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<br />3. HMR No. 55 treated the variation of 1- to 6-hr and 6- to 24-hr ratios in <br />general storms with elevation such that the ratios were either constant <br />or increasing with increasing elevation. In HMR No. 55A, the elevation <br />variation of these ratios is treated differently, particularly on the <br />most steep east-facing slopes of the Wind River and Big Horn range, and <br />along the Rocky Mountains near Pikes Peak and portions of the Sangre de <br />Cristo Mountains. For the most part the ratios drop off with increased <br />elevation throughout the steep slope region. <br /> <br />The combined effect of these changes is discussed in section 10.3.3, where it <br />is shown that general-storm reductions up to 40 percent are realized at some <br />locations. Somewhat lower reductions (10-25 percent) are obtained from the <br />local-storm procedure presented in section 12.4. Numerous other changes have <br />been made to the text to make the discussion compatible with the changes <br />mentioned above. Additional changes of a lesser nature have been included to <br />correct typographical errors and other features noted in HMR No. 55 since its <br />publication. <br /> <br />Because of user concern that this report be a stand-alone reference tool, the <br />text has been prepared to read as an original study report, and only limited <br />reference is made to differences from that presented in HMR No. 55. It is the <br />authors' sincere intent that these modifications result in a minimum <br />inconvenience in terms of their impact on design applications. The authors hope <br />that this report has been strengthened by having taken the time to make the <br />changes. <br /> <br />The reader is reminded that, as in the 1984 report, the results presented in <br />this study represent a reasonable use of available storm data and state-of-the- <br />art procedures. Knowledge of the many factors that influence the quantity of <br />precipitation to fall at any specific location is still incomplete. Much <br />research remains to be done in the area of orographic precipitation processes. <br />As additional understanding develops, perhaps in the form of physical based <br />models, or addi tional storm data, some changes to the present study may become <br />necessary. While it is recognized there are somE' who consider these results to <br />be overly conservative or highly controversial, the authors believe they have <br />provided the best response to the definition of PMP available for this region at <br />this time. <br /> <br />xvii <br />