Monday – Thursday 3/27-30

Issued: Mon, Mar 27, 2017 at 8AM

Expires: Thu, Mar 30, 2017

Conservative terrain choices and attentive snowpack observation will reduce your risk to triggering a persistent avalanche problem. Thinner areas above terrain traps should be avoided.

Avalanche Center Tsaina Lodge Spring Full Moon Bon Fire FUNraiser

Friday April 14 presenting Acoustic Avalanche

Above 2,500ft Moderate

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

MONDAY TUESDAY WEDNESDAY & THURSDAY

DANGER SCALE

 

 

PERSISTENT:
Elevation:
  Above 2500′
Aspect:
more likely on northerly aspects
Terrain:
unsupported steep slopes with thin coverage
Sensitivity:
  Stubborn
Distribution:
  Isolated where windslab exists over facets/depth hoar
Likelihood (Human Triggered):
   Possible
Size:
  Small – Large
Danger Trend:
   Steady
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:   Windslab building over weak snow i.e. facets and/or depth hoar is a growing concern due to our thinner and weaker snowpack. There have been recent reports of significant collapses (large whumphs) in areas on the northerly and easterly outreaches of our Inter-mountain zone, and into the Continental zone. Human triggered pockets could lead to an avalanche stepping down to basal weakness; most likely to be triggered by heavy loads i.e. snowmachines or several people, in thin areas such as near ridgelines or rollovers.

March 20 snowfall only amounted to a few inches in the Continental zone. Since then, north wind has been transporting this dusting in wind exposed areas.

Below 2500′ the snowpack has a bit more strength than the alpine due to old raincrusts holding it together.

Find more photos and observations at the bottom of the page. Sharing your observations creates an informed community.

Recent Avalanche Activity

Continental (Interior) Specific: 

  • Report from March 25: reports of upper elevation (>4500′ elevation) human triggered windslab to size D1.5 to a foot thick releasing off steep slopes, mostly in the Maritime to Intermountain areas
  • Report from March 24: significant collapses, as large as whole basins whumphing, in areas on the northerly and easterly outreaches of our Inter-mountain zone, and into the Continental zone.

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.
Sarah Carter

Forecaster: Sarah Carter