Tuesday-Friday 4/18-4/21

Issued: Tue, Apr 18, 2017 at 8AM

Expires: Fri, Apr 21, 2017

Cornices are starting to fall, bringing the entire seasons snowpack down in a massive avalanche. Winds are picking up creating fresh windslab.

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

TUESDAY WEDNESDAY THURSDAY & FRIDAY

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

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

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:

 

intermountain-zone-iconInter-Mountain (Transitional) Specific: The snow is starting to melt off in the lower and mid elevations especially in areas with lots of sun exposure. Above 4000′, the more northerly aspects, glaciated areas, and wind protected spots, powder snow can be found. Generally speaking, the maritime zones have seen much more snow than the intermountain/continental zones. This has led to a deeper more stable snowpack. With winds picking up today and yesterday, there is a possibility of some fresh windslab popping off near peaks and ridges. The winds should keep things a little cooler than the last few days, but with the amount of sun at this time of year, wet avalanches are still a concern. A rockfall created a massive avalanche on, “The Wall/Tomahawk” see photos in the Maritime forecast.

Snow transport Wed, Apr 14 from strong NE outflow.

Sharing your observations creates an informed community.

Recent Avalanche Activity

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

  • April 12-16 With more direct sun, more wet loose releasing out of steep, south aspects entraining snow to D2.5, sometimes to ground
  • April 7?: Sun induced slab avalanche on the WSW face of Sapphire

    WSW face of Sapphire. 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.
Kyle Sobek

Forecaster: Kyle Sobek