Update, Monday, November 20, 2017 at 7:45 am

Issued: Mon, Nov 20, 2017 at 8AM

Expires: Tue, Nov 21, 2017

UPDATE: 11/23/17 at 7:30am

An avalanche fatality occurred yesterday on the President’s Ridge area of Marmot Mountain at approximately 3700′ on a Southerly aspect.  One person was caught, carried and killed.  More information and accident reporting to come. ADN article here.

The avalanche hazard will likely remain elevated today and through the weekend. Strong Easterly winds, sustained for 20 hours, on Monday, November 20th, reached 30 mph gusting 51 mph. These winds built dangerous, sensitive, wind slabs at mid to upper elevations which continue to be an avalanche problem.

We are not issuing an updated avalanche advisory at this time. The next scheduled advisory is for Saturday, November 25th. Updates will continue to be shared through our facebook site.

If you head into the backcountry this holiday and into the weekend, use extreme caution.  Dangerous avalanche conditions exist and human triggered avalanches are likely in specific areas.

 

Above 3,500ft Considerable

2,500 to 3,500ft Moderate

Below 2,500ft Low

Degrees of Avalanche Danger ?

1. Low
2. Moderate
3. Considerable
4. High
5. Extreme

Avalanche Danger Rose ?

Avalanche Problems ?

Problem Details

BOTTOM LINE: The avalanche hazard is rising to CONSIDERABLE today with strong sustained winds.

Likelihood: Natural avalanches will be possible today and human triggered will be likely.

Travel Advice: Dangerous avalanche conditions,. Careful snowpack evaluation, Cautious route finding, and conservative decision-making essential.


WIND SLAB: Today’s winds have begun to pick up. At 6am at 4,500′, gusts hit ENE 29 mph. This verifies the NWS forecast for today, calling for NE 21-39 mph above 3,000′. It looks like we are not going to escape the wind this time. Expect winds to transport up to 8″ of low density snow (from the last two brief storms) and build sensitive wind slabs at mid to upper elevations, generally on SW to West aspects. The aspect location could change with wind direction changes through today and this evening. Expect strong winds to build 1-2 foot deep wind slabs today.

Older, persistent slabs, such as the one mentioned in avalanche activity below, will be buried, difficult to identify and will compound the avalanche hazard.

This is a great day to avoid the mountains and the hazard. Give the mountains their space, and give them a day or two to adjust to new snow loads and avalanche problems.


More information here on specific avalanche problems.

Recent Avalanche Activity

On 11/18 a human triggered persistent slab avalanche (old wind slab formed 11/13-14) was triggered at 5k’ on an east aspect. The avalanche was small, D1, 5″ deep, and stubborn to trigger and propagate.

Recent Weather

 

When you check the weather forecast, make sure to check out the NWS RECREATIONAL FORECAST for Hatcher Pass.  NWS puts extra time and resources into this forecast specific to the mountains at Hatcher Pass, Turnagain Arm and Thompson Pass.


NWS point forecast here


State Parks snow report here


 

Additional Info & Media

Posted in HPAC Forecasts.
Jed Workman

Forecaster: Jed Workman