Modeling AgI targeting effectiveness for five generalized weather classes in Utah

Rawinsonde observations from the 1991 and 1994 Utah/NOAA field programs were stratified into five classes based on temperature profiles. The classed soundings were used to initialized the Clark mesoscale model to simulate AgI transport from three operational generator sites in the valley upwind of the Wasatch Plateau in central Utah. The goal was to generalize ranges of conditions which would allow successful targeting of valley-released AgI. Not unexpectedly, the most unstable sounding class produced the best targeting. This class was the coldest of the five, producing more effective ice nuclei from the available AgI because of the temperature dependence of this ice nucleating agent. In general, the modeled results were in agreement with selected case studies of field observations. Wind characteristics were also shown to be important for successful targeting.