Western disturbance linked to Nepal flood, Pg10

Key Highlights:

• A devastating flash flood occurred in Nepal on Wednesday, with investigations ongoing into its causes.
• A Western Disturbance that brought rain to northern India is being considered a potential contributor to the weather conditions preceding the flood.
• Nepal authorities are investigating if an earthquake triggered a landslide or an ice avalanche, leading to a sudden surge of water.
• The World Meteorological Centre, Beijing, reported persistent heavy to intense rainfall in the southern Himalayan foothills and southern Tibet in the days leading up to the flood.
• Officials from the India Meteorological Department (IMD) noted the Western Disturbance persisted as a cyclonic circulation over north Haryana.

Detailed Insights:

• The Western Disturbance moved eastwards, increasing rainfall activity across the northeast and Himalayan region.
• The interaction between various weather systems and the region's hilly terrain likely played a significant role in the flood event.
• Preliminary assessments suggest an ice avalanche may have blocked a river, causing water to accumulate before a sudden release downstream.
• Accumulated rainfall between August 16 and 25 reached heavy to intense levels in some locations in Nepal and southern Tibet.
• A monsoon depression over northern India is forecast to bring continued moderate to heavy rain to Nepal over the subsequent three days.
• India and Nepal maintain established mechanisms for sharing crucial hydrological and weather forecast information.

Key Concepts Involved:

• Western Disturbance: An extratropical storm originating in the Mediterranean region that brings sudden winter rain to the northern parts of the Indian subcontinent.
• Flash Flood: A rapid flooding of low-lying areas, typically caused by intense rainfall associated with severe thunderstorms or tropical storms.
• Monsoon Depression: A low-pressure system that forms over the Bay of Bengal or Arabian Sea during the monsoon season, bringing widespread heavy rainfall.