Abstract
Abstract. From 6 to 8 November 1982 one of the most catastrophic flash-flood events was recorded in the Eastern Pyrenees affecting Andorra and also France and Spain with rainfall accumulations exceeding 400 mm in 24 h, 44 fatalities and widespread damage. This paper aims to exhaustively document this heavy precipitation event and examines mesoscale simulations performed by the French Meso-NH non-hydrostatic atmospheric model. Large-scale simulations show the slow-evolving synoptic environment favourable for the development of a deep Atlantic cyclone which induced a strong southerly flow over the Eastern Pyrenees. From the evolution of the synoptic pattern four distinct phases have been identified during the event. The mesoscale analysis presents the second and the third phase as the most intense in terms of rainfall accumulations and highlights the interaction of the moist and conditionally unstable flows with the mountains. The presence of a SW low level jet (30 m s−1) around 1500 m also had a crucial role on focusing the precipitation over the exposed south slopes of the Eastern Pyrenees. Backward trajectories based on Eulerian on-line passive tracers indicate that the orographic uplift was the main forcing mechanism which triggered and maintained the precipitating systems more than 30 h over the Pyrenees. The moisture of the feeding flow mainly came from the Atlantic Ocean (7–9 g kg−1) and the role of the Mediterranean as a local moisture source was very limited (2–3 g kg−1) due to the high initial water vapour content of the parcels and the rapid passage over the basin along the Spanish Mediterranean coast (less than 12 h).
Highlights
As other mountainous Mediterranean regions, Andorra (Eastern Pyrenees) is regularly affected by intense precipitation events and subsequent flash floods
The historical catastrophic heavy precipitation event (HPE) recorded in Andorra from 6 to 8 November 1982 has been analyzed in detail and, for the first time, using mesoscale model simulations at 2.5 km horizontal resolution with the French Meso-NH model
The analysis has a twofold objective: to describe the synoptic environment in which the HPE developed and to identify the mesoscale mechanisms that lead to steady rainfall over the Eastern Pyrenees as well as the features of the moisture inflow feeding the precipitation systems which were fairly well reproduced by the model
Summary
As other mountainous Mediterranean regions, Andorra (Eastern Pyrenees) is regularly affected by intense precipitation events and subsequent flash floods. The most catastrophic case for at least the last 30 yr in terms of rainfall accumulations and human losses in Andorra (Fig. 1) took place from 6 to 8 November 1982 This episode, associated with a very strong windstorm, affected the neighbouring areas of SE France and NE Spain (Catalonia) producing historical precipitation amounts in the Pyrenees such as the 610 mm recorded in 48 h in Py (France). In Andorra, the huge flood impacts on the landscape, roads and infrastructures caused important economic losses estimated at EUR 24 million (Fig. 2) This flood event is compiled among one of the major flood disasters in Europe and is included in the 1950–2005 inventory reported by Barredo (2007) and subsequent studies like Gaume et al (2009), where preliminary analysis results conclude that the most extreme flash floods are greater in magnitude in the Mediterranean countries than in the inner continental countries. Summary and concluding remarks are given in the final section
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
