Skymet Weather, the private weather forecast agency, has predicted today that four-month long Southwest Monsoon which gives about 70 percent of India’s annual rainfall, will be normal. Monsoon rains rains this year will be at 100 percent – with an error margin of +/-4 percent – of the long period average (LPA) of 887 mm for the four-month period from June to September.
As 65 percent agricultural land in the country is rainfed, Monsoon plays very crucial role in the agriculture sector and Indian economy as the sector gives livelihoods to over half the country’s population. The upcoming Kharif season is entirely based on Monsoon rains.
According to Jatin Singh, CEO, Skymet, “Devolving La Niña and gradual warming of Pacific is ruling out the possibility of excess rains. Nevertheless, Nino index and neutral IOD (Indian Ocean Dipole) may not have any adverse impact on the Monsoon performance and thus, Monsoon 2018 is likely to be normal”.
These are some key factors that have a major impact on the performance of Southwest Monsoon. Presently, weak La Niña conditions are prevailing over the Pacific Ocean and most likely, the transition of La Niña to ENSO neutral conditions would take place during March to May. In fact, three-monthly Nino index shows that by MJJ (May-June-July) there is over 60 percent chance of neutral, 24 percent chance of La Niña and 14 percent chance of El Niño coming into existence.
IOD is in the negative phase but within the neutral limits at present. However, weather models are indicating that IOD would possibly shift near normal during the second half of Monsoon.
Meanwhile, MJO (Madden–Julian oscillation) is currently inactive but it is too early to comment on its impact on Monsoon.
Pre-Monsoon heat is considered as a positive indicator and points towards normal Monsoon. Similar conditions are presently prevailing across the country. In fact, weathermen are of the view that pre-Monsoon season would be slightly below normal, paving way for intense heat before the onset of Monsoon.
Formally Monsoon season begins on June 1, but the final commencement of its journey keeps varying every year. Although, a difference of five to seven days is considered as normal.
Kerala is the first state from where the Southwest Monsoon hits the Indian mainland in June 1, during its four-month long journey. During this time, Monsoon also arrives in Tamil Nadu, including Kochi, Trivandrum and Chennai. It also touches the border of the northeastern states during the same time frame.
Thereafter, around June 5, Southwest Monsoon sets in over North Karnataka, some parts of Telangana including Hyderabad, Andhra Pradesh. Meanwhile, Monsoon covers almost entire Northeast India including the cities of Agartala, Guwahati, Shillong, Imphal and Dispur.
On June 10, Monsoon arrives over almost entire Maharashtra, Odisha and West Bengal, including Mumbai and Kolkata. In fact, during this time, a few parts of Chhattisgarh, Jharkhand and Bihar also welcomes Monsoon rains.
Monsoon’s next stops are Gujarat, Madhya Pradesh, East Uttar Pradesh, Bihar and Jharkhand where it reaches around June 15. Thus, Monsoon rains begin in Ranchi, Patna, Varanasi, Bhopal, Indore, Surat and Ahmedabad.
Thereafter, in a normal situation, between June 28 to July 1, Southwest Monsoon covers entire Uttar Pradesh, Delhi, Uttarakhand, Himachal Pradesh, Jammu Kashmir and over some parts of Rajasthan, Punjab and Haryana. Cites like Lucknow, Jaipur, Dehradun, Shimla, Srinagar and Amritsar begin to receive Monsoon rains by this time.
By July 15, Southwest Monsoon covers the entire country, including rest of Rajasthan. Skymet Weather had accurately predicted below normal Monsoon rains for 2017 to the tune of 95 percent rains of LPA.