Met department moves from weather forecasting to nowcasting

The India Meteorological Department (IMD) has operationalised its location-specific nowcasting weather services across the country.

This service, through Earth System Science Organization (ESSO) and IMD, covers 117 urban centres. The service is currently on experimental basis and would nowcast severe weather conditions like thunderstorms, heavy rainfall and depressions over land three to six hours beforehand, using data from Doppler weather radars, a release by the Ministry of Earth Sciences said. The service also includes web inputs.

Origin, development or movement of severe weather phenomena are regularly monitored through all available observing systems, such as automatic weather stations, automatic rain gauges and Doppler weather radars. These are assimilated to generate predictions prepared both in text as well as in graphic form on three-hour time range. Web GIS rendering of the nowcast is also being started for enhanced spatial representation of the severe weather intensities associated with warnings.

The High Performance Computing (HPC) system at the ESSO-National Centre for Medium Range Weather Forecasting (NCMRWF) and ESSO-IMD has provided the opportunity to assimilate satellite radiance data into the global or regional forecast systems. It has also helped in enhancing the spatial resolution of the global forecast systems from about 50 km grid scale to about 22 km grid scale.

In order to capture the characteristics of the severe weather in real time, state-of-the-art 24X7 monitoring system, comprising 14 Doppler weather radars have been made functional in cities which include Agartala, Chennai and Delhi. The Doppler weather radars at Mumbai and Bhuj are undergoing site acceptance tests while in Bhopal it is still under commissioning. The commissioning of Doppler weather radars is put on hold at Goa, Paradip and Karaikal for want of clearances from the Ministry of Defence and is under the consideration of Committee of Secretaries.

Installation of Doppler weather radars across the whole country would take place in a phased manner as various factors such as site selection and available and emerging technology variants have to be taken into consideration.

Despite the logistical challenges, the Government has decided to set up and enhance gradually its observational network for monitoring abnormal weather patterns and upgrading its forecasting capabilities, so that advance warning can be provided to National Disaster Management Authority (NDMA), Ministry of Home Affairs, and Ministry of Agriculture to tackle the impacts of the adverse and extreme weather phenomena.