Extended western disturbance activity through winter and spring, which has already generated surplus rainfall for the entire country so far during March, is expected to continue into the ongoing last week of the month and even into the first week of April, according to an outlook by India Meteorological Department (IMD).

No significant heatwave conditions are expected anywhere in the country during these two weeks, the IMD said. businessline has already cited global models as saying April may stay cooler due to expected widespread thunderstorm activity as the pre-monsoon season sets in. Outgoing Longwave radiation is forecast to stay negative to neutral, indicating sustained cloud cover and normal to variously wet conditions until April end, as per these models.

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Surplus rain so far in March

The IMD said thunderstorms and rain over North India and parts of Central and Peninsular India during many days during the ongoing week (March 23 to 29) will keep maximum temperatures below normal over most parts. No significant heatwave conditions are likely over any part of the country during the week as also for the one that follows (March 30 to April 5)

The unusual western disturbance activity has generated 25 per cent surplus rainfall for the country as a whole during March 1 to 22, it said in a status update. Central India recorded the maximum excess of +213 per cent during this period, followed by South Peninsula (+140 per cent); East and North-East India (+24 per cent), while North-West India alone recorded a deficit of (-31 per cent). But the latest week, ending March 22, has turned in a surplus (+68 per cent) for North-West India too.

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Implications for monsoon

The weekly surplus for the other regions are as follows: Central India, +1,232 per cent; South Peninsula, +723 per cent; and East and North-East India, +204 per cent. While the clouding and thundershowers capped the heat after an unusually warm February, continued wet weather as indicated by global models into April may not be a good sign for the ensuing South-West monsoon from June, which is already under the shadow of an evolving El Nino in the Pacific.

In its latest forecast, the IMD said that an incoming western disturbance as a cyclonic circulation has reached Iran and neighbourhood, and will track eastwards towards North India during the next 2-3 days. A cyclonic circulation lies waiting over South-West Rajasthan. Towards the South, a trough runs from Rayalaseema to South Jharkhand. They will combine to bring another bout of wet weather varyingly over the country during the ongoing week (March 23 to 29) as follows:

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Outlook for this week

North-West India: A fresh spell of rains and thunderstorms activity may commence and hold until Saturday, with isolated hailstorms over Punjab, West Rajasthan, the Jammu division, Himachal Pradesh, Uttarakhand, Punjab, Haryana, Chandigarh, West Uttar Pradesh, North Rajasthan, and Uttarakhand.

Central India: Mainly dry weather during next two ays, followed by a spell of rainfall and thunderstorms/hailstorms activity, especially over Madhya Pradesh, Vidarbha, and Chhattisgarh until Sunday. Mainly dry weather thereafter.

South India: Isolated to scattered light/moderate rainfall, thunderstorms, and lightning likely over Tamil Nadu, Puducherry, Karaikal, Kerala, Mahe and Andhra Pradesh during the next seven days. A fresh spell of rain and thunderstorm activity may commence over Telangana, Kerala, Mahe, and interior Karnataka from Friday to Sunday.

North-East India: Scattered to fairly widespread light/moderate rainfall, thunderstorms and lightning likely during next five days. Thursday’s isolated heavy rainfall over Arunachal Pradesh and Assam and Meghalaya will be followed by fresh spell of isolated heavy rainfall over the North-Eastern states from Sunday to Tuesday.

East India: Mainly dry weather likely during next 3 days, followed by a fresh spell of rain, thunderstorms and hailstorms activity from Sunday to Tuesday.

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Outlook for next week

Two fresh active western disturbance during April 30-April 2 and April 2-4 combining with induced cyclonic circulations will bring scattered to fairly widespread rain, lightning, hailstorms, and thunderstorms over the hills of North-West India and adjoining plains; and isolated to scattered rain, thunderstorms, hailstorms, and lightning over parts of Central India and East India during many days of the week.

A trough and a cyclonic circulation over South Peninsular India will trigger isolated to scattered rainfall, thunderstorms and lightning likely during many days of the week. Scattered to fairly widespread light/moderate rain activity with thunderstorms and lightning may continue over North-East India during the week. Overall, rainfall activity is likely to be above normal over the South Peninsula and the hills of North-West India and adjoining plains as well as over North-East India. It is likely to be near normal over rest parts of the country.