Wednesday-Saturday April 5-8

Issued: Wed, Apr 05, 2017 at 8AM

Expires: Sat, Apr 08, 2017

Arctic Man 2017
Use normal caution in avalanche terrain. Please wear your beacon and carry a probe and shovel. Low danger does not mean no danger.

Up your skills: join Alaska Avalanche Information Center staff Wednesday April 5 11am-1pm to practice your Avalanche Rescue Skills. Stop by the Avalanche information kiosk; we’re across from the showers on the corner of Racer’s Row, not too far from the beer tent.

Above 4,000ft Low

3,000 to 4,000ft Low

Below 3,000ft Low

Degrees of Avalanche Danger ?

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

Avalanche Danger Rose ?

Avalanche Problems ?

Problem Details

WEDNESDAY THURSDAY FRIDAY & SATURDAY

DANGER SCALE

 

WIND SLAB OVER PERSISTENT WEAK LAYER:
Elevation:   Above 3000″
Aspect:  Lee to north wind
Terrain:   Near ridges, gully walls, rollovers
Sensitivity:   Stubborn
Distribution:   Specific
Likelihood (Human Triggered):   Unlikely
Size:   Small – Large
Danger Trend:   Steady
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>

North side of Courage Mountain April 3, 2017   Photo: Conrad Chapman

SNOWPACK DISCUSSION: Snow coverage is thin, 20 inches or less in the lower elevations near Summit Lake. April 1st 2” of new snow fell in the Arctic Man parking lot, and up to 8” of new snow in higher elevations. Climbing higher up into the Hooodoo Mountains, the snowpack is a bit deeper but variable in hardness and depth due to wind distribution. Windslab, blown in by northerly wind is laid into gullies. Generally, the snowpack consists of windslab layers over loose sugar snow (facets & depth hoar). The windslab varies from rock hard to punchy soft, no signs of propagation have been observed over the last two days. We did receive word of a small rider triggered avalanche yesterday, a good reminder that human triggered avalanches may be unlikely, but they are not not impossible. 

Video showing layers of hard cohesive snow over weak punchy facets

 

 

Recent Avalanche Activity

Yesterday April 4th around 4 pm: snowmachine and rider triggered a small pocket of windslab on a steep sun-warmed slope. As the rider crested up and over, the 6″- 2′ slab released just under the ridgetop. If it is sunny again today, expect similar activity to be possible. These are stubborn and unlikely, but a good reminder of the Poor structure: Windslab over sugary facets. All partners should be Rescue Ready.

Recent Weather

Weather: Partly cloudy with a few flurries and some flat light. No significant accumulation over the week. Daytime temps in the high 30s, night time lows in the teens Fahrenheit. Light variable wind.

Additional Info & Media

SNOW HISTORY: Valdez 2/24 AM Thompson Pass 2/24 AM
24 Hour Snow / Water Equiv. <0″/0″ 0″ /0″
Storm Snow /Water Equiv. (2/22-2/23) 0.6” /0.05″ 1″ /0.1″
Current Snow Depth 48″ 49″
February Snow / Water Equiv. 44.9″ /5″ 43″ / 5.1″
Total Winter Snowfall / Water Equiv. 222.8″ /20.9” 282″ / 27.7″
Snowload in Valdez ~ lbs/sq. ft.

 

SNOWFALL at OTHER STATIONS:
LAST 24 HRS (2/24 AM)/STORM TOTAL (2/22-23)/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″/ 1″ / 0.1″
SNOW DEPTH & WATER SURVEY (2/1/2017) Depth Snow Water Equivalent
Milepost 2.5 Valdez  41.5″  9.8″
Milepost 18 43.9″ 9.5″
Milepost 29 Worthington Flats 61.5″ 16″
Milepost 37 Tsaina River bridge 42.1″ 9.3″
This survey is done the first week of each month.

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 EARAC Forecasts.
Sarah Carter

Forecaster: Sarah Carter