| This research aims to identify upper atmospheric synoptic scale patterns that are associated with class V avalanches on Mt. Shasta, California. Located in the Southern Cascade mountain range, Mt. Shasta is within the coastal avalanche zone, thus receiving storms with abundant snowfall, higher snow density and high temperatures. Class V avalanches are the largest and most destructive types of avalanches that can occur. Fifteen class V avalanches (ten storm events) have been observed on or near Mt. Shasta in the last 115 years. Avalanche observation activity in the Mt. Shasta region has been inconsistent, resulting in incomplete avalanche documentation, yet meteorological records for the City of Mount Shasta have been continually collected from 1890 to present. Historical meteorological records, combined with applied analysis of atmospheric processes, provide the foundation for this research. Composite and anomaly analysis plots and a correspondence analysis, identify synoptic patterns and relationships between: 250mb wind field, surface temperature, 500mb geopotential height field, 700mb precipitable water and atmospheric thickness. Results indicate that there is a strong correlation between synoptic scale warm air and moisture advection, strong winds, and low geopotential heights and the formation of large, naturally occurring, class V slab avalanches on Mt. Shasta. |
