Skymet Weather, the country's leading private forecaster, expects the South-West monsoon to make an onset over Kerala coast on May 30 , with a model error of +/-2 days. Based on the data from 1961-2019, the normal date of onset over the Kerala coast is June 1 with a standard deviation of one week.
National forecaster India Meteorological Department (IMD) is expected to soon come out with its projected date of monsoon onset over Kerala.
Onset of the monsoon over Kerala is largely influenced by the oceanic conditions, both in the Arabian Sea and Bay of Bengal, Skymet Weather said. The likely cyclone formation in the Arabian Sea will be of consequence for advance of the monsoon stream over Indian territorial waters, it added.
The cyclone with the moniker 'Tauktae' as per the naming protocol, will vacate the Indian region by May 22 following which the westerly winds and cross equatorial flow will strengthen over Arabian Sea. Arrival of a periodical Madden Julian Oscillation (MJO) wave with moderate amplitude into the West Indian Ocean (and adjoining South Arabian Sea) will only aid the process. Given this, the pre-monsoon showers will get intense over Kerala.
Skymet Weather has already released its long-range forecast for the monsoon season, which it expects to be ‘healthy normal’ assessed at 103 per cent (with an error margin of +/- 5%) of the long period average (LPA) of 880.6mm for the 4-month period from June to September. This would make it third consecutive year of 'normal or above normal monsoon', it said.