KOLKATA: August ended with a rain deficit of 34% in Kolkata, the highest the city has clocked in more than a decade. Lack of enough low-pressure systems and absence of depressions are responsible for the showers slowing down last month, said weathermen. The last time Kolkata had a deficit in August was in 2018 when the city received 23% less precipitation than normal. Kolkata received 229 mm rain last month against a normal mark of 335.2 mm.
Gangetic Bengal, too, recorded a deficit of 18% in August this time. In 2019, however, Kolkata ended August with a 60% surplus.
August is the second wettest of the monsoon months, behind July. Normally, four low-pressure systems strike during the month with a couple of depressions occurring, too. “This August was unusually dry with just two low-pressure systems forming. The last one had formed last week near the Odisha coast but it did not have a strong enough impact. It led to intermittent drizzles but that were not enough to push the rain count up. The first low-pressure, too, was a weak one,” said Regional Meteorological Centre (RMC) director G K Das.
What made the month even drier is the elusive monsoon trough that continued to pass through north Bengal.
“While south Bengal had a secondary monsoon trough passing through it, the primary trough didn’t slide down to Bengal. It triggered heavy showers across north Bengal that received 49% excess rain in August,” added Das.
In 2019, Kolkata received 198 mm rain between August 16 and August 18 which is 14% of the normal seasonal count (June-Sept) of 1,324.1 mm. The month had ended with a 60% surplus. “There was no such deluge last month which could wipe out the deficit,” explained Das.
August 2017 had turned out to be moderately wet with a rain count of 385.9 mm, 15% above the normal mark. In 2016, the city had received 74% more than the normal count in August.
In 2013, the city had received 103% more than the normal count in August. That was the wettest August in recent years. Rain happens in cycles and a wet July is usually followed by a moderate August. “But there’s no specific rule. Showers depend on the presence and activity of systems that drive rain in monsoon. Typically, the more frequently you have the systems, the better are the chances of heavy rain. But this August has been a good one,” said Das.
