West Bengal: Regional Meteorological Center (RMC) of West Bengal recorded the heaviest downpour of this year and season as well. Base observatory at Alipore observed 144mm rainfall in the past 24 hours, ending at 8.30 am today morning. This is the first 3 digit rainfall for Kolkata during this monsoon season which takes the monthly rainfall to 286mm, very close to the normal of 300.6mm. This also is the 3rd highest 24 hours rainfall in the last decade, the highest being 162.6mm recorded on 26th June 2018.
The timely arrival of the monsoon over West Bengal in general, and the capital Kolkata in particular, has set the pace. The formation of a low-pressure area over the Bay of Bengal on June 11th, followed by its movement inland, caused fairly widespread rain and thundershower over Gangetic West Bengal, including Kolkata.
This weather system of cyclonic circulation is still meandering over the region, resulting in active monsoon conditions which are not likely leave anytime soon and may reorganize to produce active or vigorous monsoon conditions for the next 10 days. The intensity will, of course, vary during this time, peaking between the 19th and 21st of June.
From June to September, all four monsoon months in Kolkata receive record rainfall in excess of 300mm, with July being the wettest with nearly 400mm. The monsoon over Kolkata is early to arrive and late to depart, and the rains invariably last until mid-October.
The main drivers of monsoon rains in Kolkata are low-pressure areas or depressions forming over the Bay of Bengal, as well as the monsoon trough. Today’s forecast calls for moderate to heavy rain and thundershowers, along with lightning and squally winds, with 30-40mm of rain possible in 24 hours.