The 9–10 November 2001 Algerian Flood: A Numerical Study

Abstract

On 9–10 November 2001, Algeria was struck with its most devastating flood since records were first kept in 1908 (Fig. 1). The f lood was caused by an intense meso-?1-scale cyclone that struck the west side of the city of Algiers, producing accumulated rainfall up to ~285 mm and onshore winds of ~33 m s?1, resulting in some 740 deaths. Fortunately, the overall cyclogenesis event was detected by the European Centre for Medium-Range Weather Forecast (ECMWF) model, enabling the Office National de la Meteorologie de Algier (ONMA) to issue a flood forecast as early as 5 November. Whereas the apparent predictability of the event suggests a controlling role by large-scale forcing, closer examination reveals that significant mesoscale development led to the actual weather pattern within the Algiers locale.