Tropical Cyclone Iggy

[Somerset Squall]

A new tropical cyclone has formed in the southeast Indian Ocean. 09S has an intensity of 35kts. The cyclone is forecast to head southeastwards towards Exmouth, NW Australia over the next few days as ridging builds northeast of 09S. Exmouth, and, to a lesser extent, communities to the immediate east need to watch 09S as conditions appear favourable for significant intensification once the current moderate shear eases. This shear is confining most of the convection to the western quadrant of TC 09S currently but the reduction in shear should result in an increase in centralised convection. JTWC are expecting a peak of 80kts.

EDIT: BOM have just given the cyclone the name Iggy.

Edited January 25, 2012 by Somerset Squall

[Konstantinos]

http://tropic.ssec.wisc.edu/real-time/storm.php?&basin=austwest&sname=09S&zoom=4&img=1&vars=11111000000000000000&loop=0

Edited January 25, 2012 by Konstantinos

[Somerset Squall]

Iggy has strengthened to 45kts. Iggy is still under moderate shear but convection has started to build closer to the LLC. Shear is much lower to the south and this is where Iggy is headed. Sea temperatures are around 29C, which is supportive of further intensification. Iggy is forecast to head southeastwards in response to a steering ridge to the northeast. In a few days time, the track becomes a little uncertain but the favoured option is for Iggy to turn towards the southwest before reaching the Pilbara Coast, in repsonse to a bulding ridge over the interior of NW Australia.

[Styx]

Producing extreme heat ( up to 42 degrees ) and windy conditions as far south as Perth, as high pressure south of WA and Iggy combine to increase the pressure gradient.

[Somerset Squall]

Interesting point that Styx, certainly sweltering in Perth!

Iggy has strengthened to 55kts. The cyclone has developed a central dense overcast feature, showing shear has eased. The cyclone is now forecast to strike the Pilbara Coast instead of moving southwestwards. This is because the ridge over the interior of Australia is no longer expected to be quite as strong and instead the ridge to the northeast will continue to have (streadily decreasing) influence allowing a southeast track to the coast. A southwestward turn is still expected thereafter but it should be too late to stop a landfall. Waters are very warm which could support an intense system as the upper level winds are now favourable. One to watch.

Edited January 27, 2012 by Somerset Squall

[Konstantinos]

[Somerset Squall]

The track forecast has shifted westwards again today, away from Australia. This is due to the ridge over southwest Australia building strongly and taking away the steering influence from the receeding equatorial ridge. Iggy has intensified slightly to 60kts. The cyclone is struggling to sort out it's inner core and may only intensify by another 15kts or so before conditions deteriorate.

[Somerset Squall]

Iggy peaked at 65kts (cat 1 SS scale) yesterday but has now weakened to 55kts as it drifts southwestwards well west of land. The cyclone has never quite had an impressive satellite signature and the lack of strengthening could be due to the broad inner core. Conditions will deteriorate over the next day or so anyway leading to a firm weakening trend.

[Somerset Squall]

Iggy has unexpectedly restrengthened to 65kts. An eye has become increasingly well defined in satellite imagery. The restrengthnening is down to the fact that Iggy has moved over waters that are much warm warmer than average.The ridge over Western Australia is expected to break down allowing Iggy to recurve onto the western coast, but the cyclone should be in a much weakened state then due to cooler waters and higher shear.

[Somerset Squall]

Iggy crossed the coast unusually far south for a tropical cyclone, just north of Perth, SW Australia. Iggy brought high winds and heavy rain but nothing damaging. The LLC dissipated as it headed towards the Great Australian Bight.