Saturday, April 12, 2014 at 6:36 am

This advisory expires in 24 hours

BOTTOM LINE

Moderate avalanche hazard at mid elevation (2500′-3500′) and high elevation (above 3500′) on northwest, north, and northeast aspects with slope angles of 40° or steeper for dry loose avalanches. Moderate hazard at mid (2500′ – 3500′) and lower (below 2500′) elevations for wet loose avalanches on south aspects.

Low hazard at all other aspects and elevations. Low hazard does not mean no hazard.   

 Click here for a description of the North American Public Avalanche Danger Scale

RECENT ACTIVITY and CONDITIONS

Hatcher Pass received 4-8” of new snow on 4/5 and 4/6. Temperatures remained steady throughout the week, dipping in the teens at night, rising into the lower thirties during the day. Cooler temps the past couple days have contributed to significant surface hoar growth and near surface faceting. This moderate weather cycle has once again preserved most of what Hatcher has to offer this time of year, a tasty multi-faceted sandwich with surface hoar and some sun softened south faces.

On an interesting note, isolated collapsing and cracking have been observed on ENE, N, and NE open low angle terrain for more than two weeks with no sign of a slab avalanche. Test results show low energy. Typically, collapsing and cracking are indicators of instability that contribute to slab avalanches. This tells us that poor structure still exists in the lower snowpack that could be problematic in the future.

AVALANCHE CONCERN 1

Natural dry loose avalanches occurred on northerly aspects above 40 degrees within 24-48 hours of receiving new snow on 4/5 and 4/6. The new snow fell on an old loose faceted surface and some surface hoar. This bed surface has made for a super fast sliding surface. These avalanches have been small to moderate in size.

Human triggered dry loose avalanches have been observed since the new snow deposits. Cold temps have continued to drive moisture out of the new snow, turning it into a surface hoar and faceted surface. It is still possible to human trigger dry loose avalanches on north, northwest, and northeast aspects above 40°.  If triggered, the sluffs are large enough to swoop you off your feet, take you over a cliff, or injure you. Sluff management is a must if skiing steep northerly terrain.

AVALANCHE CONCERN 2

Natural and human triggered wet-loose avalanches have been observed on south aspects at low and mid elevation in the afternoon.  Six to ten inches of new snow from last weekend is being heated by the sun, and is sitting on a stout crust acting as a slick sliding surface for wet-loose activity. Pay attention to aspect and time of day to avoid triggering wet slides.

Under the crust, facets persist. In the future warmer weather will begin to weaken this crust, and increase the likelihood of larger wet-loose or wet slab avalanches with greater consequences.

AVALANCHE CONCERN 3

Cornices continue to build in size and stature with last weeks new snow. They still loom over most leeward aspects with awe inspiring size. Increasing temps are weakening bonds in the cornices and will increase the likelihood of cornice collapse. A cornice collapse is the perfect trigger for a large dry loose avalanche on any steep northerly slope. Stay far from these hazards as spring moves forward.

 TREND

A pattern change in on the horizon. The forecast calls for increasing clouds and warmer temperatures with some potential precipitation Saturday through Tuesday/Wednesday.

Avalanche activity will decrease unless any rapid change occurs, in the form of rain, snow, or significantly warmer temperatures.

 

–Allie Barker

If you are out and about HP and see an avalanche or have a snow observation, please share it with us by clicking on these links or under the observations tab in the menu bar or email us at info@hatcherpassavalanchecenter.org. We would like to hear from you!