Mumbai is likely to end up with a seasonal rain deficit of 28% in south Mumbai and 18.3% in the suburbs, as the monsoon ends on September 30.
The Colaba observatory recorded 1,604.8mm against the seasonal normal of 2,053.1mm between June 1 and September 28, while the suburbs received 1,823.2mm against the 2,231.6-mm benchmark for the season. According to officials from the India Meteorological Department (IMD) the existing weather conditions are unlikely to lead to substantial rain till September 30.
“A drop in rain in July and August is the main cause. Apart from Vidarbha and isolated parts of central Maharashtra, the whole state has received scanty rainfall,” said KS Hosalikar, deputy director general, western region, IMD. “Surplus rain was recorded between June 17 and 24 and in early September,” he said.
This year, Mumbai saw a combination of record highs and lows through the season. The rain received in the city in June reached an all-time high of 1,106.7mm at Santacruz and 866.3mm at Colaba, after the heavy rain on June 19 -- 208.8mm of rain at Colaba and 283.4mm at Santacruz.
Mumbai also recorded the driest August in the past 10 years, with only 155.8mm at Santacruz and 188.2mm at Colaba from August 1 to 31, against the monthly average of 530mm.
Mumbai also recorded the second lowest rain for September at 203.5mm at Santacruz (representative of monthly total for the city).
The monsoon for the city is from June 1 to September 30, although it may rain before and after the period. “There might be one or two isolated spells of rain because of moisture incursions along the Konkan coast in the next two days, but nothing specific to Mumbai,” Hosalikar said.
Meanwhile, private weather-forecasting agency at Delhi, Skymet, has calculated a 19.4% deficiency for Mumbai city (Skymet does not take separate averages for the city and suburbs). While the city is supposed to get an average of 312mm in September, it recorded 204mm this month. “The season total for four months is 1,833 mm till September 27, against the average of 2,275mm,” said GP Sharma, vice-president, meteorology, Skymet. “We do not expect any significant weather change in the city over the next 10 days.”
Sharma said apart from active offshore troughs in June and September, rain-bearing factors have remained insignificant to make up for the required rainfall. “Major factors like El-Nino (phenomenon caused when warm water from the western Pacific Ocean flows eastward and alters winds bringing in rain-bearing systems) continue to be very strong. Other factors such as the Madden Julian Oscillation (rain bearing wind system) and Indian Ocean Dipole (difference in temperatures over Arabian Sea compared to Bay of Bengal) were not favourable for monsoon this year,” said LS Rathore, director general of meteorology, IMD.