| Abstract: | ABSTRACT: A major objective of this work was to develop a method applicable to the Intermountain region for estimating the probability of n consecutive dry days, where n ≤ 30 days. One result was a computationally simple method of producing the desired estimates directly from the rainfall record. For a consecutive dry-day period of n days, these estimates are equivalent to those obtained from a Markov model of order n-1. The efficacy of a simple Markov model was also evaluated. In this climatic region, the simple Markov model produces probability estimates of consecutive dry days that are too conservative, especially at long dry-day periods. In this data set, it was found that the longer the dry-day sequence, the more conservative the Markov estimate. The source of these conservative estimates is the strong dry-day persistence, which is characteristic of summer weather in the Intermountain region. In this region, the best estimates of the probability of consecutive dry days are probably those obtained directly from a representative rainfall record and smoothed by the partial sums of a fourier Series. |
