Avalanche Advisory, Martin Luther King Day, at 7:30 AM

Issued: Mon, Jan 16, 2017 at 8AM

Expires: Tue, Jan 17, 2017

A Winter Weather Advisory is in effect for Hatcher Pass through 8 PM today.

We will continue to update this advisory throughout the day, as necessary.

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

Considerable avalanche hazard at upper elevations on all aspects. Dangerous avalanche conditions,. Careful snowpack evaluation, cautious route-finding, and conservative decision making essential. Natural avalanches possible, human triggered likely. Small avalanches in many areas; large avalanches in specific areas; or very large avalanches in isolated areas.

Moderate hazard at mid-elevations and low hazard at low elevation.

The avalanche hazard could rise to high by this afternoon or evening if HP receives the forecasted 8-12 inches of snow.

Continue to check back here periodically for updated information and avalanche danger rating changes. If the avalanche hazard rises to high or extreme, we will issue an avalanche warning through the National Weather Service in addition to an updated avalanche warning here.

The National Weather Service has issued and extended a winter weather advisory in effect for Hatcher Pass through 8:00 PM today.

With a substantial, new weather event today, we are still in the ASSESMENT MIND SET:  There is a high degree of uncertainty about conditions, such as when first encountering the terrain for the season, entering new terrain, following a lengthy period with limited observations, or after substantial weather events.  Select conservative terrain in which to operate confidently while more information is gathered to gain confidence in the hazard assessment. 

 


Avy Problem 1 Storm Snow

Human triggered, storm snow avalanches, will be likely to trigger and natural avalanches possible, at upper elevations, on all aspects, on slopes 35° and steeper.  This hazard will increase throughout today as snow accumulation increases. If wind speeds at upper elevations rise above 12 mph or begin gusting above 15-20 mph, expect wind transport of new and old, low density snow, to build cohesive storm slabs. Low density snow does not require as much wind speed to transport as higher density snow. Look for flagging and plumbing at ridgeline if visibility allows.

Storm snow avalanches will be possible to human trigger at mid-elevations and unlikely at low elevations.

 

wind transport skyscraper

Pictured here: wind transported new snow on the Hatch Peak ridgeline Saturday afternoon, as well as a possible natural loose snow avalanche in the shadows. A couple spells of increased wind speeds between Jan 14th and 15th will have deposited cohesive slabs 6-10″ thick on NW to NE aspects at upper elevations. These will be sensitive to human triggers.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Persistent Slab

Human triggered, persistent slab avalanches will be likely to trigger, and natural avalanches possible, at upper elevations in isolated locations. This problem is isolated to previously wind loaded slopes near ridgelines, cross loaded features, and around mountain passes. Positively identifying these locations based on snow texture or clues, will be near impossible, now that they have been covered in approximately 18″ of snow since 1/13. Avoid large open slopes, starting zones and open bowls to minimize your exposure.

Human triggered persistent slabs will be possible in very isolated locations at mid-elevation, and unlikely at low elevation.

 

Loose Snow

Natural loose snow avalanches will be possible, and human triggered likely, at upper and mid-elevations on all aspects, on slopes 40° and steeper. These may have enough volume to sweep you off your feet and carry you into terrain traps and other hazards, such as rocks or over cliffs.

 

 

 

Recent Avalanche Activity

Recent Weather

Additional Info & Media

trend kompass
The avalanche hazard will increase throughout the day as new snow accumulates. An increase in wind speeds could increase the avalanche hazard quickly. It will be possible for the avalanche hazard to reach high danger, if HP receives the forecasted snow totals. Check this advisory periodically throughout the day for updated information and avalanche danger rating changes.

 

 

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Posted in HPAC Forecasts.
Jed Workman

Forecaster: Jed Workman