Western Disturbance

Western Disturbance occurs in India, Pakistan and Nepal to describe an extratropical storm originating in the Mediterranean, that brings sudden winter rain and to the northwestern parts of the Indian subcontinent. This is a non-monsoonal precipitation pattern driven by the Westerlies. The moisture in these storms usually originates over the Mediterranean Sea and the Atlantic Ocean. Extratropical storms are a global, rather than a localized, phenomena with moisture usually carried in the upper atmosphere (unlike tropical storms where it is carried in the lower atmosphere). In the case of the subcontinent, moisture is sometimes shed as rain when the storm system encounters the Himalayas.

Western Disturbances are important to the development of the Rabi crop in the northern subcontinent, which includes the locally important staple wheat.

Disturbances in winter like the one pictured bring moderate to heavy rain in low-lying areas and heavy snow to mountainous areas of the Indian Subcontinent]] Western Disturbance causes winter and pre monsoon season rainfall across northwest India. Winter months Rainfall has great importance in agriculture, particularly for the rabi crops. Wheat among them is one of the most important crops, which helps to meet India’s food security. During the season, normally 4-5 western disturbances in a month can be seen over northwest India. Some of the western disturbances bring well-distributed and good rainfall, while some pass with negligible rain or sometimes no rain. The Western disturbance affects day-to-day weather of northwest India especially during winter season. It is usually associated with cloudy sky, higher night temperatures, unusual rain etc. Over the Indo-Gangetic plains, it brings cold wave conditions and occasionally dense fog and cold day conditions. These conditions remain stable until it is disturbed by another Western Disturbances.