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--~ ,- ~ daily and monthly mean of 14 gauges located in or near the watershed with corresponding values simulated by the nested models. Of particular interest to this study were results from modeling with the MM4 soundings. Correlation analysis indicates ~t:.hat the model has useful application (correlation of 0.64) in estimating winter daily watershed precipitation when local soundings are employed. However, when MM4 generated soundings are employed, the nested models appear unable to simulate daily precipitation, but can sinrolate winter monthly totals at a useful level(correlation of 0.71). A comparison of probability plots of: the gauge daily values versus the corresponding simulated values indicates that the nested modeling approach yields similar distributions except at. zero and small precipitation amounts. The LSPM is not able to properly simulate precipitation from low shallow moist clouds. Work is ongoing to improve this model feature. In summary, the nested models approa.ch, with the MM4 model and the LSPM, can produce daily and monthly precipitation estimates that should be useful for climate studies, and perha.ps, some operational needs in the case of the LSPM initialized with locaLl soundings. When initialized with MM4 generated soundings, the LSPM should function as a useful tool in the study of global climate change effects at the watershed level. In the near future, the LSPM will be run with MM4 soundings in whichMM4 is initialized with GCM output from a lon9-term base run and a companion doubled-C02 run. A thorough study of I1lested model error growth and propagation remains to be accomplished. ACKNOWLEDGMENTS This study was conducted as part of' Reclamation's Global Climate Change Response Program. Owen Rhea assis.t:.ed in developing the Colorado terrain profiles. Dave Matthews assisted in MM4 sounding p~eparation and Flippo Giorgi and Gary Bates supplied MM4 run information developed using the computing facilities of NCAR (sponsored by the National Science Foundation). Karen Morris and Ra Aman provided some computer programming support. REFERENCES Anthes, R. A., 1977. A Cumulus Parameterization Scheme utilizing a One- dimensional Cloud Model. Mon. Wea. Rev., lOS, pp. 270-286. Anthes, R. A., and T. T. Warner, 1978. Development of Hydrodynamical Models Suitable for Air Pollution and Other Mesometeorological Studies. Mon. Wea. Rev., 106, pp. 1045-1078. Anthes, R. A., E. Y. Hsie, and Y. H. Kuo, 1987. Description of the Penn State/NCAR Mesoscale Model Version 4 (MM4). NCAR Technical Note, NCAR/TN-282 + STR, National Center for l\tmospheric Research, Boulder, Colorado, 66 pp. Giorgi, F. , and G. T. Bates, 1989 . The Climatological Skill of a Regional Model Over Complex Terrain. Mon. Wea. Rev., 117, pp. 2325- 2347.