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isohyetal analysis, evaluation of terrain, and evaluation factors to estimate the relative contribution of atmospheric influences on precipitation in individual storms. of meteorological forces and terrain The traditional approach to developing PMP estimates is to maximize observed precipitation amounts for moisture and transpose these maximized values to other locations. The traditional approach to moisture maximization and transposition, as well as some modifications to these procedures, are discussed in chapter 8. Several different approaches were examined, each of which has advantages and disadvantages. These approaches were developed to extend the usefulness of the maximization and transposition procedure in orographic regions. The basic procedure provides estimates of the amount of precipi tat ion that results from free atmospheric forcing effects. These amounts were transposed throughout the CD-103 region. The amount of intensification that would occur at various locations as the result of terrain lifting was then estimated. The method of evaluatinp; this orographic contribution and how it should be used to modify the convergence PMP is the subject of chapter 9. An explanation of the development of the general-storm PMP index maps is given in chapter 10. Primary focus was given to 24-hr 10-mi2 precipitation amounts, since station daily rainfall observations are most plentiful and modified transposition techniques can be developed with the greatest reliability for such small arefs. Estimates were also developed for 1-, 6-, and 72-hr durations for the 10-mi area. To provide estimates for the range of area sizes and durations needed for this report, depth-area and depth-duration relations are required. Development of the depth-area relations is discussed in chapter 11. These proc'2dures provide PMP estimates for 1, 6, 24, and 72 hr for area sizes to 20,000 mi in nonorographic portions and 5,000 mi2 in the orographic portions. These can be used to prepare depth-duration curves for any area size within the limits of the report. The intermountain region between a generalized crestline of the Sierra Nevada and Cascade Mountains and the Continental Divide is relatively isolated from major moisture sources. Large precipitation amounts for very small areas and short durations in this region do not result from general storms. Within this region a local convective event, isolated in time and space, produces the maximum precipitation amount for these short durations and small areas. Chapter 12 discusses the development of the local-storm criteria. The consistency and reliability of PMP estimates for various durations and area sizes are discussed in chapter 13. General comparisons are made with previous individual drainage estimates and generalized estimates within the region previously prepared by NWS. Comparisons are made with some major storm rainfall amounts. A final comparison is made with 100-yr return period values from NOAA Atlas 2 (Miller et al. 1973). Chapter 14 focuses on the procedures for drainages. This chapter summarizes procedures earlier chapters of the report. computinp; PMP for specific developed and discussed in the Chapter 15 provides some concluding remarks and suggestions for studies. Particular attention is focused on studies which are needed to the usefulness of the estimates developed in this and other PMP reports. future enhance 10