Western Disturbances to Bring Rain to Uttar Pradesh

• 19 Feb 2024

Why in News?

According to the India Meteorological Department, Delhi, Punjab, Haryana, and parts of Uttar Pradesh are expected to receive light to moderate rain, thunderstorms, and hailstorms in the coming days with an intense spell of snowfall in the western Himalayan region.

Key Points

• A fresh active Western Disturbance is projected to affect northwest India. The weather system is expected to have widespread impacts, with diverse weather conditions observed across multiple regions.
• The Western Disturbance is expected to cause significant changes in usual weather patterns, and communities are advised to stay prepared for these changes.
  • Authorities have been urged to gear up for any necessary measures to ensure public safety.

Western Disturbances

• These are a series of cyclonic storms that originate in the Mediterranean region, travel over 9,000 km to bring winter rains to northwest India.
  • A Western Disturbance collects moisture from the Mediterranean Sea, Black Sea, and Caspian Sea and traverses over Iran and Afghanistan before hitting the western Himalayas.
• While the storm systems occur throughout the year, they travel to India mostly between December and April because the trajectory of the subtropical westerly jet stream, which transports them, shifts during the winter months to the rim of the Himalayas.
  • For the rest of the year, the jet stream travels from above the Himalayas to the Tibetan Plateau and China. Its trajectory changes as per the position of the Sun.
• Significance for India:
  • Western Disturbances are the primary source of snowfall that replenishes the Himalayan glaciers during winter.
    • These glaciers feed major Himalayan rivers like the Ganga, Indus and Yamuna as well as myriad mountain springs and rivulets.
  • These low-pressure storm systems help farmers in India grow their rabi crop.
• Issues:
  • The Western Disturbances 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, destroying infrastructure and impacting life and livelihoods.

India Meteorological Department

• IMD was established in 1875. It is the National Meteorological Service of the country and the principal government agency in all matters relating to meteorology and allied subjects.
  • It works as an agency of the Ministry of Earth Sciences of the Government of India.
• It is headquartered in New Delhi.
• IMD is also one of the six Regional Specialized Meteorological Centres of the World Meteorological Organization.