The Telegraph
Saturday , October 15 , 2011
Since 1st March, 1999
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Time for clear blue sky, rains exit

Siliguri, Oct. 14: Monsoon has bade goodbye to sub-Himalayan Bengal and Sikkim, making way for clear skies that is likely to last for the next one-and-a-half months.

“Monsoon made an exit from Bihar and Jharkhand the day before yesterday. It had crossed over to the sub-Himalayan West Bengal and Sikkim, from where it left yesterday. It is currently crossing Orissa and the Bay of Bengal. Now that the rainy season is over, we are in for clear blue skies and sunny days for the remaining part of October and November,” Indranil Sengupta, the assistant meteorological officer of the Regional Met Office in Jalpaiguri, said.

Although the maximum temperature recorded in Siliguri yesterday and today was 33 degrees Celsius, 3 degrees above the normal of 30 degrees Celsius, weather experts said the mercury will gradually come down by the end of the month.

“The temperature saw a rise in three degrees above the normal yesterday during the day time because of very less cloud cover that resulted in high insulation. But it will gradually decrease by the end of the month because the sunrays have shifted position to the south of the Equator on September 30 and we will be receiving inclined rays henceforth,” Sengupta said.

Officials said sub-Himalayan West Bengal (SHWB) and Sikkim received an average of 1864.8mm of rainfall from June 1 to September 28 this year, six per cent lower than the normal average rainfall of 1986.4mm.

“Any deviation of minus or plus 19 per cent of rainfall from the normal figure is considered normal. So, we can say that the region has received fair amount of rainfall this year,” said Sengupta.

He added that there will be a dry spell in the “post-monsoon season” with November receiving little or no rainfall.

“The post-monsoon season is usually pleasant with clear skies and sunny weather. There may be slight showers in October because of local cloud formations but November will be relatively dry with little or no rainfall. This is because there is no moisture in the air around that time which can aid in cloud formation that can cause rains,” Sengupta said.

He said the dry weather is expected to last till the beginning of December when winter sets in and the region is under the influence of the western disturbances — strong winds from the Mediterranean that trigger sudden showers and occasional snowfall in northern and northeastern India.

“Western disturbances are climatic phenomenon that usually affect Jammu and Kashmir during different times of the year before they cross over to Tibet. They are generally not able to influence the plains of central India and SBHW during the monsoon as the wind current from the south-west prevents them from penetrating the areas,” Sengupta said.

He added that during the winters, however, the wind blows from the northwest and west and helps the western disturbances move southward that cause sudden showers in the central and eastern parts of the country.

“Sometimes a secondary system of low pressure forms (in SHWB and Sikkim) because of the influence of western disturbances causing good amount of rain and snowfall in the hilly places in the region. We can expect some showers in the area from December onwards if the western disturbances are strong,” Sengupta said.

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