After declaring the onset of the southwest monsoon, the India Meteorological Department (IMD) now appears to look for the mercy of ‘rain gods’. Even four days after the declaration of the onset of the monsoon over Kerala, one of the main criteria for declaring the arrival of monsoon – that 60% of the enlisted weather stations under the State should record 2.5 mm of rain for two consecutive days – is yet to be fulfilled.
The other two criteria are that the depth of the westerly winds should be maintained up to 600 hPa (hectopascal) and the outgoing longwave radiation (OLR), which is a measure of cloudiness, should be below 200 watt/square metre. Though these two criteria were met on May 29, the day the IMD announced the arrival of monsoon over Kerala, the first criteria that 60% of the enlisted 14 weather stations – Minicoy, Amini, Thiruvananthapuram, Punalur, Kollam, Alappuzha, Kottayam, Kochi, Thrissur, Kozhikode, Thalassery, Kannur, Kudulu and Mangalore – should report rainfall of 2.5 mm or more for two consecutive days, continues to be unfulfilled.
Already the IMD has come in for sharp criticism from various quarters for showing ‘undue haste’ in declaring the arrival of the monsoon over Kerala without meeting all the criteria. The rain data of the enlisted weather stations shows that between May 27 and June 2, the required rainfall of 2.5 mm or above was recorded only May 29 and June 1, two different days, instead of the mandated two consecutive days. In short, the IMD will have to wait further to meet all its criteria meant for the declaration of arrival of monsoon.
A senior IMD source told The Hindu that though there may be some isolated heavy rains over Central Kerala on Thursday and Friday due to the influence of strong westerly winds from the South Arabian Sea, the monsoon is expected to enter its active phase in the State only by June 6-7. The synoptic conditions such as strong lower winds and strong lower and upper air convergence are favourable for the advancement of the monsoon.
But an offshore trough along the coasts from Gujarat to Kerala is yet to take shape, the formation of which is critical for bringing good spell of monsoon over Kerala, said the source.
The IMD had earlier forecast that the monsoon would hit the shores of Kerala on May 27 with an error margin of plus or minus four days.
