Tuesday – Friday

Issued: Tue, Dec 20, 2016 at 8AM

Expires: Fri, Dec 23, 2016

Choose conservative routes. Windloading near ridgelines is adding stress to persistent weak layers in upper start zones.

Above 2,500ft Considerable

1,800 to 2,500ft Considerable

Below 1,800ft Moderate

Degrees of Avalanche Danger ?

1. Low
2. Moderate
3. Considerable
4. High
5. Extreme

Avalanche Danger Rose ?

Avalanche Problems ?

Problem Details

3-considerable 3-considerable



Elevation: Above 2000′ elevation
Aspect: All
Terrain: Primarily steeper than 35 degrees
Sensitivity: Responsive
Distribution: Widespread
Likelihood (Human Triggered): Likely
Size: Small to Medium
Danger Trend: Steady
Forecaster Confidence: Fair


Elevation: Mostly above 2500′
Aspect: All
Terrain: Steep rocky slopes where facets exist under old windslab
Sensitivity: Stubborn
Distribution: Specific
Likelihood (Human Triggered): Possible
Size: Small to Medium
Danger Trend: Steady
Forecaster Confidence: Poor

Sensitivity: Non-reactive, Stubborn, Responsive, Touchy
Distribution: Isolated, Specific, Widespread
Likelihood: Unlikely, Possible, Likely, Nearly Certain
Size: Small, Medium, Large, Very Large (size scale <here>)
Danger Trend: Increasing, Steady, Decreasing
Forecaster Confidence: Good, Fair, Poor



Over the past four days, since Saturday December 17, two feet of new snow has accumulated. The new snow is settling and wind drifted to knee deep where wind affected.

On 12/17 a deep hard slab natural avalanche was observed on the northwest aspect above the main gully of North Odyssey above Milepost 27.5, reinforcing the concern the sugar snow (facets) on the ground have the potential to release the entire season’s snowpack.

  • December 17th: Snowmachines caused cracking down to the persistent weak layer.


Find more photos and observations at the bottom of the page. Sharing your observations helps others make informed decisions.

Recent Avalanche Activity

  • Signs of instability were seen and felt by skiers and riders December 18 & 19: cracking, whumphing, and collapsing throughout Thompson Pass area. Scroll down below the forecast to view observation submissions.
  • December 17th a natural avalanche was spotted in the main gully of North Odyssey that released to the ground.

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):  20 / 30
Ridgetop Wind Forecast (mph): E / 10-20
Snowfall (in):  4-5
past 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction 0 S / 15
Max Wind Gust (mph) / Direction 0 SE / 25
Temperature Min / Max (*F) 18 /31 12 / 25

Weather Forecast: 4-5 inches of snowfall possible Tuesday, tapering to cloudy skies and possibly a few snowflakes Wednesday. Clear breaks Thursday. Light to moderate onshore south-easterlies until outflow northerlies return with the clearing skies. Temperatures in the mid-teens until dropping into single digits Thursday.

Additional Info & Media

SNOW HISTORY: Valdez 12/20 AM Thompson Pass 12/20 AM
24 Hour Snow / Water Equiv. 9” /0.73″ 7″ /0.8″
Storm Snow /Water Equiv. (12/20) 9” /0.73″ 7″ /0.8″
Current Snow Depth 31.49″ 27″
December Snow / Water Equiv. 59.8″ /3.6″ 40″ / 3.3″
Total Winter Snowfall / Water Equiv. 82.2″ / 7.7” 112″ / 11.6″
Snowload in Valdez 17 lbs/sq. ft.


Nicks Valley at 4200 ft (in): 7″
Upper Tsaina at 1750 ft (in): ~5″
Sugarloaf at 550 ft (in): ~5″
SNOW DEPTH & WATER SURVEY (12/6/2016) Depth Snow Water Equivalent
Milepost 2.5 Valdez  13.2″  2.3″
Milepost 18 15.4″ 2.1″
Milepost 29 Worthington Flats 32.2″ 6.4″
Milepost 37 Tsaina River bridge 24.1″ 4.1″
This survey is done the first week of each month beginning in December.

Weather Quicklinks:

  • NWS forecast for Northeast Prince William Sound <here>
  • NOAA NWS spot forecast for Thompson Pass <here>
  • Thompson Pass RWIS weather station <here>
  • MP 30 Nicks (Happy) Valley weather station at 4200 feet <here> (scroll to Nicks Valley)
  • Valdez Glacier UAF weather station at 6600 feet <data here> <map here>
  • Further weather resources <here>


  • Maritime (Coastal) – from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  • Inter-mountain (Transitional) – between Thompson Pass and Rendezvous Lodge.
  • Continental (Interior) – the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).

Photo of Thompson Pass <here>

Map of Valdez Forecast areas and recreating zones <here> (Thank you Trevor Grams)

Run map of some of the forecast area (2MB download)<here> (Thank you Sean Wisner)

NEWS: Our region is “one of the snowiest places on earth” – Serendipity / Rendezvous snowfall record set in 1963 <here>.

Free smart phone avalanche forecasts at: http://www.avalancheforecasts.com/

Posted in VAC Forecasts.
Pete Carter

Forecaster: Pete Carter