Avalanche forecast

Maritime

Valdez Avalanche Center
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Avalanche danger

Alpine
3 · Considerable
Treeline
3 · Considerable
Below
1 · Low
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Highlights

The avalanche hazard is CONSIDERABLE above 1500'.  Human triggered avalanches are likely up to 2 feet in depth and natural avalanches are possible. Heavy new snowfall along with rising temperatures and strong wind has elevated the hazard.  Continued precipitation over the next 24 hours will keep the hazard elevated.  

The hazard is low below 1500' due to minimal snow coverage and rain at low elevations.  Keep in mind that avalanches may be able to run into low elevations in defined avalanche paths.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–2.5

    Human triggered avalanches are likely today up to 2 feet in depth.  Conservative terrain choices and advanced route finding skills will be necessary today to safely navigate wind loaded storm slabs on a variety of aspects in whiteout conditions.

    Moderate to heavy snowfall arrived yesterday afternoon with rain and freezing rain on the downstream side of Keystione Canyon.  8 inches of snowfall was reported by DOT and Nicks weather station before switching to rain around 4am at road levels.  This new snow is falling on a very hard bed surface, which may make bonding initially difficult.  Moderate to strong winds were observed and recorded yesterday with changing wind direction, but were predominantly North.  Expect to find wind loading on a variety of aspects that could make assessing loading patterns challenging.  An additional foot of snowfall is possible today above 3000' with rain below.

    In addition to precipitation and wind, there was also a sharp increase in temperatures during yesterdays evening hours.  This change puts additional stress on the snowpack by creating an upside down storm slab, which in turn increases the sensitivity and likelihood for a person to trigger an avalanche.  

     

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    Rain on snow will create the possibility for wet loose avalanches to be human triggered and naturally occur in steep terrain.  In the Maritime zone this will only be a concern at mid elevation, due to a lack of snow at low elevation and snowfall occuring at upper elevations.

Avalanche Discussion

Our snowpack is undergoing a drastic change from wind damaged surfaces of every variety caused by brutal strong arctic winds to now being pressured by a warm and wet low pressure system originating from the Pacific Ocean.  This sort of drastic change will create an increase in the hazard level for any snowpack, but especially so for our thin early season snowpack.  Use caution during this period and give the snowpack time to adjust to these changes.   In addition to avalanche hazards, there are many other obstacles out there , including rocks that have just been shallowly covered, open water, and shallowly bridged crevasses.

The increase in avalanche hazard is being fueled by a very interesting and dynamic series of low pressure systems that are currently affecting our area.   As the storm arrived yesterday temperatures were at or near 0 degrees F on Thompson Pass and North.  Warm air rode over the top of this cold dense air bringing in moderate to heavy precipitation.  This inversion drove strong North winds at the surface with Southerly winds at upper elevations.   This setup is what was driving freezing rain in Valdez during the day yesterday.   As the day moved on and the jet stream moved overhead warm air began to win out and erode the cold air at the surface creating sharp temperature spikes like the one seen at Thompson Pass where the temperature rose 30 degrees in 3 hours during the evening hours.

Warm air will continue to pump into our area through Thursday before snow lines slowly settle to an expected 1500' by Friday.  

Bottom line: The avalanche hazard will stay elevated while this week's storm plays out and our early season snowpack attempts to adjust.  During this time of adjustment, it is possible for the snowpack to become overloaded in places and produce natural avalanches.  Human triggered avalanches are likely.

 

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