The second heatwave singeing the city this season shows no sign of waning.
The revival of westerlies has once again pushed up the mercury level to cause scorching conditions. From 42.5ºC on Saturday, the maximum temperature surged to 42.9ºC on Sunday, five notches above the normal temperature for the day, fulfilling the conditions needed for the meteorological office to declare a heatwave.
Worse, it has claimed that heatwave conditions would continue to torment residents for at least three more days, with the maximum temperature hovering around 43ºC. The weather is likely to remain unusually dry, which coupled with the heat, causes a burning sensation on the skin when people step out in the sun without cover.
Heatwave is not new to Patna but what is quite unusual is that Bihar has lately turned into the hottest region in the country. “Bihar is by and large, showing the highest temperature recordings in not only the eastern zone comprising Bengal, Odisha, Jharkhand and the Northeast but also perhaps, the entire country. Only the interior parts of Odisha such as Sambalpur are somewhere closer to high temperature recordings in Bihar. Meanwhile, Patna is managing to occupy centre stage in maximum temperature recordings in the state,” said Ashish Sen, director, India Meteorological Department (IMD), Patna.
True to Met director’s words even Delhi’s infamous summer hasn’t been able to keep pace with the Celsius surge in Patna. The maximum temperature in Delhi was recorded at 36.9ºC on Sunday and the average maximum temperature forecast for the city over the next few days is around 39ºC. The average maximum temperature forecast for Patna, on the other hand, for the next five days is around 42ºC.
Desert cities like Jaipur and Jaisalmer were also cooler than Patna by several degrees on Sunday. Golden City Jaisalmer recorded a maximum temperature of 38.1ºC, whereas Pink City Jaipur recorded a high of 39.8ºC.
Back in Patna, the weather office declares a heatwave condition, when the maximum temperature rises five degrees above normal to either touch or cross 40. The normal temperature in Patna around this time is 37ºC. The first heatwave of the season to hit Patna was declared by the Met office on May 11, when the maximum temperature jumped to 43.5ºC, seven notches higher than the normal. The city experienced a heatwave for four consecutive days only to slide down to 39.9ºC last Thursday.
High temperatures were seen in other parts of the state also. Gaya was almost equally hot as Patna at 42.7ºC. Bhagalpur also burned at 42.2ºC.
“The maximum temperature in Patna slightly slid on Thursday and Friday owing to a cyclonic circulation over sub-Himalayan Bengal and adjoining areas in Bihar. This led to moisture incursion, particularly in northeastern Bihar, resulting in a fall in temperature. However, the cyclonic circulation has neutralised now and westerly winds have again become strong in the region, reviving the heatwave conditions,” said Sen.
The westerlies dominating the lower level of the atmosphere triggered heatwaves on both occasions. Being dry, the westerlies allow solar rays to directly penetrate the lower level of atmosphere, pushing up the maximum temperature. High temperature conditions, along with dry conditions in the lower level of atmosphere, are also leading to a surge in discomfort factor, which is a mixture of high temperature and relative humidity.
“We measure the discomfort factor by simply adding the maximum temperature and relative humidity. The discomfort factor is said to be prevailing at a place when the combination of the maximum temperature and relative humidity at a place is higher than 55ºC. Sunday’s discomfort index was around 65ºC between 2.30pm and 3pm,” said Sen.