Lawinenlagebericht

Continental

Valdez Avalanche Center
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Lawinengefahr

Hochgebirge
2 · Mässig
Waldgrenze
3 · Erheblich
Unterhalb
3 · Erheblich
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Veraltet — dieser Lagebericht ist last year abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

The avalanche hazard is Considerable below 3500 feet and Moderate above.  Rain on snow has saturated the upper snowpack.  Human triggered and  natural wet loose avalanches are likely in terrain steeper than 35°.  Upper elevations are beginning to see the formation of storm slabs 3-6 inches in depth and will continue to build through the day.  These could be triggered in specific areas where the wind has created deeper pockets.

Expect for storm slabs depths to build over the coming days and become the primary avalanche problem by Monday.

Avalanche Forecasts are issued Wednesday-Sunday at 8 am.  

Lawinenprobleme

  • Loose Wet

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

    Rain on snow is saturating the upper snowpack on all aspects below 3500'.  Human triggered wet loose avalanches are likely in terrain that is steeper than 35°.  The depth of wet loose activity will be dependant upon the terrain.  Steep slopes will allow wet loose to easily initiate, and long continuous slopes will allow entrainment to occur.  Wet loose activity that entrains large amounts of snow will have the potential to trigger wet slab avalanches that would be more destructive.  

    Patience is reccommended today.  This rain event will add strength to the snowpack below 3500' once the slopes are able to thoroughly freeze.  In the meantime, Dangerous avalanche conditions exist in steep terrain below 3000'.  Cautious route finding and conservative terrain choices are reccommended.  Avoid travelling on or below slopes that drain into terrain traps.

     

    Large wet loose natural activity on Snowslide Gulch 4/2

    Photo: Gareth Brown

  • Storm Slabs

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

    Shallow storm slabs are beginning to form above 3500'. Winds have been light with a few moderate spikes reported on weather stations.  Today, it will be possible for a person to trigger small pockets of wind loaded storm snow in steep high elevation terrain.  Storm totals above 4000' are estimated at 3-6" so far with an additional 3-6" possible in the next 24 hours.  Additional snowfall along with dropping temperatures will allow storm slabs to build in depth and are expected to be mostly right side up.  

    It is unclear at this point how well this new snow will bond with the old.  Warm temperatures would normally promote bonding. However, 2 weeks of prior high pressure and diurnal temperature swings has created near surface facets in the upper snowpack.  Winds and above freezing temperatures towards the end of the high pressure have likely broken down these facets to some extent, but that interface will be something to pay attention to for this upcoming week.

    If you make it to upper elevations today, pay attention to new snow amounts, the amount of wind redistribution, and how well the new snow is bonded.  Small inconsequential test slopes and hasty hand shear pits are both useful tools for todays snowpack situation.

Avalanche Discussion

Observed Avalanche Activity last 72 hours: 

4/2- Natural wet loose D2-3 avalanches off Snowslide Gulch and South Three Pigs.

4/2- Numerous D1-2 wet loose avalanches

Forecast Discussion:

The latest extended period of clear weather ended with a switch to southerly winds that ushered in a much warmer air mass while skies remained clear.  This change shot the freezing line to 5000', and has prevented temperatures from dropping below the freezing mark for the last 4 days at all valley locations in our forecast area.  Valdez has not seen below freezing temperatures for nearly 2 weeks.  At the beginning of this warm air mass wet loose activity was highly aspect dependant, as it was driven by solar activity.  The primary driver has now switched to rain on snow that has become moderate to heavy overnight throughout the forecast area.  Today all aspects will have the potential to produce wet loose and potentially even wet slab avalanches below 3500' that could be human triggered or could fail naturally.  

The freezing line is forecasted to drop to near 1000' by tonight which will allow for storm slabs to begin to more meaningfully accumulate and wet loose hazard to SLOWLY decrease.  Snow takes much longer to refreeze  and gain strength especially when clouds remain, than it takes snow to destabilize when dry snow encounters rain.

Only shallow storm slabs currently exist with Nicks reporting 4" of accumulation in the last 24 hours.  Another 3-6" is expected during the day today, with more substantial snowfall expected in the coming days as the freezing line drops and more moisture arrives.

The 3/16 layer of Buried surface hoar has been removed from our avalanche problem list.  Continued observation of this layer within our forecast area has shown the weak layer in question to be highly deformed (rounding), laying flat, mixed with other rounded grains and unreactive in stability tests.  The most recent spike in temperatures has further decreased the likelihood of this layer being reactive in the our forecast area as warm temperatures and moisture continue to promote rounding and mixing of the layer with other rounded grains.  This layer should continue to be monitored for those travelling outside of the forecast area especially in zones to the south and east of Marshall Pass where this layer continues to be reported as preserved.

Additional Information:

Watch out for cornices. A couple of cornice falls have been observed in the Continental region as well as more remote zones outside the forecast area.

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- 4/6 24 hour Snow Water Equivalent Inches Height of Snow April Snowfall Inches Season Total Snowfall Valdez    0    .31    38     0 N/O     Thompson Pass    0    N/O   N/O     0    ~500 Nicks    4    N/O    131    0 N/O 46 Mile    0     .40   18    0 N/O

Abgedeckte Regionen