IMD warns of fresh spell of hailstorm, rainfall from Thursday: What experts say

Thunderstorms and hailstorms have started impacting different parts of the country since March 16.

From record heat in February to a sudden onset of pre-monsoon thunderstorm activities in mid-March, the weather has left people puzzled and farmers extremely concerned. The two extremes—early heat in February and March leading to warm land surface and onset of pre-monsoon activity— are in fact linked, meteorologists said. While not very unusual, experts said pre-monsoon activities started relatively early this year.

“Convective clouds develop when there is heating. During February we saw temperatures that are over 5 to 6 degree C above normal over most parts. The soil was very dry and hot which creates a triggering mechanism. Over the head Bay of Bengal and Central Arabian Sea two anti-cyclones formed, which brought in a lot of moisture. Plus, other low level cyclonic circulations formed and a western disturbance also impacted the Western Himalayas,” explained M Mohapatra, director general, IMD.

“But one of the main factors in triggering widespread hailstorms in many parts of the country are upper level westerly winds blowing at 120 kmph and penetrating up to Peninsular India. These colder winds brought down the freezing level so it started to rain in the form of ice which is hail,” added Mohapatra.

Squally weather and rain have damaged wheat crop in almost all key producer states, but finding out the extent of losses might take weeks, according to preliminary assessments by a panel formed in view of anticipated early-summer heatwaves, HT reported on Monday.

On Monday, IMD said a cyclonic circulation is lying over northeast Rajasthan and an east-west trough is running from this cyclonic circulation to Nagaland in lower tropospheric levels. Another cyclonic circulation is lying over southwest Rajasthan in lower tropospheric levels. A trough/wind discontinuity is running from interior Tamil Nadu to central Chhattisgarh in lower tropospheric levels. On Tuesday, IMD said: a fresh active western disturbance is likely to affect northwest India from March 23 along with other existing synoptic features.

“These are very typical pre-monsoon activities. I think these have started a little early this year but they are not unusual. There have been years in the past also when hail has destroyed crops in many states. For such activities deep clouds need to form and for that moisture from the Bay of Bengal and the Arabian Sea is needed. Interactions with low latitude tropical circulation are also seen. These activities can be triggered by the warm land surface,” explained M Rajeevan, former secretary, ministry of earth sciences.

“We normally see this in April or in some years during March end. But February was very warm this year, thereafter the west coast also experienced high temperatures in early March. Heat can cause atmospheric instability and high clouds needed for development of thunderstorm activity. We are seeing multiple weather systems at once. There are western disturbances, there is an induced cyclonic circulation over northwest Rajasthan, a trough extending from northwest Rajasthan to interior Karnataka, all at the same time. Entire country is seeing thunderstorm and rainfall activity,” said Mahesh Palawat, vice president, climate change and meteorology at Skymet Weather. He added that between March 23 and 25, thunder activity is likely over Punjab, Haryana, Delhi, West Uttar Pradesh.

IMD on Tuesday said moderate rainfall/thundershowers were observed over most parts of northwest, Madhya Pradesh, east and northeast India while heavy rainfall occurred at isolated places over Himachal Pradesh, Sub-Himalayan West Bengal, Punjab, Haryana, West Uttar Pradesh, Tamil Nadu, Assam and Meghalaya. Hailstorm was observed over Jammu, Kashmir, Ladakh, Gilgit, Baltistan, Muzaffarabad, Himachal Pradesh, Uttarakhand, Punjab, Haryana, Chandigarh, Delhi, Uttar Pradesh, Rajasthan, Madhya Pradesh, Vidarbha, Chhattisgarh and Odisha. Maximum temperatures are in the range of 22-27 degree C over Punjab, Haryana, Chandigarh, Delhi, north Rajasthan, Uttar Pradesh, Bihar and northeast states; in the range of 24-34 degree C over rest parts of the country except over Western Himalayan region where these are in the range of 15-21 degree C. Maximum temperatures are 7-10 degree C below normal over north Rajasthan, Himachal Pradesh, Uttar Pradesh, Bihar, north Chhattisgarh; 4-7 degree C below normal over rest parts of the country except peninsular India.

A fresh spell of rainfall and thunderstorm activity is likely to commence over the north-western region from March 23 with isolated hailstorm likely over Punjab, Haryana, West Rajasthan on March 23 and over Himachal Pradesh, Uttarakhand, Punjab, Haryana, Chandigarh and West Uttar Pradesh on March 24; light rainfall with thunderstorm, lightning and gusty winds likely over interior Maharashtra, Madhya Pradesh and north Chhattisgarh on March 21 and reduce significantly thereafter. Thereafter, a fresh spell of rainfall & thunderstorm activity is likely to commence over the region from March 24, IMD warned on Tuesday.