As the southwest monsoon begins its withdrawal phase in the country, it has become certain that Kerala will end up in the category of rain-deficient meteorological divisions.
Till September 19 of this season beginning from June 1, the State has received only 80 per cent of the normal rainfall for the period. The sun, on its journey from the northern hemisphere to the southern, will cross the equator at 2.49 p.m. on September 22. The wind-flow patterns are already changing as the equatorial region is now getting warm.
Satellite imagery and surface observations on Thursday indicated a considerable decrease in moisture over extreme west Rajasthan, West Haryana, and Punjab, suggesting the beginning of the withdrawal of the southwest monsoon from the country, according to the India Meteorological Department.
By September 30
The withdrawal happens in an anticlockwise direction, beginning from northwest India and backing down across central India, east India, the Bay, and finally the peninsular India. By September 30, the withdrawal of the southwest monsoon from the country will be usually complete. Just as Kerala is the gateway of the monsoon into the mainland of the country, it is also the gateway through which the monsoon makes its final exit from the mainland.
The meteorological indications are in favour of a sunny week ahead for the State. It is unlikely that the State would receive much more rainfall during the last 10 days of the season, judging from the wind-flow changes now happening over the subcontinent. The southwesterly wind regime over the subcontinent is changing and the withdrawal of the monsoon will be complete with the complete settling of the southwesterly wind regime.
Kerala scene
Kerala is one of the 11 meteorological divisions in the country deficient in rainfall at this stage. There are 36 meteorological divisions in all, of which two (Lakshadweep and Andaman) have received excess rainfall (exceeding 20 per cent of the normal). Twenty-three divisions have received normal rainfall (between minus 19 per cent and plus 19 per cent of the long-period average). The country as a whole is only 5 per cent on the minus side in monsoon rainfall.
All districts in the State have received less than the long-period average monsoon rainfall up to September 19: Alappuzha by 33 per cent, Kannur 10 per cent, Ernakulam 20 per cent, Idukki 17 per cent, Kasaragod 7 per cent, Kollam 35 per cent, Kottayam 22 per cent, Kozhikode 5 per cent, Malappuram 21 per cent, Palakkad 18 per cent, Pathanamthitta 35 per cent, Thiruvananthapuram 38 per cent, Thrissur 17 per cent, and Wayanad 47 per cent.
In meteorological parlance, up to 19 per cent less than the long-period average rainfall is considered normal rainfall. Therefore, according to the IMD’s classification, the districts of Idukki, Kannur, Kasaragod, Kozhikode, Palakkad, and Thrissur have received normal rainfall so far this season, while the other eight districts have received deficient rainfall.
The State Disaster Management Authority had last week declared the districts of Wayanad, Thiruvananthapuram, Kollam, and Idukki as drought-affected. The summer months of April and May can be expected to bring drinking water scarcity in several parts of the State and also power supply restrictions.
