Three days since its arrival over southern Maharashtra, southwest monsoon on Sunday covered Mumbai and the remaining parts of the state, announced the India Meteorological Department (IMD).
While on Saturday, the Santacruz observatory recorded 19.7 mm of rain and Colaba 11.2 mm, Mumbai did not witness any rainfall on Sunday. Rainfall, wind speed and direction as well as type of cloud cover are considered to declare the onset of southwest monsoon over a region.
According to the new onset dates released by IMD, monsoon arrived in the state on June 10 and would cover the whole of Maharashtra by June 15.
The Met office warned of very heavy to extremely heavy rainfall along the west coast of Maharashtra and the southern states on Monday. An orange alert (to be prepared) with forecast of heavy to very heavy rainfall has been issued for Monday and Tuesday for Mumbai, Thane, Palghar and the remaining districts of the west coast, parts of central Maharashtra as well as isolated areas of Vidarbha and Marathwada. Heavy rainfall at isolated places is likely in Goa and Konkan region during the next 24 hours, it added.
Monsoon in Mumbai arrived three days later than its usual onset date of June 11. However, its progression is not likely to be called delayed as a standard deviation of five days has been budgeted for by the IMD.
Last year, Mumbai had witnessed its most delayed onset in the last 45 years with southwest monsoon arriving in the city on June 25. The onset date was June 9 in 2018 and June 12 in 2017. From June 1 to June 14, Mumbai had recorded 208.5 mm rain. The average city rainfall for June is 493.1 mm.
“Conditions are becoming favourable for further advance of southwest monsoon in Gujarat, Madhya Pradesh and remaining parts of Chhattisgarh, Jharkhand, Bihar and some parts of east Uttar Pradesh in the next 48 hours,” read the IMD bulletin.
Independent meteorologists, meanwhile, said that pre-monsoon showers are prominent in the state and weather conditions are not conducive enough to declare monsoon onset. “The process of declaring the progression of southwest monsoon over a region has been highly subjective. It is relying heavily on the observed rainfall (which at present is due to pre-monsoon thunderstorms and not monsoon) than the wind direction. The wind pattern over a region needs to be seriously considered, while declaring the monsoon’s progression,” said Akshay Deoras, meteorologist and PhD researcher at the department of meteorology, University of Reading in the UK.
On Saturday, heavy rainfall lashed parts of Marathwada and south Konkan. In 24-hours since 8.30 am on Saturday, Mokhada in Palghar had recorded 120 mm of rainfall, followed by Ulhasnagar (110 mm), Jalgaon (82 mm), Matheran (81.4 mm), Ratnagiri (41 mm) and Nashik (31 mm).
Since June, the state has recorded excess rainfall with all districts receiving either normal or above normal rainfall.