Role of large scale moist dynamics in November 1-5, 1994, hazardous Mediterranean weather

Abstract

Investigation of the role of moist dynamics in the atmospheric processes during the abnormally intensive stormy period of November 1-5, 1994, over the Mediterranean region is presented. Analysis focuses on the eastern Mediterranean area employing 96-hour model predictions over the Mediterranean region with the Florida State University (FSU) global spectral model. Sensitivity simulations differ only by prescribing the initial moisture fields in the selected regions located in the Arabian Sea, Red Sea, and over large areas in the low and high latitudes. Both the tropospheric trajectories and the model tests suggest that the heavy rains over the eastern Mediterranean were associated with unusually intensive propagation of air masses from the Arabian Sea region, which took place before and during the first 24 hours of the period. Air masses from the Arabian Sea participated also in the intensive developments in Italy and southern France on November 5, 1994. According to the model simulations the convective processes over the equatorial Africa play a major role in the developments. Also, the intensification of the upper tropospheric westerly winds due to the convection over the equatorial Africa stimulates the northward extension of the Red Sea trough which consequently diminishes the moisture influx for the tropical convection and therefore seems to serve as a negative feedback. Copyright 1998 by the American Geophysical Union.