No rain in sight: IMD’s false alert leaves city flummoxed

An old joke in Mumbai says that when the India Meteorological Department (IMD) issues a monsoon red alert, you can be sure there will be bright sunshine. As if to prove this right, the city soaked in sunshine for a good part of what was to have been a day of heavy showers.

A ‘red alert’ indicates a ‘warning (take action)’, with rainfall forecast to be more than 204.4 mm. Rainfall between 115.6 mm and 204.4 mm is categorised as ‘orange alert’ or ‘be prepared’.

On Thursday, the IMD made up for it by downgrading the red alert to an orange alert for Mumbai, Thane and Palghar at 3 p.m. It maintained a red alert for Raigad for Thursday and Friday. The IMD has issued an orange alert for Mumbai, Thane and Palghar for Friday and said rainfall will reduce after that. Between 8.30 a.m. and 5.30 p.m., Mumbai received only 0.1 mm rain.

As always, social media users responded to the alert with humour, while others expressed dismay. One Twitter user, @rohan_b2, tweeted: “#mumbairains hardly showed up today. When we can do a moon landing which is 99% accurate, why can’t we predict the earth’s atmosphere accurately?”

A civic official, on condition of anonymity, said, “I can understand if an extremely heavy rainfall warning leads to heavy rainfall. But how can it be diametrically opposite? A red alert means the entire State machinery gears up for it, and one work day is lost. Someone needs to find out why this is happening.”

Akshay Deoras, a meteorologist and Ph.D. researcher at the University of Reading, U.K., who has been tracking the Indian monsoon closely, had tweeted on Wednesday night that Mumbai will see only light to moderate showers on Thursday and that sustained disruptions were unlikely in Mumbai.

“At the moment, cyclonic circulation is to the south west of Mumbai. Over the night, it reached this part of the Arabian Sea from Southern Maharashtra. This movement was very well simulated in models, so there was never any possibility of extremely heavy rain in the city today. This is not the first time this (false alarm) has been given.” The forecasters should have learnt from previous false alarms, he said.

“Extremely heavy rainfall alerts are issued on days when the city is already flooded. Warnings are then downgraded on the following day, but by then schools and colleges have already lost a day. Weather models do not often indicate the possibility of more than 200 mm rainfall in Mumbai, so understanding of the weather systems is very important. Ultimately, the job of a forecaster is to analyse weather patterns on the basis of his/her judgment/expertise.”

Mahesh Palawat, chief meteorologist, Skymet Weather, said, “There was some rainfall on Wednesday night but the weather system moved rapidly towards North East Arabian Sea overnight, due to which this happened. Besides, India uses American weather models which are not so successful in tropical countries. These days, due to climate change, there are sudden changes in weather patterns, which models are not able to interpret. They will have to be refined. Besides, Mumbai’s Doppler radar does not show cloud intensity clearly unlike the one in Delhi. I think IMD is being very cautious.”

Kirankumar Johare, professor of physics and electronics in a Nashik college, said, “IMD’s forecasting manual is outdated. If there was a shift in cyclonic circulation, that should have been caught by dynamic models and by forecasters. Where is the accountability of forecasters?”

K.S. Hosalikar, deputy director general, IMD Mumbai, did not respond to calls and texts. Former deputy director general of IMD Mumbai, R.V. Sharma said the IMD models are good, but there are errors in interpretation at times. He said, “Sometimes, subjective errors are carried forward. Occasionally, ‘plus-minus’ is allowed but the margin of error can be reduced.”

For Saturday, IMD has issued a ‘yellow’ alert, while there are no alerts for Sunday and Monday. What will come to pass is anyone’s guess.

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Printable version | Oct 6, 2022 8:41:33 pm |