The Bottom Line: The overall hazard is moderate above treeline due to a challenging snowpack structure and recent wind loading.
The snowpack has been settling since the last major round of storms that ended Dec 19th. Above 4000' the snowpack averages over 300cm deep and has good strength and structure. Below the rain line from the historically warm and wet October the snowpack is significantly shallower and has more problem layers: facet-crust combos and basel facets.
Problem 1: Wind Slab.
Location: all aspects above treeline. Size: small to large. Likelihood: possible. Sensitivity: stubborn. Wind Slabs up to 2' thick have formed predominantly lee to the NE. Winds slab can be identified by dense, cohesive snow, cracking, and a hollow or drum like feel. Look for wind slab below ridge lines and close to Thompson. 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.
Location: all aspects below 4000' and possibly even higher near shallow parts of the snowpack such as rock outcroppings. Size: small to large+. Likelihood: unlikely. Sensitivity: stubborn-unreactive. There are multiple rain crusts layered with facets widespread throughout the region. There are also basel facets 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 or snow machine hitting a sweet spot.
1 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'.
Over the past few days several small wind slabs released near Thompson Pass from human triggers and several more small cornices released naturally, south facing 3-4000'.
Since Dec 23 there has been little snow and light to moderate winds (mainly from the NE). 2" at Thompson pass. Trace at 46 mile. 4" in Valdez.
The NWS Rec Forecast can be found HERE:
318 PM AKST Thu Dec 27 2018
The Thompson Pass Mountain Forecast covers the mountains (above
1000 ft) surrounding Keystone Canyon through Thompson Pass to
Temp at 1000` 20 F 26 F
Temp at 3000` 23 F 23 F
Chance of precip 70% 50%
(above 1000 FT) 0.04 in 0.03 in
(above 1000 FT) 1-3 in 1-2 in
Snow level sea level sea level
Wind 3000` ridges NE 15-30 mph E 5-12 mph
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.
Beacon Practice Workshop: Friday Dec 28, 6-7:30pm Mike's Palace in VALDEZ. 45 Minutes inside review then 45 minute outside practice (bring snow boots). Free for VAC members ($25/annual) or $5 suggested donation.
The overall hazard is moderate and all 3 zones have the same forecast. Click 'full forecast' to get more info. The VAC is hosting a beacon practice session Friday Dec 28th, 6-7:30 in Valdez...come brush off your rescue rust!
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