Friday – Monday 3/31-4/3

Issued: Fri, Mar 31, 2017 at 8AM

Expires: Mon, Apr 03, 2017

Rising temperatures and more precipitation transitioning to rain will further test the new and old snow structure.

Expect conditions to change quickly as wet avalanche concerns will show themselves.

The beginning and end of a tour could have very different snow conditions.

Friday April 14: VAC Full Moon FUNraiser with Acoustic Avalanche @  Tsaina Lodge

Above 2,500ft Considerable

1,800 to 2,500ft Considerable

Below 1,800ft Considerable

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

 

STORM SLAB:
Elevation: All
Aspect: All
Terrain: All
Sensitivity: Responsive
Distribution: Widespread
Likelihood (Human Triggered): Likely
Size: Small – Large
Danger Trend: Increasing
Forecaster Confidence: Fair

WET LOOSE:
Elevation: <3000′
Aspect: All
Terrain: All
Sensitivity: Responsive
Distribution: Widespread
Likelihood (Human Triggered): Possible
Size: Small
Danger Trend: Increasing
Forecaster Confidence: Fair

PERSISTENT SLAB:
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:  

A few more inches of snow is accumulating on top of an upside down snowpack that has developed during a warm spell Wednesday, peaking in the high 30s down near the port and mid to high 20s near 3000′. 2+ feet of snow has been measured in the port and on Thompson Pass, with more likely in the upper elevations which is colder and dryer.

Expect loose wet snow activity to show itself today as temperatures warm and snow turns to rain.

On Thompson Pass (and likely elsewhere), a couple new melt-freeze crusts have formed up to ~2600′. A thinner (1″, 4F) crust near the surface sandwiched several inches of soft snow between a thicker (~3″; 1F+) melt freeze crust almost a foot down. Hand shear testing demonstrated poor crust bonding with very easy results when isolating columns. Propagation was supported at ~2400′ on Thompson Pass on Thursday, when a large collapse occurred of the new storm snow (thick crust and everything above) resting on buried facets below. In areas where the facets did not reside, bonding of new snow was good.

Higher elevations exposed to wind will likely have fresh wind slab formation that has been bonding well to underlying snow thus far (Q3 w/ steps), unless it is sitting on a persistently weak grain (old facets). A small collapse of newly blown in shallow slab on rocks occurred at ~3000′ on Thompson Pass on a southerly aspect.

The further you get from the pass the new snow levels dramatically decrease. This has been a trend all season, with most of our storms hammering the maritime zone, while leaving the intermountain/continental zones high and dry. Tuesday, heavy snowfall (1”/hour) was falling at 46 Mile slowing decreasing into the interior with only a dusting in Kenny Lake.

Given the poor structure in the interior, you are most likely to trigger a storm slab with a chance of it stepping down to a persistent slab. The interior region, and even some parts of the intermountain region, have a persistent weak layer that has the potential to release the entire season’s snow pack in a very large, catastrophic avalanche. This persistent weak layer is going to be put to the test with the adding up snow load over the next week.

This may be what happened in the large chute on the east face of Mt. Tiekel. It was reported to have avalanched (D2.5) March 28th with in the last 24 hours with dirt in the debris.

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

Recent Avalanche Activity

Continental (Interior) Specific: 

Poor visibility have limited observations: please share if you have seen anything!!!

  • March 28: The large chute on the east face of Mt. Tiekel release a D2.5 avalanche which dusted the highway
  •  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
  • 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:

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