Monday-Thursday 4/10-4/13

Issued: Mon, Apr 10, 2017 at 8AM

Expires: Thu, Apr 13, 2017

We have shifted to springtime conditions: avalanche danger decreases with overnight cooling and increases with daytime warming.

Plan your day accordingly to minimize exposure.

Friday April 14: VAC Full Moon Spring Fling FUNraiser with Acoustic Avalanche at the Tsaina Lodge     Grab a partner and boogie!!!

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, southeast, southwest
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:

Continental (Interior) Specific:  

Our Interior region received 1-2″ water equivalent during the March 27-April 6 storm, compared to the 2-4″ on the coastal side of Thompson Pass.

The storm snow is reportedly settling and bonding well to old layers. The exception is a few upper elevation and thinner areas where buried near surface facets are still reactive. The tail end of the precipiation, April 4-6, pushed temperatures above freezing to 4500′ on the north side of the pass and up to 5500′ in the maritime.

April 6-8 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. In shallow areas, wet loose has scoured directly to the ground.

Due to the poor structure, persistent slab problems are still a concern. Weak faceted snow underneath storm slab and/or hard windslab has the potential to be human triggered and step down to weak basal layers. Continue to monitor this structure as temperatures rise and rapid deformation of upper slab stresses what tenuous bonds there are. In addition keep an eye on surface hoar and near surface facets as these could be of concern should they be buried by additional snowfall.

Sharing your observations creates an informed community.

Recent Avalanche Activity

Continental (Interior) Specific: 

  • 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: Contrad Chapman