WMOD00317 ‎(2)‎

• Title: A Comparison of the Potential of Cloud Seeding to Enhance Mountain Snowpack in Colorado During Dry, Normal and Wet Winters
• Date: 1/1/1983
• State: CO
• Weather Modification - Doc Type: Report

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TABLE 5
Percent of long-term maximum spring snowcourse water content for
mountainous sub-regions of Colorado in 1977 and 1981.

Sub-region
Spring South North East Central West Central Combined
1977 35 52 52 48 46
1981 47 61 59 46 56

Percentages for the two e~tremely dry winters for each sub-region are
somewhat lower than the lowes;t reported during 1961-74 and particularly
low in the south in 1977 (3~5 percent). '!be lack of very dry winters
during the study period precludes drawing definitive conclusions regarding
opportunity for seeding during drought periods.

What constitutes a dry or wet winter in each sub-region during the
study period is difficult to determine. We decided to consider winters
with water content less than or equal to 80 percent of the long-term
average as dry and those with water content greater than or equal to 120
percent of the long-term aVE!rage as wet. Winters with water content
between 80 and 120 percent of the long-term average were considered
normal. Many other criteria are possible; these criteria were chosen
partly because they allowed classification of two to four of the 13
winters in each sub-region as dry and wet.

Identifying Storms

Storms were identified from interPOlated border point soundings.
First, the sounding that best represented the air mass about to enter the
state was determined. The aVl:rage 700 millibar (rob) wind direction for
the 10 border point soundings was computed and a sounding chosen whose
wind direction to the center of the mountainous area of the state was

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