Thursday-Sunday 3/16-19

Issued: Thu, Mar 16, 2017 at 8AM

Expires: Sun, Mar 19, 2017

While the wind and snow continue to blow, come enjoy the VAC Basecamp FREE classes that begin Friday in the One Love Lot (MP 29.5). Check our Facebook page for more details!

Citizen Science Opportunity in Thompson Pass: March 18, 2017: 9:30am at DOT Camp (MP 27).  Join VAC forecasters, staff, and volunteers in measuring the snow cover throughout Thompson Pass. Learn more at www.nasacso.org or at the Fat Mermaid March 16 & 17 @ 5:30pm.

 

Above 2,500ft Moderate

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

THURSDAY FRIDAY SATURDAY & SUNDAY

DANGER SCALE

 

WIND SLAB:
Elevation:
  Above 2000′
Aspect:
   Lee to northerly winds
Terrain:
  Near ridgelines, rollovers, and gully walls
Sensitivity:
   Stubborn
Distribution:
Specific
Likelihood (Human Triggered):
  Possible
Size:
Small – Large
Danger Trend:
  Decreasing
Forecaster Confidence:
   Fair

PERSISTENT SLAB:
Elevation:
  All
Aspect:
  All
Terrain:
Most
Sensitivity:
  Non-reactive
Distribution:
  Widespread
Likelihood (Human Triggered):
  Unlikely
Size:
  Small – Large
Danger Trend:
  Decreasing
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: 

Despite a dusting in the interior yesterday, Valdez has not seen significant snowfall for one month as of today. 13 of the last 16 days had 50 mph wind gusts, approaching 100 mph at the beginning of this month. This wind cycle has completely scoured and stripped all peaks and ridges of their snow. Glacial ice has been exposed in areas normally visible mid summer. Entrances to “normal” ski runs aren’t even fathomable. There is practically NO soft snow for skiing, snowboarding, or snowmachining in the Valdez region, yet some far off wind protected pockets have held some inconsistent soft snow/facets. Human triggered avalanches are still possible. If you do decide to recreate in the mountains today, the snow will most likely be hard and sketchy. Skiers, know self arrest skills. Snowmachiners, be prepared to total your sled. In regards to avalanches ask your self, “what lies underneath this hard snow?” If it’s sugar (facets), which it probably is, it can avalanche. You are most likely to trigger this slab where the snowpack is the thinnest.

The last reported human triggered avalanche was March 11th in this region on Mt. Tiekel. Testing from March 15 near MP 50 demonstrated continued poor snow structure with the ability to support easy-moderate propagation results.

The Interior region of the Chugach has seen significantly less precipitation compared to coastal areas. Ground level facets (sugar snow) were found on a widespread scale through out this part of the range. These facets take time, possibly even an entire season to change their structure into something less avalanche prone. The likelihood of triggering an avalanche on these facets is low, but the consequences could be fatal.

Thompson Pass gap winds still scouring into the snowpack.

Rain Crust from mid Feb.

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: 

  • March 11 report of upper elevation skier triggered avalanche that ran on a previously released slope (March 3rd?) which has reloaded. The hard slab avalanche fracture crown was two feet deep, propagated 400 feet across the start zone, and ran 1000 feet. The skier was able to ski off the moving slab and wasn’t captured.
  • Recently reported from Mar 7: 2x D1 AS soft slabs (3500’ SW 20cm and 4000’ NE 15cm), long running dry loose and several collapses on low angle terrain.
  • Mar. 2: Just up the road at Milepost 40, human triggered winds slabs were triggered on lee aspects of a cross-loaded ridgelet. Expect similar in the continental zone where basal facets further complicate things.

Human triggered windslab below Crudbusters. Photo via Jed Workman

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.

Forecaster: Kevin Salys