Tuesday-Friday 2/28-3/3

Issued: Tue, Feb 28, 2017 at 8AM

Expires: Fri, Mar 03, 2017

The North outflow winds are back. If you ski or high mark a slope with wind affect, it has a much greater chance of sliding than unscathed powder snow.

Above 2,500ft Considerable

1,800 to 2,500ft Moderate

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

TUESDAY WEDNESDAY THURSDAY & FRIDAY

DANGER SCALE

 

WIND SLAB:
Elevation:
  Above 3000′
Aspect:
   Lee to northerly winds
Terrain:
  Near ridgelines, rollovers, and gully walls
Sensitivity:
  Responsive
Distribution:
Specific
Likelihood (Human Triggered):
  Possible
Size:
Small – Large
Danger Trend:
   Increasing
Forecaster Confidence:
   Poor

PERSISTENT SLAB:
Elevation:
  All
Aspect:
  All
Terrain:
Most
Sensitivity:
  Non-reactive
Distribution:
  Widespread
Likelihood (Human Triggered):
  Unlikely
Size:
  Small – Large
Danger Trend:
  Decreasing
Forecaster Confidence:
  Poor

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 Interior region of the Chugach has seen significantly less precipitation compared to costal areas. Mid January Basal Facets (sugar snow) were found on a widespread scale through out this part of the range. These Basal Facets take time, possibly even an entire season to change their structure into something less avalanche prone. The likelihood of triggering an avalanche on these Basal Facets is low, but the consequences are high (could be fatal). This is why travel techniques (1 at a time) are crucial in exposed areas i.e. through/under an avalanche path, terrain traps.

Four feet of new snow was found February 16th at Milepost 54, rain soaked it to ~2800′ elevation during the February 13th/14th warm and wet storm, this storm triggered several avalanches (size 2+) running on Basal Facets. A few inches of soft snow have accumulated over that crust.

Surface hoar and near surface facets formed February 18-22. New windslabs may be covering this weakness.

Crudbusters Surface Hoar to 6mm

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

Continental (Interior) Specific: 

  • No slab avalanches have been observed as of 2/18 above timberline, but VERY limited observations have been made.
  • 4′ of new snow reported at 56 mile last week below timberline, rain has fallen on this new snow, with only a dusting of new on top.
  • Rain fell above timberline all the way through Pump Station 12 and into Kenny Lake (Feb 13)

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 Continental Forecasts.
Kyle Sobek

Forecaster: Kyle Sobek