Pre-monsoon rain lashes parts of the western suburbs as IMD has issued a yellow alert until 24 June, at Andheri in Mumbai. (EXpress photo by Sankhadeep Banerjee)Parts of Mumbai woke up to heavy showers on Monday morning amid a yellow alert issued for the region. However, the city’s wait for the official onset of the southwest monsoon continues, with the India Meteorological Department (IMD) stating that monsoon conditions are likely to advance into Mumbai within the next 48 hours.Offering respite from the prolonged dry spell, moderate to heavy rain lashed pockets of the western suburbs and the island city during the early hours of Monday. Data from the Brihanmumbai Municipal Corporation’s automatic weather stations showed that between 6 am and 7 am, the highest rainfall was recorded in Bandra at 70 mm, followed by Worli (61 mm), Dadar (58 mm), Adarsh Nagar in Worli (44 mm), Malabar Hill (44 mm) and Juhu (25 mm).Also Read | Covid-19, H1N1, RSV: Doctors on weather changes and rising respiratory illnesses in MumbaiWhile the western suburbs and island city recorded average rainfall of 10 mm and 17 mm respectively, the eastern suburbs remained largely dry, recording no rainfall. Pre-monsoon rain lashes parts of the western suburbs as IMD has issued a yellow alert until 24 June, at Andheri in Mumbai. (Express photo by Sankhadeep Banerjee)However, after the early morning spell, rain activity tapered off across the city. Both the IMD’s Santacruz and Colaba observatories recorded zero rainfall between 8.30 am and 5.30 pm on Monday.Meteorologists attributed the early morning showers to pre-monsoon activity. “At present, the southwest monsoon has advanced up to Alibaug in Maharashtra. Conditions are favourable for its further advancement as the westerlies are active. We are closely monitoring the developments and expect the southwest monsoon to reach Mumbai within the next 48 hours,” a senior IMD scientist told The Indian Express.Also Read | Yellow alert for Mumbai as monsoon arrival nears, water woes to continueThe normal date for the onset of the southwest monsoon in Mumbai is June 11. This year, however, after advancing rapidly from Kerala to south Maharashtra by June 6, the monsoon’s progress slowed considerably.According to IMD scientists, the delay was caused by the absence of dominant monsoon features such as an offshore trough, low-pressure systems or cyclonic circulations over the Arabian Sea and the Bay of Bengal.Story continues below this adWith the monsoon yet to arrive, even pre-monsoon rainfall has remained below normal. Between June 1 and the morning of June 22, the IMD’s Santacruz observatory recorded only 38 mm of rainfall, while the Colaba observatory received 26 mm, marking a significant departure from normal rainfall levels for this period.Rain activity, however, is expected to intensify over the coming days. The IMD has issued a yellow alert for Mumbai and neighbouring districts, including Thane and Palghar, until Thursday morning, warning of thunderstorms accompanied by moderate rainfall and gusty winds.