According to catastrophe modeling firm AIR Worldwide, Tropical Cyclone Nilam began crossing the Tamil Nadu coast at about 4:30 PM local time (11:00 UTC) with maximum wind speeds of about 80-90 kilometers per hour, gusting to 100 km/h. Landfall took place about 40 miles south of Chennai, the capital of Tamil Nadu state, between the town of Mahabalipuram, an historic port and temple site, and Kalpakkam, the site of a nuclear power facility that supplies electricity to the region and is home to several other nuclear installations and research agencies.
According to AIR, extensive damage to traditional housing (thatched roofs and huts), which are not insurable, is expected, and to standing crops and power lines. Minor damage to power and communication lines by uprooted trees has been reported, as noted above, but by the onset of nightfall there have been no reports of significant damage to large or otherwise insurable structures.
The Indian Meteorological Department (IMD) has reported that the storm’s central pressure at landfall was about 992 mb. It also reported that as much as 25 cm (10 inches) of rainfall has fallen along most of Tamil Nadu’s northern coastal districts and coastal southern Andhra Pradesh, the state to Tamil Nadu’s north, over the past 24 hours. A storm surge of 1-1.5 meters (3.2 to 5 feet) over the astronomical tide has been reported in some places, which is high enough to inundate low-lying areas of Chennai, Kanchipuram, and Tiruvallur in Tamil Nadu and parts of Nellore District in Andhra Pradesh.
“Tropical Storm Nilam formed on Sunday, October 28, when an area of deep convection developed and transformed into a depression in the southwestern region of the Bay of Bengal,” according to Dr. Peter Sousounis, senior principal scientist at AIR Worldwide. “The system was upgraded to a deep depression on October 29, and after further intensification it was declared a tropical cyclone the next day, yesterday. Influenced by upper-air circulation, the system started moving to the northwest at a speed of about 18 km/h after remaining nearly stationary northeast of Sri Lanka for some time, where about 4,000 people have been dislocated by flooding caused by the storm.”
In Mahabalipuram, trees have been uprooted and lamp posts have blown over. Several areas of the town have power outages. In addition, the Chennai Mass Rapid Transport System—an elevated metropolitan railway line—has been shut down in anticipation of Nimal’s winds causing problems with overhead wires.
Dr. Sousounis concluded, “Nimal’s low level circulation center over land is becoming elongated, causing the storm to weaken as it continues to track generally northwestward across southern India. The IMD expects Nimal to dissipate below a tropical cyclone threshold intensity of about 65 km/h (40 mph) over the next 24 hours. However, the IMD continues to warn of heavy to very heavy rainfall over that time period, with extremely heavy precipitation of 25 cm (10 inches) or more in some isolated locations along the northern Tamil Nadu, southern Andhra Pradesh, and Puducherry coasts, and, in interior Tamil Nadu, for the next 48 hours.”
