135 days without rain, driest winter-spring spell in 17 years

KOLKATA: The city is experiencing a rare inter-seasonal dry spell, which will touch 136 days on Friday, making this year's winter to spring transition period the driest since 2005-2006's record of 172 rainless days.
Having begun on October 26, 2022, this year's exceptionally dry winter-spring period seems to be mimicking the last such rare occurrence which started on October 25, 2005, and continued until April 16, 2006. Normally, Kolkata winters see intervals of light showers and clouds around mid-January, caused by western disturbances. In January last year, over 12mm of rain was recorded over six days.
Director of Regional Meteorological Centre G K Das said this is a very rare occurrence. However, he said there is a chance that this year's spell may be broken by March 15. A nor'wester predicted for March 10 or 11 in northwestern Bengal will create a 10% chance of a thunderstorm in Kolkata. "It is unlikely that the nor'wester will cause rainfall in Kolkata around March 10 or 11. If at all, there may be about 10 minutes of rain. But it will not be sufficient to bring respite from the rising heat," said Das.
Over the last week, the mercury has been inching towards and beyond a maximum temperature of 34°C. After consecutive days of sunshine, the appearance of clouds around noon on Wednesday and Thursday could possibly indicate an imminent change in weather conditions.
Apart from containing the rising heat, winter rain is necessary to minimize air pollution. January's air quality index (AQI) showing the worst air pollution in that month in five years has been attributed to the lack of rain. The Central Pollution Control Board reported that Kolkata is the second-most polluted city in winter from 2022 to 2023, after Delhi. However, high wind speeds and rising heat since the end of February improved the city's air quality considerably.
The period between March and May sees around a dozen thunderstorms in Kolkata on an average. Many of these turn out to be squalls with a wind speed of 45km/hr or more. But conditions need to get conducive for thunderstorms or nor'westers.
Despite predictions of thunderstorms on March 11 in the western districts of Bengal, including Purulia, Jhargram, West Midnapore, Bankura and West Burdwan, due to the nor'wester, it is likely that the minimal cloud formation in Kolkata over Wednesday and Thursday will be replaced by sunshine.