Valdez

Forecast Expired

Above 4,000ftConsiderable

2,000 to 4,000ftModerate

Below 2,000ftLow

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

Storm Snow:

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

 The only new natural avalanche activity in the Thompson Pass corridor was small, wet point-releases off the Nicks and Python Buttresses.  These originated from 3500-4000′ and did not entrain more snow.

 Public observers witnessed natural avalanches on the Valdez Glacier Lake, Hogsback  Ridge and wet slide avalanche activity in the ice climbing areas of Keystone Canyon, Sheep Creek, Bear Creek, and Mineral Creek.  

  The avalanche near Valdez Glacier Lake was a glide crack release off a 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

   Skies began to clear the afternoon of 12/10 and temperatures slowly began to drop.  Overnight skies were clear with light winds. The morning of 12/11 has dawned clear with some lingering low stratus. The wind has switched from onshore to offshore and is now blowing  lightly from the NE. Temperatures have dropped below freezing down to sea level and at 6 am the Thompson Pass temperature was 27 F.

Today skies should remain clear during the morning hours, before a low pressure system in the Gulf begins to spin clouds into our area this afternoon. Winds are forecast to be light out of the NE with highs in the upper 20’s for 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`      36 F         29 F

Temp at 3000`      24-31 F      21-31 F

Chance of precip   40%          40%

Precip amount
(above 1000 FT)    0.03 in      0.04 in

Snow amount
(above 1000 FT)    0 in         trace

Snow level         700 ft       sea level

Wind 3000` ridges  NE 9-19 mph  NE 8-18 mph

Remarks...None.
  24h snowfall (inches) HN24W (inches)* Hi Temp (F) Low Temp (F) Dec snowfall Season Snowfall
Valdez 0 ? ? 27 7 31
46 mile 0 .05 36 25 ? ?

Nicks snotel

(4500′)

0 0 31 29 ? ?
* HN24W= total water received last 24 hours in inches

Additional Information

 Rain runnels were apparent in the snow below 2500′.  With temperatures falling below freezing, the snowpack will begin to lock up and gain strength. From 2500′ to 3200,’ there were 4″ of moist snow sitting on a rain crust.  Above this, the snow became drier and the 12/9-10 storm had consolidated to about a foot thick. Storms from the last week were very warm and fell upon drier, colder snow.  It is a good sign that natural avalanche activity was very limited, but we are still within 48 hours of a significant weather system.  The snowpack is gaining strength but does so slowly.  If you venture into avalanche terrain today, use terrain progression as a tool.  Start with small slopes that have no consequence, before committing to larger slopes.

 Human triggered avalanches are  still likely today in the upper elevations.  Avoid wind loaded slopes above 32°.  Windslab will often have a hollow, drum-like feel.  Also watch out for cornices that have likely grown in size over the last few days and will be adjusting to their new weight.

 In moderate elevations where rain fell on snow,  expect the hazard to decrease as temperatures cool.  Finding a rain crust on the surface will be a good indicator that the snow surface has refrozen and is beginning to gain strength.

 The hazard will SLOWLY decrease as temperatures cool off.  The snowpack will need time to adjust to its new load.  Be patient, and avoid cross-loaded gullies, avalanche paths, and terrain traps.  Careful decision making and route finding will be necessary.  

If you travel into the upper elevations today, 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.

Announcements

The avalanche hazard is Considerable today at Upper elevations.  Triggering wind slab avalanches up to 2 1/2 feet deep will be likely today on NE through NW aspects, especially on the lee side of ridge lines.  Avoid travel in avalanche paths today and stay away from runout zones.  The snowpack is becoming more stable with cooling temperatures, but needs time.  With limited observations from the upper elevations, the hazard remains considerable.