Heatwave to continue in east, rain may bring relief in north

Heatwave conditions are likely to continue over large parts of eastern India, particularly Bihar and West Bengal, over the next four days, according to the India Meteorological Department (IMD), which has issued an orange alert for the region that has experienced temperatures in the 40-44 degrees Celsius (°C) since April 12.

At the same time, IMD predicted a wet spell over northwest India (including Delhi) between April 18 and 20, with possibility of a heavy well spell over the western Himalayan region on April 18 and 19. This, the Met said, is due to a western disturbance is impacting the western Himalayan region, and an induced cyclonic circulation lying over north Pakistan and Punjab in the lower tropospheric level.

“Heatwave conditions are likely to continue over West Bengal and parts of Bihar for next four days. Accordingly, we have issued an orange alert for the region in view of humidity and high temperatures. People should take precautionary measures. The region is likely to see thunderstorm activity from Day 5 when heatwave conditions may abate,” said Naresh Kumar, scientist at IMD.

“We are also expecting a wet spell over northwest India for 4 days. The cloud patch will move gradually starting with Punjab and then Haryana, Delhi and Uttar Pradesh. We can expect heavy rainfall over the Himalayan region starting Wednesday because the trough is quite deep and the region is receiving a lot of moisture from the Arabian Sea. Maximum temperatures will drop marginally after rainfall,” Kumar added.

Over the last few days, maximum temperatures were above normal by 3-5°C over many parts of north India, in some parts of east and northeast India, and in isolated pockets over Madhya Pradesh and coastal Andhra Pradesh. Heatwave conditions have prevailed in isolated pockets over Gangetic West Bengal for a week now; in coastal Andhra Pradesh for the last five days, in Bihar for four days, and in Punjab and Haryana for two days.

On April 5, the global average sea surface temperatures (SSTs) was 21.1 degree C , a new record according to data released by Climate Change Institute at University of Maine. It hasn’t cooled much since. On April 16 , it was 21 degree C, the same as the previous record set in March 2016.

Heatwave conditions are also likely in isolated pockets over sub-Himalayan West Bengal and Sikkim, Odisha, and Jharkhand during next two days, IMD said. However, there is likely to be a gradual fall in maximum temperatures over northwest India by 2-4°C during the next three days, and then a rise of 2-3°C after that, the Met added.

No significant change in maximum temperatures is likely over central India during next two days, followed by a 2-3°C fall in the subsequent three days.

Forecasts from Indian National Centre for Ocean Information Services (INCOIS) also show that the south Bay of Bengal and south Arabian Sea are expected to temperatures of a record 30-plus degrees C SST this week. There are also patches of strong marine heat waves over south Arabian Sea along Kerala and Karnataka and over Bay of Bengal along Bangladesh and West Bengal according to the Marine Heat Wave Tracker created by the Marine Heatwaves International Working Group.

“We are not expecting any thunderstorm activity or lowering of temperatures over east India particularly WB and Bihar before April 21. Till then warm, northwesterly winds will be blowing there,” said Mahesh Palawat, vice president, climate and meteorology, Skymet Weather.