAT 20-25 KNOT WESTERLY WINDS

HAVE STARTED TO WRAP TIGHTER INTO THE EASTERN SEMI-CIRCLE OF THE

SYSTEM. SURFACE OBSERVATIONS FROM THE COCOS ISLANDS AND BUOY 56507

ALSO INDICATE STRENGTHENING EASTERLY FLOW INTO THE LLCC WITH 20-KNOT

SUSTAINED WINDS, SLP NEAR 1005 MB AND 24-HOUR SLP FALLS OF 1.5 MB.

ADDITIONALLY, THE 850 MB VORTICITY SIGNATURE HAS BECOME STRONGER AND

MORE SYMMETRIC WHILE THE MID-LEVEL TEMPERATURE ANOMALY ON THE 01/19Z

AMSU CROSS-SECTION HAS STRENGTHENED TO +2C FROM NEGATIVE VALUES 24

HOURS AGO. UPPER-LEVEL ANALYSIS CONTINUES TO DEPICT A FAVORABLE

ENVIRONMENT CHARACTERIZED BY WEAK TO MODERATE VERTICAL WIND SHEAR

AND GOOD RADIAL OUTFLOW ASSOCIATED WITH A DEVELOPING ANTICYCLONE

OVER THE CENTER. ANIMATED WATER VAPOR IMAGERY SHOWS GOOD EQUATORWARD

OUTFLOW AND EXPANDING POLEWARD OUTFLOW AIDED BY A WEAK UPPER-LOW TO

THE SOUTH. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30

KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1000 MB.

BASED ON THE IMPROVED ORGANIZATION AND FAVORABLE ENVIRONMENT, THE

POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE

WITHIN THE NEXT 24 HOURS IS GOOD.

[Cookie]

98S

[Somerset Squall]

South Indian Ocean:

98S, as Cookie has said, is becoming better organised. Convectional banding is increasing, and very recently, the convection covering the centre has expanded significantly. I expect 98S to become a tropical cyclone very soon, almost certainly within the next 24hrs.

Invest 99S has formed in the Northern Territories of Australia, near Darwin. Widespread convection and showers are showing signs of rotation over land. 99S is gradually moving westwards and it appears the disturbance will soon move over water. As waters in the region of the Josef Bonaparte Gulf are around 32C, don't be surprised to see a tropical cyclone rapidly form like Laurence did. However, it's not certain 99S will make it over water, so development is not certain by any means.

South Pacific:

No invests.

[Cookie]

99S

[Cookie]

98S

really doesn't look good at the moment

[Somerset Squall]

Indeed Cookie, 98S is being badly sheared, which has largely diminished the convection associated with LLC. Development into a TC is a lot less certain now, but BOM and JTWC are still keen on bring 98S to TC status as shear is expected to ease. The LLC is still well defined so any relaxation in shear should allow the persistant convection to come back.

[Somerset Squall]

South Indian Ocean:

98S is recovering. Chances for development were downgraded to poor by JTWC but now has been upgraded to fair as convection has blown up to the west of the LLC again. Warm waters and high moisture are combatting high shear to sustain this low in the hostile shear. MeteoFrance are keen on making 98S a tropical cyclone still, so it needs to be watched.

99S has a huge amount of convection associated with it, but it is not well organised and 99S lacks a well defined LLC. In addition, 99S has dived southwards quicker than expected, taking the system back inland. Therefore, development into a TC is now unlikely.

South Pacific:

No invests.

[Cookie]

91P

Australian Government Bureau of Meteorology

Western Australia

Tropical Cyclone three-day outlook for the Western Region

Issued at 10:25am WST on Thursday the 14th of January 2010

Valid until midnight WST Sunday

Existing Cyclones in the Western region:

Nil.

Potential Cyclones:

A weak low north of the Pilbara coast is expected to gradually develop in the

next few days as it moves to the west. The low is not expected to produce gales

today or on Friday but may reach cyclone intensity on Saturday or Sunday by

which stage it should be more than 500 km north northwest of Exmouth. It is not

expected to directly impact the coast during the outlook period.

Likelihood of a tropical cyclone being in the Western Region:

Friday :Low

Saturday :Moderate

Sunday :High

NOTES: Development Potential is an estimate of the chance of each system being a

tropical cyclone in the Region for each day.

Very Low: less than 5% Low: 5% - 20%,

Moderate: 20% - 50% High: Over 50%

[Somerset Squall]

South Indian Ocean:

98S developed into cat 5 Very Intense Tropical Cyclone Edzani, the strongest storm since Bento in 2004. This is quite remarkable given the disturbance's struggle against shear in early life.

99S dissipated.

Invest 90S has persisted over Northern Madagascar over the last few days. 90S has now moved southeastwards and resides between the east coast of Madagascar and La Reunion. The disturbance is poorly organised, with sporadic convection over an elongated LLC. Favourable poleward outflow may allow the LLC to tighten up and the convection become more persistant. 90S has some work to do before it becomes a TC however.

Invest 91S, as Cookie mentions above, has formed several hundred miles north of Exmouth, Western Australia. The LLC is weak, but has retained some persistant (but limited) convection over the last 6 hours. If this trend continues, then the LLC should strengthen, and BOM seem very keen to make 91S a tropical cyclone over the next couple days. Waters are warm, and at the moment at least, shear is low. This certainly favours development, espcially as 91S is a small system which could spin up rapidly.

