Continental

Problemi valanghivi

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  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta quota
  • Limite del bosco
  • Sotto il limite del bosco

  Probabilità

  Likely

  Dimensione

  1–2

  Snow has returned to sea level with 5" of new snow as of 6 am in Valdez.  Snowfall is expected to turn to rain during the day and when this transition occurs wet loose avalanche activity is expected.  Wet loose avalanches will be larger today as the overnight snowfall will contribute to the potential mass of slides that occur.

   The potential size of wet loose slides is directly correlated to the depth of wet snow and the vertical relief and shape of the slope(does the slope fan out? or does it funnel? Is the wet snow shallow? or Deep?).  The consequences of wet loose activity can be compounded by terrain traps or cliffs.  Dragging a pole basket through the surface of the snow downward on a slope can give you an idea of how much entrainment potential the surface snow has (does it drag straight through? or does it collect snow and spread out as you drag the basket?).  The more entrainment that happens the greater the potential for wet loose to occur in terrain steeper than 35°.

  This problem is expected to grow in depth and distribution as rain is expected to continue through the weekend and become heavier.  

   

• 

  Storm Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta quota
  • Limite del bosco
  • Sotto il limite del bosco

  Probabilità

  Likely

  Dimensione

  1.5–2.5

  Moderate precipitation over the last few days is forecasted to become heavy today with 2-3 feet of snowfall expected over the next 48 hours above 2000'.  Snow levels are forecasted to hover around 1600', but with the strong southerly flow piling warm air into the coast it is very possible that the snow line could go higher.

  On 1/24 storm slabs were found to be 1 foot in depth at 3000' in the Cracked Ice area.  This new snow was found to be right side up with a strong upper snowpack below.  The avalanche hazard will increase today not from a problem with the existing snowpack, but rather from the high precipitation rates that are expected today that will stress the upper snowpack.

  Moderate to strong southerly winds will also play a role in creating areas of unstable snow by loading the lee side of terrain features with deeper storm slabs.  Pay attention to the amount of new snow and the amount of wind redistribution that is present in the area you choose to travel.  Watch for red flags such as snowfall rates of greater than 2"/hour, shooting cracks and collapsing.  The presence of any one of these red flags is an indicator that there is the potential to trigger an avalanche on slopes steeper than 30°.

  

• 

  Deep Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta quota
  • Limite del bosco
  • Sotto il limite del bosco

  Probabilità

  Possible

  Dimensione

  2.5–3.5

  January has been characterized by multiple major snowfall events that have transitioned our snowpack from one that is relatively thin for our region to a deep maritime snowpack.  Once snowfall stops and the snow is allowed to settle and adjust to its new load we will be left with a strong snowpack.  In the meantime while heavy snowfall is occurring DANGEROUS AVALANCHE CONDITIONS EXIST.  

  The storm on the 11th and 12th put enough pressure on the snowpack to flush out the major persistent weak layers of concern in our mid elevations.  We are not necessarily concerned about a specific layer in our snowpack but rather the continual accumulation of heavy snowfall during this month has not allowed the snowpack to fully adjust, creating the potential for deep slab avalanches during times of intense precipitation rates.  

  There is no way to know what the threshold of the snowpack is in different areas.  Keep it simple and avoid large connected slopes steeper than 30° with significant elevation relief.  If travelling in avalanche terrain group up well out of the way of avalanche runout zones.  Previous avalanche cycles this month have paved many runout zones which will allow natural avalanches that do occur to run long distances.