Western disturbance are systems which originate over Mediterranean Sea and move in easterly direction towards Western Himalayas. They usually give winter rains and snowfall over states of Western Himalayas and winter rains over Indo Gangetic plains.
As they move from west to east that is why they are called as western disturbances. The moisture of these systems usually originates over Mediterranean Sea, Caspian Sea and Black Sea.
Their impact starts from the month of October and continues until March over Western Himalayas. Peak intensity is during December and January when heavy snowfall occurs over hilly states of Western Himalayas leading to mudslide, landslides and avalanches. As the sun starts moving towards Northern hemisphere in the latter part of March, western disturbance also starts moving North over upper latitudes.
Now we are approaching mid-March therefore the intensity and frequency of Western disturbances will start reducing. Chances of moderate to heavy snowfall over Western Himalayas are almost nil. However, weak Western disturbances may continue until third week of March which may give isolated a rain and slow over upper reaches of hilly States.
