Comments
Thunderstorms in North-West India are a normal pre-monsoon feature, but the severity of recent ones was because they lined up across the region around the same time when western disturbances moved in. There is nothing to suggest that this would affect the advance of the South-West monsoon into the region just yet, according to KJ Ramesh, Director-General, India Met Department (IMD).
Enough time
The heating season extends into May and June and there is still enough time left. The monsoon arrives over Delhi by the end of June only.
Thunderstorms and dust storms are instruments that nature leverages intermittently to keep rampaging heat waves over North-West India at bay.
“They are bound to occur after the third day or fourth day of sustained heating of land. What has happened this time is that they have been timed with the arrival of periodic moisture-laden western disturbances,” Ramesh told BusinessLine .
Frequency up
“If you take out the North-West, thunderstorm activity has been just as usual elsewhere - Kerala, North-East India, Odisha, West Bengal. For instance, the ongoing Kal Baisakhi season in East India is a climatological phenomenon.”
What is of some interest though is that frequency of western disturbances, which was less than normal during the winter months, has picked up in the hot season that followed. But it has not crossed limit even during the hot season.
As for strength of the thunderstorms, one can see that weak or unplastered structures with thatched or asbestos roof or mud walls had suffered the most. Uprooted trees and collapsed transmission lines were only to be expected.
According to Ramesh, thunderstorms don’t come out of the blue. One can observe the signals at least least 30 to 40 minutes in advance, with at least one side of the horizon getting engulfed by dark and threatening clouds.
Advance signals
“And then you will see visibility reducing, darkness increasing even during mid-day, the ‘downdraft’ bringing in strong winds and the ambient weather changing fast. You have a 30 to 40-minute window to ensure safety even without a formal warning,” he said.
IMD issues coloured warnings with respect to thunderstorm forecast from day one to five. But it cannot take a call on which part of the day a thunderstorm can rear its head and when it would die out.
This kind of localised forecasting is best achieved through ‘nowcasts’ which monitor the actual time of onset and movement of severe weather, according to which warnings are issued.
Comments
COMMENT NOW
Comments
Comments have to be in English, and in full sentences. They cannot be abusive or personal. Please abide by our community guidelines for posting your comments.
We have migrated to a new commenting platform. If you are already a registered user of TheHindu Businessline and logged in, you may continue to engage with our articles. If you do not have an account please register and login to post comments. Users can access their older comments by logging into their accounts on Vuukle.