Intense DANA Storm Triggers Severe Flooding in Spain

Why in the news?

Heavy rainfall from the DANA weather pattern has led to flash floods across southern and eastern Spain, submerging towns, disrupting transport, and affecting millions, with rainfall expected through 31st October.

Intense DANA Storm Triggers Severe Flooding in Spain

About the Flash Floods in Spain Caused by Extreme Rainfall:

  • Torrential rains struck southern and eastern Spain starting 28th October night, flooding towns and villages, blocking roads, and impacting millions of people.
  • Some regions saw more than a month’s worth of rainfall in one day; Andalusia recorded four times its typical October rain within 24 hours, with certain areas receiving 150-200 litres of rain in just two hours.
  • Rainfall is expected to continue until at least October 31st, amplifying the risk of further floods.

Understanding DANA (Isolated Depression at High Altitudes):

  • Known as “gota fría” or “cold drop,” DANA occurs when cold air descends over warm Mediterranean waters, creating atmospheric instability.
  • Warm, moist air at the sea’s surface rises rapidly, forming dense clouds that lead to intense rainfall in hours.
  • This pattern is linked to the polar jet stream, a fast-moving high-altitude wind current separating polar and tropical air; when cold air detaches from the jet stream and collides with warmer Mediterranean air, it results in a “cold drop.”

Understanding Tropical Cyclones :

  • Definition: Cyclones in tropical regions (Tropics of Capricorn and Cancer), with winds exceeding 63 km/h.
  • Formation: Develop over warm ocean waters near the equator, powered by sea heat, and influenced by trade and westerly winds.
  • Characteristics: Calm, low-pressure centre; closed isobars; speeds often over 120 km/h; seasonal; move east to west.

Classification and Categories:

  • IMD Classification: From Depression (31-49 km/h) to Super Cyclonic Storm (222+ km/h).
  • Saffir-Simpson Scale: Categories 1 (119-153 km/h) to 5 (252+ km/h); Category 3+ indicates severe damage potential.
  • Regional Names: Known as Hurricanes, Typhoons, Cyclones, or Willy-Willies, depending on location.

Naming and Landfall:

  • Naming Process: Managed by six RSMCs and five TCWCs; IMD names for the Indian Ocean under WMO/ESCAP.
  • Landfall: Cyclone’s eye crosses land, bringing strong winds, rain, and storm surge; differs from a “direct hit.”

Sources Referred:

PIB, The Hindu, Indian Express, Hindustan Times