Lawinenlagebericht

Continental

Valdez Avalanche Center
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Lawinengefahr

Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Kernpunkte

The avalanche hazard is Moderate at all elevations. In upper elevations, it may be possible for a person to trigger an isolated windslab that is up to a foot deep.   Warm temperatures and potentially rain at lower elevations will create the possibility of natural and human-triggered wet loose avalanches today.  

Public avalanche forecasts are issued Wednesday- Sunday at 8 am

Lawinenprobleme

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Wet loose avalanches will be possible at elevations below 1500 feet where warm temperatures and rain are expected to occur today. Cloudy conditions will limit any solar-triggered activity on higher south-facing slopes.  With temperatures just above freezing and small amounts of rain, we don't expect a big wet cycle but this will be something to keep an eye on. If you travel at lower elevations pay attention to how temperature and precipitation is affecting the upper snowpack. In areas where snow becomes sticky and produces rollerballs, the wet loose hazard is increasing. 

     Observations from Keystone Canyon on Wednesday showed only a very thin melt-freeze crust at the surface with ~6 inches of dry snow beneath.  If this crust is able to break down during the heat of the day, dry snow will become susceptible to wet loose activity.  Wet loose activity is expected to be confined to the 6-10" of settled new snow that has fallen over the last week.  

     When assessing wet loose hazards, it is essential to take the hazard in relation to the terrain you are exposing yourself to.  Are there terrain traps? Are there consequences if I were to be swept off my feet by even a small avalanche? 

    The size and shape of the terrain above you along with the amount of loose snow available to slide, directly correlates to the size of the wet loose activity that can occur. Terrain traps and exposure below you compound consequences.

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Isolated areas of windslab up to a foot thick may be encountered in mid and upper elevations today.  Observations throughout our forecast area from the last week have shown few signs of instability in most areas. The exception is small areas of instability where the wind has stiffened and deepened old storm snow.  These include slopes below high-elevation ridges in wind-channeled terrain or cross-loaded gullies. Watch for signs of wind-loaded snow such as fresh wind lips, and areas that have a pillowed look or rippled texture especially if you travel in complex or unfamiliar terrain. 

    For better stability and riding quality, seek out areas that are unaffected by wind, luckily these areas are pretty easy to find right now.

     

    Signs of instability within a small pocket of wind loaded snow. Loveland Basin 2/19

    Photo: Gareth Brown

Avalanche Discussion

Observed Avalanche Activity last 72 hours: 

Numerous small wet loose slides at low/mid elevation on the South side of Thompson Pass

For information about the previous Deep slab avalanche cycle, click the avalanches tab below the bottom line statement once you have entered the full forecast for a partial documentation of activity.

Three Pigs natural avalanche information click link here.

For a more detailed Keystone Canyon observation with full pit profile click link here.

Forecast Discussion:

Generally good stability has been observed throughout our forecast zones for the last several days. Gradual changes including warming temperatures, additional snow, and increasing solar input have been slowly affecting our upper snowpack.  For the last week including today, effects on overall stability have been minor. Small wet loose slides in lower elevations and south-facing slopes have been the only observed activity over this period.   

New snowfall amounts over the last week have been light and gradual with 6" settled down low and up to 10" up high.  This has not caused a dramatic increase in the avalanche hazard as storm slabs remain shallow and winds have been light.  This new snow is falling on buried surface hoar up to 3k, with very developed grains between 1500'- 2500' depending upon location.  Despite the weak snow at the interface at specific elevations, shallow slabs (~6") have not yet created an issue except for consequential low-elevation terrain.  Above 3k the new snow is well bonded to old wind-affected surfaces with a notable low amount of spatial variability. 

For the near future, we expect more gradual change with moderately impactful weather.  Lingering wind slabs will continue to gain strength in upper elevations.  Warming temperatures into next week may drive an increase in wet loose activity.

Wet loose avalanches are a concern at low elevations in steep terrain.  

At low elevations in Keystone Canyon there ~6 inches of dry snow above a rain crust from late January. Below this crust is a layer of facted snow.  These facets showed signs of propagation in ECT tests when isolated.  This has not been listed as a specific avalanche problem as it is unlikely for a person to cause the rain crust to fail on a slope of any reasonable size due to its connective strength.   There is a concern though, that this layer could produce human-triggered avalanches up to 1 foot in depth on steep unsupported slopes where the continuity of the rain crust could be compromised and act as a slab.

The deep slab avalanches that occurred in late January are now believed to be a dormant problem that will require a significant change in weather to reactivate.

 

Additional Information:

Active rockfall has been recently reported in Keystone Canyon.

A weather and snowpack season history is available by clicking on the Season Summary tab which is located below the bottom line statement once you have entered the full forecast.

Season Snowfall Data

Location 24 hour Snowfall Inches- 2/19 24 hour Snow Water Equivalent Inches Height of Snow February Snowfall Inches Season Total Snowfall Valdez   0    0    50     10      Thompson Pass    0    0   N/O    9    ~500 Nicks    0    0    143    6 N/O 46 Mile    0     0   24    4 N/O

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