Hatcher Pass

The last observed avalanches were on January 4.

Pinnacle peak avalanche observation here.

1/4/2020 – Human triggered persistent slab avalanche, 1 foot deep, on Pinnacle peak, Northwest, 5100′. Relatively small slab avalanche, but with serious secondary consequences if caught, since the avalanche ran over a cliff.

1/4/2020 – Human triggered persistent slab avalanche on Far Side Variation, Northwest, 4700′. Also a relatively small slab avalanche, but large enough to injure a person.

The last natural avalanches occurred on New Years. Pictured below is an example of the avalanches that naturally released during and just after the new years storm.

Microdot, North, 4800′. New Years avalanche cycle. Numerous slopes were wind loaded and failed naturally.

Triggering a small, soft slab avalanche, 3-8″ deep, will be possible today in specific terrain, on leeward, South to West aspects, at upper elevation.

While strong winds have persisted in Palmer and Wasilla and the Matanuska Valley over the last two days, Hatcher Pass winds have remained calm to light up until last night. Winds overnight at the Marmot weather station (4500′) produced peak gusts for a short period of time, 15-29 mph, for 5 hours. Winds have settled down this morning and are expected to remain light, NE 6-12 mph through the day.

East Northeast winds overnight have transported available low density snow and deposited fresh wind drifted, cohesive slabs on leeward aspects.  These slabs are sitting on persistent, faceted, weak snow grains. Slabs may release above you and propagate further than expected due to the faceted, weak layer problem. Visual clues, such as smooth snow pillows may assist in identifying problem areas. Pole, or probe testing, will also help you to identify an upside down snowpack, where stiffer snow sits over weaker snow. Cracking and collapsing are bulls eye clues for this avalanche problem.

Yesterday’s winds were calm for most of Hatcher Pass, however, strong winds in the Matanuska Valley may have affected the southeastern boarder of Hatcher Pass. Some wind flagging was observed along the Arkose ridgeline. If you venture into this area today, anticipate this avalanche problem to be more severe until proven otherwise. This means slabs may be easier to trigger and may be bigger than what we see in the core portion of our forecast area today.

Wind loading yesterday in the Matauska Valley.

If the winds continue to remain light, expect this hazard to slowly improve through the weekend.

Small loose dry avalanches will be possible to human trigger, on any aspect, on slopes 40° and steeper. Approximately 6″ of loose snow sits on firm, smooth surfaces. While these types of avalanches may not be large enough to injure you, they may have enough volume to catch you and wash or drag you into terrain traps, such as rocks and cliffs, which will compound the hazard.

Ski cutting can be a safe and effective technique for mitigating this hazard, if properly executed.

Glide Avalanches

The last observed glide avalanche release that we know about was on December 7 on the southeast face of Hatch Peak. This activity is a month old, and seems to be in dormancy. However, glide cracks are still present and could release at any time. Many glides are now barely visible from this week’s new snow. Caution should be taken to not ski/ride into these terrain traps. It’s important to note that glide releases can happen in warm or cold weather, are not temperature dependent, and predictability is next to impossible. Any glide avalanche will be large and capable of burying, injuring, and/or killing a person. We recommend avoiding being on or under any locations with glide cracks.

Cornices

Due to plentiful snow this season and strong wind events, cornices are overhanging and large. Cornices are difficult to predict the timing of natural release. There have already been a few releases this season involving people and old cornice debris and large chunks are present at the base of some slopes. If traveling under cornices, limit the time of your exposure. If you are approaching cornices from behind, use extreme caution, gain a safe viewpoint to identify safe entries onto slopes below, and do not step out on overhanging cornice features.

Cornice failures may be large, and the mass of a cornice may be large enough to injure or kill a person. Cornices may also entrain more loose snow, which could carry you into additional hazards.