Monsoon in India: The India Meteorological Department (IMD) declared the onset of monsoon in India on Thursday with its onset over Kerala, a week later than normal. The IMD said that during the past 24 hours, Kerala has received widespread rainfall.
“Southwest Monsoon has set in over Kerala today, the 08th June, 2023 against the normal date of 01st June,” the IMD said in a tweet.
Monsoon advanced into remaining parts
"Southwest Monsoon has advanced into the remaining parts of the south Arabian Sea and some parts of the central Arabian Sea, the entire Lakshadweep area, most parts of Kerala, most parts of south Tamil Nadu, the remaining parts of the Comorin area, Gulf of Mannar and some more parts of southwest, central and northeast Bay of Bengal today. Thus, Southwest Monsoon has set in over Kerala today against the normal date of June 1," the IMD said in a statement.
The weather department said the clouding also increased over the southeast Arabian sea and the strength of Westerly winds in the lower levels has increased. "During past 24 hours, clouding has increased over Southeast Arabian sea with Outgoing Longwave Radiation(OLR) being <200 watts/meter2. The depth of westerly winds over Southeast Arabian sea extends upto middle tropospheric levels. The strength of Westerly winds in the lower levels has increased and is about 19 knots. There has been widespread rainfall over Kerala during the past 24 hours. Considering all the above-satisfied conditions, Southwest Monsoon has set in over Kerala today," it said.
"The Northern Limit of Monsoon (NLM) now passes through lat. 13.5°N/ Long. 55°E, lat. 14.0°N/ Long. 60°E, lat. 13.5°N/ Long. 65°E, lat. 13°N/ Long. 70°E, Cannur, Kodaikanal, Adirampattinam, lat. 12.0°N/ Long. 83.0°E, 16.0°N/88.0°E, 18.5°N/90.0°E, 22.0°N/93.0°E," the IMD said.
Conditions favourable for further advance of Southwest monsoon
It further said that the conditions are favourable for further advance of the Southwest monsoon into some more parts of the central Arabian Sea, remaining parts of Kerala, some more parts of Tamil Nadu, some parts of Karnataka and some more parts of southwest, Central and northeast Bay of Bengal and some parts of northeastern states during next 48 hours.
However, the weather forecasting agency has earlier predicted a mild monsoon onset over Kerala and weak progress beyond the southern peninsula under the influence of Cyclone 'Biparjoy'. The southwest monsoon normally sets in over Kerala on June 1 with a standard deviation of about seven days. In mid-May, the IMD said the monsoon might arrive in Kerala by June 4. Skymet had predicted the monsoon onset over Kerala on June 7, with an error margin of three days.
Monsoon onset over Kerala widely varied
Over the last 150 years, the date of the monsoon onset over Kerala has varied widely, the earliest being May 11 in 1918 and the most delayed being June 18 in 1972, according to IMD data. The southwest monsoon arrived in the southern state on May 29 last year, June 3 in 2021, June 1 in 2020, June 8 in 2019 and May 29 in 2018.
Research shows a delay in the monsoon onset over Kerala (MOK) does not necessarily mean a delay in the monsoon onset over northwest India. However, a delay in the MOK is generally associated with a delay in onset at least over the southern states and Mumbai. Scientists say a delayed MOK also does not impact the total rainfall over the country during the season.
India expected to get normal rainfall
India is expected to get normal rainfall during the southwest monsoon season despite the evolving El Nino conditions, the IMD had earlier said. Northwest India is expected to see normal to below-normal rainfall. East and northeast, central, and south peninsula are expected to receive normal rainfall at 94-106 per cent of the long-period average.
Rainfall less than 90 per cent of the long-period average is considered 'deficient', between 90 per cent and 95 per cent is 'below normal', between 105 per cent and 110 per cent is 'above normal' and more than 100 per cent is 'excess' precipitation.
Normal rainfall is critical for India's agricultural landscape, with 52 per cent of the net cultivated area relying on it. It is also crucial for replenishing reservoirs critical for drinking water, apart from power generation across the country.
Rainfed agriculture accounts for about 40 per cent of the country's total food production, making it a crucial contributor to India's food security and economic stability.