The southwest monsoon is likely to be normal in north and south India, above-normal in central India and below-normal in east and northeast India, the India Meteorological Department (IMD) said on Tuesday.
Releasing its second long range forecast for southwest monsoon 2021, IMD Director General Mrutunjay Mohapatra said June is likely to witness normal monsoon which is also the sowing season.
He said the monsoon this year is likely to be normal in the country as a whole.
The news augurs well for the economy, battered due to the coronavirus pandemic. The southwest monsoon is one of the primary drivers of the country's economy, which is largely based on agriculture and its allied activities.
Large parts of the country rely on the four-month rainfall season for agriculture and also for filling reservoirs.
"We are expecting a good monsoon which will help the agriculture sector," Mr Mohapatra said in an online briefing.
"Quantitatively, the monsoon seasonal (June to September) rainfall over the country as a whole is likely to be 101 per cent of the Long Period Average (LPA) with a model error of plus or minus four per cent," he said.
Most parts of the country are expected to receive normal to above normal rainfall during the season, Mr Mohapatra added.
However, there are some regions in east and northeast India like eastern parts of Bihar, some parts of West Bengal, Assam, Meghalaya, Jammu and Kashmir, Ladakh, adjoining Himachal Pradesh, southwest peninsular India, specifically some parts of Kerala, coastal Karnataka and some parts of interior Maharashtra and some parts of interior Tamil Nadu where the probability of below normal activity is predicted.
Rainfall in the range of 96-104 of the LPA is categorised as normal. The LPA of the season rainfall over the country as a whole for the period 1961-2010 is 88 centimetres.
In its first long range forecast for the southwest monsoon 2021 released on April 16, the IMD had predicted rainfall to be 98 per cent of the LPA which also falls under the normal category with an error margin of plus or minus. But it has now upgraded its forecast to 101 per cent of the LPA which is on the higher side of the normal range.
The southwest monsoon in 2019 and 2020 was above normal.
The IMD has four divisions -- the east and the northeast, northwest, central India and south peninsula.
Mr Mohapatra said there is a 40 per cent chance of a normal rainfall, 22 per cent above normal, 12 per cent excess and 18 per cent below normal.
"The southwest monsoon seasonal (June-September) rainfall is most likely to be normal over northwest India (92-108 per cent) and south peninsula (93-107 per cent). Seasonal rainfall is most likely to be below normal over northeast India (below 95 per cent) and above normal over central India (over 106 per cent)," the IMD said.
Mr Mohapatra said spatial distribution suggests normal or above normal seasonal rainfall is most likely over many areas of northwest and central India, and eastern parts of southern peninsula.
Below normal seasonal rainfall is most likely over some areas of north, east, northeast parts of the country and western parts of the south peninsula, he said.
Mr Mohapatra said the latest global model forecasts indicate the prevailing neutral ENSO conditions are likely to continue over the equatorial Pacific Ocean and possibility of development of negative Indian Ocean Dipole (IOD) conditions over the Indian Ocean during the monsoon season.
El Nino, La Nina, positive and negative IOD are believed to have an influence over the Indian monsoon.
El Nino and La Nina are associated with the heating and cooling of the equatorial Pacific Ocean respectively. Negative and positive IOD are also linked to the heating and cooling of the Indian Ocean waters respectively.
Mr Mohapatra said conditions are favourable for the southwest monsoon to make an onset over Kerala on June 3. The normal onset date for monsoon's arrival in Kerala is June 1 which marks the commencement of the four-month rainfall season.
He added that from this year, the IMD will give a monthly rainfall forecast for all four months of the season.