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<br />separation line (sec. 3.2.1 and fig. 3.0. Since <br />application of HMR No. 52, the 105th meridian, was set <br />geographical limits of HMR No. 51, consideration <br />reasonahleness of changing the western limit to HMR No. <br /> <br />the western limit to <br />to be consistent with <br />was given here to <br />52. <br /> <br />the <br />the <br />the <br /> <br />The review led to the conclusion that a more appropriate western limit would he <br />the orographic separation line. HMR No'. 52 should be applied to PMP estimates <br />from the present study between the 103rd meridian and the orographic separation <br />line. However, for those nonorographic regions that lie west of the 105th <br />meridian, yet east of the orographic separation line, notably in eastern Montana <br />and Wyoming, the application of HMR No. 52 procedures should be considered <br />tentative. Incomplete consideration was given to storms within this region to <br />permit use of HMR No. 52 procedures without additional study. Such study will be <br />a part of recommended future considerations discussed in chapter 15. <br /> <br />1.9 Organization of the Report <br /> <br />This report has been organized to provide a complete and logical progression <br />through the various concepts, procedures, or methodologies used to develop the <br />PMP estimates for the region. Sufficient background material is included in each <br />chapter to give an understanding of the material wi thout reference to other <br />sources. <br /> <br />An important factor, basic to the development of any PMP estimate, is an <br />understanding of the meteorology of major rain storms that have occurred in the <br />region. Chapter 2 provides this information. Major storms that have occurred in <br />and near the region are listed. A brief description is given of the weather <br />situations and time and space distributions of the precipitation associated with <br />some of the more important storms. The review of major storms leads to a storm <br />classification system. This system differs from others that have been presented <br />in previous hydrometeorological studies in that it is directed solely toward <br />classifying storms on the basis of the primary causative factor for the <br />precipitation over the region. <br /> <br />Chapter 3 presents a discussion of the topography of the region. The slope, <br />elevation of the terrain, and intervening barriers to moist airflow are <br />considered. The inflow directions of moist air in major storms discussed in <br />chapter 2 were used to develop a terrain classification system and prepare an <br />effective elevation and barrier map in chapter 3. <br /> <br />Moisture supply available for producing precipitation is among <br />important factors in development of PMP estimates. The maximum <br />moisture within the region is discussed in chapter 4. Chapter 5 <br />discussion of the moisture that was available in the major storms <br />occurred in and near the CD-103 region. <br /> <br />the more <br />available <br />provides a <br />that have <br /> <br />Chapter 6 provides an overview of the procedures used to develop the PMP <br />estimates of this report. <br /> <br />Precipitation in the CD-103 region is produced by a combination of both <br />orographic lifting and atmospheric forcing functions. In chapter 7, a procedure <br />is explained that uses a comparison of individual precipitation ohservations, <br /> <br />9 <br />