Expect very heavy rain in Mumbai, Thane today: IMDUpdated: Jul 04, 2020 00:42 IST
The island city and suburbs on Friday recorded over 100 millimetres (mm) of rain in a day. South Mumbai recorded more rain than the suburbs, with an intense rain spell of 157 mm in approximately three hours.
Between 8.30am and 5.30pm on Friday, the city saw very heavy rain, with 161.4mm and 102.7mm of rain recorded at Colaba and Santacruz weather stations respectively. “Both the city and suburbs from Friday morning onwards had very intense connective clouds that had the potential to cause 30-50 mm rain per hour within three hours. Similar intense rain is expected on Saturday followed by a drop in intensity from Sunday onwards,” said KS Hosalikar, deputy director general, western region, India Meteorological Department (IMD).
For today, IMD has issued a red alert (extremely heavy rainfall) for Mumbai, Thane, Palghar and Raigad. A red alert directs authorities to take necessary action for extremely heavy rain at isolated places in a region. For Sunday, a yellow alert (be updated for heavy rain at isolated places) has been issued for Mumbai, Thane, Raigad, Ratnagiri, and Sindhudurg. An orange alert (heavy to very heavy rain) has been issued for Palghar, for Sunday.
“The active monsoon current is being triggered by three weather systems — a cyclonic circulation over south Gujarat at the lower and mid-tropospheric level that is likely to persist for at least two days; an offshore trough running from Maharashtra to Kerala coast; and high convergence due to strong westerly to southwesterly winds, carrying a lot of moisture from the Arabian Sea over the coast,” said Hosalikar.
In addition to this, a vortex (localised low-pressure circulation) will form over the Mumbai region, said Akshay Deoras, independent meteorologist and PhD researcher at University of Reading.”This will lead to rain enhancement over the weekend. Intense spells are expected during Saturday afternoon, evening; and Sunday morning. Rain-related disruptions are expected with rainfall accumulation higher towards Palghar, Thane and Raigad,” said Deoras.
Professor Sridhar Balasubramanian, department of mechanical engineering and IDP Climate Studies at Indian Institute of Technology Bombay, said, “Very heavy rains can’t be ruled out with some places likely to get 200-250 mm in a 24-hour period. There will be waterlogging and possibility of localised flooding. Caution needs to be exercised in these difficult times.”
IMD classifies 20-30mm rain per hour as intense spell; 30-50mm per hour as very intense rain; 50-100mm per hour as extremely intense rain spell; and over 100mm per hour as cloud burst. IMD further classifies 15.6-64.4mm as moderate rain; 64.5-115.5mm rain as heavy; 115.6-204.4mm as very heavy; and over 204.5mm as extremely heavy rain.
For the first time during monsoon, IMD on Friday released an impact-based forecast that highlighted high risk due to very to extremely heavy rain. It indicated waterlogging in many parts of low lying areas, localised and short term disruption to municipal services such as water, electricity etc; major disruption of traffic flow; and also suggested the possibility of collapse of old buildings and tree fall incidents. In such circumstances, IMD has suggested action in the form of proper regulation of traffic and restrict movement of citizens in affected areas.