Valdez

Forecast Expired

Above 4,000ftConsiderable

2,000 to 4,000ftConsiderable

Below 2,000ftModerate

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

Deep Slab:

Likelihood:

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

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Avalanche Activity

Numerous D3 avalanches were observed on the east side of the road, north of Thompson Pass.  Between Gully 1 and Cracked Ice, every buttress had significant avalanches originating from ~3000-3500 ‘, NW-NE aspects.  Gully 1 and 2 had debris in the drainages, with Gully 2 running a considerable distance into the flats.  These avalanches most likely ran between 12/29 and 12/31 during a significant spike in temperatures.  There were many other naturals during this period.  Many of these have been filled in by new snow and are being blowing in by the current wind event, making them hard to see.

12/31 Numerous small-medium natural avalanches observed below 4000′ on steep rollovers on the north side of the pass.

12/30  Natural avalanche observed on Cracked Ice Butress at 2700′.  ~300 meters wide, 1 meter+ deep.  Connected through gullies and over ridges.

D3 avalanche on east face of Mt. Tiekel (MP 50). Ran into top 1/3 of apron.

12/28- Several natural avalanches reported in the 54 mile area near brush line.  100′ wide and ran 300′.  Depth was not observed.

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

1/5: North winds were strong again last night with gusts up to 40 mph. Expect snow showers from last night to taper off today.  Highs will be in the single digits for Thompson Pass with continued strong north wind.

 

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`      12 F         1- 7 F

Temp at 3000`      7 to -15 F   2 to - 8 F

Chance of precip   80%          30%

Precip amount
(above 1000 FT)    0.05 in      0.04 in

Snow amount
(above 1000 FT)    1 in         trace

Snow level         sea level    sea level

Wind 3000` ridges  NE 10-30 mph  NE 8-22 mph

Remarks...Winter Weather Advisory remains in effect through
noon today. Wind chills between -35 F to -45 F this morning.
  24h snowfall (inches) HN24W (inches)* Hi Temp (F) Low Temp (F) January snowfall Season Snowfall Snow height 
Valdez 5 .35 13 0 8 78 37
46 mile Trace 0 -6 -23 2 43 12

Thompson Pass “DOT”

2 .08 -5 -13 16 311 96

 HN24W= total water received last 24 hours in inches

Additional Information

Northeast winds at Thompson Pass were up to 40 mph, with stronger winds at higher elevations. We have also received a couple more inches of snow, which will allow wind slabs to continue to build. This has created instabilities near the surface on lee slopes, (SE-NW).  Avoid areas that have fresh wind slab and slopes that are receiving active wind loading.  Human triggered avalanches 1-3′ deep will be likely, and could step down into deeper layers of the snowpack, creating very large avalanches.  The hazard will remain steady until wind speeds decrease or available snow for transport is exhausted.

 The snowpack is gaining strength with falling temperatures and the end of precipitation.  BUT…. We have a problem layer that is now buried deep within the snowpack.  This poses multiple problems that may make decision making difficult.  Since this layer is buried deeply, it may not show the normal signs of instability- shooting cracks, collapsing.  Also, it may allow multiple people to ski or snowmachine on a slope before someone finally finds the sweet spot and triggers an avalanche.  This type of avalanche will be most likely triggered from areas where the slab is thinner and the weak layer is closer to the surface, near rock outcroppings, or other thin areas of the snowpack.  

 The new snow has opened up different access points.  Use caution as you step forward into new zones.  New snow combined with strong winds from different directions has created a lot of spatial variability in our area.  Careful snowpack evaluation and conservative terrain choices will be critical today.  

 There have been limited observations from interior locations due to low snow at lower elevations.   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 mid and upper elevations.  Human triggered avalanches are likely on recently wind loaded slopes.  Thompson Pass is in the midst of an outflow wind event.  Abundant recent snowfall, combined with strong north wind will easily be forming fresh windslab.  Avoid wind loaded slopes and areas that are experiencing active wind loading. The hazard will remain steady until wind speeds decrease or available snow for transport is exhausted.