Lawinenlagebericht

Intermountain

Valdez Avalanche Center
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Lawinengefahr

Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Kernpunkte

The avalanche hazard is Considerable above 1500'.  Dangerous avalanche conditions exist in many areas throughout our forecast zones. Avalanches large enough to bury a person have been recently observed in terrain over 30 degrees. Safe travel protocols will be essential today. Human-triggered avalanches 1-3 feet deep are likely depending on new snow amounts in the area you travel.  Natural avalanches are possible

Avalanche Forecasts are issued Wednesday-Sunday at 8am.  

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2.5

    Dangerous avalanche conditions exist in all three snow climate zones.  18-30 inches of new snow since the 16th has been observed that overlies buried surface hoar in many areas.  This is currently a widespread problem and is expected to be found in all forecast zones. Slabs will be thickest in upper elevations in the maritime zone where an expected meter of snow has accumulated from the most recent storm. Slab thickness becomes thinner as one moves north Through the Pass toward our continental zone.  Although there is variation in depth, slab avalanches large enough to bury a person are likely through all areas. Deeper slabs may be stubborn to triggers today so remember seeing tracks on a slope does not necessarily mean there is no avalanche hazard. Thinner slabs in the Continental Zone are expected to be more sensitive to human triggers. 

    Recent observations indicate Considerable Hazards throughout all zones and include the following:

    -a small natural or possible remote trigger on Loveland, 

    -multiple larger naturals reported by heli ops in the Keystone Glacier area, 

    -numerous naturals on Mile High at mid and upper elevations

    -Nerourous D2 slabs above Shoup Glacier - mid-mountain. 

    Additionally,  Southerly aspects have all three ingredients necessary to produce an avalanche: Slab(new snow), weak layer(buried surface hoar), and a bed surface ( old melt freeze crust.

    This problem is currently widespread and will likely take a while to heal. Expect this to apply to all aspects and elevations for today. Slabs may be especially sensitive on S-facing slopes that have buried crusts in addition to the weak layer of surface hoar.   

    Conservative terrain choices are recommended.  Slab depths are in the range that can readily be triggered by a person or machine and are deep enough to produce avalanches that are large enough to injure, bury, or kill a person.  The current setup could remain sensitive to human triggers for an extended period, more observations are needed and patience is advised.  

    (3/19/2025)

     Natural avalanche in the books that likely failed on 3/16 BSH

    Photo: Eagan Gleasson

  • Loose Wet

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

    A warm and sunny day will create wet loose hazards.  Temperatures dropped to 20 degrees F last night so there may be a delay to the start of any wet loose activity. Expect solar aspects to produce wet slides large enough to bury or a person today as they gradually warm to above freezing. 

    Wet loose activity is a secondary concern to problem 1 listed above.  Steep terrain that produces wet loose activity will also have the potential for slab avalanches to fail naturally or be human-triggered.   Avoid steep terrain that is being heated up by the sun.  Even small slopes can be dangerous if they are above terrain traps or exposure.  

    Expect southerly aspects to be active in the coming days when the sun is out as new snow sheds from sunny slopes in the form of slab avalanches and wet loose activity.

Avalanche Discussion

Observed Avalanche Activity last 72 hours: 

Numerous D1-D2 Natural and Human triggered avalanches reported from all forecast zones yesterday.

Forecast Discussion:

New snow since 3/16 has now settled into a cohesive slab creating a persistent slab avalanche problem. Human-triggered avalanches are likely today 1-3 feet in depth. Snowfall totals are highest near the coast, with 2-3 feet reported and less so on Thompson Pass with near 2 feet @ 5000' observed on 3/19.  The Continental zone had much lower snow totals between 4-12 inches, but numerous natural and human-triggered avalanches were reported in that zone as well.

Prior to this last storm, we had enjoyed a period of Moderate to Low avalanche Hazard. Problems were easy to assess and short-lived.  This is not currently the case with our current setup. We have large amounts of new snow on top of a significant weak layer of buried surface hoar in many areas. This is creating a hazardous situation that may take a while to heal since surface hoar can persist for a long time.  An example of this is the month-old buried surface hoar in Turnagain Arm that has been recently producing avalanches. This will likely be our primary hazard for the near term and possibly longer. Checking the forecast and observation platform regularly will be the best way to stay informed on this situation. More updates coming soon.

This setup is not only dangerous but can be difficult to assess.  The first person to ski a slope is not necessarily the one that will trigger an avalanche, a slope can fail after numerous tracks have been laid down.  Digging snowpits is a good tool, but can give misleading results as buried surface hoar can be easily missed depending upon where you dig.  In addition, ECTN results are not necessarily an indication that the slope is safe. Deep burial of surface hoar layers may create false stable results in pit tests. It is important to consider that we have several factors pointing to an unstable snowpack. These include: a persistent buried weak layer, a thick cohesive slab, recent avalanche activity, and increasing temperatures in many areas.   Conservative terrain choices and cautious route finding are recommended.  Only expose one person to a slope at a time, know your safe zones maintain good communication with your group, and watch out for other groups that may be recreating in the same area.

This will ba an on going problem so expect more info soon. 

Additional Information:

Watch out for cornices. A couple of cornice falls have been observed in the Continental region.

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- 3/20 24 hour Snow Water Equivalent Inches Height of Snow March Snowfall Inches Season Total Snowfall Valdez    0    0    58     18 N/O     Thompson Pass    0    0   N/O     ~24    ~500 Nicks    0    0    146    15 N/O 46 Mile    0     0   22    5 N/O

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