The weather bureau has issued a yellow alert for Friday and Saturday predicting the possibility of thundershowers and heavy rain across isolated areas. After minimal rain activity over the first 10 days in September, monsoon revival is expected from Saturday onwards, said independent meteorologists.
According to the rainfall forecast for Mumbai, Thane and Palghar, cloudy conditions with the possibility of moderate rain or thundershowers can be expected in the city and suburbs on Friday, and heavy rain across isolated areas on Saturday.
As per the India Meteorological Department (IMD), an off-shore trough at the mean sea level runs from the Maharashtra coast to the Kerala coast.
“Combined with this, an east-west shear zone over peninsular India and land heating leading to tall cloud formation, will account for an increase in moisture, lower level westerly winds and increase in rain intensity for the west coast, north Konkan including Mumbai in coming days,” said Mrutyunjay Mohapatra, director-general, IMD.
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Over the past 24 hours, only light showers were recorded in the city. Between 8.30 am Wednesday and 8.30 am Thursday, the suburbs recorded 5.6 mm rain while 4 mm rain was recorded in south Mumbai.
During the first 10 days of September, Mumbai has witnessed only 5.5 percent of rainfall recorded during the first 10 days of September 2019. This month, the suburbs recorded 43.3 mm rain while 56.4 mm was recorded in south Mumbai between September 1-10. Last year, the suburbs had recorded 801.4 mm rain while south Mumbai recorded 464.6 mm over 10 days. However, from September 1-10 2018, only 33.6 mm and 12.4 mm rain was recorded in the suburbs and south Mumbai.
“Intra-seasonal variability is there but a specific trend from year-on-year rain for a specific period cannot be established as every monsoon is different. No rain-bearing weather systems had formed over Bay of Bengal or the Arabian Sea through the first 10 days of this month,” said Mohapatra.
The first 10 days of September have also witnessed the least amount of rain as compared to the first 10 days of June, July and August. Independent meteorologist and PhD researcher at the University of Reading, United Kingdom, Akshay Deoras said under the influence of a few monsoon low-pressure systems, the offshore trough will strengthen, thereby leading to some moisture incursion in coming days.
“Most of this activity will be of light to moderate intensity (especially during this weekend), so there is no severe weather threat involved. The monsoon is expected to remain active in the region over the next 10 days,” he said.
The city can expect overcast skies again from Saturday with the possibility of heavy rain for Mumbai, Thane, Raigad, Pune and ghat areas between Sunday and Tuesday, said professor Sridhar Balasubramanian, department of mechanical engineering and IDP Climate Studies, Indian Institute of Technology, Bombay. “Rainfall is expected to be between moderate to heavy at around 70-80 mm over 24 hours during this period,” he said.