Item: Five Seasons of Detailed Surface Hoar Observations: What Have We Learned?
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Title: Five Seasons of Detailed Surface Hoar Observations: What Have We Learned?
Proceedings: International Snow Science Workshop 2016 Proceedings, Breckenridge, CO, USA
Authors:
- Jordy Hendrikx [ Department of Earth Sciences, Montana State University, Bozeman, MT, USA ]
- Tom Leonard [ Yellowstone Club Ski Patrol, Big Sky, MT, USA ]
Date: 2016-10-02
Abstract: Since the start of the 2011-12 season the Yellowstone Club Ski Patrol have diligently been collecting detailed observations of surface hoar (SH) presence or absence at 16 sites across Pioneer Mountain in SW Montana, USA. These manual observations have been taken on at least three days per week, and on many additional days when SH formation seemed possible. We now have over 280 days of SH / non-SH observations at 16 sites, at varying elevations, with different aspects and sky view exposures. To our knowledge there is no other data set on manual observations of SH at the mountain range scale, with this combined spatial and temporal coverage. In addition to the manual observations, we have 15 minute observations of temperature and humidity at 1.5m, sky view exposure at all sites, and 15 minute wind speed and direction at half of the sites. Using these data we have examined the dominant controls that explain the spatial patterns of surface hoar at the mountain range scale. Our results show that small-scale site characteristics which influence micrometeorological conditions and the local site level sky view exposure can greatly influence the spatial variability of surface hoar, over and above that which aspect alone can explain. Furthermore, synoptic scale analysis using NCEP/NCAR synoptic composite maps provides insight for SH absence on days when conditions would seem to be conducive for SH formation. These results highlight our incomplete understanding of the SH formation processes at this scale, and have implications for both regional and local scale avalanche forecasting.
Object ID: ISSW16_P3.07.pdf
Language of Article: English
Presenter(s):
Keywords: Spatial variability, Surface hoar, Synoptic approach, Forecasting
Page Number(s): 965-969
Subjects: avalanche forecasting spatial patterns surface hoar
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