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<br />co <br /> <br />upward moving cloudy air sufficient time to develop drops by coalescence in the <br />relatively undiluted cloud cores. The model calculations show that the growth of panicles <br />by collision and coalescence with cloud droplets can produce particles of the observed <br />sizes at the appropriate levels. Despite the relatively cold cloud base temperature (3 C), <br />the coalescence process was still active due to the nearly adiabatic cores. <br /> <br />5. CONCLUSIONS <br /> <br />The above observations represent only one wintenime storm occurring over <br />Morocco, and therefore caution must be taken in extrapolating these results to other <br />winter storms. These results, however, show a typical winter storm sequence, and reveal <br />some of the basic precipitation mechanisms active. <br />During the frontal passage, a seeder-feeder type mechanism was active in the <br />Atlas mountains, with an upper level stratiform deck feeding aggregates of dendrites and <br />stellars into a lower level supercooled cloud layer. Some regions of the system had lower <br />cloud top heights, and no upper level cloud to provide ice crystals, allowing for long- <br />lived regions of supercooled liquid water. Post frontal stratocumulus clouds had an active <br />coalescence process in convective regions, leading to drop freezing and subsequent <br />riming. Model calculations verified this behavior, and showed that the moderate updrafts <br />and high liquid water contents were responsible for the rapid growth. Aggregates of <br />dendrites and stellars were obselVed in the stratifonn regions of this cloud. <br /> <br />ACKNOWLEDG~NTS. - <br />The authors gratefully acknowledge the suppon of the U.S. Agency for <br />International Development for making this research possible. The data collection effons <br />by the University of North Dakota Citation crew are well appreciated. We also <br />acknowledge the tireless efforts by Dr. David Matthews (resident Scientific advisor in <br />