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

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of the Grand Mesa episodes lasted over a day and a half (38
hours> compared with only 24 hours for the Arizona episodes.

Table 3-6

CUmulative Percentage Comparison of Episode statistics
For Arizona Mogollon Rim (MR) and Colorado Grand Mesa (GM) Areas.

Episode Precipe Episode
CUmulative Duration Hours Hours
Percent MR GM MR GM MR GM
10 <1 <1 2.1 4.5 5 10
25 -1 -1 5.5 11 9.5 18
50 -1 -1 12 21 21 24
75 7.5 14. 24 39 30 42
90 16 24 34 53 35 52
95 24 38 40 75 38 65
100 50 106 50 106 50 106

Table 3-6 suggests that precipitation was generally observed
to fall within shorter time periods in Arizona than in Colorado.
Twenty-five percent of the precipitation hours in Arizona
were in episodes of 5.5 hours or less compared to 11 hours
for the Grand Mesa episodes while three-quarters of the precipi-
tation hours in Arizona were in episodes of 24 hours or less
duration compared to 39 hours (over a day and a half> for
the Grand Mesa. Furthermore, a quarter of the total precipitation
fell in episodes of 9.5 hours or less in Arizona compared
to 18 hours (nearly twice as long> on the Grand Mesa. Some
75 percent of the total precipitation fell in episodes of
30 hours or less in Arizona as compared with 42 hours on the
Grand Mesa.

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