WMOD00285 ‎(2)‎

• Title: Feasibility Study of Wintertime Cloud Seeding to Augment Arizona Water Supplies
• Date: 1/1/1987
• State: AZ
• Weather Modification - Doc Type: Report

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Table 5. - Daily precipitation frequencies for each of a wet, normal and dry
winter at station group GP5.*

PRECIPITATION FREQUENCY

Stat ion
group GP5 Winter Condition
Preclpltatlon Wet (1982-83) (1981-82) Dr Ll..!J80-81 )
range (in) Nor'm
0 135 159 156
>0 - 0.2 24 14 14
>0.2 - 0.4 8 4 6
>0.4 - 0.6 5 2 2
>0.6 - 0.8 2 1 2
>0.8 - 1.0 1 1
>1.0 - 1.5 4
>1.5 - 2.0 1
>2.0 - 2.5 1
Total cases 181 180 181

*Precipitation measurements were generally taken at 1800 local.

Given in tables 6-12 are the frequency counts with stratification by pre-
ci pi tat i on category, season type and 500 mb temperature. The temperature
intervals selected, -5 to -10 oC, -11 to -20 oC, -21 to -26 oC, and -27 oC
and colder, are likely to be of importance to the index-ation of cloud seed-
ability (Mielke et al., 1971). The results for the southern mountain sites,
obtained by extrapolation with the Winslo~' sounding, must be interpreted with
due regard to the distance and intervenin~J barrier presence. Several important
features were noted as follows:

1. On the Mogollon Rim most cases with precipitation amount
~ 0.2 inch occurred with 500 mb temperatures in the -11 to -20 oC
interval. This was true in wet, normal and dry winters. A distant
second in counts was the temperature interval -21 to -26 oC (same
precipitation interval). Counts for the Mule and Chiricahua
Mountains were generally lower.

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