Intensity of Western disturbance has impacted the wind pattern and its speed in winter this year. This has led to unpredictable weather and harsh winter. Due to frequent western disturbances, north and north-western India including Punjab, Haryana, Jammu & Kashmir, Himachal Pradesh and Uttrakhand witnessed unprecedented snowfall, rains in December and January.
Cold wave conditions persisted in most parts of north India on Saturday with many places in Himachal Pradesh and Uttar Pradesh receiving rains, while the Kashmir Valley and Ladakh reeled under sub-zero temperatures.
According to India Meteorological Department ( IMD), this year, however, January has witnessed four western disturbances in just first 18 days of the month as compared to six in December last year. "A fresh western disturbance is expected on January 20, which affects western Himalaya regions and plains of North West India. This will also brings snowfall and rain with thunderstorm in western Himalaya regions," it said.
"The frequent western disturbance in winter has impacted wind pattern and its speed. Easterly wind, which is common in January are less influential or weak as compared to the northwesterly wind. Due to weak easterly wind, severe cold wave conditions are prevailed over north, northwest and central India. The intensity of western disturbances has brought snowfall and rainfall in hills and plains in India," officials said.
According to IMD, western disturbances are very frequent visitors to north India during the winter months from December to March, with a normal frequency of around 3-4 per month. Research shows that the frequency of western disturbances has come down over the past few decades as around six to seven western disturbances per month used to affect the north during winters before the 1960s.
The previous disturbance-the fourth one to affect India in January 2020-reached its peak January 13, causing heavy rainfall across Jammu & Kashmir, Himachal Pradesh, and a few other neighbouring states in the process. It also caused heavy snowfall over the north Indian states, which subsequently triggered avalanches that killed at least ten people in Jammu and Kashmir.
Due to third western disturbance, between January 13 and 14, multiple areas in North Kashmir, such as the higher reaches of Gurez, Bandipur, Kupwara, Nowgam, and Baramulla received unprecedented heavy snowfall. Temperature in North Glacier in Siachen fell down to minus 57 degrees Celsius, while fresh snowfall recorded in Gurez Sector amounted to 51 cm, with 117 cm in Machhil Sector, 56 cm in Keran and Tangdhar Sector, 122 cm in Naogaon Sector, and 61 cm in Uri and Gulmarg sectors.
As far as Delhi is concerned, it's usually remains weather free during this time of month, with only few spells of winter rains in between. January 2020 is witnessing one of the rainiest spell this time.
"The disturbance travels from the "western" to the eastern direction. Disturbance means an area of "disturbed" or reduced air pressure. Western disturbances typically originate as low-pressure systems over the Mediterranean Sea. It brings sudden winter rain to the north-western parts of the Indian sub-continent is called Western Disturbance. It is a non-monsoonal precipitation pattern driven by the westerlies. High-altitude westerly winds push these systems towards India. On the way, the disturbances gather moisture from various sources including Mediterranean, Caspian, and sometimes even the Arabian Sea. The influence of western disturbances is maximum over north and northwest India during the winter season from December to February," said Dr Kuldeep Srivastava, senior scientist of IMD.
In Himachal Pradesh, Shimla received light snowfall while some parts of the state received light rain. Several tourist hotspots, including Manali, Kufri and Dalhousie, shivered at sub-zero temperatures. The cold wave conditions persisted in the Kashmir Valley and Ladakh, with the two neighbours witnessing sub-zero minimum temperatures that led to frost formation on roads and caused inconvenience to motorists.
