Valdez

Forecast Expired

Above 4,000ftConsiderable

2,000 to 4,000ftConsiderable

Below 2,000ftConsiderable

Degrees of Avalanche Danger

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

Persistent Slab:

Likelihood:

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

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Problem 3

Storm Snow:

Likelihood:

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

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Avalanche Activity

12/26- Skier triggered avalanche on Cracked Ice Buttress: N aspect, 2500′, 37° slope, 18 inches deep, 100 feet wide, ran 200-300 feet. SS-ASu-D1-R1-I

12/24- Skier triggered avalanche on Python Buttress: NW aspect, 2700′, 35° slope, 60 feet wide, ran 200-300 feet.  SS-ASu-D1.5-R1-O

12/18- A large glide release was reported off Snowslide Gulch middle peak size 2.5.

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

12/28: NE winds 60-70 MPH accompanied with 6-8 inches of snowfall at Thompson pass was the story the night of the 27th.

On the 28th snowfall will continue with up to an additional foot of snow expected.  Winds are expected to diminish and move to the south.

 

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`      26 F         23 F

Temp at 3000`      22 F         21 F

Chance of precip   100%         100%

Precip amount
(above 1000 FT)    0.43 in      0.50 in

Snow amount
(above 1000 FT)    6-8 in       2-6 in

Snow level         sea level    sea level

Wind 3000` ridges  S 6-21 mph   LGT/VAR

Remarks...Winds aloft early this morning will be northeast
40 to 60 mph.
  24h snowfall (inches) HN24W (inches)* Hi Temp (F) Low Temp (F) Dec snowfall Season Snowfall Snow height 
Valdez 3 .18 21 17 32 56 28
46 mile 6 .5 15 1 16

Thompson Pass “DOT”

6-8  “wind affected” 10 -3

 HN24W= total water received last 24 hours in inches

Additional Information

Below 4000′ we are developing the perfect recipe for avalanches.  Bed surface, weak layer and a slab.  The 12/9 rain crust will act as our bed surface.  Above the rain crust is our weak layer, a 5 cm layer of facets that has been created by the recent cold weather. Last but not least is our slab, this has been created by snowfall that started 12/22 and is approaching  4′ at Thompson Pass.  This slab is growing in size with heavy snow forecasted through the weekend.  If we receive more significant snowfall it is possible that the weak layer will be overcome by the weight of the new snow and we will see a natural avalanche cycle.  Watch for the hazard to move to high with additional snowfall.

Above 4000′ forecast confidence is low.

There have been limited observations from interior locations due to low snow at lower elevations.  There was a report from 54 mile/ Hurtle creek area that storm totals are in the 18″ range above 4000′.  Use caution if you travel in these areas.

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 Moderate.

Video taken 12/20 in the Mt. Dimond area showing reactive test slopes.   https://vimeo.com/user106668057/review/380916811/02da5d1cc7

Announcements

The avalanche hazard is Considerable at all elevations.  Human triggered avalanches are likely today and natural avalanches are possible on all aspects.  Thompson Pass has received 6-8 inches of new snow coupled with 60 MPH northeast winds gusting to 70 MPH.  This has created deep drifts of new snow that will be sensitive to triggers.  Avoid travel in avalanche terrain today. Expect hazard to increase to high with the additional snowfall that is forecasted through the weekend.