Date of Award:

5-2019

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Watershed Sciences

Advisor/Chair:

Peter Wilcock

Co-Advisor/Chair:

Sarah Null

Third Advisor:

Robert Davies

Abstract

Unusually wet spring seasons in the Intermountain West (IW) have been linked to a wind fluctuation in higher levels of the atmosphere near the equator. Strong westerly winds during October-January often result in unusually wet conditions in the following spring. Average winds near the equator at 75,000 feet above the earth’s surface can be split into different categories according to wind direction: westerly (positive), easterly (negative), and transitional. Composites of winter and spring precipitation anomalies based on these different categories show that strong westerly winds occur in October-January prior to most extreme spring precipitation events. Drier springs tend to occur after easterly winds the preceding fall. Analysis of the atmospheric processes causing this wind pattern suggests that the intensity of spring precipitation in the IW may be forecast, based on winds in the upper atmosphere months in advance. These findings are useful for the IW because extreme wet springs could lead to floods, such as those in spring 1983 and 2011, and affect the amount of water available from spring runoff.

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