Avalanche Advisory

---------- Terrace & Coastal Areas ----------
  Tuesday Wednesday Thursday
---------- Smithers & Interior Sections ----------
  Tuesday Wednesday Thursday
Below Treeline 2 - MODERATE 2 - MODERATE 2 - MODERATE
Fair. The snowpack structure is complex and various between areas and
even between drainages. Figuring out how stressed the snowpack is, and
how it will respond to bouncing between the spring sun and wintery
storms is challenging.
Primary Concerns:
  • Storm Snow: Snow and wind have loaded (and will continue to load) NW-NE slopes which means¬†wind slabs on the lee
    side of ridges and similar terrain features. It also means cross loaded
    slopes and gulleys on more E'ly and W'ly facing terrain features.

    The reason my concern is more widespread than just wind slabs is
    because in some areas there's surface hoar below the new snow: it grew
    quickly Friday and Saturday, it sits on a crust on solar apsects, and
    it reportedly can extend into alpine areas. 

  • Solar Radiation: TUESDAY:¬†Recent
    snow is likely warm and weaken rapidly with the April sun on southerly
    facing slopes. In some places the new snow rests on a smooth, slippery
    crust or, even worse, a crust with a layer of surface hoar above it.
  • Cornice:
    Cornices continue to grow with moist, warm, and windy conditions.
    Falling chunks are hazardous unto themselves; cornice triggered slab
    avalanches compound the problem, especially if nasty deep weak layers
    (the famous PWLs or Persistent Weak Layers) come into play.

Special Message:   We compiled a photo analysis from a few recent incidents (click here).
Although they aren't from deep coastal snowpack areas, they're
instructive. There's lots of similar terrain in the NW region and this
winter you lack the typical strong coastal snowpack.

Travel Advisory:  
Issued: Mon, Mar 30 Next Scheduled Update: Thu, Apr 2

"Low confidence"
Because of the complex layering in the snowpack, most of the people
that work up in the region that I've been chatting with seem to echo
this sentiment. Solutions to this problem include:

  • Margins for error - pick
    your terrain a little more conservatively, stick to what you're sure is
    safe and don't be too quick to stick your neck out.
  • Safe travel rituals
    - continually ask "what if it happened now?" This helps you pick where
    you park yourself to watch your buddies ride, where you eat lunch (not
    in the sun at the bottom of a baking slope), knowing your escape route
    before hitting a slope, ...
  • Terrain Traps¬†- minimize
    exposure to terrain that works against you by increasing the
    consequences of a slide: cliffs, gulleys, "toilet bowls", sparse trees
    that act like a cheese grater, ....

What I like right now is deep snowpack areas, terrain where the snow
gains some support from below, and consistent lower angle slopes
without overhead hazards.

The sunny weather forecast Tuesday makes me very suspicious of sunny slopes - they could start releasing naturally. 

Avalanche Activity:  
Issued: Mon, Mar 30 Next Scheduled Update: Thu, Apr 2

Few recent avalanches reported, but the weather limited the number of
eyes in the mountains Monday, and what they could see. I expect some
natural activity near Terrace given the new snow and wind. I also
expect solar triggered avalanches on Tuesday if it warms up and the sun
shines strongly. See the sidebar for details regarding a size 3.0
avalanche triggered by a snowmobile in the South Douglas area; even
though it's a few days old, it remains relevant.

Issued: Mon, Mar 30 Next Scheduled Update: Thu, Apr 2

Monday's storm snow varies across the region with 40 - 60 cm estimated
near Terrace, much less elsewhere. SW winds have created slabs on the
north through east sides of exposed ridges and similar terrain
features. This snow rests on crusts (solar aspects), surface hoar
(don't know too much about its distribution but may include the typical
shady treeline elevations plus above buried suncrusts, and possibly
into alpine elevations), or just older storm snow.
There are several PWLs buried deeper in the snowpack that are producing moderate to hard "pops" and "drops" in compression tests  - the depth and distribution of these layers varies across the region. The uppermost (consisting of surface hoar, facets and/or a crust) is approximately 40 cm deep in the inland section and 70-140 cm deep in the coastal part of the region.

View Avalanche Observation Summary


Issued: Mon, Mar 30 Next Scheduled Update: Thu, Apr 2

Unsettled weather with snow, wind, and clouds continued Monday on the
coastal side of the ranges; however, interior sections were drier with
a mix of sun and cloud.

Tuesday: Light
to moderate west wind. A dry day with sunny breaks. Slightly cooler
temperatures with freezing level near 500m is forecast, BUT SOLAR
RADIATION will likely warm all southerly facing slopes quickly.

Wednesday: The
next Pacific frontal system is expected to arrive with strengthening
winds backing to the south and strengthening. Moderate precipitation
for coastal and southern areas, light precipitation for inland and
northern areas.

Issued by: ilya storm

Important Notice: This is a regional forecast and significant variation may
exist within the forecast area. The information and danger ratings are intended
as a trip planning aid for recreational, backcountry users of avalanche
terrain; they are not meant to be used as the sole factor in determining the
avalanche danger presented by a specific slope. Always include local weather,
snowpack and avalanche observations in your decision to travel in avalanche
terrain. Observations and experience may lead to different conclusions from
what is reported or recommended. See disclaimer for further details. The
technical data used to produce these bulletins is obtained from a variety of
sources, including various government agencies and private companies that
participate in an industry-wide daily information exchange program. These
contributors provide data, resources, and funding without which the Canadian
Avalanche Centre could not provide this avalanche information.

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