Runs of Dry and Wet spells during southwest monsoon and onset of monsoon along the west coast of India

Abstract

The daily rainfall data of five stations on the Konkan coast of India during 'the southwest monsoon have been analysed to determine the frequencies of rain and no-rain periods of various lenths. The use of persistence as an aid for forcecasting rain periods following runs of rainy days of dry days of different lengths is discussed.

                   Runs of dry days during the southwest monsoon months have 'also been studied by the theory of extreme values (Jenkinson Probability Method) and the probable maximum run of dry days with zero rainfall in each month has been worked out for various periods giving an idea of the lengths of breaks during the monsoon months due to weakening or temporary withdrawal of the monsoon current.

                 The runs of dry days from 1 May and I June have been separately analysed to estimate the latest possible date of commencement of the monsoon from 1 May and I June and the results are compared with the normal dates of onset of the southwest monsoon.