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precipitation amounts of at least 15 inches above 10,000 feet (see Hansen et al., 1988). Secondly, the analysis of streamflow by Jarrett and Costa (1982) shows the peak streamflow on many streams in the Front Range above approximately 7,500 feet are due to snowmelt and not extreme rainfall events. The paleohydrologic work by Jarrett and Costa (1988) to estimate past floods would suggest that the stream channels above 7,500 feet have not experienced large rain produced floods in the past 10,000 years. These two perspectives are not necessarily in conflict, but they do raise a significant scientific question of what level of probability ofa storm event should dams be expected to provide protection from floods. If the numerical models could simulate large rainstorms at higher elevations, the controlling physical processes could be identified and used to imp:rovl~ our understanding of this phenomena. The format of the workshop was to start with a series of presentations by individuals with experience developing and/or using large modds. They included Bill Cotton (CSU), Terry Clark (NCAR), John Snook (NOAA) and Hany Orville (SDSMT). Lou Schreiner also gave a brief discussion of the plans of the USBR to IIse models to contribute t.o the PMP work. b. Presentation summary Bill Cotton's presentation included a series of experiences with the CSU-RAMS model and some speculation of the use of RAMS to simulate storms at higher elevations with heavy rain. He indicated that a spatial resolution of 1-2 kin would be required to simulate large storms. He anticipated the environment of the large storms includes: . synoptic ridge . shortwave trough . low level jet . stationary front . weak winds aloft . weak vertical shear Initialization of the model is very important and information of soil moisture and vegetation is really needed. He hypothesized tha.t dry soil at higher elevations could lead to stronger upslope winds in developing convection. In regards to the idea that there might be an elevation limitation on heavy rain, h,~ thought high mixing ratio air might be used by storms before it gets to high elevations and that much of the high elevation precipitation could fall as hail. He talked about the complexity of the cloud microphysics and indicated that the newest version was not running in the model at this time. Terry Clark discussed the use of the Clark model in several areas which included wind storms, forest fires, and a project specifically related to precipitation in Arizona for both summer flash floods and winter precipitation. He showed comparisons of model simulations with observations of precipitation. Results of the comparisons indicated the 20