Friday-Monday 4/28-5/1

Issued: Fri, Apr 28, 2017 at 8AM

Expires: Mon, May 01, 2017

The VAC is wrapping up daily avalanche forecasts for the season this weekend on April 30. While the avalanche hazard will remain well beyond that date, we will monitor any critical developments and post updates only when deemed necessary. Please continue to share your observations so those still recreating in the mountains can stay in tune with the quickly changing snowpack. Thank you all for another great season in the amazing Chugach!!!

The snowpack continues to melt, weaken and fall off the mountains as warm season sets in. Rain, warm temperatures and direct sun can accelerate this process. Limit your lingering below steep slopes to avoid issues.

Above 2,500ft Considerable

1,800 to 2,500ft Considerable

Below 1,800ft Considerable

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

DANGER SCALE

 

 

WET AVALANCHES:
Elevation:
   Below 5500′
Aspect:
   East in AM, South all day, then West in PM
Terrain:
Steep terrain near rocks and vegetation.
Sensitivity:
   Touchy when warmed.
Distribution:
   Specific.
Likelihood (Human Triggered):
  Likely when warmed.
Size:
  Small-Large
Danger Trend:
   Increasing quickly each day with warming temperatures, falling with freezing at night
Forecaster Confidence:
   Good

CORNICE FALL:
Elevation:  all
Aspect:   
all
Terrain:
corniced ridgelines
Sensitivity:   
Responsive 
Distribution:   
Specific
Likelihood (Human Triggered): 
Possible
Size:  
Small to Large
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, Large, Very Large (size scale <here>)
Danger Trend: Increasing, Steady, Decreasing
Forecaster Confidence: Good, Fair, Poor

AVALANCHE PROBLEM TOOLBOX <here>

SNOWPACK DISCUSSION:

Continental (Interior) Specific:

When you add the weight and weakening properties of rain on snow, natural avalanche activity from above is possible. Wet avalanche can travel greater than expected distances and are incredibly dense and powerful. Limit any exposure to overhanging snow and evaluate the snow underneath you as you travel through the mountains. It may be difficult to see signs of red flag activity when the visibility is poor. If the snow is shifting easily under skis or machine and you can easily sink deep into underlying layers of snow, consider calling it a day. Large, crushing, wet slabs can be triggered quite deep this time of year. There is a chance for some snowflake accumulation up high, but it just depends on the air temperatures and mixing patterns up high.

Sharing your observations creates an informed community.

Recent Avalanche Activity

Continental (Interior) Specific: 

  • April 23 Natural wet slab D2.5 above Deserted Glacier, west aspect, 5800′. Lots of south and west cornice failure and wet loose activity into the Woodworth and Deserted Glaciers.

    April 14: reports of cornice failure triggering slab avalanches on steep upper elevation slopes in the Continental zone (see photo)

  • April 14 Cornice failure triggered slab avalanche in the Nelchina area    Photo: Jed Workman

  • March 31: skier triggered size D2 avalanche at 3500′ North aspect. 40-60cm storm slab failed on buried near surface facets with a old windslab as the bed surface. A possible sympathetic released lower on the same slope, with a crown depth 60-100cm, harder slab.

Recent Weather

See Maritime Zone for updated weather.

Additional Info & Media

Weather Quicklinks:

SNOW CLIMATE ZONES:

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

Photo of Thompson Pass

thompson-pass-ski-runs

Interactive Map of Valdez Forecast Areas w/ Many Resource Layers (Trevor Grams)

climate-zones-topoclimate-zones-satellitegoogle-earth1

Run Map of Thompson Pass Area (Sean Wisner) (2MB download)
VAC Run Map Thompson Pass

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 Continental Forecasts.

Forecaster: Kevin Salys