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<br />incomplete description of the supercoQled water structure and distribution in <br />Sierra Nevada storms. Supercooled water was found in many parts of storms where <br />it was not previpusly identified. In particular, significa~t amounts of super- <br />c~oled 'water often ~ppear~dat altitu~es'below minimum cl~arance.for safe flight <br />(Heggli, 1986). A recent investigation by Heggli and Reynolds (1985) found that <br />storms having split front characteristics developed supercooled water following <br />the passage of the upper level front. In a series of cases studied by Heggli <br />(1985), supercooled water was shown to increase near the time of cirrus passage. <br />Studies like this are limited by the case study approach which emphasizes the <br />features of a few or sometimes a single storm. A broader study, evaluating all <br /> <br />storms, was warranted. <br /> <br />In this paper, we provide a comprehensive analysis of the evolution and <br />distribution of supercooled water in Sierra Nevada storm systems that occurred <br />during the period that the radiometer was available to SCPP. In performing this <br />analysis, storm types were identif'ied that accounted for the majority of storms <br />that occurred in the project area from 1983/84 through 1986/87. The storm <br />.. typing was based on synoptic characteristics such as storm trajectory and cloud <br />features. <br /> <br />The objective of this study is to describe how supercooled water evolves <br />near the Sierra Nevada crestline during each of the storm types. The relation- <br />ship between liquid water presence in clouds and large scaie storm features is <br />considered. Altitudes and temperatures of liquid-bearing cloud layers are also <br />estimated using data from the radiometer and collocated rawinsondes. The <br />results clarify previo"us findings )'eported by the SCPP and provide a basis for <br />improved conduct of regional weather modification programs. <br /> <br />2 <br />