Hatcher Pass

Last weekend, an extreme wind event damaged homes throughout the valley, left tens of thousands without power, and obliterated our thin snowpack. 

What's left is a harsh moonscape of frozen tussok, exposed rock, and dense now. 

The avalanche hazard is LOW. Weak snow still exists under dense slabs formed by extreme winds, but triggering an avalanche is unlikely.  

SPECIAL ANNOUNCEMENTS:

Big thanks to Backcountry Bike and Ski for hosting and everyone for coming out to our first State of the Snowpack chat of the season!

We have an app for easy access to avalanche information and observations on the go. You can download the app for free in the Apple App Store or the Google Play Store.

UPCOMING EVENTS:

Saturday, December 13th, 12-3 pm @ Hatcher Pass - HPAC and partners will be hosting a FREE rescue day at the Fishhook Lot from 12-3 pm. All skill levels and styles of recreating are welcome. We will have snowmachine-specific rescue tips with AMDS and Saferiders, as well as novice, intermediate, and advanced rescue clinics with Anchorage Nordic Ski Patrol, Skeetawk Pro Patrol, Alaska Mountain Rescue Group, and HPAC forecasters. 

The Mat-Su Borough and the State of Alaska both declared a disaster in the wake of last weekend's windstorm. This declaration helps validate many of our nervous system's responses to over 72 hours of increasingly extreme winds. 

Here are the stats from Hatch Peak:

• Wind began in earnest the afternoon of December 5th and didn't abate until the morning of the 9th.
• Winds were elevated for 72 hours between December 6th and 8th, with the hourly average remaining over 25mph during that time
• On Monday the 8th, winds intensified to their greatest, with hourly average wind speeds reaching nearly 60mph, and gusts up to 78 mph. 

What this did to Hatcher Pass's thin, faceted snowpack is impressive. The intense winds stripped many slopes and loaded others, triggering a widespread cycle of natural avalanches on many aspects throughout the forecast area. Now, after the dust has settled, upper elevations resemble a harsh moonscape, with frozen tussocks, exposed rocks, and patches of firm snow. When you get a little closer and a little more granular, things don't get much prettier. Wind-affected snow is everywhere, with slabs ranging in density, thickness, and distribution. Since the storm ended, forecasters in the field have encountered wind slabs ranging from 2 inches to 2 feet thick, with densities ranging from 1 finger and breakable, to knife-hard and boilerplate. These slabs were mostly deposited into gullies, depressions, and tight terrain features, but a broader distribution exists in some upper elevation alpine bowls. 

What survived is plenty of weak, faceted snow. In protected areas, an inch or three of breakable crust protects a foot or more of large-grained facets.  As you gain elevation and increase your slope angle, thicker, more dense slabs are hiding their own layers of old faceted snow. Due to the chaotiv and extreme nature of the winds, slabs formed below ridgelines and in tight gullies and depressions. In many locations, the tight terrain features are helping hold the slabs in place, but where the slabs exist in more open terrain, it could still be possible to trigger a small avalanche. Approach wind-loaded slopes with caution and travel one at a time. Consider the consequences of a rocky slide or long fall. 

Recent Avalanches:

On Tuesday, a party triggered a small avalanche while ascending the lower flanks of Marmot. 

Over the week, forecasters have continued to observe evidence of natural avalanches triggered by last weekend's wind. This includes size 2 slides in April Bowl, as well as smaller avalanches off both aspects of Marmot, Martin Mine, Hatch Peak, and Microdot. See all recent observations here.