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EXPIRED ON April 15, 2018 @ 5:47 amPublished on April 14, 2018 @ 5:47 am
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Issued by
Nick Meyers - Shasta-Trinity National Forest
LOW danger exists for all aspects and elevations. Normal caution is advised. Watch for falling rime ice off exposed cliffs on the upper mountain, especially in the Helen Lake, Trinity Chutes, Redbanks areas. Smooth, firm snow surfaces provide the chance for a long slide for life on many routes currently. Climb and descend with care, know how to use your ice axe and crampons, wear a helmet. Be prepared for any type of weather in the springtime.
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Forecast Hotline: (530) 926-9613
Below Treeline is the lowest of three elevation bands used in the advisories. It extends from valley floors or snowline to Near Treeline. Open areas and sparse trees are possible. Snowfall tends to be less than the other elevation bands. Tree cover shelters the snow from wind effects.
×Near Treeline is the middle of the three elevation bands used in the advisories. It is a transition zone between dense forests and treeless alpine areas. It is the narrowest of the three elevation bands, extending only a few hundred feet above and below the treeline. It varies locally, and is not a constant elevation or width.
×Above Treeline is the highest of the three elevation bands used in the advisories. It includes alpine areas where the most snow falls and the winds are the strongest. It is not an exact elevation, but a characteristic of the terrain, beginning as the treeline transitions into open slopes extending to ridges and the tops of the highest peaks.
×North American Avalanche Danger Scale
Avalanche danger is determined by the likelihood, size and distribution of avalanches.
Watch for signs of unstable snow such as recent avalanches, cracking in the snow, and audible collapsing. Avoid traveling on or under similar slopes.
Safe backcountry travel requires training and experience. You control your own risk by choosing where, when and how you travel.
North American Avalanche Danger Scale
Avalanche danger is determined by the likelihood, size and distribution of avalanches.
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Natural and human-triggered avalanches unlikely.
Small avalanches in isolated areas or extreme terrain.
Safe backcountry travel requires training and experience. You control your own risk by choosing where, when and how you travel.
North American Avalanche Danger Scale
Avalanche danger is determined by the likelihood, size and distribution of avalanches.
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Natural avalanches unlikely; human-triggered avalanches possible.
Small avalanches in specific areas; or large avalanches in isolated areas.
Safe backcountry travel requires training and experience. You control your own risk by choosing where, when and how you travel.
North American Avalanche Danger Scale
Avalanche danger is determined by the likelihood, size and distribution of avalanches.
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision making essential.
Natural avalanches possible; human triggered avalanches likely.
Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.
Safe backcountry travel requires training and experience. You control your own risk by choosing where, when and how you travel.
North American Avalanche Danger Scale
Avalanche danger is determined by the likelihood, size and distribution of avalanches.
Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
Natural avalanches likely; human-triggered avalanches very likely.
Large avalanches in many areas; or very large avalanches in specific areas.
Safe backcountry travel requires training and experience. You control your own risk by choosing where, when and how you travel.
North American Avalanche Danger Scale
Avalanche danger is determined by the likelihood, size and distribution of avalanches.
Avoid all avalanche terrain.
Natural and human-triggered avalanches certain.
Large to very large avalanches in many areas.
Safe backcountry travel requires training and experience. You control your own risk by choosing where, when and how you travel.
Weather and Current Conditions
Disclaimer
This advisory does not apply to Ski Areas or Highways and is for the Mount Shasta, Castle Lake and Mount Eddy backcountry. Use this information for guidance only. You may find different conditions in the backcountry and should travel accordingly.
A natural wet loose avalanche cycle occurred at the tail end of our recent storm. Numerous natural wet loose avalanches were observed on E-SE-S-SW-W-NW aspects between 7,000-9,000 ft on the south side of Mount Shasta on Gray Butte, Green Butte, Yellow Butte and in Sun Bowl. All avalanches were destructive size 1 (relatively harmless). The avalanches failed within the 6 inches of recent wet storm snow. Mostly likely, the storm snow was rained on overnight on 04/06 causing the avalanche cycle. The avalanches ran 100-600 vertical feet. They all initiated at a point, and entrained snow as they flowed downhill. Debris piles were 1-2 ft deep.
Additionally, a stout rain crust 1-2 inches thick has formed 8,000 ft and higher. The rain crust is supportable and very slick. The rain crust exists as the snow surface up to at least 9,000 ft and likley exists at higher elevations as well. Rain runnels were observed up to 8,500 ft. Snowmobile travel above 8,500 ft was extremely difficult due to the slick rain crust. At elevations 7,800 ft and below, 6 inches of wet sloppy snow exists at the snow surface.