Monday-Thursday 4/10-4/13

Issued: Mon, Apr 10, 2017 at 8AM

Expires: Thu, Apr 13, 2017

Springtime conditions: avalanche danger decreases with overnight cooling and increases with daytime warming.

Plan your day to minimize your exposure to steep slopes later in the afternoon.

Friday April 14: VAC Full Moon Spring Fling FUNraiser with Acoustic Avalanche at the Tsaina Lodge

Above 2,500ft Moderate

1,800 to 2,500ft Moderate

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

MONDAY TUESDAY  WEDNESDAY & THURS.

DANGER SCALE

WET AVALANCHES:
Elevation:
   Below 5000′
Aspect:
 South, East in AM, West in PM
Terrain:
Steep terrain near rocks and vegetation.
Sensitivity:
   Touchy when warmed.
Distribution:
   Specific.
Likelihood (Human Triggered):
   Possible
Size:
  Small-Large
Danger Trend:
   Increasing quickly each day with warming temperatures, falling at night
Forecaster Confidence:
   Good

PERSISTENT SLAB:
Elevation:
  Above 2500′
Aspect:
 All
Terrain:
Slopes > 35*
Sensitivity:
   Stubborn on northerlies, Touchy when warmed by sun
Distribution:
   Widespread
Likelihood (Human Triggered):
   Possible
Size:
  Small – Large
Danger Trend:
   Decreasing
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:  

A few natural slab avalanches were observed Sunday April 9 triggered by sun/daytime warming on westerly aspects (see photos in avalanche activity section and observation page.) In the heat of the afternoon, the near surface facets (NSF) buried March 27 appear to be failing and allowing the new slab to move off the steeps with crowns zippering between rock bands. Until these persistent NSF change, this activity might prove to be reactivated each time the overlying slab is warmed.

The storm that ended April 6 laid down 2-4 inches of water equivalent in our upper elevations; 3-4 feet of snow up high on the coastal side with rain below ~3600′. Much less precipitation fell interior of Thompson Pass. The tail end of the precipitation, April 4-6, pushed temperatures above freezing to 4500′ on the north side of the pass and up to 5500′ in the maritime, this created some variations within the storm snow layers, and some micro crusts down low. Daytime green house effect (short wave radiation bouncing between the snow surface and cloud cover) and periods of direct sunshine caused wet loose activity to entrain and step down, releasing slab avalanches to size D3 April 6-8. In really shallow areas, wet loose has scoured directly to the ground.

With a few flurries, keep an eye on surface hoar and near surface facets getting buried, as these could be a future concern.

Sharing your observations creates an informed community.

Recent Avalanche Activity

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

  • April 9: new natural slab avalanches on the WSW face of Sapphire and west aspect in the Books.

    April 9 Avalanche in motion on west face in the Books. Photo: Bobby Lieberman

    April 9 WSW face of Sapphire. Fresh natural slab avalanche. Photo: Steve Schumm

     

     

     

 

  • April 6-8 Large wet debris running far into flats on south side of Tone’s Temple.

    April 6-8 Wet loose triggered slabs off of southerlies along Worthington Glacier.

    April 6-8 Sun triggered loose slides off Girls Mountain south face.

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.

Forecaster: Contrad Chapman