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UK context#uk#synoptic#plume

Spanish Plume

At a glance

A tongue of hot, unstable air pushed north from Iberia ahead of an Atlantic trough. Sets up most of the UK's biggest thunderstorm days.

Deep dive

A Spanish Plume event features:

  • An elevated mixed layer originating over the Meseta (Iberian Plateau) — steep mid-level lapse rates, often 8+ K/km.
  • Warm, moist low-level air advected from the Bay of Biscay or southern UK coast.
  • A capping inversion that suppresses early convection.
  • An upper trough or shortwave approaching from the Atlantic, providing lift and 0–6 km shear.

When the cap breaks — usually late afternoon or evening — storms go explosive. Classic plume days include July 1968 (Dutch 'Woensdrecht' supercell outbreak), July 2005 (Birmingham F2), 10 July 2023, 12 June 2024.

On plume days, watch the mid-level dry slot on satellite and the theta-e gradient on mesoanalysis to nail the target.