E-Paper
Monsoon onset in Kerala likely today: IMD forecast
The monsoon arrives first in Kerala around June 1. It is expected to cover the rest of the country by July 5. The monsoon onset has been delayed by two days, IMD said in its revised forecast on Sunday
Conditions are favourable for the onset of monsoon in Kerala on Thursday, two days behind schedule, as south-westerly winds have strengthened, resulting in an increase in rainfall in the state, the India Meteorological Department (IMD) said in a statement on Wednesday.
The arrival of monsoon, crucial to the country’s farm-dependent economy, is announced based on factors such as wind speed, consistency of rainfall, intensity, and cloud cover.
“The spatial rainfall distribution has increased over Kerala. Westerly winds have strengthened in the lower levels over the south Arabian Sea and deepened,” the IMD statement said. It cited satellite imagery and added that there is an increase in cloud cover over the Kerala coast and adjoining southeast Arabian Sea. “The... conditions [are] likely to favour further enhancement in rainfall activity over Kerala during the next 24-hours. Hence, the monsoon onset over Kerala is likely in the next 24 hours.”
In its second long-range forecast on Tuesday, IMD said monsoon rainfall was likely to be normal at 101% of the long-period average (LPA) after two years of above-average rainfall. LPA is the average rainfall (88cm) recorded in India every year between June and September from 1961 to 2010.
In 2020 and 2019, the monsoon was above normal at 110% and 109% of LPA. In 1996, 1997, and 1998, the monsoon was normal at 103.4%, 102.2%, and 104%, respectively, according to IMD.
“Conditions are favourable for monsoon onset over Kerala. We said this morning that it’s likely to arrive in the next 24 hours. We will issue updates on its onset,” said M Mohapatra, director general, IMD.
IMD cited the strengthening of lower level south-westerly winds and said that widespread rainfall was likely in the north-eastern states this week, including heavy rainfall in Arunachal Pradesh, Nagaland, Manipur, Mizoram, and Tripura on Wednesday.
It also predicted fairly widespread rain accompanied by thunderstorms, lightning, and gusty winds in the western Himalayan region and the adjoining plains of north-west India on Wednesday and Thursday; apart from scattered to widespread rain accompanied by thunderstorm, lightning, and gusty winds in parts of south Peninsular India during the week.
India receives about 70% of its annual rain during the four-month monsoon that is crucial for rice, soybean, and cotton cultivation. Good rainfall has been a prime reason for the farm sector’s resilience for two years, and its ability last year to buck the Covid-19 pandemic.
Meanwhile, India recorded 18% excess rain during the pre-monsoon period from March 1 to May 31. Of 36 subdivisions, 17 recorded over 60% excess rainfall to be categorised as “large excess”; 9 subdivisions recorded 20 to 59% excess rain in fell in “excess” bracket; 6 subdivisions received (-19 to 19%) rain to be categorised as “normal” and only 4 subdivisions received -59 to -20% rainfall. Most of central, east and west India recorded large excess including parts of peninsular India like Kerala, coastal Karnataka, Konkan and Goa. Most of northeast India including Arunachal Pradesh, Assam, Meghalya, Tripura, Mizoram and Manipur and all of Jammu, Kashmir and Ladakh region were rain deficient.
“There were two cyclones in May – Tauktae and Yaas. Tauktae which formed over Bay of Bengal interacted with a western disturbance which was affecting the Western Himalayan region. There was rain over north and west India for 2-3 days continuously. Yaas also brought good rains to east India. Peninsular India was affected by an easterly wave activity especially northeastern southern peninsula. So overall the water table came up and temperature was very comfortable all of May. There were very few heatwave events,” said DS Pai, head of climate research and services, IMD Pune.
“We also had one of the coolest Mays since record keeping began. Temperature data is being assessed,” said OP Sreejith, scientist, Climate Monitoring and Forecast, IMD Pune.
While the cyclones have left soil conditions moist in most parts of the country, Pai said sowing should be well timed with monsoon progress. “We are expecting monsoon to progress quickly after June 7 to 10. There may be slightly slow progress before that. Farmers should decide on sowing Kharif crops in consultation with agromet and agriculture scientists,” added Pai.
The standard precipitation index (SPI) shows a large part of central, north, east and west India are either “extremely wet” or “severely wet.” SPI is an index used for drought monitoring and is negative for drought, and positive for wet conditions. Most parts of the northeast and Peninsular India are also dry with some pockets severely and extremely dry indicating drought like conditions.
But extremely wet conditions are not necessarily good for agriculture. “When the annual rainfall is normal and pre-monsoon rainfall is excess during the Kharif season, the deficit may increase. This is because as the soil organic matter is low, water holding capacities are lower. So excess pre-monsoon rain may not result in holding soil moisture,” explained G V Ramanjaneyulu, executive director, Centre for Sustainable Agriculture, Hyderabad.
