The Bottom Line: The avalanche hazard is moderate at and above treeline due to newly forming wind slabs that are likely to be triggered by riders in steep terrain. There is still also the unlikely but high consequence potential of deeper Persistent Slabs....
Problem 1: Wind Slab.
Distribution: all wind affected aspects above treeline. Size: small. Likelihood: likely. Sensitivity: reactive.
Description: The wind increased Thursday blowing the new soft snow and forming Wind Slabs up to 2' thick predominantly leeward to the northeasterly winds. Wind slab can be identified by dense, cohesive snow, cracking, and a hollow or drum like feel. Look for wind slab below exposed ridge lines and in proximity to Thompson Pass. Stiff wind slabs can lure riders well onto the slab before failing. Stick to wind-protected areas where the surface snow is still soft and fluffy (better riding conditions usually anyway).
Problem 2: Persistent Slab.
Distribution: all aspects below 4000' and possibly even higher near shallow parts of the snowpack such as rock outcroppings. Size: large+. Likelihood: unlikely. Sensitivity: stubborn-unreactive.
Description: There are multiple rain crusts layered with facets throughout the region (reported only up to 4000'). There are also BASEL facets (weak sugar snow) at the bottom of the snowpack . . . These problem layers are gaining strength and potentially either dormant or waiting for a large load such a big storm, cornice drop, or snow machine hitting a trigger point. If you choose to ride on slopes over 35 degrees choose slopes with clean run-outs and careful selection of group spacing and safe zones. See video of a stability test on our Facebook page, from January 3 2019.
Additional Concern: Glide Avalanches.
There are open cracks from the port to 42 mile between 3500-4000' on multiple aspects. It is important to remember glide cracks can release into full-blown avalanches at any time and are not associated with human triggers. The best way to manage this problem is to limit (AKA avoid) travel underneath and beside them.
The current list of open glides cracks from West to East:
Several small wind slab avalanches (less than 1' deep) were triggered by skiers in steep terrain on a south facing slope at 4000', near the Tsaina Lodge on January 3rd.
A large avalanche was reported on Dec 23rd: a slab avalanche near the ridgeline of RFS, below the cornice. It was reported as possibly a size 2.5, persistent slab that ran 800-1000'.
Please share your field observations including signs of stable snow HERE.
Clear and sunny skiers, moderate north winds, and cold temperatures are forecasted through the weekend (Jan 6th).
The most recent NWS rec Forecast can be found HERE:
313 PM AKST Thu Jan 3 2019
The Thompson Pass Mountain Forecast covers the mountains (above
1000 ft) surrounding Keystone Canyon through Thompson Pass to
Temp at 1000` 2-8 F 12 F
Temp at 3000` 7-16 F 7-16 F
Chance of precip 0% 0%
(above 1000 FT) 0.00 in 0.00 in
(above 1000 FT) 0 in 0 in
Snow level sea level sea level
Wind 3000` ridges NE 15-35 mph NE 10-35 mph
BIG PICTURE: The New Year's Eve storm brought nearly 2.5" of SWE to Valdez and almost another 1" on the 2-3rd of January. That is a LOT of snow and rain in 5 days and it accumulated to over 3' above 2000' near Thompson Pass. Both of these storms had little wind and we have seen surprisingly little avalanche activity. Above 4000' the snowpack averages over 300cm deep and has good strength and structure (few lemons). Below the rain line from the historically warm and wet October, 3500-4000', the snowpack is significantly shallower and has more problem layers: facet-crust combos and BASEL facets (all the way to sea level). There is barely enough snow to build a slab avalanche or travel off trail below 1000'.
TREND Jan 4-6: The overall snowpack should continue to absorb the new load well as old layers keep gaining strength (rounding). Building winds are rapidly changing the surface conditions and building new wind slabs. In sheltered places we have the potential for surface hoar growth (cold, calm, clear nights) - if you see surface hoar PLEASE let the VAC know!
If you get out riding, please send in an observation.
Do a rescue practice with your partners. Always carry a beacon, shovel, and probe, and KNOW HOW TO USE THEM.
Practice good risk management, which means only expose one person at a time to slopes 30 degrees and steeper, make group communication and unanimous decision making a priority, and choose your terrain wisely: eliminating unnecessary exposure and planning out your safe zones and escape routes.
The avalanche hazard is moderate at and above treeline due to newly forming wind slabs and old Persistent Slabs. All three zones have the same forecast through Sunday Jan 6th unless conditions change. Please click FULL FORECAST for more information.
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