Date of Award

2016

Document Type

Open Access Thesis

Department

Geography

Sub-Department

College of Arts and Sciences

First Advisor

Cary J. Mock

Abstract

Snowfall distribution in southern Alaska during large snowfall events (>12 inches/day) is complex and dependent on several small-scale factors. Output from highresolution WRF simulations was used to provide further insight into factors that contribute to differences in precipitation patterns. Common synoptic patterns among large snowfall events and cities were studied to create a snow climatology for seven cities in southern Alaska based on the predominant wind flow at the surface and aloft and the location of the surface low and 500 mb height field. Results aid in understanding the synoptic set-up for large snowfall events in each city and provide insight for increased skill in future forecasting applications. In addition, a snow avalanche climatology was created for two ski areas to understand avalanche occurrences and their triggers in southern Alaska. Avalanches have increased in frequency but decreased in size in the last 50 years, with increased avalanche mitigation techniques in more recent years in both locations. Although a majority of the documented avalanches were artificially triggered during the period of record, avalanches were evaluated for seasonal avalanche-climate relationships and separated into climate classifications based on a decision tree previously developed in the literature. Results confirm previous research with Eagle Crest and Alyeska achieving coastal and intermediate climate classifications respectively. Daily weather conditions during extreme avalanche years illustrate the seasonal variations are also governed by snowpack processes. The relationships between avalanches and large snowfall events were explored and common synoptic patterns were found. Correlations remained low, however, because large snowfall events only account for a small percentage of total snow. Teleconnection indices were evaluated for their influence and relationship with snow and avalanche occurrences to see if large snowfall events and avalanches could be predicted on a seasonal timescale. Results indicate the need to evaluate changes in atmospheric patterns on a daily to weekly timescale to improve forecast skill. This requires moving away from monthly to seasonal analysis to better account for the shifts and fluctuations that surround the formation and occurrence of extreme snow and avalanche events in southern Alaska.

Included in

Geography Commons

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