[Somerset Squall]

South Pacific:

Invest 92P has formed in the Gulf Of Carpentaria. An ill defined LLC is embedded within a monsoon trough (MT). Waters are hot in the Gulf, but unless the LLC seperates itslef from the MT, then it won't be able to develop. Shear is low currently in the area, which is why BOM are suggesting some slow development of 92P as it remains practically stationary.

[Cookie]

91S

THE POTENTIAL FOR THE DEVELOPMENT OF A

SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS POOR.

92P

[Somerset Squall]

South Indian Ocean:

90S beriefly became well organised last night, with deep convection building near an increasingly well defined LLC. However, shear has taken 90S back to square one, with convection highly disorganised and the LLC significantly weakened. As 90S is moving south of cooler waters and sustained shear, chances for further development are poor.

91S has changed little in organisation in the last 36hrs. The LLC remains pretty well defined, but strong easterly shear has removed convection from the centre of the low and sheared it to the west. In fact, this morning it looks as if very little convection remains at all in any quadrant of the low. However, as the LLC is well defined, and shear is expected to ease later today or early tomorrow, there is still a fair chance of a tropical cyclone forming over the next couple days.

South Pacific:

92P is getting better organised in the Gulf Of Carpentaria. The LLC seems to have become a seperate entity from the monsoon trough that spawned it, and covection remains deep close to the centre. With low shear, and sea temps in the high twenties celcius, formation of a tropical cyclone seems likely in the next day or so provided the 92P stays over water.

[Cookie]

92P

[Cookie]

92P

[Somerset Squall]

South Indian Ocean:

90S became a potent extratropical storm well south of Madagascar. The transition is surprising as 90S was only a weak disturbance in it's tropical life.

91S has continued to suffer from easterly shear, despite previous forecasts of it easing. Shear is very difficult to predict, but is currently expected to remain at least at a moderate level. The LLC is still fairly well defined heading towards Cocos Island, but organised convection continues to be in short supply. Chances are poor for TC development at least in the short term.

Invest 94S has formed near the Kimberly coast of NW Australia. Shear is moderate to high, and the convection is showing little signs of robust rotation at present. Shear will likely hamper further development.

South Pacific:

Despite favourable conditions, 92P has failed to become a tropical cyclone. The invest has been too involved with the monsoon trough that spawned it and therefore the LLC did not consolidate sufficiently. 92P is moving very near to the west coast of the Cape York Peninsula and will be inland soon, which will further hinder development. There is a chance in the long term of slow development if the low survives into the Coral Sea.

[Cookie]

94S

[Somerset Squall]

South Indian Ocean:

91S remains unimpressive. The LLC is visable clearly on satellite imagery, but only because it's devoid of any significant convection. Continued strong shear makes development unlikely.

94S has become better organised today, and chances are rising for it to become a tropical cyclone. An small LLC appears to have developed, and convection is persisting over it. In addition, the low appears to be forming banding features. Shear has eased signicantly since yesterday, and should remain at low levels to allow further development of 94S. There is a good chance of it becoming a TC over the next day or so as it approaches the Kimberly Coast of Australia.

South Pacific:

92P has emerged from the Cape York Peninsula into the Coral Sea. The system has become marginally better organised today, with convection rotating around a broad LLC. However, due to a reversal in steering currents, 92P is expected to soon turn back to the west over land, therefore it probably won't have time to develop into a TC.

Invest 95P has formed near the Solomon Islands. Deep convection is flaring in a large area, but is showing little sign of organisation. If an LLC is present, it is slack at best. It's difficult to tell if one is present due to the messy convection. Shear is reletively low and waters very warm (around 30C), so slow development is possible.

[Somerset Squall]

South Indian Ocean:

Very little is left of 91S, and the invest appears to be on the verge of dissipation.

94S has become Tropical Cyclone Magda.

South Pacific:

92P has remained stationary off the east coast of the Cape York Peninsula. Moderate shear has been impinging on the system, however, it now appears to be easing. In response, a huge and intense area of convection has blown up near the LLC, and the low appears to be deepening. There is a greater chance of a TC forming now, especially as the westward motion back towards the coast seems to have holted for now.

95P has become better organised over the last 24hrs whilst crossing the Solomon Islands. Convection is organising into curved bands around a developing LLC. Shear is low and waters are warm, which suggests that further development is likely. There is a fair chance of a TC forming here over the next couple days if the favourable environment persists.

[Somerset Squall]

South Indian Ocean:

Shear has eased over 91S today, which has allowed some modest convection to build over the well defined LLC. However, shear is prgged to rise again tomorrow which makes the chances of 91S becoming a TC in the near term poor.

South Pacific:

92P became TC Neville.

95P is moving westwards towards the coast of the Cape York Peninsula, and is unlikely to develop into a tropical cyclone. See thread "Tropical Depression 04F" for more information.

Edited January 22, 2010 by Somerset Squall

[Somerset Squall]

South Indian Ocean:

91S dissipated.

Invest 97S has formed 175nm northeast of Port Louis, and about 350 miles northeast of La Reunion. Some deep convection is persisting over a consolidating LLC. Shear is low and waters warm, which suggests a tropical cyclone may form soon if the organisational trend continues. However, on the southward track, 97S will reach cooler waters in about 48hrs. So the long term outlook is poor but 97S certainly has good potential to become a TC for a short period.

South Pacific:

95P became TC Olga.

Invest 96P formed and became TC Nisha.

[Cookie]

97S