Mumbai saw sunny conditions despite ‘heavy rain’ forecast; 4th false alarm this season
Contrary to prediction of 204.4mm rain, city got 0.3mm, suburbs 1mm till 8.30pm; IMD, Skymet, independent experts all got it wrongUpdated: Sep 20, 2019 08:32 IST
Contrary to the weather department’s forecast of extremely heavy rain (red alert) for Thursday, sunny conditions were witnessed during the day, followed by light showers in the evening. Not just the India Meteorological Department (IMD), but private weather forecasting agency Skymet as well as independent meteorologists, too, got their predictions wrong.
This is the fourth false alarm on extreme rain in Mumbai by the weather bureau. The earlier errors were twice in July and once on September 5.
An extremely heavy rain forecast indicates the rainfall will be over 204.4mm over 24 hours. Between 8.30am and 8.30pm on Thursday, Mumbai suburbs recorded 0.3mm rain, while 1mm was recorded in south Mumbai.
A red alert directs the state and municipal authorities to take precautionary action in case of widespread extremely heavy rain; an orange alert asks for preparedness, while a yellow alert directs municipal bodies concerned to stay updated on rain forecasts. Following the alert, the state education minister declared a holiday for all schools and colleges along the Konkan coast.
“Extreme rainfall warnings were issued based on what the weather models were depicting. If the likeliness of intense rain activity is foreseen, it is our duty to inform all stakeholders to ensure precautions are taken before the event occurs,” said Mrutyunjay Mohapatra, director general, IMD. “On Thursday, heavy to very heavy rain was seen in north of Mumbai, towards Palghar and surrounding areas, but this kind of variation can be expected with forecasts. It is not so accurate worldwide and differences in extreme weather events can take place in a distance of 30-40km. The system, which was likely to give extreme rainfall is present, but shifted towards Arabian Sea. While heavy to very heavy rain will continue over parts of north Konkan, Mumbai can expect moderate showers with isolated heavy spells.”
Skymet conceded they issued an incorrect forecast. “We thought the upper air cyclonic circulation (UAC) towards north Maharashtra would remain stagnant and lead to intense rainfall, but it moved to the northwest, towards the Arabian Sea, leading to a decrease in rain activity,” said Mahesh Palawat, vice-president meteorology and climate change Skymet. “All agencies got it wrong as all models indicated the possibility of intense rain, but there were dynamic weather changes.”
IMD downgraded its forecast at 1pm on Thursday to an ‘orange alert’ and issued a forecast for intermittent rain in the city and suburbs with heavy to very heavy falls at isolated places for Friday. Over the past 24 hours, (8.30am on Wednesday to 8.30am on Thursday), the Santacruz weather station recorded 69.4mm rain (heavy), while 16.6mm (moderate) was recorded at Colaba. On Wednesday night, loud claps of thunder and flashes of lightning with heavy rain were recorded across parts of the Mumbai suburbs, Navi Mumbai, Thane and further north of the Mumbai Metropolitan Region from 10pm onwards. On Thursday, Palghar recorded very heavy showers.
While 15.6mm to 64.4mm of rain is considered ‘moderate’, 64.5mm to 115.5mm ‘heavy’, and 115.6mm to 204.4mm ‘very heavy’.
Independent meteorologists said such localised changes in weather systems are tough to detect. “After the UAC moved into the sea, almost 100km off the Mumbai coast, there was not enough moisture from the Arabian Sea, as the winds were not favourable. As a result, the rainfall got dumped into the Arabian Sea itself,” said Sridhar Balasubramanian, associate professor, department of mechanical engineering and associate faculty, IDP Climate Studies, IIT- B.
First Published: Sep 20, 2019 00:18 IST