Low pressure area to bring heavy rain next week: IMD
The remnant of a low-pressure system from the east is likely to emerge and under its influence, a low-pressure area is likely to form over north Bay of Bengal around August 4, IMD said.Updated: Aug 03, 2020 01:21 IST
India’s monsoon rains, exactly at 100% of the so-called long period average of LPA on Saturday, the halfway mark of the four month season, but with a 9.5% deficit in July, the most critical month of the four, will likely increase this week in the core monsoon zone, The India Meteorological Department said on Sunday. The northwest part of the country, though, including Delhi, are unlikely to benefit from this.
The remnant of a low-pressure system from the east is likely to emerge and under its influence, a low-pressure area is likely to form over north Bay of Bengal around August 4, IMD said. This is likely to be the first significant low-pressure area formation this monsoon which can bring monsoon rains in central and peninsular India according to IMD’s Sunday bulletin.
“Since June 21 no low-pressure area had formed over Bay of Bengal. Low pressure areas are the main rain bearing systems during monsoon which bring rain to the core monsoon zone. A cyclonic storm is forming over the west Pacific, remnants of which are likely to enter Bay of Bengal and form a low-pressure area,” said DS Pai, senior scientist at IMD Pune.
The absence of a low-pressure area has hit parts of the country hard.
Since June 1, northwest India has a rain deficiency of 18% and central India has a deficiency of 5%. This falls well in the plus or minus 20% of normal range.
It has also been a dry July, the month which typically sees around a third of monsoon rainfall, and which, along with June, is the most critical month for agriculture in India.
In July central India or the core monsoon zone recorded a deficiency of 22.3%. In northwest India, Delhi has a 27% deficiency; Rajasthan has a 24% deficiency; Ladakh, Jammu and Kashmir and Himachal Pradesh have recorded 62%, 49% and 28% deficiency respectively.
These areas are unlikely to see much rain this week, but the southern part of the country and central India will. “Under the above favourable scenario, monsoon will enter to active phase over the central and peninsular India from August 4 onwards for subsequent 3-4 days. Widespread and very heavy rain is also likely over Konkan and Goa during August 3 to 5. Mumbai and Madhya Maharashtra including the ghat areas are also likely to be affected by very heavy rains. Heavy to very heavy rain is likely over many places in Coastal Karnataka and Kerala,” IMD said.
The July deficiency is a rare occurrence. “In the absence of any low-pressure area forming over Bay of Bengal, for the first time in five years July recorded a 9.5% deficiency. But now a low-pressure area is forming over north Bay of Bengal which can travel inland over central India and bring a lot of rain to Odisha, Andhra Pradesh, Telangana, Chhattisgarh. Due to strengthening of south westerly winds, the west coast is also likely to get very heavy rain. We are monitoring Mumbai for very heavy rains between August 3 and 5,” said RK Jenamani, senior scientist, national weather forecasting centre. Jenamani’s research work shows the number of depressions forming over Bay of Bengal during monsoon months particularly July are on a decline.
For the season, as of Saturday, monsoon rains showed a 12% excess over east and northeast India; 18% deficiency over northwest India; 5% deficiency over central India; and 13% excess over peninsular India.
Presently, cool El Nino Southern Oscillation (ENSO)-neutral conditions are prevailing over the equatorial Pacific Ocean. Sea surface temperatures over the region are likely to cool further. There is enhanced probability for development of weak La Niña conditions during August-September-October season, IMD has forecast.
“Both cool ENSO neutral conditions and weak La Nina conditions in September are favourable for rains which is why we are expecting a normal monsoon this year—around 102% of the long period average,” added Pai. La Niña is characterized by unusually cold ocean temperatures in the Equatorial Pacific and is associated with normal or above normal rains over India.