SIMULATION OF A LONG-LIVED MESO-BETA SCALE CONVECTIVE SYSTEM OVER THEMEDITERRANEAN COAST OF SPAIN .1. NUMERICAL PREDICTABILITY

An unusually long-lived (33 hours), devastating (local maximum rainfal l rate over 800 mm/24 hr) meso-beta-scale (diameter smaller than 200 k m) convective system that occurred over the Mediterranean coast of Spa in has been simulated reasonably well by means of a regional numerical model. Several runs of the model including parameterized convection a nd boundary conditions of varying degrees of complexity have been perf ormed. In most of these experiments, the main characteristics of the e vent, namely its stationarity and duration, are captured. The direct r elationship between the Lagrangian lifetime of a meteorological system and its degree of deterministic predictability seems to be corroborat ed by the results: It appears that the meso-alpha-scale forcing that p receded and favoured the MCS was especially well predictable, and once initiated, the simulated MCS seems to have several feedback mechanism s helping to extend its life. Results are encouraging, because they re veal that it might be possible to predict very severe episodes of smal l MCSs such as the one shown here sufficiently in advance.