Sunday – Wednesday

Issued: Sun, Dec 04, 2016 at 8AM

Expires: Wed, Dec 07, 2016

 

Beware triggering windslabs. Brutal windchill.

Above 2,500ft Considerable

1,800 to 2,500ft Moderate

Below 1,800ft Low

Degrees of Avalanche Danger ?

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

Avalanche Danger Rose ?

Avalanche Problems ?

Problem Details

GENERAL DANGER RATING OUTLOOK

SUNDAY MONDAY TUESDAY & WEDNESDAY
2-moderate 2-moderate

DANGER SCALE

WIND & PERSISTENT SLAB:

Elevation: All, particularly treeline and alpine
Aspect: All where exposed to wind
Terrain: Ridgelines, rollovers, cross-loaded features
Sensitivity: Responsive
Distribution: Specific features
Likelihood (Human Triggered): Likely
Size: Small to Medium
Danger Trend: Steady
Forecaster Confidence: Good
Details: North wind is creating new slabs and adding weight and stress on persistent facets (sugar snow) lower in the snowpack.

AVALANCHE PROBLEM SCALE DESCRIPTORS:

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

LIST OF AVALANCHE PROBLEMS <here>

SNOWPACK DISCUSSION:
One to two feet of new snow fell Thursday December 1st. Northerly outflow winds to 80mph across exposed terrain has redistributed the snow into hard windslab and drifts.

Windslabs have released naturally and stepped down to deeper, persistent, weak layers. Both mid-pack and ground level faceted sugar snow layers fail in tests with hard slab precariously sitting on the weak sugar snow.

20161202 Strong Outflow Winds

20161202 Strong Outflow Winds

20161202 Outflow winds at the gap

20161202 Outflow winds at the gap

Find more photos and observations below: at the bottom of the page. Sharing your observations helps others make informed decisions about where and how to go.

Recent Avalanche Activity

  • 20161203 Bald Boy & Adjacent Sympathetic?

    20161203 Bald Boy & Adjacent Sympathetic?

  • 20161203 Triggered from below

    20161203 Triggered from below: Odyssey Lake

  • Clear skies Friday and Saturday, December 2nd and 3rd, revealed a scattering of naturally releasing avalanches due to wind loading on mostly southerly aspects with one northerly exception:
    • North face of Odyssey: D2 cross-loaded slab release: crown already filling back in: ripped to rocks in a sections of the track
    • MP 33-35: North side of highway: South faces of Max High and peak to the left: wind slab and loose dry to size D2
    • West Peak above airport: D2 loose snow coming out of steep, rocky terrain running down a chute several hundred feet
20161202 N Odyssey Cross Loaded Slab Release

20161202 N Odyssey Cross Loaded Slab Release

20161202 Mile Post 33 Natural Avalanches

20161202 Mile Post 33 Natural Avalanches

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F): -10/0
Ridgetop Wind Forecast (mph):  NE/40-60
Snowfall (in): 0
WIND & TEMPERATURE Past 24 Hours: Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction 25 / NE 43 / NE
Max Wind Gust (mph) / Direction 30 / NE 60 / NE
Temperature Min / Max (*F) 19 / 28 -10 / 2

Beautiful views. Cold. Brutal windchill. Chance of a snowflake Tuesday and Wednesday.

Additional Info & Media

SNOW HISTORY: Valdez 12/4 AM Thompson Pass 12/4AM
24 Hour Snow / Water Equiv.  0” /0″ 0″ /0″
Storm Snow /Water Equiv. (11/30-12/1) 19” /1.4″ 8″ /0.6″
Current Snow Depth 18″ 18″
December Snow / Water Equiv. 19″ / 1.4″ 8″ / 0.6″
Total Winter Snowfall / Water Equiv. 41″ / 5.5” 80″ / 8.9″
Snowload in Valdez 10 lbs/sq. ft.

 

SNOWFALL for LAST 24 HRS at OTHER STATIONS:
Nicks Valley at 4200 ft (in): 0
Upper Tsaina at 1750 ft (in): 0
Sugarloaf at 550 ft (in): 0
SNOW DEPTH & WATER SURVEY (date) Depth Snow Water Equivalent
Milepost 2.5 Valdez  ?″  ?″
Milepost 18 ?″ ?″
Milepost 29 Worthington Flats ?″ ?″
Milepost 37 Tsaina River bridge ?″ ?″
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>

SNOW CLIMATE ZONES:

  • 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 <here>

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