How to calculate southwest monsoon withdrawal dates in sri lanka​

Following a unified approach, an objective criterion has been developed for the determination of yearwise onset and withdrawal dates of the summer monsoon over the 19 subregions across India. In total 14 meteorological parameters are considered in the development of the objective criteria, two of which represent heating over south Asia-Middle East sector and Tibet-Himalaya-Karakoram-Hindukush Highlands (THIKHIHILS), two intensity of the general atmospheric circulation (GAC) over eastern hemisphere, three intensity of regional circulations and seven local hydro-meteorological conditions.