Morning fog that refused to lift till very late and a Celsius bar that kept soaring with each passing hour marked the day after X-mas in the city.
A trough of low pressure over Bengal, Bihar and adjoining eastern Uttar Pradesh ensured a “foggy morning under a thin cloud cover” and “an uncharacteristically warm winter afternoon”.
The minimum temperature rose to 16.5 degrees Celsius, three degrees above normal, early on Thursday.
Dense morning fog over both Delhi and Calcutta threw flight schedules between the two metros out of gear. The Jet Airways flight from the Capital arrived at 2.40 pm, while the Indian Airlines (IA) flight touched down at 3.30 pm, both more than six hours behind schedule.
Civil aviation minister Shahnawaz Hussain was held up in Calcutta for over eight hours before taking that flight.
The IA morning flight to Delhi, that took off from Calcutta at 9.30 am, was diverted to Ahmedabad as the aircraft failed to land in the Capital because of poor visibility. The Jet Airways flight left in the afternoon, about eight hours behind schedule, while Air Sahara cancelled its morning flight to Delhi.
As the temperature rose steadily in the city, Alipore Meteorological office director K.K. Chakraborty said the trough of low pressure was “partly blocking the North Wind” and so the minimum temperature was likely to rise further over the next couple of days. “Under the influence of the trough, we also recorded a trace of rainfall on Thursday,” added Chakraborty.
The weather office also detected a depression over the Bay of Bengal on Thursday at some distance from the Indian coast, headed east. “We are closely monitoring the depression,” said Chakraborty.
The shift in the weather pattern in Calcutta and its adjoining areas began on Wednesday, when an upper-air circulation suddenly developed over Bihar and adjoining sub-Himalayan West Bengal. The trough of low pressure developed later.
Last week, the mercury had soared when the wind course changed direction and started blowing from the south-west. Weather watchers said the moisture that had entered the land from the Bay of Bengal last week when the wind was blowing from the southwest was yet to dry up. This, combined with the warm mornings, was causing dense fog. So far, the coldest days recorded this season were December 10 and December 11, when the mercury dipped to 13.9 degrees Celsius.