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<br />4. Stable, orographic clouds, relatively rare during the 1976-77 <br />season, occurred more frequently during the 1977-78 season. They <br />were quite deep with cold tops and, upon close examination, contained <br />banded or cellular structure. <br /> <br />5. Multicells (clusters of cells) occurred frequently in Sierra Nevada <br />storms and were generated by the merger of individual cells. They <br />normally moved much slower and at relatively large angles to the <br />steering wind. <br /> <br />6. Seedab1e regions (low ice crystal concentrations and high 1 iquid <br />water content) appear to be strongly local ized and to be associated with <br />convection. Stable, orographic clouds seem to have no seedab1e region <br />unless they occurred at low altitudes near the crest.. Isolated and <br />embedded cells were generally favorable for seeding on the upwind side <br />of the element. Postfronta1, convective cells appeared to be highly <br />seedab 1e near their format ion zone at the 1000-m e1 E!V at ion and 1 ess <br />seedab1e as they progressed toward the crest. High 1 iquid water con- <br />tent, low ice crystal concentrations, and strong updrafts over a rela- <br />tively small area occurred on the southwest side of cells. Low liquid <br />water contents, high ice crystal concentrations, and weak downdrafts <br />over a large area occurred on the north-east side of cells. <br /> <br />7. Prefrontal storm conditions were influenced strongly by a low-level <br />jet of warm, moist air blowing parallel to the barrier. The low-level <br />jet was present across the entire Sacramento-San Joaquin Valley. The <br />average height of.the jetl s maximum speed was about 1.7 km. The direc- <br />tion of the jet's ranges was from south-southeast to west-southwest with <br /> <br />1-4 <br /> <br />.I' <br /> <br />e <br /> <br />e <br /> <br />e <br />