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<br />4 <br /> <br />Libya and Tunisia, and an orographic cloud has formed over the high Atlas mountains <br />(Fig. 3b). Over the plains random cumulus clouds are present. The 12Z soundings from <br />December 8 and 9 taken at the foot of the Atlas mountains at Beni-mellal (150 km <br />southeast of Casablanca and 80 km upwind of the crest line) are shown in figure 4. The <br />December 8, 12Z sounding shows the presence of two saturated layers, associated with <br />two distinct stratiform cloud layers. The lower layer is 2700 meters thick, extending <br />from 7 C (cloud base temperature) to -11 C. The second layer is relatively thin, and is <br />separated from the lower layer by a 500 meter dry layer. The cloud top temperature of <br />this upper layer is -16 C. The satellite photograph (Fig. 3a) shows that the eastem half of <br />Morocco is covered by stratiform cloud at this time.. <br />Twenty four hours later, the Beni Mellal sounding shows a relatively cooler air <br />mass and the presence of an inversion at 600 mb, with dry air above the inversion, and a <br />saturated layer below (figure 4b). The saturated layer is associa'ted with an orographic . <br />cloud over the Atlas mountains, and is clearly evident in the satellite photograph at this <br />time (Fig.3b). Aircraft observations showed that this orographic cloud consists of a <br />stratiform layer with embedded convection. The cloud top temperature for this <br />orographic cloud was -17 C, with corresponding base temperature of 2 C. This type of <br />cloud is typical of the post-frontal period of these storms. The nonhwest wind at 500 mb, <br />and upper level subsidence indicate an approaching ridge and the end of the storm. <br />The storm just described represents a typical winter time precipitation event, and <br />generally produces significant amounts of rainfall over the plains and snowpack over the <br />mountains. <br /> <br />3. MICROPHYSICAL OBSERVATIONS <br /> <br />a. December 8th <br />