Cyclone Thane

Cyclonic Storm Thane (06B)

Very severe cyclonic storm (IMD scale)
Category 2 (Saffir–Simpson scale)
Cyclone Thane over the Bay of Bengal close to the Indian coast on December 29, while near its peak intensity
Formed	December 25, 2011
Dissipated	December 31, 2011
Highest winds	3-minute sustained: 140 km/h (85 mph) 1-minute sustained: 165 km/h (105 mph)
Lowest pressure	969 hPa (mbar); 28.61 inHg
Fatalities	48 total
Damage	$235 million (2011 USD)
Areas affected	Southern India, Sri Lanka
Part of the 2011 North Indian Ocean cyclone season

Very Severe Cyclonic Storm Thane (IMD designation: BOB 05, JTWC designation: 06B, also known as Cyclone Thane) was the strongest tropical cyclone of 2011 within the North Indian Ocean. Thane initially developed as a tropical disturbance within the monsoon trough to the west of Indonesia. Over the next couple of days the disturbance gradually developed further while moving towards the northwest, and was declared a Depression during December 25, before being declared Cyclonic Storm Thane during the next day. As it was named, Thane started to turn towards the west under the influence of a subtropical ridge of high pressure before its development slowed down during December 27, as a strong outflow and marginally favourable sea surface temperatures fought with persistent vertical wind shear. After its development had slowed down during December 27, Thane became a Very Severe Cyclonic Storm during December 28, before as it approached the Indian states of Tamil Nadu and Andhra Pradesh, it weakened slightly. Thane then made landfall early on December 30, on the north Tamil Nadu coast between Cuddalore and Puducherry and rapidly weakened into a depression.

On December 23, the Joint Typhoon Warning Center (JTWC) reported that a tropical disturbance had developed within the monsoon trough about 1540 km (960 mi) to the east of Medan in Indonesia. Convection surrounding the system had started to consolidate over a weak low level circulation centre, that was being fed by an enhanced westerly flow associated with the precursor system to Tropical Cyclone Benilde. Over the next couple of days the disturbance gradually developed further while moving towards the northwest, with a Madden–Julian oscillation increasing the system boundary layers rotation. The JTWC then issued a tropical cyclone formation alert on the system during December 25 before designating as Tropical Cyclone 06B later that day as 1-minute wind speeds near the centre reached 65 km/h (40 mph) which is equivalent to a tropical storm. The India Meteorological Department (IMD) also reported during December 25 that the disturbance had organised sufficiently to be declared Depression BOB 05, while it was located about 1,000 km (620 mi) to the southeast of Chennai, India.