On the cloud microphysical processes during the November 2, 1994 hazardousstorm in the southeastern Mediterranean as simulated with a mesoscale model

A mesoscale model (CSU RAMS) model with cloud microphysics is used for anal ysis of the November 1-2, 1994 weather developments over the eastern Medite rranean (EM). The hazardous weather processes of the period are successfull y simulated. According to observations, as well as the modeling results, th e main areas with very intensive precipitation were located over Egypt and southern Israel. Results of the simulation are used to evaluate the role of the cloud microphysics of the storm. Analysis of time variations of the mo del, derived from microphysical characteristics, is made at several locatio ns along the path of the storm. The processes at the locations represent di fferent stages of the storm development. The results show that during this intense storm, cloud microphysical proces ses experienced at least two phases of development. During the first phase, which was associated with initiation and intensification of the mesoscale convective system (MCS), the condensate, mainly composed of cloud water, ex isted in the deep layer from 3 to 10 km. It was evidently formed by condens ation and collection processes in the slowly developing updrafts. During th e second phase, associated mainly with frontal type cloud developments, the clouds were much less vertically developed and were characterized by less intense cloud processes. Pristine ice particles were found at about 10 km d uring most of the period. Vertical development of the clouds was less activ e than during the first stage. Observed rapid decrease of the rain intensit y over Israel was mainly a consequence of the transformation process. At th e same time, the increase in dustiness of the air over the region during th is time could also have contributed to, this decrease although the role of this factor is nor completely clear. (C) 2000 Elsevier Science B.V. All rig hts reserved.