Eastern Alaska Range (Deltas)

Eastern Alaska Range Snow Observations

A small fraction of terrain frequented by backcountry travelers has a professional avalanche forecast available. For this reason, the Alaska Avalanche Information Center encourages users to share what they see.Deltas map

The Delta Range (Eastern Alaskan Range) accessed from the Richardson Highway between Paxson and Donnelly Dome is a fantastic winter playground.

Please contribute your avalanche, snow and weather observations in the comments below. This is a data-sparse area; shared observations create an ongoing history of snow and weather that can help recreationists plan and prepare for success in the backcountry.
natalie ski summit lake
snowmachines near summit lake

If you have suggestions for links or improvements to this page, please email scarter@alaskasnow.org

Area Links
Other helpful links:
Slope Angle Maps creates a map like this to help you recognize avalanche terrain and plan routes. The slope angles are averages – ground truthing and cross referencing is still necessary.



12 thoughts on “Eastern Alaska Range (Deltas)

  1. Had a guest last weekend, a backcountry skier, who went up the Fossil Creek drainage (southern end of Rainbow Ridge, area of recent avalanche casualty) with his son. Upon his return to our Lodge at Black Rapids, he reported finding avalanche debris piles in the valley floor. He and his son skied in the valley floor due to the conditions they found. This finding is significant in that less than two weeks earlier I had been up that valley and found no evidence of any new slides. He surmised that there is a very slick sliding surface near ground level and that any subsequent snowfall builds up just enough to slide again.

  2. December 28, 2014 above MP 206 Richardson Highway, Rainbow Ridge area
    Whumphing still significant. Peaks and ridgelines were flagging from strong SE wind in Canwell and Castner valleys. -10C temperature. Tests on 31 degree NW slope near a small ridge at 3200′ showed facets collapsing above the basal melt freeze crust. Height of snow 58cm. 20cm soft snow over hard old windslab sitting on 1-4finger facets (persistent weak layer responsible for the whumphing and the fatal avalanche Dec.6). This poor structure is not going away quickly.

  3. Media coverage on the Rainbow Ridge accident that killed a backcountry skier December 6th:
    -Friends, Family Mourn Avalanche Victim; Expert Advises Recovery Operation Delay
    By Tim Ellis, KUAC – Fairbanks | December 15, 2014 http://www.alaskapublic.org/2014/12/15/friends-family-mourn-avalanche-victim-expert-advises-recovery-operation-delay/
    -Alaska skier recounts avalanche that killed his friend
    Fairbanks Daily News-Miner December 9, 2014
    -Avalanche Survivor Says Mountain Gave Warning Sign
    ABC News December 9, 2014
    -Skier Killed in Avalanche in Unstable Alaska Mountains
    NBC NEWS December 7, 2014

  4. December 8, 2014 Rainbow Ridge area
    Several natural and 1 human triggered fatal avalanche in the last 3 days. Widespread whumphing and cracking. Snowpack has poor structure and is unstable. Windslab over facets.

  5. April 12, 2014 Report of a large slab release set off by a skier on Idem Peak up Trims creek. Two skiers caught but both OK.

    • Follow this link to photos of the moderate sized slab avalanche.


      account by a witness:

      I wouldn’t call it a large slide. not small, but moderate/medium sized.
      It was in the Trims Glacier basin on the SW side of Item Peak in the Deltas.
      Low 30ish degrees south facing slope of the SW ridge of Item Pk.
      Snow from the past week had not bonded well enough to March’s sun affected surface.
      Lens shaped slab was thicker in the middle than at the crown, near the rocks. Skiers traversed into it from above.
      Yes, 2 skiers caught and swept away by it, both stayed on top and skied away from the scene.

      Account from one of the skiers involved.

      The avalanche I set off last weekend really blindsided me, although that was no excuse for me to cut the slope above my partner, with the result that we both got caught!
      Bad form! Despite the snowfall the previous week, conditions looked and acted quite stable, especially on windward slopes (strong southerly flow last weekend). But, the snow had arrived with northerly winds, apparently, and there’s both a sizeable layer of unconsolidated, faceted snow below the last snowfall, with a weak surface hoar layer on top of a barely noticeable sun crust…overall not terribly avalanche prone, but in places bad enough that we started a small slab avalanche in a rather unlikely spot.

      • Witnesses dug a pit on a mid-20 degree SW facing roll of the Trims Glacier. Same day as the smallish slab avalanche.

        We did a Rutsch-block test on a 3ft by 6ft isolated block about 4 feet thick.

        The top 14 inches formed a soft slab which failed and shifted on the second of my two knee bends.
        It shifted, but didn’t run right off the block.

        We interpreted the sliding surface as a paper thin “sun crust” from the
        prolonged snowless period in March.
        We found 3 ice layers in close proximity about 3-4 ft down. These were
        All the March and older snow was well bonded and lightly to moderately
        We found no depth hoar or facets in the top 4 ft. (on a glacier).
        We took this result as a “yellow light” and decided to abandon our route up
        the Trims Glacier, as it would require skinning up increasingly steep slopes
        and putting multiple people in the line of fire.
        Basically the new snow that had fallen over the past week hadn’t bonded
        sufficiently to the underlying old surface. We only did one snow test.

  6. March 23, 2014 McCallum Creek drainage
    clear skies, high temp of +1C, calm-light variable wind
    Evidence of old avalanche cycle; many old wet/windslab avalanches to size 2 observed on steep west and south aspects above 3400′.
    Wind has blown the recent snow back down to rain runneled surface in many exposed areas. Some windslab collapsing and cracking under the weight of multiple skiers, but no movement.
    In McCallum Creek drainage we found 100cm snowpack. A thin windskin over 10cm of fist snow and a layer of surface hoar sitting above a knife crust. The midpack has several meltfreeze crusts interspersed with facets. The lower pack was pencil- facets. ECTP4 in facets just under a knife crust down 16cm.

    Stability: Good

  7. March 22, 2014 Knoll above Isabel Pass 3500′
    clear skies, -9C, calm, foot pen 40cm
    Wind affected surface snow. The most recent avalanche activity looked to be steep, pockets at ridgeline ~ triggered by the strong north wind March 20(?) One windslab avalanche was observed on a west aspect at about 4000′. Debris of older wet slab avalanches to destructive size 2.5 was seen on south and southwest aspects. A number of the old crowns were at about 4500′. Many released near the ground.

    We dug on both the north and south aspects of a small ridge at about 3500′. The snow structure was similar – lots of facets interspersed between several different melt freeze and ice crusts.
    The south aspect had considerably less snow <1meter. ECTP18 down 39cm sudden collapse in depth hoar to 4mm.
    The north aspect had more than 1 meter. The north side had received the most recent windload. We found surface hoar to 5mm just under a thin windskin. ECTP14 & RB6 (most of block) down 14cm resistant planar in 2mm facets.

    Powder was found on wind protected north aspects. Ski pen ~15cm.

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