Tuesday – Friday 3/28-31

Issued: Tue, Mar 28, 2017 at 8AM

Expires: Fri, Mar 31, 2017

8” of new snow and more on the way. The likelihood of starting an avalanche is rapidly increasing. The road run can, has, and will avalanche.

Avalanche Center Tsaina Lodge Spring Full Moon Bon Fire FUNraiser

Friday April 14 presenting Acoustic Avalanche

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

TUESDAY WEDNESDAY THURSDAY & FRIDAY

DANGER SCALE

 

STORM SLAB

Elevation: All
Aspect: All
Terrain: All
Sensitivity: Responsive
Distribution: Widespread
Likelihood (Human Triggered): Possible
Size: Small – Large
Danger Trend: Increasing
Forecaster Confidence: Good

WIND SLAB:
Elevation:  
Above 3000′
Aspect:
   Lee to northerly winds
Terrain:
 Near ridgelines, rollovers, and gully walls
Sensitivity:
  Responsive
Distribution:
 Specific
Likelihood (Human Triggered):
Likely
Size:
 Small – 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:

intermountain-zone-iconInter-Mountain (Transitional) Specific: 

With 8” of new snow in town and on the pass, storm and wind slab avalanches are our primary concern. Before this storm, there was enough cold and clear weather to produce a hoar frost (surface hoar) layer in certain areas. Buried hoar frost is the perfect weak layer for the new snow to avalanche on. Ask your self, ” how is the new snow is bonding to the old snow, and is the new snow settling enough to form a cohesive slab that I can hold in my hands?”

In the more dry intermountain and continental areas, there is a lurking danger that lies deep in the snow pack. Sugar snow (facets) make up for the majority of the snowpack near the ground. This is a deep persistent slab which has low probability, high consequence. Reports of massive whumping have confirmed this deep persistent layer. It is most likely to be triggered by heavy loads ie. snowmachines or several people, especially in thin areas such as near ridge lines, rocky spots, or rollovers. As more snow falls, the entirety of the snowpack will be put to the test, and we might see an avalanche consisting of the whole season’s snowpack.

Find more photos and observations at the bottom of the page. Sharing your observations creates an informed community that everyone benefits from at some point.

Recent Avalanche Activity

intermountain-zone-iconInter-Mountain (Transitional) Specific:  

  • Human triggered avalanches sizes D2-2.5 likely on steep wind affected rollovers, ridgelines, and gully walls.
  • March 25 reports of upper elevation (>4500′ elevation) human triggered windslabs to a foot thick releasing off steep slopes. With a D1.5  remotely triggered slide on a southerly aspect between 4,500′-5,500′.

    Loose snow triggered soft slab: ~30cm crown. Gully One (Vertigo)

  • March 24: Small D1 R1 skier triggered wind slab on the west facing wall of Snatch (Gully 2). Recently loaded by NE outflow winds
  • March 22: Small skier triggered slide in Nick’s, size D1, west facing, wind loaded slope.

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 Intermountain Forecasts.
Kyle Sobek

Forecaster: Kyle Sobek