Turbulent April: Kolkata Airport issued 41 wind warnings – Times of India

KOLKATA: For weathermen at Kolkata airport, last month has been unlike any April in recent memory with the average wind blowing at twice the usual speed.
The winds forced the meteorological office at the airport to issue warning for light aircraft 41 times during the month. In the past, the maximum number of warnings issued during the month was around 10 times.
Warning for light aircraft is provided to regional flights, corporate, charter planes, Coast Guard aircraft and helicopters belonging to Indian Air Force as well as private companies that can be threatened by winds beyond 17 knots or 31 kmph. Sheer winds can make operation of light aircraft a major challenge. However, operations of larger aircraft like the Airbus A-320 or Boeing B-737 that are commonly used for intercity flights aren’t affected in this condition.
“We have all noticed the anomaly in temperature in April with average maximum temperature higher than before. This was owing to absence of nor’wester activity in and around Kolkata during almost the entire month. But we have recorded another peculiar weather phenomenon in April. And that is the wind pattern. Average intensity of wind has been almost twice as high this April,” a weather official said.
While the average wind speed during pre-monsoon is usually 8-10 knots or 15-19 kmph, it has increased to 14-16 knots or 26-30 kmph. “In the past, the maximum time when the wind exceeded 17 knots in April was 10 times. This April, the wind speed touched 17 knots 41 times,” he said. The winds have mostly been south-westerly or south-easterly.
Climatologist and geographer Nairwita Bandyopadhyay said the possible reason for the high winds experienced last month was the extremely high land surface temperature that led to quick low-pressure formation and ingress of cooler air to replace the vacuum, and hence, the high velocity winds.
Calcutta University geography professor Lakshmi Narayan Satpati, too, said difference in pressure gradiants are becoming more intense at regional or local level due to general change in weather pattern. “Another reason for this phenomenon could be change in building density in Dum Dum. The mushrooming of buildings could cause a tunnelling or funnelling effect. But this requires more study at the micro level,” he said.