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Fog expected to envelop plain areas again

November 19, 2017

ISLAMABAD: With a cold and dry weather likely to prevail over most parts of the country, fog and mist is expected to reemerge in coming days mainly in the plains of Punjab and KP. But this spell of hazy days will be short due to another upcoming system of rainfall.

The recent rainfall not only helped fizzle out the smoggy conditions from all over the country but also brought in the needed cold of the winter months.

The minimum temperature fell to 7°C in Islamabad early on Saturday while it was 1°C in Murree.

Isolated rains and thunderstorm with snowfall are likely over the hills in Malakand, Hazara, Rawalpindi divisions as well as Kashmir and Gilgit-Baltistan.

However, the coming 10-12 days are likely to be mainly cold and dry across the country and with the presence of moisture on the ground, fog regeneration is expected in the plain areas. The Met Office said fog and smog would not be as dense in coming days as it was in the recent past because the floating dust in the air had largely settled down.

“As the fog will be thin, the sunshine is likely to create a low pressure over the region,” a Met Office official said, adding: “This low pressure will invite high pressure cold winds along with clouds from the west bringing a new wave of rainfall.”

The official predicted countrywide rainfall along with snowfall over hills in the last days of the month.

The winter rains contradict the pattern of the monsoon rains that arrive in the summer months from the Bay of Bengal.

The monsoon rains are based on tropical pattern as the clouds generate from the seas into tropic areas and are accompanied with strong fast moving winds.

While the winter rains arrive from Europe through Central Asia and are generated at the North Pole, these patterns are called ‘frontal climate’.

The clouds are carried by cold but slow moving winds which is why the dripping rains in the winter drop the mercury level.

“The sunshine in South Asia develops the low pressure which invites high pressure winds from Europe,” the official added. “But there is another development in the region that resists the regular flow of winds from Europe to South Asia - the high pressure pattern at Tibet Plateau.”

The official added that the two main high pressure zones which restricted rainfall in the region were Tibetan High, which also caused dryness and created the Gobi desert, and Arabian High, which restricted rainfall mainly in the summer months not only in the Gulf region but also in southern Iran and Balochistan.

Published in Dawn, November 19th, 2017