Thursday-Sunday 2/16-19

Issued: Thu, Feb 16, 2017 at 8AM

Expires: Sun, Feb 19, 2017

Unreliable visibility and large amounts of new snow will make for strategic route planning with back-up plans.

Continuously evaluate the new snow in non-consequential terrain and proceed conservatively.

This Saturday, February 18, Kyle Sobek is leading a Backcountry & Avalanche Riding Safety Field Session. 9am-4pm. More details. Learn READY RIDER skills.

Above 2,500ft Considerable

1,800 to 2,500ft Considerable

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

THURSDAY FRIDAY SATURDAY & SUNDAY

DANGER SCALE

 

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

WIND SLAB:
Elevation: 
Above 1800′
Aspect: 
Mostly north and west
Terrain:
Near ridgelines, rollovers, and gully walls
Sensitivity:
Responsive
Distribution:
Specific
Likelihood (Human Triggered):
Likely
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:

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

With 28″ of heavy new storm snow in the last 72 hours, start zones are primed to release storm snow and wind slab avalanches. Rain line went as high as 2500′. Southeast winds picked up early February 14th and drifted the new storm snow. Human triggered avalanches are likely in steep, mid-upper elevation steeps that are windloaded.

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:  

  • Large avalanches reported at Milepost 38, 42, and 50 during this storm Feb.13-15 so far.

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 Intermountain Forecasts.

Forecaster: Kevin Salys