Tuesday-Friday 2/21-24

Issued: Tue, Feb 21, 2017 at 8AM

Expires: Fri, Feb 24, 2017

The danger rating of Low danger doesn’t mean no danger. Expect new windslabs to form both with clear skies northerly outflow winds and with Wednesday’s few inches of new snow drifted by southerly onshore winds.

Remember to ALWAYS use travel techniques to your advantage. Don’t expose yourself to danger when you don’t have to. Ski/Highmark one at a time.

Above 2,500ft Low

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





Above 3000′
  Lee to NE wind (and S winds after Wednesday)
 Near ridgelines, rollovers, and gully walls
Likelihood (Human Triggered):
 Small – Large
Danger Trend:
Forecaster Confidence:

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



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

30″ of heavy snow mixed with rain below +-3000′ fell around the Thompson Pass region last week. A widespread avalanche cycle occurred during this storm, flushing out weak layers that might have been persisting deep in the snow pack. Look for where these large avalanches occurred and make a mental note of this-> these slopes won’t produce large avalanches until the temperatures rise above 32F. This goes the same for slopes that didn’t avalanche during the storm-> just waiting for additional weight, like a human to trigger a large destructive avalanches.

In elevations above the rain line expect copious amounts of new snow. Use small, non consequential slopes to test how the layers with-in the new snow are boding before exposing your self.


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:  

Observed Feb. 18:

  • Numerous large(D3+) Wet Slab avalanches ran during the storm last week in the Tsania Valley that hit the valley floor
  • Natural Sluffs (Loose Snow) Observed on North Aspects in the Tsania Valley(before the glacier), while no natural activity was observed in the Tonsina Glacier area

Observed Feb 16:

  • Many mid storm avalanches released up to D2.5 off of steep faces: Several on north face of Odyssey, School Bus, Vertigo, Snatch, 40.5 Mile Ridge/Wilburs

Below Vertigo, crown filled in similar to Snatch and School Bus.

School Bus and North Odyssey Gully debris.

  • Extensive shallow slab releases on mid+ elevation southerly aspects below Bald Boy to Hippy Ridge (MP 29-37): seemed to be pulling out on persistent weaknesses: likely surface hoar or near surface facets formed last week.

Below Baldy & Little Girls

Thin crowns at MP 33

Hippy Ridge: Widespread mid-elevation activity…weak layer likey recently buried surface hoar or facets. Upper elevations had blown back in.

  • Large deeper avalanche releases on basal weaknesses at the ground below Max Low and Wilbur’s on 40.5 Mile Ridge

Max Low released at rocks. Pit dug on Feb 8 right next to this crown.

Wilburs: lower central slab was deeper and looked like it pulled out to rocks.

Reported Feb.13-15 during the storm:

  • Large avalanches at Milepost 38, 42, and 50

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>


  • 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


Interactive Map of Valdez Forecast Areas w/ Many Resource Layers (Trevor Grams)


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.
Pete Carter

Forecaster: Pete Carter