Multiple weather systems at play resulting in summer not feeling like summer at all so far
Multiple weather systems, including anti-cyclones, troughs, and western disturbances, have led to unexpected weather across India, including thunderstorms, hailstorms, and below normal temperatures. The conditions are likely to continue for two to three days, followed by another spell of thunderstorm activity. The India Meteorological Department has issued a warning for rainfall with lightning and high-speed wind bursts in several states. Maximum temperatures have been below normal across most of the country, except for Tamil Nadu, Puducherry, Karaikal, Kerala, and Mahe. The unexpected weather is likely to continue until the first week of May.
It doesn’t feel like summer in many parts of the country, and given how hot it was just a week ago that saw record high temperatures in some regions, everyone has been pleasantly surprised.
The reason, according to M Mohapatra, director general, India Meteorological Department is that there are “multiple weather systems at play”.
“There was heating in (early and mid) April which makes conditions conducive for triggering thunderstorms. There are anti-cyclones over Bay of Bengal and Arabian Sea. There is also a trough or circulation over Madhya Pradesh and over south Tamil Nadu. (And there is a ) western disturbance over the Western Himalayan region...,” he explained.
The result: after a long and intense heat spell of nearly 10 days, including over Northeast India, several parts of the country are experiencing unexpected weather. There are thunderstorms and hailstorms over parts of Northwest and Northeast India, rains over central and peninsular India, and below normal temperatures (for this time of the year) in almost the entire country.
And it’s likely to stay that away at least in the short term. “This is likely to continue for two to three days followed by another spell of thunderstorm activity,” said Mohapatra.
On Monday, IMD issued a warning for rainfall with lightning and bursts of high speed wind (30 to 40 kmph) with hail storms over parts of Uttar Pradesh, East Madhya Pradesh, Himachal Pradesh, Uttarakhand, Chhattisgarh, Odisha, Jharkhand, Gangetic West Bengal, Vidarbha, Telangana, Tamil Nadu and Kerala.
A western disturbance is lying over northeast Rajasthan and neighbourhood. A cyclonic circulation is lying over central Madhya Pradesh and another over south Tamil Nadu. A trough/wind discontinuity is running between these two cyclonic circulations. A fresh western disturbance is also likely to affect the Western Himalayan region from April 26, IMD said on Monday.
Not surprisingly, maximum temperatures were below normal across most parts of the country. The only places where they have been above normal are Tamil Nadu, Puducherry, Karaikal, Kerala and Mahe.
“During this season, there are three main features that impact weather. The location of anticyclones over Bay of Bengal and Arabian Sea; western disturbances and easterly waves. This year the troughs associated with the western disturbances are very deep. There are anticyclones over Bay of Bengal and Arabian Sea which are much stronger than normal and on the trough line between them is the region where thunderstorm activity is taking place. A lot of moisture from the ocean is pumped over this region. There are easterly waves which also influence thunderstorm activity. In a couple of days, we are going to see more thunderstorm activity across the country till the first week of May,” explained Soma Sen Roy, senior scientist at IMD.
An anticyclone is an area of high atmospheric pressure.
Interestingly, similar thunderstorm activity was recorded in mid-March also over several parts of the country. Early heat in February and March led to warm land surface temperatures and onset of pre-monsoon activity, meteorologists said. During February, maximum temperatures were several notches above normal over most parts of the country, especially the west coast. In February, maximum temperatures touched 29.54 degrees Celsius (monthly national average) according to IMD. The average maximum or day temperature was 1.73 degrees C above normal over the country during February and average minimum temperature, 0.81 degree C above normal.
That trend continued for the first two weeks of March before it cooled down sharply. April has seen a similar trend, although the heat wave was concentrated over the eastern parts of the country particularly Bihar, West Bengal, Sikkim, Odisha and northeastern states. Gangetic West Bengal, for instance, recorded heat wave conditions for nine days at a stretch since April 11.
But things cooled down sharply starting April 23.
