What do you mean by Western disturbances?

Hint: Cyclonic disturbance in the weather phenomena in the month of winter, that is brought in by the westerly flow from the Mediterranean region.

Complete answer:
The word “Western” means the direction from which it originated towards the Indian region while “disturbance” refers here as air in the low-pressure system tends to be unstable or disturbed. In this, it basically comes at the time of Winter season brings moderate or heavy rainfall in low lying regions and snowfall in mountains areas in the Indian subcontinent. It is important for the development of the agricultural purpose of the Rabi crop which includes the local wheat.

The main impact of Western Disturbances is: -
∙ It usually happens with a cloudy sky, a higher temperature at night, and unusual rain.
∙ In the area of Ganga plains, it would occasionally bring cold waves and dense fog.
∙ This type of climate remains stable until there is any disturbance by another western weather.
∙ When western disturbance comes across Northern India we could see an earlier monsoon in some parts of that region.
∙ Western disturbance plays a huge role in the cultivation of Rabi crops and has a great impact.
∙ If there is excessive precipitation it can lead to crop damage, floods, landslides and avalanches.

Mediterranean disturbance in that region leads to Western Disturbance in the Northern Areas which would bring monsoon in the winter season but it is not important it a western disturbance can take place in any season.

Note:
 It is being calculated that about 5-10 % of monsoon is received annually in the year by Western Disturbance.