By Dr. R. H. Patil
Department of Agricultural Meteorology, UAS, Dharwad
The southwest monsoon which is spread over four months from June till the end of September and delivers some 880 mm rainfall i.e., three-fourth of total annual rainfall across the country has reached the Kerala coast on June 3, two days later than earlier forecasted.
IMD New Delhi today proclaimed that southwest monsoon arrived Kerala coast on June 3, two days later than the earlier forecast of June 1 and three days later than the long-period average of May 31.
IMD declares the onset of monsoon only after the fulfilment of certain conditions: one of them is 60% out of 18 meteorological stations in Kerala, including one from Mangaluru port, should record 2.5 mm or more rainfall for two consecutive days after May 10. Apart from fulfilling this condition, IMD also looks at the strength of westerly winds along the Kerala coast and the outgoing long-wave radiation (OLR). Westerly winds should be strong and OLR values must be above 200 during the previous 10 days leading up to the onset of the monsoon.
IMD, New Delhi on June 2, considering the latest development in ocean waters and westerly winds circulation patterns, revised its data and released second stage long-range forecast (LRF).
In its press release stated that rainfall during Kharif season (Jun-Sep) is going to be ‘normal to above normal and well distributed. Further, it stated that monsoon over the whole of India is going to be 101% of the long period average (LPA) with a model error of ±4%, while private weather forecaster Skymet stated that it’s going to be 103% of LPA with ± 5 %.
As per the IMD forecast monsoon in Karnataka is going to be relatively weak during the initial period and likely to cover the entire Karnataka between 8 and 10, June.
The LPA of Kharif season rainfall for the country averaged for the period from 1961 to 2010 is 886 mm.
During 2019 and 2020, buoyed by two consecutive above normal rainfall seasons, achieved record food grain production and going by the current forecast country may see record food grain production during 2021 as well with a possible third consecutive normal to above normal rainfall.
Skymet also stated that there is a 70% chance that this year monsoon is going to be normal (between 96 to 104% of LPA) and 15% above normal (between 105 to 110% of LPA). That is 85% falling under the category of normal to above-normal which is good news for the farming community.
As per Skymet forecast June, July, August and September months will have 70, 75, 80 and 19% chances of normal monthly rainfall, and 20, 10, 10 and 60% chances of above-normal rainfall, respectively. This suggests that September is going to above-normal rainfall, hence likely to witness an extended period with the delayed withdrawal of a monsoon.
The IMD earlier had showed that the SW monsoon is likely to be normal in the north and south India, above normal in central India, and below-normal in the east and northeast India.
Adding to that the latest forecast suggests some risk in north Interior Karnataka and going by the strength of monsoon Karnataka as a whole and NIK, in particular, may witness good monsoon only from the third week of June. In this context, farmers of North Interior Karnataka are advised to take up sowing of green gram, black gram, soybean, cotton, maize, paddy and groundnut only if optimum summer followed by pre-monsoon showers were and are being received and/or have source/facility to provide irrigation soon after sowing to tide over the dry period until the monsoon arrives.
However, sporadic light to moderate pre-monsoon showers with thunderstorms are expected across the NIK region on 3rd, 4th and 5th June, which may encourage farmers to take up sowing while expecting the monsoon. Otherwise, it is safe and better to wait until proper monsoon rains come. Many farmers in Kalaghatagi, Alnavar, Khanapur, Dharwad and Hubli taluk have already taken up sowing paddy, maize, green gram and soybean on some area, who are advised to provide one light irrigation for uniform emergence, optimum crop stand and early vigour.