The Telegraph
Monday , December 14 , 2015
 
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Warmest Dec 13 in 12 years

Calcutta had its warmest December 13 in 12 years on a day when weather scientists, ironically, spied the first stirrings of winter in the musty air.

"Where? How?" Nabanita Ghosh of Deshapriya Park might wonder, echoing thousands of other Calcuttans forced to spend December nights with their ceiling fans on.

G.C. Debnath, the deputy director-general of the India Meteorological Department in Calcutta, said two of the four weather systems responsible for the city's December of discontent had dissipated and that the other two would fade over the next 48 hours.

"Till Saturday, all four systems had been injecting moisture into the air. Two of them, a trough of low pressure and a high-pressure belt over the Odisha coast, are still active in places and causing moisture to enter inland from the Bay of Bengal. But once the trough fades away, the high-pressure belt that is linked to it will go as well and make conditions favourable for the North Wind to bring back the chill," he told Metro.

Light rain had been forecast for Sunday but that didn't happen. The weather office reassured the city that neither the absence of rain nor the day's minimum temperature reading of eight degrees above normal had altered the equation.

"Since the low-pressure trough remains active, we still have to say there is a 60 per cent chance of light rainfall on Monday. But the chill that has been forecast for Wednesday and beyond isn't dependent on rain," Debnath said.

The mercury shot up to 22.7 degrees Celsius on Sunday mainly because of excessive moisture in the city air blocking the flow of the North Wind, which is the life force of winter in these parts.

The normal minimum temperature in the second week of December is 15 degrees Celsius. Based on meteorological data since 2004, the lowest December 13 temperature in more than a decade is 14.4 degrees Celsius, recorded in 2005.

The minimum temperature on December 13 last year was 16.1 degrees Celsius.

The North Wind ferries cold from the Himalayas across the plains of central India to Calcutta and its surroundings. But cyclonic circulations and a trough of low pressure have combined to cut off this wind source this year.

Minimum relative humidity, a measure of the moisture trapped in the atmosphere, rose from 58 per cent on Saturday to 64 per cent on Sunday as the water vapour level in the air kept increasing. The absence of rain added to the stuffy feeling.

At noon, the maximum temperature was just 26 degrees Celsius, but relative humidity was very high at 79 per cent. The RealFeel temperature, weather portal AccuWeather.com's index for the impact of heat and humidity on your skin, was 33 degrees Celsius.

There have been such variations in day and night temperature for several days. While clouding has kept the day temperature in check, the minimum reading has increased and so has the impatience of Calcuttans waiting for winter.

"It feels strange to be using the ceiling fan in December," said Nabanita.

"I can't believe it is the middle of December and I was in half sleeves while travelling in the afternoon," said 60-year-old Ranjit Bhowmick, who drove from his Prince Anwar Shah Road home to Krishnagar with the car AC continuously on.

The reassuring news is that all things remaining the same, the temperature would drop to 16 or 17 degrees Celsius by Wednesday.

The North Wind is currently very cold because of snowfall in Kashmir, which is the primary reason why the mercury is tipped to plummet the moment the low-pressure trough goes away.

How has the warmest December in many years affected you? Tell [email protected]


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