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2. The second and somewhat stronger level of confirmation will have been achieved if the adjusted P values also indicate positive treatment effects in FT and TT rainfall in the six hours after initial seeding for the B days. Again, failure to satisfy this level of conf'irmation precludes moving on to the third and final level. 3. The third and highest level of confirmation will have been achieved if the adjusted P values also indicate positive treatment effects in FT and TT rainfall in the six hours after initial seeding for the A & B days. According to these specifications, FACE-2 failed to confirm the results of FACE-1 (Woodley et al., 1983). The first and weakest level of confirmation was not achieved. Contrary to the confirmatory specifications and the hypothesized conceptual model of seeding effects, the mean rainfall time profiles peaked earlier on seed days than on non-seed days. Since the first level of confir- mation was not achieved, progressive consideration of the other confirmatory analyses was precluded. Exploratory analyses were then conducted to determine if seeding effects were indicated. Most of the FACE-1 analyses wre repeated on the FACE-2 data, espe- cially the covariate analyses which were precluded from the confirmatory speci- fications. The most important of the replicated analyses indicated that the seed day FT and TT rainfalls were larger than the respective non-seed day rain- falls, but the rainfall increases were small and statistically non-significant (Woodley et al., 1983). More recently, additional exploratory analyses have attempted to assess treatment effects in FACE-1 and FACE-2 through a guided exploratory linear modelling approach (Flueck et al., 1984). The individual and residual linear model results suggest that positive target area treatment effects are indicated in both FACE-1 and 2. The comparable yearly results indi- cate that seven of the eight summers during which FACE-1 and 2 was conducted had indications of rainfall increases due to seeding. In one year a rainfall decrease due to seeding is indicated. Woodley et al., (1983) suggest that the probable reasons for the relatively weak FACE-2 results are: a) an unknown and possibly intermittent seeding effect, b) inadequate predictor equations that account for natural rainfall variability and, c) a limited sample size. Since the FACE program did not directly and systematically measure the meteorological processes relevant to the precipita- tion process in the FACE clouds and the intermediate responses to seeding, understanding of the physical reasons for the tantalizing FACE-1 and 2 results will not be possible. 4. SCPP The SCPP (Sierra Cooperative Pilot Project) is a winter orographic cloud research program with the goal of developing a practical cloud seeding capabi- lity for increasing the streamflow of the American River Basin of the Central Sierra Nevada of California. The primary scientific objective of SCPP is to define those conditions giving rise to precipitation increases, decreases or no change by the prescribed treatment of winter orographic clouds and cloud systems. 5