New Delhi: This year, India has found itself in the throes of two diametrically opposite weather extremes. As Northern India forlornly looks at an extended winter, with a series of western disturbances in February and early March; the southern region, was in the grip of inclement heat wave conditions on March 6, the India Meteorological Department (IMD) said.
Previously, the IMD had forecast two days of heat wave conditions in Tamil Nadu, the coastal Andhra Pradesh and Rayalaseema, the Down to Earth reported. It further said, "Heat wave need not be considered till maximum temperature of a station reaches at least 40 degree Celsius for plains, and at least 30 degree Celsius for hilly regions, for two or more days continuously.”
Heat waves, after lightning strikes and earthquakes, are the third biggest cause of deaths in the country. The Indian government, however, doesn't classify it as a 'natural calamity' and it was only in 2016, that the IMD came up with advisories for heat waves for the first time.
On March 6, the Dharmapuri Station in Tamil Nadu recorded a maximum temperature of 40.2 degrees Celsius — the highest temperature ever recorded in March in the area — exceeding the previous record 40 degree Celsius in 1996.
Similarly, Vellore recorded highest temperature in the state at 40.6 degree Celsius, while Thiruthani saw temperatures soaring up to 40.5 degree Celsius. Other stations like Tiruchirapalli, Salem, Madurai and Karur Paramathi also recorded maximum temperatures rise close to the 40 degree mark, the Down to Earth reported.
Andhra Pradesh, meanwhile, also saw similar spikes. Two stations at Tirupathi and Cuddapah in Rayalaseema recorded a maximum temperature of 40.4 degree Celsius and 40 degree Celsius, respectively. Five other stations saw temperatures rise above 38 degree Celsius, it added.
Meanwhile, two more western disturbances (WDs), the 16th and 17th this season, will bring rainfall and extend the chilly winds in the northern plains, while snowfall is expected in western Himalayas on March 6 and March 11, the IMD added.
The WDs are storms with cold air at their centre that start at the Mediterranean region and will bring precipitation to north and north-western India. An IMD official said, "This is an unusual situation and we haven't seen such intensity. We aren't expecting a lot of rain on March 6, since it appears to be a feeble one. Snowfall is likely in Jammu and Kashmir and Himachal Pradesh - in the plains there will be cloudy skies and light rain."
Why is it so cold in northern India?
The cold wave in northern India has lasted well into February and officials largely attributed this to weak WDs coming into the country from the west.
Usually, there are three to five strong WDs in December, but last year saw just one WD and this too, limited themselves into hilly states of Jammu and Kashmir, Himachal Pradesh and Uttarakhand. These, officials added, didn’t influence the weather in northern plains which made the cold wave more persistent.
With WDs continuing into February with unusual intensity, officials explained that the increased intensity could be due to the “rupture of the polar vortex into three smaller vortices earlier in January 2019”. This is the same phenomenon which was responsible for the unusually cold winds and temperatures to the US in the latter part of January and February.