Severe weather events like severe storms, lightning, intense rainfall, etc are very common over the NER of India. In India, each year lightning alone kills more than 2,500 people and it ranks first in terms of killing among all the natural calamities (Report of National Crime Record Bureau, India). The NER of India is also no different. With the constantly increasing use of electronic devices in the industrial and domestic sphere, the vulnerability to lightning damages is growing in leaps and bounds. Lightning is often associated with gusting winds, intense rainfall, hails, etc.
NESAC has developed a methodology for nowcasting of severe thunderstorms by integrating data from weather stations, Doppler weather radars, satellites, and numerical weather prediction models. A thunderstorm potential map is prepared for entire NER of India, indicating the areas where thunderstorm development is expected within next three hours from the time of issue of the forecast. The forecast is made available through NESAC website and also are directly communicated to the concerned stakeholders in each state of NER of India.
NESAC has also initiated research to provide location based lightning warning services. The data from lightning detectors from different network over NER of India are used and assimilated is numerical weather prediction models to provide location specific lightning as well as severe weather warning with an actionable lead time.
In NESAC, TS Nowcasting is provided in two forms, first by preparing a thunderstorm potential map based on numerical weather prediction model outputs, and then by preparation of thunderstorm bulletins based on real time weather watch using data from Doppler weather radar, Satellites, and automatic weather stations. The services are provided from 15th March to 15th June every year, as frequency of TS is highest during this period.
The severe weather nowcasting services from NESAC are consumed by the following community/organizations:
- ASDMA and other State Disaster Management Authorities of NER
- Flood and River Erosion Management Agency of Assam (FREEMA)
- North East Electric Power Corporation (NEEPCO)
- District Disaster Management Authorities from NE region of India
The TS bulletin and potential map was issued thrice daily with TS bulletin having validity of four hour and TS potential map having validity of three hours. The TS potential map uses WRF model based forecast of atmospheric instability indices (like convective available potential energy, convective inhibition energy, K index, Lifted Index, etc) and relative humidity. The TS potential map predicts the potential location where thunderstorm occurrence is likely during a given time. TS warnings in both TS bulletin and potential map is categorized in five category (Nil, Low, Moderate, High, and Severe) based on the likely intensity of the thunderstorm. So, the users can get the idea about the potential thunderstorm occurrence zone based on the different categories. Similarly the lightning forecasting services are provided for every hour during the peak lightning period, viz. Mid March to mid June every year. The forecast is disseminated through NESAC website as well as through direct communication.