The India Meteorological Department (IMD) recently reported an impending western disturbance that will likely impact the Himalayan region. The anticipated result is a fairly widespread occurrence of light to moderate snowfall, as well as rains in the plains of Jammu.
What are Western Disturbances?
Western Disturbances, or WDs, are extra-tropical storms that originate from the Mediterranean region. Characterized by low-pressure areas, these disturbances bring sudden showers, snow, and fog in northwest India. The terminology, “western disturbance,” is derived from the disturbance’s west-to-east travel pattern. These disturbances traverse easternwards on high-altitude westerly jet streams, enormous fast wind currents moving from the western to the eastern direction across the globe.
The Concept of Disturbance
In weather terminology, ‘disturbance’ refers to an area of disturbed or reduced air pressure. This occurs due to nature’s innate tendency to maintain equilibrium; the air in a particular region always attempts to normalize its pressure levels.
Understanding “Extra-Tropical Storms”
In the term ‘extra-tropical storm’, ‘storm’ denotes low pressure. Being outside the tropics, the storm is termed ‘extra-tropical’. The WD is named as such because it forms and originates outside the tropical region.
Effects of Western Disturbances
A significant feature of WDs is their association with diverse weather phenomena like rainfall, snowfall, and fog, particularly in northern India. These disturbances bring rain and snow in Pakistan and northern India. The moisture that WDs carry primarily originates from the Mediterranean Sea and/or the Atlantic Ocean.
Weather and Agriculture: The Impact of Western Disturbances
WDs play a crucial role in bringing winter and pre-monsoon rain, which is vital for the growth of the Rabi crop in the Northern subcontinent.
The Negative Side of Western Disturbances
However, WDs are not always bearers of good weather. At times, they can trigger severe weather events like floods, flash floods, landslides, dust storms, hail storms, and cold waves. Such events result in casualties, infrastructure destruction, and significant impacts on people’s livelihoods.
The 2013 Uttarakhand Floods: A Case of Controversial Western Disturbances?
Expert opinions regarding the role of Western Disturbances in triggering extreme weather events vary greatly. The controversy is exemplified by the case of the 2013 Uttarakhand floods. These devastating floods claimed over 5000 lives following three days of relentless rainfall. The role of WDs in this disaster, however, remains disputed among weather experts.