Despite heavy showers, July ends with 15% rain deficit

KOLKATA: Despite the occasional spells of heavy downpour and steady, continuous drizzles this July, Kolkata remained relatively dry and ended with a

rain deficit

of 15%. The city’s seasonal rain count, however, remains healthy with an excess of 15%. This is the second time in the last five years that the city had a rain deficit in July. The city received 40.9mm rain till 5.30pm on Wednesday.


But the July deficit is not a major and can turn in the coming weeks, said

weathermen

. The normal July count in Kolkata is 522mm. Since monsoon rain is driven by lowpressures and cyclonic circulations, the frequency of the latter will determine the eventual rain count, they said. “We had just one depression and three low-pressures last month, which is normal. The deficit is not big one and should be wiped out in the course of August. Kolkata receives showers till late Septembers so the final seasonal count could be an excess,” said Regional Meteorological Centre (RMC) director GK Das.

In 2017, Kolkata received 72% excess rain in July. The deficit, though, could come down in the next 2-3 days, weathermen pointed out. The city received a continuous downpour through the night on Tuesday. It didn’t stop before Wednesday afternoon, leaving

several areas waterlogged

. It was the cyclonic circulation over Bangladesh and adjoining

West Bengal

that triggered the heavy rain, according to Das.

“The circulation has slowly started moving towards Bihar, which will gradually reduce the impact on Kolkata and south Bengal. It may continue to drizzle occasionally in Kolkata till Thursday afternoon and the sky will remain overcast. But heavy or continuous showers like Wednesday are unlikely,” said Das. The city may remain cloudy and occasional drizzles may remain cloudy till August 4.

Since monsoon rain occurs in cycles, occasional lean patches are usual, said a weather scientist. “The volume and intensity of rain depends on the frequency of systems like lowpressures and circulations. Systems were rare in early July so it mostly drizzled, with fewer heavy spells. A depression formed during the last week of the month, triggering heavy rain and it made up the deficit,” he said.

Till the third week of the month, Kolkata’s July rain count was 51% below normal. While the deficit was huge, it dropped considerably after a depression over north-west Bay of Bengal that triggered heavy showers across the region.

July 2017 had been the second wettest in Kolkata in a decade with rain count clocking a phenomenal 72% above the normal mark for the month. The city was drenched by showers at regular intervals and with almost equal intensity. While Kolkata has a July deficit of 15%, Gangetic Bengal has a smaller deficit of 6% for the month.