Tuesday – Friday 3/28-31

Issued: Tue, Mar 28, 2017 at 8AM

Expires: Fri, Mar 31, 2017

Conservative terrain choices and attentive snowpack observation will reduce your risk to triggering a persistent avalanche problem. Thinner areas above terrain traps should be avoided.

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 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

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

PERSISTENT:
Elevation:
  Above 2500′
Aspect:
more likely on northerly aspects
Terrain:
unsupported steep slopes with thin coverage
Sensitivity:
  Stubborn
Distribution:
  Isolated where windslab exists over facets/depth hoar
Likelihood (Human Triggered):
   Possible
Size:
  Small – Large
Danger Trend:
   Steady
Forecaster Confidence:
  Poor

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:  

With 8” on the pass but only 2” at 46 mile, the avalanche problem is increasing. 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.

Recent Avalanche Activity

Continental (Interior) Specific: 

  • Report from March 25: reports of upper elevation (>4500′ elevation) human triggered windslab to size D1.5 to a foot thick releasing off steep slopes, mostly in the Maritime to Intermountain areas
  • Report from March 24: significant collapses, as large as whole basins whumphing, in areas on the northerly and easterly outreaches of our Inter-mountain zone, and into the Continental zone.

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.
Kyle Sobek

Forecaster: Kyle Sobek