A strong spell of rain, winds and a brief hailstorm struck Dum Dum and its neighbouring areas on Thursday afternoon, disrupting flight operations and forcing the aircraft carrying chief minister Mamata Banerjee to hover for more than an hour over the city’s sky.
Mamata was returning from Andal.
Calcutta airport officials said the chief minister’s plane, a Falcon 2000LXS 12-seater aircraft, took off from Andal at 3.39pm and was scheduled to land in Calcutta at 4.07pm.
“However, due to thunderstorm, rain, and hailstorm conditions, flight operations were stalled at the Calcutta airport during that time,” said an airport official.
Flight operations at the Calcutta airport were suspended
from 4.22pm to 5.02pm, he added.
According to sources, the aircraft entered Calcutta’s sky at 4.02pm. The pilot was initially given two alternatives: either return to Andal or divert to Ranchi.
“However, the pilot said he would hold in the sky. The aircraft was asked to hold around the Behala area,” said an official. Other flights were holding too, he added.
“The air traffic control was asked to give the CM’s flight priority for landing,” he said.
Finally, at 5.04pm, the CM’s aircraft was cleared to land. It touched the runway at 5.19pm, said an official. He noted it was the first flight to land after operations resumed.
The first aircraft to take off from Calcutta was IndiGo’s Mumbai flight at 5.02pm.
An IndiGo flight from Bhubaneswar to Calcutta and another from Calcutta to Guwahati were among those delayed by the rough weather. A SpiceJet flight from Chennai to Calcutta was diverted to Varanasi.
“In total, 10 flights were delayed. Six of these were departures, and four were headed to Calcutta,” an airport official said.
“It was a localised thunderstorm. Most parts of Calcutta were dry, but Dum Dum and neighbouring areas received a sharp spell of rain, hail, and strong gusts of wind,” said a Met official in Alipore.
Between 4pm and 5.30pm, Dum Dum recorded 27mm
of rain. A peak wind speed
of 57kmph was measured around 4.50pm. The hailstorm lasted for around 10 minutes, he said.
A weather scientist said hailstones are formed when thunderstorm updrafts (strong currents of air that are moving up) carry raindrops into extremely cold areas of the atmosphere, where the raindrops freeze.
The hailstones then grow larger by coming into contact with liquid water drops that freeze on the hailstones’ surface. Hails start falling when the thunderstorm’s updraft can no longer support the weight of the hailstones.
Earlier on Thursday, the Met office issued an “enhanced thunderstorm” alert for Bengal.
“An upper air cyclonic circulation lies over south Gangetic Bengal adjoining north Odisha and extends up to 1.5km above mean sea level.... In the presence of a favourable wind pattern and strong moisture incursion from the Bay of Bengal, enhanced thunderstorm activity is very likely,” said a bulletin.
The intensity of the showers is likely to be on the higher side in north Bengal, where heavy rain is likely on Friday and Saturday. Calcutta is likely to get at least one spell of thunderstorm between Friday and Saturday, said the Met official in Alipore.
Around 2.10pm on Thursday, the Met office issued a nowcast (alert for an imminent weather event), which said “moderate thunderstorms” were likely in North 24-Parganas during the next couple of hours.
Another came around 4.10pm, accompanied by similar alerts for Calcutta and South 24-Parganas. But eventually, most of Calcutta remained dry. The conditions were breezy for a while.