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All the west of the CD storms occurred during July or August except for the Rifle Creek storm of May 1993 and Muddy Creek storm of June 1994. Monsoon moisture and disturbances played a major role in the formation of each of these storm events. Surface gust fronts and thunderstorm outflow boundaries or gust fronts were the major contributing sub-cloud layer forcing features, While it was not listed, differential heating of higher topography played a pivotal role in storm initiation for each of the events. It is interesting to note that while the cloud shear values were quite low, in general, the cloud layer winds were stronger than the low level winds in all but two events, Strong low-level winds appear to be missing from CD-West storms and this factor may limit the availability, duration and amount of rainfall. In general the PWI values were around an inch after being corrected for elevation, The exceptions were the recent Saguache and Dallas Creek storms that averaged about 1.20 inches or about 20 per cent moisture than the other events. Surface dew points averaged about 53F while surface temperatures were in the 70s. These results are consistent with the relatively high elevation of the events above 8,000 feet. While deep monsoon moisture is present for each event, it is not properly reflected in the Surface -500mb PWI. Since the surface used for the mountain PWI is 8,000 feet, and not 5,000 feet or lower, it is roughly 20-40 percent less than either the east of the CD PWI or a sea level PWI by default of its elevation. Clearly, 8,000 feet of rock cannot be saturated by atmospheric water and this fact represents a limiting factor in rainfall production, If the PWl's in Table 2 are adjusted to a standard 5,000-foot elevation, the values average about 1.24 inches or about the same as those presented in Table 1. If the PWl's associated with the Saguache and Dallas Creek storms are adjusted to 5,000 feet, the storm PWI values increase to 1.44 inches or the wettest atmospheric PWI's "observed" with any of the extreme precipitation events listed in Table 1 or 2. This exercise of elevation adjustment provides an objective means of comparing PWI for the storms. The comparison suggests that the Dallas Creek and Saguache Creek storms were truly significant precipitation events. Finally, these factors appear to be reflected in the average storm rainfall of 4.42 inches for CD-West storms. While estimated storm total rainfall of the Opal storm of 1990 and the Saguache storm of 1999 are about 7,00 inches based on unofficial point amounts, reliable observations and storm re-constructions do not support these high values for areas of greater than 1 square mile within the storms. It appears that CD-West storms are less proficient rainfall producers than the CD-East storms. If this observation is correct, the question can be asked: why? Some quantifiable answers are offered in the final section of this paper that could have a profound impact on site.specific PMP calculations made in mountainous areas of Colorado and the adjacent foothills/plains interface. 4. Significant differences in the CO-West and the CD-East storms This study has focused on the 16 key extreme precipitation events that have been identified by the Colorado Extreme Precipitation Committee for evaluation by all practitioners producing a site specific PMP along and west of 105 degrees west in Colorado. A detailed summary of the atmospheric structure has been created for each of these events using the data sets collected for the Colorado Extreme Precipitation study. Significant quantifiable differences appear to exist in the atmospheric structure for storms observed east and west of Colorado's Continental Divide. These differences provide a significant opportunity to provide physical options to reduce PMP rainfalls west of the Continental Divide in Colorado. Table 3 summarizes the key differences observed in the storms from Tables 1 and 2. 4