WESTERN DISTURBANCE (Syllabus: GS Paper 1 – Geography)

Context: The western disturbance activity witnessed a southward dip in December, causing good rainfall over central India, but either deficient or scanty rainfall over most of northern India in December.

Western Disturbance

• About: It is an important weather system causing precipitation in the Western Himalayan region during the Indian Winter months (non-monsoonal).
• Formation: Originating in the middle and upper latitudes, it is an extratropical storm system.
• Non-Monsoonal Precipitation: The precipitation pattern affecting northern India is non-monsoonal and stems from the Mediterranean region, resulting in both rainfall and snowfall.
• Impact on Surrounding Nations: Beginning as non-monsoonal precipitation in the Mediterranean, the weather system moves eastward, influencing various regions in Pakistan, India, and neighboring countries.
• Causes: When the Himalayas and western parts of central Asia intersect with the jet stream in the upper atmosphere, creating a low-pressure area and subsequent disturbance.
• Outcome: In the northern regions of India, this weather phenomenon results in rainfall in plains and snowfall in mountainous areas.
• Declining Intensity Trend: Over recent years, there has been a declining trend in the intensity of Western disturbances, with Uttarakhand and Himachal Pradesh experiencing 47% and 40% less rain than usual from October to December in 2023.
• Impact of Climate Change: The consequences of climate change include a diminishing intensity and frequency of western disturbances, leading to reduced post-monsoon season rainfall and snowfall. This, in turn, affects agriculture and water availability in mountainous regions.
• Decline in Apple Production: Prolonged drought and insufficient snowfall contribute to a decline in apple production, highlighting the environmental changes impacting the region.