Intense Tropical Cyclone Felleng

[Somerset Squall]

Tropical Cyclone 13S has formed, several hundred miles east of northern Madagascar. Winds are currently at 35kts. The cyclone has developed in a marginally favourable environment of warm sea temps, fair poleward outflow but moderate to high shear. These conditions are expected to remain similar over the next couple of days, so 13S will find it difficult to strengthen significantly in this time frame. Thereafter, shear is expected to ease, allowing for greater intensification. The cyclone is heading westwards currently along the northern side of a steering ridge to the south. In about 4 days time, 13S should reach the western extent of the ridge and turn southwestwards. At this point, 13S will be in a favourable environment for strengthening and will be very close to northeast Madagascar, so we will need to keep an eye on this cyclone.

[Somerset Squall]

13S has moved westwards over the last couple of days, without much development. However, the storm now seems like it is strengthening in response to reduced shear and strong outflow. Intensity has risen to 40kts, and the cyclone has been named Felleng. Felleng, in latest satellite imagery, has much more expansive convection and increased convective banding, signs of a maturing system. Felleng is expected to continue heading westwards along the north side of a ridge for the next couple of days followed by a turn to the south just east of Madagascar as Felleng reaches the western periphery of the steering ridge. Felleng is likely to bring very heavy rains to the east coast of Madagascar, but if the southward turn happens too late, then Felleng may make landfall- and the cyclone is expected to become intense. Both JTWC and MeteoFrance agree on a turn south just off the coast however.

Edited January 28, 2013 by Somerset Squall

[Somerset Squall]

Felleng is looking much more impressive this evening. Sustained winds are now at 55kts. The cyclone has expanding convection and curved banding features. Won't be long before an eye develops IMO. The conditions are certainly very favourable currently, with low shear and excellent outflow.

[Somerset Squall]

Felleng has strengthened further overnight, and sustained winds are now at 65kts, a cat 1 hurricane equivalent on the SS scale. An eye has developed in the central dense overcast feature- which is pretty circular (indicative of very low shear). The eye is not all that well defined currently, but I would be surprised if that remains the case for long. The environment supports further intensification, perhaps rapid.

Felleng is about 12 hours away from making the southward turn. The turn is expected to be quite sharp as the ridge to the south re-orientates north to south to Felleng's east.

Edited January 29, 2013 by Somerset Squall

[Somerset Squall]

Felleng has rapidly intensified this afternoon. Winds are now 90kts, cat 2 on the SS scale. JTWC now expect Felleng to peak at 115kts (cat 4).

[Somerset Squall]

Felleng has further intensified and has been upgraded to an Intense Tropical Cyclone by MeteoFrance. Sustained winds are now 105kts, cat 3 on SS scale. The eye is large, but well defined. Felleng has about another 24hrs to strengthen further before outflow weakens and shear starts to slowly rise.. Rainbands from Felleng could affect La Reunion, despite Felleng being forecast to slide southwards midway between Madagascar and La Reunion., keeping the strongest winds and heaviest rains away from land..

[Somerset Squall]

Felleng peaked at 115kts, cat 4 on the SS scale, shortly after I last posted. Felleng only held that intensity for 6 hours as shear increased as caused Felleng to weaken. Intensity has been in decline ever since, and is now at 70kts. For now, waters are warm, but as Felleng continues to slip southwards, cooler sea surface temperatures will join shear in weakening Felleng at a quicker pace.

Edited February 1, 2013 by Somerset Squall

[Somerset Squall]

Felleng continues to quickly move southeastwards and has almost finished the transition to an extratropical storm. JTWC have issued their last advisory.