THIS SNOWPACK SUMMARY EXPIRED ON February 3, 2015 @ 11:00 pmSnowpack Summary published on February 3, 2015 @ 6:00 am
Issued by Ben Bernall - Kootenai National Forest
Avalanche Character 1: Deep Slab
Deep Slab avalanches are destructive and deadly events that can release months after the weak layer was buried. They are scarce compared to Storm or Wind Slab avalanches. Their cycles include fewer avalanches and occur over a larger region. You can triggered them from well down in the avalanche path, and after dozens of tracks have crossed the slope. Avoid the terrain identified in the forecast and give yourself a wide safety buffer to address the uncertainty.
Our snowpack continues its positive transition to a very strong durable column. Failure deep or at the ground is on large faceted crystals immediately below the Thanksgiving rain crust. This rain crust has been our benchmark layer for the entire season. However we observed this layer decomposing at most locations. This deep slab is difficult to trigger but would be exceptionally destructive when triggered.
Our current snowpack is providing the ideal bed surface for forecasted storm loading (3-6 inches) and wind transport (southwest 14 mph) Monday afternoon and Tuesday. Current surface snowpack conditions are very firm. Our snowpack continues to lag severely (65%) behind annual averages for SWE. Backcounrty travelers should exercise normal cautions until our next storm arrives Tuesday. If the forecasted storm loading and wind transport materialize, then extra caution and good decision making must accompany the increased hazard.
Yesterday, I visited Horse Mountain along the East Front of the Cabinet Range. At 5806 feet I found 32 inches of snowpack on an east aspect. The top inch is new snow from overnight. The next 5 inches is a sandwich of knife hard layers and 4 finger soft snow. Below this is a 3 inch 1 finger hard layer on a 1 inch pencil hard crust. Below this is a 15 inch pencil hard slab on top of the 3 inch pencil hard crust from Thanksgiving. Below this crust is 4 inches of loosely consolidated large facets. The Extended Column Test produced no propagation (partial or full) on any layers.
Weather and CURRENT CONDITIONS
Since the Friday January 30th advisory, weather in the Kootenai Region has been cool and mostly dry. All SNOTEL sites are reporting below freezing temperatures from Friday afternoon through Monday monring. Temperatures during this period have been mostly in the 20's F. Most Snotel sites are showing light increases in SWE (0.2-0.3 inches) except Bear Mountain which reports a 0.7 inch increase. Weather yesterday at Horse Mountian (5806 feet) was overcast, very light snow, nearly calm, 30º F with 1 inch of new snow. Forecasted weather through Wednesday is for nearly complete cloud cover, below freezing temperatures (upper 20s), southwest winds of 14 mph, and 3-6 inches of new snow. Snow transport is probable Monday afternoon and Tuesday morning.
This advisory applies only to backcountry areas outside established ski area boundaries. This advisory describes general avalanche conditions and local variations always occur. This advisory expires midnight on the posted day unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.
This website is owned and maintained by the Friends of the Idaho Panhandle Avalanche Center. Some of the content is updated by the USDA avalanche forecasters including the forecasts and some observational data. The USDA is not responsible for any advertising, fund-raising events/information, or sponsorship information, or other content not related to the forecasts and the data pertaining to the forecasts.