Tropical Cyclone Thane found its origins in the eastern Bay of Bengal late on Christmas Day. It steadily strengthened and organized over the next four days into the equivalent of a category one hurricane with 85mph winds. It then turned more westward and headed for the southeast Indian coast. The Forecast models indicated that the storm should weaken before impacting the Indian coastline because of a decrease in tropical cyclone heat potential (cooler, shallower waters), and an increase in dry air and wind shear. The wind shear did increase, but Thane was sufficiently enveloped in its upper anti-cyclone so that the wind shear didn’t do too much to the storm. The dry air, sucked off of the Indian sub-continent also had little effect on the storm until it was nearing landfall.
As Thane made landfall, it was clear that dry air was finally getting to the storm as its overall size diminished significantly. Its outer bands didn’t reach as far out, and its eye shrank dramatically and quickly collapsed once onshore. Dry air had more of an effect on the western and southern side of the storm, and outer bands were notable eroded by it. In the final hours before Thane’s landfall, outflow boundaries (caused by dry air collapsing convective thunderstorms) were noted on the northern side of the storm indicating that the storm was now completely surrounded by the dry air. However, this didn’t stop Thane from generating heavy rains across Southern India.
Indeed, in the early morning hours of December 30th, Very Severe Cyclonic Storm Thane made landfall near the coastal city of Cuddalore in Tamil Nadu, India, packing winds of 85mph and produced a storm surge of up to 5 feet. The storm’s remnants continue to generate heavy rains across southern India. Cuddalore took the brunt of the storm’s power as it was in the right-front quadrant of it’s eyewall, where the strongest winds are often located in Northern Hemisphere cyclones.
Although the storm made landfall near Cuddalore, hundreds of miles of coastline felt the affects of the storm’s strong winds, very rough surf and storm surge. Chennai, the Capital of Tamil Nadu, about 110miles north of where the storm made landfall, saw gusts to gale force and heavy rain in the outer bands of the Very Severe Cyclonic storm.
Reports from the stricken Indian states show that nearly four dozen people have lost their lives, through falling trees, electrocution, drowning, and collapsing buildings. Several thousands were displaced by the storm, and the equivalent of nearly $30million in relief has been provided by the state governments.
* Radar images from the India Meteorology Department (IMD)