Eastern Alaska Range

no further forecasts available for Arctic Man area

Issued: Sun, Apr 09, 2017 at 9AM

Expires: Sun, Apr 09, 2017

Arctic Man 2017 was a success! We had many people stop by the avalanche information kiosk asking questions about conditions and learning avalanche rescue skills. We’ll see you all next year.

If you choose to ride the Summit Lake/Isabel Pass area more this spring, pay attention to how the weather is affecting the snow. With poor snow structure, human triggered avalanches are likely during the heat of the day.

Check in at the Eastern Alaska Range Avalanche Center facebook page to share your avalanche, snow, and weather observations. LIVE TO RIDE ANOTHER DAY!

Above 4,000ft None

3,000 to 4,000ft None

Below 3,000ft None

Degrees of Avalanche Danger ?

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

Avalanche Danger Rose ?

Avalanche Problems ?

Problem Details

WIND SLAB OVER PERSISTENT WEAK LAYER:
Elevation:   Above 3000 feet
Aspect:  Lee to north wind
Terrain:   Near ridges, gully walls, rollovers
Sensitivity:   Stubborn
Distribution:   Specific
Likelihood (Human Triggered):   Unlikely
Size:   Small – Large
Danger Trend:   Increasing with daytime warming and no overnight freeze
Forecaster Confidence:   Fair

WET LOOSE AND WET SLAB AVALANCHES:
Elevation: Above 3000 feet
Aspect: slopes absorbing the sun’s heat, south and west in the afternoon
Terrain: Steeps >40 degrees
Sensitivity: Responsive
Distribution: Specific
Likelihood (Human Triggered): Possible
Size: Small – Large
Danger Trend: Increasing with daytime warming and no overnight freeze
Forecaster Confidence: Good

A few wet loose ran in the steeps Thursday afternoon April 6. Photo: Sarah Carter

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: Information gathered during the Arctic Man event showed very thin snow coverage surrounding the Summit Lake area; 20 inches average snowpack depth.  Below 4000′ the snow was quickly going isothermal – facets becoming wet during daytime thaw.

Above 4000′ ridgelines and gullies were windloaded from north wind events back in March and earlier. 2-8 inches snow fell April 1st  leaving a bit of fresh on top.  Under that new snow, the snow structure was pencil-1 finger (hard/strong) windslab layers over 4finger-fist (weak) facets and depth hoar.

As spring progresses in the area avalanches releasing to ground are expected. Travel in avalanche terrain will require careful route finding and timing. While the snow is frozen, avalanche danger is lower than in the afternoon heat when all the layers are loosening up and primed to head downhill.

evidence of old avalanche activity in upper elevations Photo: Sarah Carter

Video showing layers of hard cohesive snow over weak punchy facets

 

 

Recent Avalanche Activity

Thursday April 7  late in the afternoon a few wet loose avalanches were triggered both naturally and by humans on steeps that baked in the sun all day. The coverage is so thin, the wet snow peeled to ground.

Tuesday April 5 a snowmachiner triggered a small pocket of windslab on a steep sun-warmed slope. The crown was 6″- 2′ thick and released just under the ridge. The avalanche was a size 1, not large enough to bury & kill a person.

Recent Weather

Sunny today for the Arctic Man race. A few clouds possible. Temps in the 40s Fahrenheit near Summit Lake. Light north 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.

NOTE:

Currently, the Eastern Alaska Range Avalanche Center does not issue forecasts. We encourage all users to make educated and informed decisions whenever you choose to travel into avalanche terrain. Careful evaluation of the snowpack, cautious route-finding, and conservative decision-making should be used at all times. Consult recent user observations and available weather resources for more information.

Please refer to the public observations below or our Facebook timeline.

Observations

Tell us what you're seeing out there.

2 Comments on Eastern Alaska Range

Sarah Carter
Sarah_Carter said : Report Subscribe 8 months ago

Report of 20" on the ground near Miller Creek with snow falling and moderate to strong west-southwest wind transporting snow along highway MP 203-218. Heavy snow at times with 5-10" in the Deltas area accumulating by Saturday. Plan your New Year's adventures with avalanche eyeballs on.

  • 29/12/2016
Hank Statscewich said : Report Subscribe 9 months ago

Fellow Snow Travelers, Had a great weekend trip up the Gulkana Glacier on 11/12-11/13. Conditions were clear and cold on the way up the Gulkana Glacier with temps just below 30 and light winds. We had to rope up to cross a crevasse field where the Moore Icefall enters the Gulkana. Wind crust and sastrugi dominated the snow conditions all the way up to 6,000' elevation, we heard several large whumphs as we approached the USGS hut but were able to steer clear of the steeper slopes. Overnight the winds howled up glacier (from the SW), strong enough to blow a person over so I'm not sure I believe the Gulkana Glacier weather station which recorded a max wind gust of 17 mph. By 7 am the winds abated, clouds cleared and we made a push for the summit of nearby Cony Mountain. Snow conditions remained a mixed bag of boiler plate wind crust and sastrugi all the way to 7,400'. We skied back towards the hut and found a low angle pitch of undisturbed snow at the 6,000' level. I think this snow was partially deposited and/or sheltered from the winds the night prior. All in all it was a great early season trip, glaciers seem to be the place to ski right now as they don't have scree lurking under the surface waiting to tear up your bases. Just need to be mindful of crevasses, have the gear to haul someone out and choose safe travel routes.

  • 13/11/2016

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