Friday – Monday

Issued: Fri, Dec 16, 2016 at 8AM

Expires: Mon, Dec 19, 2016

New snow will lightly cover up hazards, and slide easily on certain surfaces. Be aware of what you are traveling above and below.

Above 2,500ft Moderate

1,800 to 2,500ft Low

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

FRIDAY SATURDAY SUNDAY&MONDAY
2-moderate 3-considerable 3-considerable

DANGER SCALE

PERSISTENT SLAB:

Elevation: Mostly above 2500′
Aspect: Mostly South and West aspects.
Terrain: Areas that have been loaded by the wind.
Sensitivity: Stubborn
Distribution: Specific
Likelihood (Human Triggered): Possible
Size: Small to Medium
Danger Trend: Increasing
Forecaster Confidence: Fair

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:

Dust on crust on the pass with 1” reported from the last 24 hours. With more snow expected today and tomorrow in addition to rising temperatures, avalanche conditions will increase as the snowpack adjusts to this new snow load.  The facets at the ground are a recipe for a dangerous avalanche, and the entire season’s snowpack could release on this layer with the right load like a snowmachine (ECTP25 on 12/14/16). Over the next few days be aware of fresh storm snow avalanches, especially in more wind protected areas where the new snow has buried a surface hoar layer (observed 12/14) which formed from the clear cold nights the previous week.

  • December 11th: A snowmachine remotely triggered a very large crack on a windloaded slope breaking deep into the snowpack.

20161211 Wind Slab Cracks

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

Recent Avalanche Activity

  • No new avalanche activity observed
20161211 North aspect of Berlin

December 11: Slab release on north aspect of Berlin Wall

 

20161210-natural-wind-slab-to-ground-in-gully-1-vertigo

December 10: Slab avalanche to the persistent weak layer ground; Milepost 29

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):  20/28
Ridgetop Wind Forecast (mph):  0-25/ SE
Snowfall (in):  6-12
WIND & TEMPERATURE
past 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction  5 / NE 19 / SE
Max Wind Gust (mph) / Direction 9/ NE 26 / SE
Temperature Min / Max (*F) 18 /24 -3 / 23

As more snow is pushing into the Valdez area from the South West, expect anywhere from 2′ inches to 1 foot of new snow with light winds in town and guests to 25 mph on the pass. As temps are continuing to warm, the ultimate questions are: how warm will it get and where will it result in rain versus snow? By Sunday and Monday, high temperatures will top out above freezing in town and reach the high 20’s (*F) on Thompson Pass before cooling again. Precipitation will continue into next week.

Additional Info & Media

SNOW HISTORY: Valdez 12/16 AM Thompson Pass 12/15 AM
24 Hour Snow / Water Equiv. 4.7” /0.25″ 1″ /0.1″
Storm Snow /Water Equiv. (12/15-12/16) 4.7” /0.25″ 1″ /0.1″
Current Snow Depth 19″ 19″
December Snow / Water Equiv. 36.7″ / 2.5″ 21″ / 1.6″
Total Winter Snowfall / Water Equiv. 59″ / 6.6” 93″ / 9.9″
Snowload in Valdez 10 lbs/sq. ft.

 

SNOWFALL for LAST 24 HRS at OTHER STATIONS:
Nicks Valley at 4200 ft (in): 2
Upper Tsaina at 1750 ft (in): 1
Sugarloaf at 550 ft (in): 3
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>

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 (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.
Kyle Sobek

Forecaster: Kyle Sobek