Title

They Just Don’t Make Storms Like This One Anymore: Analyzing the 1959 Record Snowfall Season at Mt. Shasta CA

Document Type

Article

Publication Date

2013

Publication Title

Journal of Operational Meteorology

DOI

10.15191/nwajom.2013.0105

Abstract

Extreme weather events are rare but significantly impact society making their study of the utmost importance. We have examined the synoptic features associated with a historic snowfall during February 1959 on Mt. Shasta in northern California. Between 13–19 February, Mt. Shasta received 480 cm of snow and set a single snow-event record for the mountain. The analysis of this event is challenging because of sparse and coarse-resolution atmospheric observations and the absence of satellite imagery; nonetheless, the analysis has contributed to our understanding of synoptic and mesoscale dynamics associated with extreme snowstorm events. We have used an array of methods ranging from the National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis datasets, analysis of regional sounding and precipitation data, archived newspaper articles, and reminiscences from long-term residents of the area. Results indicate that a single mechanism is unable to produce a snowstorm of this magnitude. Synoptic components that phased several days prior to this event were the following: 1) amplification and breaking of Rossby waves, 2) availability of extratropical moisture that included enhanced midlevel moisture in the 850–600-hPa layer, 3) the transition from a meridional to zonal polar jet, and 4) an active subtropical jet stream. The timing and phasing of the northern and southern branches of the polar jet stream led to an idealized long-term juxtaposition of moisture and cold air. This optimal phasing within the circulation pattern was key to the production of record snowfall on Mt. Shasta.