Friday-Monday 3/3-3/6

Issued: Fri, Mar 03, 2017 at 8AM

Expires: Mon, Mar 06, 2017

Use terrain to your advantage to avoid wind loaded gullies, rollovers and ridges.

Both natural and human triggered avalanches were seen yesterday with thicknesses up to 2+ feet.

These are red flag signs of instability: it is loading faster than it can bond to old surfaces.

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

FRIDAY SATURDAY SUNDAY & MONDAY

DANGER SCALE

 

 

WIND SLAB:
Elevation:   
Above 2500′
Aspect:
   Lee to northerly winds
Terrain:
 Near ridgelines, rollovers, and gully walls
Sensitivity:
 Responsive
Distribution:
 Specific
Likelihood (Human Triggered):
  Possible
Size:
 Small – Large
Danger Trend:
  Increasing
Forecaster Confidence:
   Fair

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:

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

Just when you thought all loose snow had already moved, strong to extreme winds continue to scour deeper and drift snow into low lying gullies, trees, crevasses and rollovers, expect firm and variable conditions with exposed old crusts, wind board and sastrugi dominating the environment. Extra effort will be necessary to seek out the wind protected nooks that harbor soft snow. Be wary along corniced and loaded ridgelines, convex rollovers and steep gully walls. Wind slab needs time to bond to underlying snow and can trigger very large and unpredictable avalanches.

Areas with wind loading have proven to be responsive. Multiple Wind Slab avalanches on Southerly aspects of Girls Mountain occurred February 28th. A wind event like this increases the avalanche hazard significantly. Test small subject slopes before stepping it up to anything with high consequence.

 

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. 28:

  • Mar. 2: Many natural wind slabs have recently released off southerly and westerly aspects loaded by the NE wind.

Human triggered windslab below Crudbusters. Photo via Jed Workman

N Odyssey Gully Wall Slide

Long crown on rollover below 27 Mile Peak

  • Feb. 28: Natural D2 wind slab avalanche near the hairpin, on the south side of Odyssey.

  • Very obvious wind flagging on the peaks and sastrugi on the Deserted Glacier

  • Multiple Size 2 Wind Slab avalanches on South Aspects on Girl’s Mountain.

 

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 Intermountain Forecasts.

Forecaster: Kevin Salys