Valdez

Forecast Expired

Above 3,000ftConsiderable

1,500 to 3,000ftModerate

Below 1,500ftLow

Degrees of Avalanche Danger

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Avalanche Problems

Problem 1

Wind Slab:

Likelihood:

  • Almost Certain
  • Very Likely
  • Likely
  • Possible
  • Unlikely

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Problem 2

Glide Avalanches:

Likelihood:

  • Almost Certain
  • Very Likely
  • Likely
  • Possible
  • Unlikely

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Problem 3

Persistent Slab:

Likelihood:

  • Almost Certain
  • Very Likely
  • Likely
  • Possible
  • Unlikely

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Avalanche Activity

12/18- A large glide release was reported off Snowslide Gulch.

12/15- Observed small natural avalanche on west aspect of Goodwills.   Released below a cliff band at the bottom of a slope, 100′ wide.   SS-N-D1-N

12/8-  An observer witnessed a glide crack avalanche.  SW aspect of peak 4690′ above the Valdez Glacier Lake. The debris reportedly ran all the way to the lake, with the deposition pile only feet away from a well used cross country ski trail.

Weather

12/19- High pressure will ease into south-central Alaska over the next few days.  This high pressure will usher in the coldest temps of the year and strong outflow winds.  Expect dangerous wind chill in Thompson Pass.

 

The Thompson Pass Mountain Forecast covers the mountains (above
1000 ft) surrounding Keystone Canyon through Thompson Pass to
Worthington Glacier.

This forecast is for use in snow safety activities and emergency
management.

                   Today        Tonight

Temp at 1000`      23 F         9-15 F

Temp at 3000`      16-24 F      4-15 F

Chance of precip   20%          20%

Precip amount
(above 1000 FT)    0.02 in      0.03 in

Snow amount
(above 1000 FT)    trace        trace

Snow level         sea level    sea level

Wind 3000` ridges  NE 20-35 mph NE 25-45 mph
  24h snowfall (inches) HN24W (inches)* Hi Temp (F) Low Temp (F) Dec snowfall Season Snowfall
Valdez 0 0 31 24 7 31
46 mile 0 0 13 6

Nicks snotel

(4500′)

0 0 24 15

 HN24W= total water received last 24 hours in inches

Additional Information

As high pressure moves in, north winds are forecasted to ramp up and become widespread.    There is up to a foot of dry snow available for transport.  Strong north wind will redistribute the surface snow and form windslab on lee aspects that could be sensitive to triggers.

With the first real cold snap of the season, we should be looking for the snowpack to begin to lose strength at the surface and below.  Surface hoar up to 4 mm has been observed up to brushline on Thompson Pass.  Much of this will likely be knocked down by wind, but not in protected areas where it will continue to grow with falling temperatures.  Below the surface, we have two significant rain crusts in the top meter of the snowpack below 4500′.  These layers, which are currently strong, will begin to lose strength as they form facets.  The longer the cold snap is, the more these layers will lose strength.

The avalanche hazard is considerable today in the upper elevations.  Fresh windslab is forming and could be reactive to triggers.   It is also possible that avalanches could step down into deeper layers of the snowpack and create much larger avalanches.  Only expose one person to a slope at a time and avoid slopes that are receiving active wind loading

The further north you go from Thompson Pass, expect thinner snowpacks.  Triggering an avalanche on a persistent weak layer will be more likely in the continental zone.

If you have traveled in the mountains, please leave a public observation.  The more info we can get from various locations will help us to get a clearer picture of the snowpack in our beautiful Valdez Chugach! 

Forecast Confidence is Low.

Announcements

The avalanche hazard is considerable at upper elevations.  Human triggered  avalanches are likely on steep terrain in areas that have recently been loaded by north wind. Good indicators for windslab are a rapid increase in depth of the new snow over a short distance, and a hollow, drum-like feel.  Shooting cracks will indicate unstable snow.  Use caution in the mountains today, avoid areas that are receiving active wind loading and avoid terrain traps.