Sunday – Wednesday 3/19-22

Issued: Sun, Mar 19, 2017 at 8AM

Expires: Wed, Mar 22, 2017

Incredibly firm and variable conditions warrant more conservative speeds and plans. Monitor persistent weaknesses buried under firm layers.

Come enjoy the VAC Basecamp FREE classes every day this week in the One Love Lot (MP 29.5). Check our Facebook page for more details!

 

Above 2,500ft Low

1,800 to 2,500ft Low

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

SUNDAY MONDAY TUESDAY & WEDNESDAY

DANGER SCALE

 

 

WIND SLAB:
Elevation:  
Above 2000′
Aspect:
   Lee to northerly winds
Terrain:
 Near ridgelines, rollovers, and gully walls
Sensitivity:
  Stubborn
Distribution:
 Specific
Likelihood (Human Triggered):
 Unlikely
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 slight dusting of snow will hide the alternating hard/soft surfaces, making travel tricky.

Human triggered windslab on weak sugar snow (facets) is unlikely right now, but high consequence. Think about refridgerator size blocks falling down the mountain with you – not pretty. Avoid unsupported slopes. It might take a large load like muliple people or a sled or two to break a thin area free – invision the windslab across the terrain, if it’s connected to a much deeper, steeper pocket over a cliff, it could cause a fatal avalanche.

The outflow northerly wind has been blowing for a month now. The majority of areas have been scoured down to the mid-February rain crust with sastrugi formations to two feet deep.

We are monitoring deeper weaknesses that could reactivate as temperatures warm this spring. March 15 test results at 3200′ on a north aspect in Gully 1 (Vertigo) produced propagation failure 180cm deep in basal facets: PST 90/180 End.

 

Rain Crust from mid Feb.

Find more photos and observations at the bottom of the page. Sharing your observations creates an informed community that everyone benefits from at some point.

Recent Avalanche Activity

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

  • March 7 report of two human triggered size D1 soft slab avalanches (3500’ SW 20cm and 4000’ NE 15cm). Plus long running dry loose and several collapses on low angle terrain.

Recent Weather

See Maritime Zone for updated weather.

Additional Info & Media

Weather Quicklinks:

  • NWS forecast for Northeast Prince William Sound <here>
  • NOAA NWS spot forecast for Thompson Pass <here>
  • Thompson Pass RWIS weather station <here>
  • MP 30 Nicks (Happy) Valley weather station at 4200 feet <here> (scroll to Nicks Valley)
  • Valdez Glacier UAF weather station at 6600 feet <data here> <map here>
  • Further weather resources <here>

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.
Sarah Carter

Forecaster: Sarah Carter