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Snow and melting of the snowpack provide the principal supply of water to much of the Western United States. Whether global warming threatens this water supply is the focus of this research. This study builds upon a previous Global Climate Change Response Program investigation. Charts were generated of four geopotential height parameters for a domain covering the eastern North Pacific Ocean and western North America. Out of 131 total winter months (from 1946-89), 35 were selected as analogues.

Monthly mean precipitation values for areas in western Montana, northern Utah, and east central Arizona were compared with median values for the 1946-89 period to determine if any significant differences existed.

The results suggest that one regional impact of global warming may be a substantial reduction in wintertime precipitation in central and southern intermountain areas such as Utah and Arizona. The study also found the situation in western Montana to be unclear. Finally, a few examples are presented to highlight some of the strengths and weaknesses of the analogue approach, and several questions regarding other potential effects of global warming on winter precipitation are addressed.


SuDocs call # I 27.2:G 51/17

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