Tuesday-Friday 2/14-17

Issued: Tue, Feb 14, 2017 at 8AM

Expires: Fri, Feb 17, 2017

Over the last 36 hours, high quantities of snow accumulation combined with strong onshore winds has led to unstable snowpack conditions.

Travel in avalanche terrain is NOT recommended.

Monitor the bonding of new to old and for density variations in the storm slab that could be the weak link.

Rain on new snow can quickly destabilize the structure and lead to avalanches.

Do not linger in or below avalanche terrain and expose only one at a time when necessary.

Above 2,500ft High

1,800 to 2,500ft High

Below 1,800ft High

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

STORM SNOW:

Elevation: All
Aspect: All
Terrain: All
Sensitivity: Responsive
Distribution: Wide Spread
Likelihood (Human Triggered): Possible
Size: Small – Large
Danger Trend: Increasing
Forecaster Confidence: Good

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

LIST OF AVALANCHE PROBLEMS <here>

SNOWPACK DISCUSSION:

Continental (Interior) Specific: 

Predominant SE winds have picked up and are steadily drifting 2 feet of new snow at Milepost 46 and loading it onto lee aspects: northerly and westerly. As the large volume of storm snow continues to build, recall the variety of surfaces that existed prior to this storm: ice crusts, wind slab, surface hoar, near surface facets. Many of these surfaces can lead to easily triggered avalanches in steep and unsupported terrain. Monitor the sensitivity of new snow before committing.

The continental zone has a much shallower snowpack and weaker basal facets than the more coastal zones. Full propagation, sudden collapsing in between crusts and at depth hoar, was possible yesterday out at 50 Mile. This huge new load of snow will test buried, weak sugar snow structures.

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 new observations reported.

Recent Weather

See Maritime Zone for updated weather.

Additional Info & Media

 

SNOW DEPTH & WATER SURVEY (2/1/2017) Depth Snow Water Equivalent
Milepost 2.5 Valdez  41.5″  9.8″
Milepost 18 43.9″ 9.5″
Milepost 29 Worthington Flats 61.5″ 16″
Milepost 37 Tsaina River bridge 42.1″ 9.3″
This survey is done the first week of each month.

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.

Forecaster: Kevin Salys