WMOD00284

• Applicant: Thompson, J.R., G.W. Wilderson, and D.A. Griffith, North American Weather Consultants
• Sponsor Name: USBR
• Title: Cloud Seeding Data Collection, and Analysis Assoc. with the Colo River Augmentation Demonstration Program
• Prepared For: USBR, Divison of Atmospheric Research
• Prepared By: Thompson, Wilderson, Griffith
• Date: 12/1/1987
• State: AZ
• Weather Modification - Doc Type: Scientific Study

intermittent precipitation occurring in a mostly random fashion,
perhaps near the beginning or end of a storm when it was less
organized.

An analysis similar to the one presented in Figure 3.4,
was done for the Arizona data set, but without the very short
duration (2 hours or less) episodes. Elimination of these
episodes reduced the number of episodes from 217 to 132 but
the precipitation hours were only eight percent less (1348
instead of 1466 hours) and the precipitation total for all
the episodes was only three percent less (51.6 instead of
53.2 inches).

The results are presented in Table 3-7, where the cumulative
percent of the episode hours, precipitating hours and episode
precipitation hours for the 217 episodes that contained the

Table 3-7

CUmulative Percentage Comparison of Episode Statistics for
Arizona Mogollon Rim Areas, Episodes of 1 Hour Minimum
Versus 3 Hour Minimum

Episode Precipe Episode
Duration Hours Precipe (Hrs)
Cumulative IHr 3Hr IHr 3Hr IHr 3Hr
Percent Min. Min. Min. Min. Min. Min.
10 <1 <3 2.1 <3 5 4.5
25 -1 3.2 5.5 7.5 9.5 7.1
50 2.8 6 12 15 21 21
75 7.5 11 24 26 30 31
90 16 21 34 34 35 37
95 24 25 40 40 38 42
100 50 50 50 50 50 50
3-47

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