What are western disturbances?

Here's a prime on this wind that come from the west towards India

Published: Monday 20 May 2019

Every winter the weather systems that drape the Himalayas with snow and feed the mountain streams with water come as visitors from far off lands.

These visiting storms or low pressure areas originate in the Mediterranean region, other parts of Europe and the Atlantic Ocean.

The winds are disturbed within a low pressure area and come from a westward direction with respect to India, hence the name western disturbance.

Then they travel towards Afghanistan, Pakistan and India along high altitude and brisk westerly winds which are perennially flowing from the west to the east across the surface of the Earth.

Along their way they pick up moisture from the Mediterranean Sea, Black Sea, Caspian Sea and the Arabian Sea.

When the WDs come up against the Himalayas they shed their moisture in the form of rain and snow.

Sometimes they move along the northern mountainous states of Jammu and Kashmir, Himachal Pradesh,  Uttarakhand towards the north eastern states while other times they move along more southward regions through Punjab, Haryana, Rajasthan, Uttar Pradesh and Bihar.

The WDs are not always the harbingers of good weather. Sometimes WDs can cause extreme weather events like floods, flash floods, landslides, dust storms, hail storms and cold waves killing people, destroying infrastructure and impacting livelihoods.

The 2013 Uttarakhand disaster which caused the deaths of over 5000 people was a result of an anomalous WD. The unusual dust storms in the summer of 2018, floods in Kashmir in 2014 and the cloud burst Leh in 2010 can also be attributed to the same reason.

The cold waves that hit northern and north western India from December 2018 to February 2019 were triggered by an absence of intense WDs in the region. The weak WDs that did arrive did not move enough in the southward direction. The cold waves continued as the intensity of the WDs suddenly increased in January.

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