Tuesday-Friday 2/21-24

Issued: Tue, Feb 21, 2017 at 9AM

Expires: Fri, Feb 24, 2017

Look for sugar snow (facets) under all the new snow. If you find sugar snow, the slab of snow over it has the potential to release.

Use safe travel techniques. Don’t expose more than one person at a time on avalanche prone slopes.

Above 2,500ft Moderate

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

TUESDAY WEDNESDAY THURSDAY & FRIDAY

DANGER SCALE

 

WIND SLAB:
Elevation:
  Above 3000′
Aspect:
  Mostly north and west
Terrain:
  Near ridgelines, rollovers, and gully walls
Sensitivity:
  Responsive
Distribution:
Specific
Likelihood (Human Triggered):
  Possible
Size:
Small – Large
Danger Trend:
  Steady
Forecaster Confidence:
  Fair

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: 

Four feet of new snow reported at 56 mile last week with rain falling on this new snow since then.

The upper elevations have limited observations but the chance of sugar snow (persistent slab) lurking in the mountains of the interior is likely.

Look for sugar snow below the new snow, and if you find this sugar snow be aware that everything above that could potentially release, even if the sugar snow is at the ground. Persistent slabs are the hardest kind of avalanches to predict -> The likely hood is low, but the consequences are always high.

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: 

2/18 Observations:

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

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.
Pete Carter

Forecaster: Pete Carter