India’s first research testbed to study Nor’westers getting ready: Here’s all you need to know

Originating over east and northeast India, south Nepal, Bhutan and Bangladesh, the nor’westers are extremely severe thunderstorms accompanied by squally winds. Though the nor’westers were less active this summer, there were occasional instances in April and early May. Strong winds and thunderstorms swept through the northern districts of West Bengal, Assam and Tripura, killing at least five people last month.

India Meteorological Department (IMD), Indian Institute of Tropical Meteorology (IITM), Pune, and National Centre for Medium-Range Weather Forecasting (NCMRWF), Delhi, will jointly develop and use this facility. It aims to study thunderstorms from the formation stage, growth, and propagation over eastern parts of the country. This will be done using meteorological instruments, drones, and other equipment that will aid in the systematic tracking of thunderstorms.

The large volumes of data generated from the facility are expected to help forecasters make timely thunderstorm predictions, issue nowcast warnings (an event in less than three hours), and ultimately save lives.

Minister of Earth Sciences Kiren Rijiju, in his written reply in the Lok Sabha this February, stated that the facility will be completed by 2026.

In the early summer months (March and April), the daytime landmass heating over these regions triggers convection over some areas of Bihar, Jharkhand, Chhattisgarh, Odisha, and sub-Himalayan West Bengal.

As these convective clouds move towards West Bengal and Bangladesh, the nor’westers mix with the warm, moist air mass hovering over the Bay of Bengal, causing significant wind discontinuity. In addition, the local hills and thick forest cover combined with the sea breeze make it ideal for developing thunderstorm cloud cells. These thunderstorm events usually prevail between two to four hours during late afternoon hours.

“Thunderstorms occur at many places in the country, but the nor’westers are severe thunderstorms that need further investigation with respect to its genesis at the micro level and other processes involved. This can help make better predictions and generate early warning mechanisms to save life and property,” IMD’s senior meteorologist K S Hosalikar, project director of the Thunderstorm Research Testbed facility, told The Indian Express.

The IMD issues a nowcast warning for extreme weather events with a three-hour lead time. With the dedicated and first-of-its-kind testbed for thunderstorms coming up, the attempt now will be to issue warnings with a better lead time and forecast exact areas that could have the maximum impact, thereby awarding the administration and the locals additional time to prepare and equip themselves better.

Even though the eastern India region is currently covered by meteorological radars supported by a network of instruments to record upper air and surface observations, the proposed research testbed will house several high-end instruments worth over Rs 25 crore that will complement these existing observational mechanisms.

Plans are underway to augment the region’s automatic weather stations and automatic rain gauges. The soon-to-be installed wind speed recorders will be important, as thunderstorms in eastern India are accompanied by strong and gusty winds. Further, the MoES plans to install radars along with a number of other vital meteorological instruments, like lightning detectors and radiometers, to improve the overall quality of its weather observation network in eastern India.

“We have plans to deploy drones and have a mobile van to track thunderstorms. This van would be equipped with sensors that will enable tracking of the thunderstorms right from its development stages,” said Hosalikar, head of IMD’s Climate Services and Research office in Pune.

Last week, the IMD and BITS, Mesra, Jharkhand, inked an MoU regarding the site for installing instruments. Importantly, the testbed will house India’s tallest meteorological flux tower, at 100 metres. The CSIR-Structural Engineering Research Centre, Chennai, has been entrusted with designing this tower.

On the current status of the testbed, Hosalikar said, “The detailed project report has been approved. We are now in the process of initiating procurement of certain instruments. Once installed, we have planned sensitivity studies at the site.”

IMD, Pune, will collate all the data generated from the testbed facility for further research and analysis.