Spring 2017

Issued: Sun, Apr 30, 2017 at 8AM

Expires: Wed, May 03, 2017

Thank you all for another great season in the amazing Chugach!!! Daily forecasts are now finished, but this does not mean there is no avalanche danger. Please plan your spring mountain adventures keeping in mind that if it is warm enough for you to shed layers, the snow will too. Read this summary blog of spring avalanche conditions from Avalanche Canada. Keep heads up.

VAC Annual Membership and Advisory Board Meeting May 3 5-7pm  Downstairs Valdez Library   Get involved! We need your feedback, ideas, and good energy to plan for another successful season 2017-18.

Above 2,500ft None

1,800 to 2,500ft None

Below 1,800ft None

Degrees of Avalanche Danger ?

1. Low
2. Moderate
3. Considerable
4. High
5. Extreme

Avalanche Danger Rose ?

Avalanche Problems ?

Problem Details

SPRING SPRING SPRING

DANGER SCALE

 

WET AVALANCHES:
Elevation:   Below 6000′
Aspect:   All steep terrain, especially aspects that have direct sun
Terrain: Slopes >35 degrees near rocks and vegetation
Sensitivity:   Touchy when thawed and/or warmed
Distribution:   Specific
Likelihood (Human Triggered):  Likely when warmed
Size:   Small-Large
Danger Trend:   Increasing quickly each day with warming temperatures, falling with freezing at night. More danger if overnight freezing does not occur.
Forecaster Confidence:   Good

CORNICE FALL:
Elevation: 
ALL
Aspect:   
ALL
Terrain:
corniced ridgelines
Sensitivity:   
Responsive 
Distribution:   
Specific
Likelihood (Human Triggered): 
Possible
Size:  
Small to 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:

Maritime (Coastal) Specific: The diurnal melt freeze cycle has created corn snowproviding for some pleasant spring riding. When the surface crusts are still frozen,  good traveling is possible. The exception being steep south facing slopes where the full depth of the snowpack has become rotten or isothermal and lower elevations where overnight temperature has not been cool enough to freeze the snow. Late in the afternoon, punchy, soft snow will limit your ability to travel and increase your risk to avalanche.

We have not seen many full depth avalanches yet, more a peeling of the onion, with wet loose and/or melt taking off layer upon layer. As the temperatures increase over the the next few weeks with less overnight freezing, expect wet slab releases possible.

Please avoid exposure to cornices. Read and listen to this sad spring cornice accident story from British Columbia earlier in April.

Sharing your observations creates an informed community that everyone benefits from at some point.

Recent Avalanche Activity

Maritime (Coastal) Specific:

  • Small wet loose over the last few sunny days out of steep rocky terrain. All elevations.
  • April 23 Natural wet slab D2.5 above Deserted Glacier, west aspect, 5800′. Lots of south and west cornice failure and wet loose activity into the Woodworth and Deserted Glaciers.

    April 23: fresh wet slab at 5800′ on west aspect above Deserted Glacier        Photo: Sarah Carter

  • April 17 The Wall/Tomahawk rockfall resulting in D3+ avalanche.
  • April 13-16 More wet loose activity in the afternoon on steep solar affected slopes

  • April 18th  “Things are coming unglued out there” Photo: Jeremy Martin

  • Large avalanche on, “The Wall/Tomahawk” caused by rockfall Photo: Jed Workman

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):  30 / 32
Ridgetop Wind Forecast (direction/mph):  South / 0-10
Snowfall (in/water equivalent):  Trace” / 0.32″
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction  5 / Var  10 / SE
Max Wind Gust (mph) / Direction  13 / WSW  15 / SE
Temperature Min / Max (*F)  40 / 49  30 / 42

Weather Forecast: Spring showers with the freezing line about 2500′ will add a few inches of new snow at the mountain tops. At Thompson Pass, temps will be fairly steady with daytime highs above freezing and nightly lows just below freezing. Light southerly onshore wind.

Additional Info & Media

SNOW HISTORY: Valdez 5/08 AM Thompson Pass 4/30 AM
24 Hour Snow / Water Equiv.  0”/0.0″ 0″ /0.04″
Storm Snow /Water Equiv. (4/30)  16.9″ /4.1″ 0″ /0.04″
Current Snow Depth 0.0″ 28″
April Snow / Water Equiv. trace″ /2.4″ 8″ / 0.84″
Total Winter Snowfall / Water Equiv. 239.8″ /25.14” 327″ / 31.44″
Snowload in Valdez ? lbs/sq. ft.

 

SNOWFALL at OTHER STATIONS:
LAST 24 HRS (4/30 AM)/STORM TOTAL (4/30)/STORM WATER EQUIV.:
Nicks Valley at 4200 ft (in): 0″ / 0″ / 0″
Upper Tsaina at 1750 ft (in): 0″ / 0″ / 0″
Sugarloaf at 550 ft (in): 0″/ 0″ / 0″
SNOW DEPTH & WATER SURVEY (4/2/2017) Depth Snow Water Equivalent
Milepost 2.5 Valdez  41.9″  11.9″
Milepost 18 40″ 11.9″
Milepost 29 Worthington Flats 62.2″ 19.6″
Milepost 37 Tsaina River bridge 46.3″ 12.5″
This survey is done the first week of each month.

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 Maritime Forecasts.
Sarah Carter

Forecaster: Sarah Carter