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At last, the southern Pacific has awoken with quite an organised tropical system dubbed TC 07P by JTWC, with winds of 45kts. Fiji Met have yet to name the system. 07P is located in the east of the basin, a couple hundred miles northeast of Bora Bora. The LLCC is very well defined but also very small. A central dense overcast has formed, flanked by strong banding. The system has developed rapidly, and given it's small size and the very favourable environment consisting of low shear, excellent dual outflow and warm water, further rapid intensification seems likely for the next day or two, before 07P moves over colder water on the forecast southerly track. JTWC expect a peak of 90kts before this happens.

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Edited by Somerset Squall

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An extract of RSMC Nadi current 3 day outlook:

Issue Time:
0400 UTC Wednesday 21st January 2015
Next Issue:
0400 UTC Thursday 22nd January 2015
Issued By: Tropical Cyclone Centre, RSMC, Nadi
Existing Tropical Cyclones:
Tropical Cyclone Niko [995hpa] Category 1 was analysed near 14.7S 150.1W north of Tahiti at 210300 UTC. It is moving south-southeast at 10 knots. Position poor.
 

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It took a long while for the first South Pacific tropical cyclone to develop, that's for sure.

 

Nevertheless, Niko seems to be undergoing a period of arrested development with convection being located on the southern and eastern side of the cyclone. However, intensification seems likely to resume shortly until Niko reaches cooler waters later this week.

 

07P_210522sair.jpg

Satellite image of Niko.

 

Sources:

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

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

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TROPICAL DISTURBANCE ADVISORY NUMBER A6 ISSUED FROM RSMC NADI Jan 22/0133 UTC 2015 UTC.

TROPICAL CYCLONE NIKO CENTRE 991HPA [CAT 1] WAS LOCATED NEAR 17.2S 148.7W AT 220000 UTC. POSITION POOR BASED ON GOES EIR/VIS IMAGERY AND PERIPHERAL SURFACE REPORTS.  CYCLONE MOVING SOUTH-SOUTHEAST AT ABOUT 09 KNOTS. MAXIMUM 10-MINUTE AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT ABOUT 45 KNOTS.  

CONVECTION PERSISTENT AND ORGANISATION HAS IMPROVED SLIGHTLY IN THE PAST 24 HOURS. THE SYSTEM LIES IN A LOW SHEARED ENVIRONMENT AND MOVING INTO AN AREA OF INCREASING SHEAR. DIVERGENCE GOOD TO THE EAST OF THE SYSTEM. OUTFLOW GOOD IN EASTERN FLANK BUT RESTRICTED ELSEWHERE. CYCLONIC CIRCULATION EXTENDS UPTO 500HPA.

DVORAK ANALYSIS BASED ON CURVED BAND WITH 0.60 WRAP YIELDS DT=3.0, MET=3.5, PT=3.0. FT BASED ON DT THUS YIELDS T3.0/3.0/D0.5/24HRS.

GLOBAL MODELS HAVE PICKED UP THE SYSTEM AND MOVE IT SOUTH-SOUTHEAST WITH FURTHER INTENSIFICATION.

FORECASTS :
AT 12 HRS VALID AT 221200 UTC 18.9S 147.4W MOV SE AT 11 KT WITH 55 KT CLOSE TO CENTRE
AT 24 HRS VALID AT 230000 UTC 21.1S 146.4W MOV SSE AT 11 KT WITH 60 KT CLOSE TO CENTRE

OUTLOOK :
AT 36 HRS VALID AT 231200 UTC 23.3S 145.7W MOV SSE AT 11 KT WITH 50 KT CLOSE TO CENTRE
AT 48 HRS VALID AT 240000 UTC 25.5S 145.5W MOV SSE AT 11 KT WITH 35 KT CLOSE TO CENTRE

THE NEXT TROPICAL DISTURBANCE ADVISORY ON TROPICAL CYCLONE NIKO WILL BE ISSUED AROUND 220800 UTC.
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JTWC has raised Niko's winds to 55kts. The cyclone appears to have developed a central dense overcast, and looks healthier than this time yesterday. JTWC expect a peak of 65kts before weakening begins.

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Overnight RSMC Nadi have revised their forecast putting the current speed at 50 knots but but not increasing over the next 36 hours, thereafter decreasing. Wind shear is moderate, outflow is restricted to the west but fair elsewhere.

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As at 23/0743 UTC wind speed is down to 45 knots now, central pressure 991 hPa. Vertical wind shear is moderate to strong, sea surface temperature about 26C. Further weakening is expected over the next 24 hours.

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Niko is on the way out. Winds are down to 40kts according to JTWC. Strong shear has left the LLCC exposed to the north of the remaining convection. Sea temperatures are just 25C beneath Niko, and are falling all the time as the cyclone continues south. Dissipation therefore, will occur soon.

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A few interesting comments from the Australian Bureau of Meteorology on TC Niko about its formation.

Weekly Tropical Climate Note

Issued 27 January 2015
Niko, first South Pacific tropical cyclone this season

On 20 January, an area of low pressure near Tahiti developed to tropical cyclone strength and tracked south across French Polynesia. Tropical cyclone Niko was not especially strong nor did the centre of the storm pass over any islands, but it caused flooding and gale force winds over Tahiti from the storm's outer rain bands.

Niko was unusual because tropical cyclones occur less frequently over the southeast Pacific compared with the southwest Pacific and usually only develop in El Niño years when sea surface temperatures in the region are warmer than normal. Sea surface temperatures across the tropical eastern Pacific Ocean, including the waters surrounding Tahiti, have been warmer than normal for several months and likely contributed to the cyclone's development. See the Bureau of Meteorology's ENSO Wrap up for official El Niño information.

It is also likely that the Madden-Julian Oscillation (MJO) contributed to the favourable conditions for tropical cyclone Niko's development. Over the past week the MJO has been present, but weak, over the tropical Pacific Ocean. This placed the MJO in a location favourable for enhanced convection over the southeast Pacific.

The MJO is forecast to remain subdued for the coming week and is not expected to be a major influence on tropical weather. See the Bureau's MJO Monitoring for more information on location and tracking of the MJO. The risk of tropical cyclone development across the South Pacific remains high while warmer than normal waters are present in the region.

Next update expected by 3 February 2015 | Product Code IDCKGEW000

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