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<br />. <br /> <br />1980) formed the basis .of a NOAA/Utah cooperative weather modification <br /> <br />research project conducted during February and March, 1981 by Hill <br /> <br />. <br /> <br />(1982) in the Beaver, Utah area. Results of that project were that ice <br /> <br />nuclei from ground generators generally did not reach cloud altitudes in <br /> <br />sufficient quantity for effective seeding of the clouds, but that signi- <br /> <br />. <br /> <br />ficaot amounts of supercooled liquid water were present in the clouds. <br /> <br />8md that most trajectories of precipitation particles forming from the <br /> <br />water would intersect the mountain. <br /> <br />Thus the clouds appeared to be <br /> <br />. <br /> <br />susceptible to seeding. <br /> <br />These results were based on only one field <br /> <br />season and therefore were preliminary. <br /> <br />Following receipt of Hill's (l982) report of the 1981 field <br /> <br />. <br /> <br />investigations contract agreements were reached between NOAA and the <br /> <br />State of Utah Department of Natural Resources Division of Water <br /> <br />Resources (UDWR) to conduct further evaluations of the Utah program. <br /> <br />. <br /> <br />The Utah Division of Water Resources was to be pr~me contractor and <br /> <br />other groups with appropriate expertise would provide <br /> <br />scientific and <br /> <br />technical assistance through subcontracts. <br /> <br />. <br /> <br />Under this contract agreement UDWR conducted a field research pro- <br /> <br />ject over and around the Tushar Mtns near Beaver, Utah from 15 January <br /> <br />to 15 March 1983. The principal results of that project are reported in <br /> <br />. <br /> <br />Long (l984a). <br /> <br />Supercooled liquid water was present ~n c loudsover the <br /> <br />mountains about two-thirds of the time according to the remote sensing <br /> <br />lidar. According to the remote sensing microwave radiometer located at <br /> <br />. <br /> <br />the' liquid base of the mountains, liquid water was present in amounts <br /> <br />greater than 0.13 mm one-half of the time or for about 4.5 hr ~n an <br /> <br />a.verage winter storm. (Note that. 1 mm of liquid water corresponds to an <br /> <br />. <br /> <br />8:verage liquid water content of 1 g m-3 <br /> <br />distributed over a cloud depth <br /> <br />-2- <br /> <br />.' <br />I <br />