Thursday-Sunday 4/20-4/23

Issued: Thu, Apr 20, 2017 at 8AM

Expires: Sun, Apr 23, 2017

Plan ahead for your spring mountain travel where timing is everything. Start early, finish early. Look at the max/min temperatures, think about your aspects and consider when the snow will start loosening up and easily fall off the mountains. Travel intentionally……

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

THURSDAY FRIDAY SATURDAY & SUNDAY

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):
  Possible
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

WIND SLAB:
Elevation:   Above 3000′
Aspect:   Southerlies
Terrain: Near ridgelines, rollovers and gully walls.
Sensitivity:   Responsive to Touchy when sitting on sun crust.
Distribution:   Specific.
Likelihood (Human Triggered):  Possible
Size:   Small
Danger Trend:  Steady
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:  The snow down low is melting fast, while up in the alpine from 54 Mile, there were reports hard windblown snow at elevation.

Cooler temps will linger through Thursday, but as clouds move in, expect temperatures to rise into the weekend….leading to greenhouse warming of the atmosphere. Continuously monitor the freezing level and weakening of the snowpack around you.  Think about how the wind, if any, is affecting the terrain surrounding you. Ask yourself, “Are the winds keeping the snow around and above me cold?” “How long has that face been baking and is it losing its bonds?” It is all about finding that right balance when the snow has just softened up and hasn’t turned into complete mashed potatoes (isothermal).

Cornices have also been falling recently, which could trigger secondary, deep avalanches below.  And don’t forget about the high elevation (4000’+) northerly aspects, which are still holding good powder….seek those out, but think about the terrain you cross to get there.

Sharing your observations creates an informed community.

Recent Avalanche Activity

Continental (Interior) Specific: 

  • 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