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<br />to conform to the satell ite photogr'aph.. Time/hei ght cross-sections of equiva- <br /> <br />lent potential temperature, temperature, relative humidity and winds from <br /> <br />soundings at Sheridan, CA for th~ 48 hr period from 0900, 26.March to 0900, <br /> <br />. . <br /> <br />28 March are shown in Fi gure 5. F'j gure 6 shows th.e radi omet'ri c: ~easurements of <br /> <br />supercooled water during the storm and the precipitation rate measured at the <br /> <br />radiometer site at Kingvale. <br /> <br />At 0000 on 27 March, a wide trough system was present over the northeast <br /> <br />Pacific. Strong near-zonal flow was present over central California and west- <br /> <br />ward into the Pacific. The storm system had already moved into the Sierra <br />Nevada at 0000, and heavy precipitation was falling across the mountains. <br /> <br />Distinct warm and cold fronts were present in this storm. <br /> <br />The warm frontal period extended from 0900, 26 March to 0200, 27 March. At <br /> <br />0900, the warm frontal boundary was present at 700 mb over Sheridan. Air above <br />the front was moist, but dry below the front prior to 1800. The warm frontal <br />cloud shield extended far ahead of the main precipitating regions of the system. <br /> <br />The cloud shield is evident on the 0100. satellite photograph. With time, as the <br /> <br />.'" <br /> <br />warm front continued to move over the region, precipitation fell into the drier <br /> <br />low level air gradually moistening the lower atmosphere. At the time of the <br />photograph, the warm frontal surface was still present over Sheridan. Precipi- <br /> <br />tation rates increased steadily as the warm front moved over the region. Super- <br /> <br />cooled water was present continuously within the frontal clouds, but generally <br />in small quantities (0.10 mm liquid water depth). No significant peaks were <br /> <br />present in supercooled water, suggesting that the liquid developed in response <br />to gradua.l lifting, probably associated with the frontal surface, rather than <br /> <br />convection. <br /> <br />11 <br />