Turnagain Pass

A natural avalanche cycle occurred two days ago during the peak of the Christmas Storm. However, we do not know yet the extent of the avalanche cycle or if any avalanches occurred yesterday.

For anyone headed out today, there will be several things to watch for. As mentioned above, we have not been able to get into the mountains yet and many unknowns exist. First, if visibility is good enough, are there any signs of recent avalanches? Crowns may be filled in by winds, but can you see debris piles? As you travel, do you feel/hear any collapsing (whumpfing)? Is the snow cracking around you? Are the ridgetop winds still blowing enough to be transporting snow and forming wind slabs? Essentially, looking for those basic Red Flags.

Other things to pay attention to is whether the wet snow surface has frozen, or is freezing. Rain may have fell as high as the top of the treeline so surface conditions could be interesting. If the surface has turned to a crust, avalanches are not likely to occur as the crust locks the snow into place. If there are steep slopes with wet saturated snow, wet loose avalanches could be triggered.

At the higher elevations, above the wet or crusty surface snow, look for how much snow did fall. Quick hand pits can be really useful for this unless the new snow is 2 or more feet deep. In this case, a shovel may be needed to dig in and see where the new snow ends and the older snow begins. It will be the higher elevations, where only snow fell, that should be the most likely place to trigger an avalanche. Both wind slabs and storm slabs could be lurking. The size of the avalanche will depend on the amount of new snow, as deep as 2-4′ in wind loaded areas. The new snow fell on a generally weak surface and it may take more than a couple days for it to bond. Easing into terrain, sticking to slopes 30 degrees or less, and not ignoring any red flags will be good ways to manage potential avalanche issues.

Storm totals for the Christmas Storm (12.25 through 12.27):

Turnagain Pass-     Rain 1.5-2″ below 2,000′, roughly 1.5-2 feet of snow above 3,000′
Girdwood Valley-   Rain 2-2.5″ below 2,000′, estimated 2-2.5 feet of snow above 3,000′
Summit Lake-         Rain ~1″ below 2,000′, roughly a foot of snow above 3,000′

*Note, the rain/snow line may have reached as high as 3,000′ at one point during the Christmas storm, but we think it was generally around 2,000′.

Until we know more, we are concerned the old weak faceted snow that sits above and below the Thanksgiving crust could still be a problem. We still have no information regarding the avalanches that occurred during the storm and if any were able to overload and release in these older layers. If a person was to trigger an avalanche that broke in these layers, the avalanche could be very large and dangerous. Estimated depths of the slab would be in the 3-5′ range. It would be most likely to happen above the rain/snow line where only snow fell. In short an avalanche like this is nothing to mess with, hence our caution.