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ARCHIVED - Forecasts expire after 24 hours.
Issued
Sun, March 31st, 2013 - 7:00AM
Expires
Mon, April 1st, 2013 - 7:00AM
Forecaster
Wendy Wagner
Avalanche risk The Bottom Line

The avalanche danger will remain MODERATE today above treeline for both wind slab avalanches and wet loose snow avalanches. Wind slabs formed two days ago were still reactive yesterday and though on the decline, should still be watched out for today. Additionally, natural and human triggered wet sluffs will be possible where warm temperatures will again moisten the snow surface on south, east and westerly aspects predominantly. Last, cornices deserve a wide berth with continued warm conditions.

Special Announcements

Today is the  2nd  ANNUAL  CORN HARVEST  – come join us anytime between 3 and 7PM!! Motorized lot on Turnagain Pass – FREE FOOD, games, prizes, etc.

Sun, March 31st, 2013
Alpine
Above 2,500'
2 - Moderate
Avalanche risk
Treeline
1,000'-2,500'
1 - Low
Avalanche risk
Below Treeline
Below 1,000'
1 - Low
Avalanche risk
0 - No Rating
1 - Low
2 - Moderate
3 - Considerable
4 - High
5 - Extreme
Avalanche risk Avalanche risk Avalanche risk Avalanche risk Avalanche risk
Travel Advice Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern. Dangerous avalanche conditions. Dangerous avalanche conditions. Very dangerous avalanche conditions. Travel in avalanche terrain not recommended. Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain.
Likelihood of Avalanches Natural and human-triggered avalanches unlikely. Natural avalanches unlikely; human-triggered avalanches possible. Natural avalanches possible; human-triggered avalanches likely. Natural avalanches likely; human-triggered avalanches very likely. Natural and human-triggered avalanches certain.
Avalanche Size and Distribution Small avalanches in isolated areas or extreme terrain. Small avalanches in specific areas; or large avalanches in isolated areas. Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas. Large avalanches in many areas; or very large avalanches in specific areas. Very large avalanches in many areas.
Avalanche Problem 1
  • Wind Slabs
    Wind Slabs
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
More info at Avalanche.org

Wind slabs formed during Friday, 3/29’s 8-10” of snow were still releasing yesterday. These were in the foot deep category and on all aspects above treeline. A few observed were: one natural that occurred on the east face of Seattle Ridge and one on the southerly tip of Tincan Proper. Check the obs page for a few more details from other observers. The sun and warm temperatures likely played a role in increasing the instability of the slabs.

Today I’m expecting these to be harder to trigger but still the primary concern due to their slab nature. The snowpack is quite variable currently with wind slabs sitting on crusts on south, east and westerly aspects (some of which have facets surrounding them) and on old wind crust/slabs on northerly aspects. Quick hand pits looking for easy shears between snow layers in the top 12-18” of the pack is one good tool to suss out any slab that has yet to heal.

Avalanche Problem 2
  • Dry Loose
    Dry Loose
Dry Loose
Dry Loose avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.
More info at Avalanche.org

Wet point release and damp point release avalanches should be expected today on south, east and westerly facing slopes approaching 40 degrees and steeper. Watch for rollerballing in the surface snow and be suspect of areas and aspects where the snow surface is warm and gloppy.

 

 

 


Additional Concerns:
Cornices. Warm temperature are known for contributing to the failure of cornices. A good thing to keep in mind when planning your route.

Surface Conditions:
Yesterday’s warmup affected the south, west and easterly aspects as well as below treeline locations. These areas that became damp or wet yesterday are likely undergoing a superficial refreeze now but should moisten through the day. Upper northerly aspects sport variable wind affected, but dry, snow.

Weather
Sun, March 31st, 2013

It was a WARM day yesterday with temperatures reaching the 40deg mark at sea level and 30F at 3,000′. Skies were partly cloudy with a few flurries (drizzle below 1500′) late in the day. Winds were light from the east (5mph gusting 15mph). The last measurable snowfall was 8-10 € on Friday 3/29.

This morning we are looking at mostly cloudy skies, fog and temperatures around freezing (32F) at 1,000′ and ~20F on the ridgelines. Temperatures should rise to the upper 30’s at 1000′ and upper 20’s at 3,500′. A chance for an inch of snow is on the radar (drizzle below 1000′) as instability showers are over the region. Winds are from the east currently, 10mph gusting ~15mph, and should remain today. I’m hoping the cloud cover will burn off a bit for the CORN HARVEST so cross your fingers.

Monday, and through the early part of this week, it looks as though a high pressure ridge will build over western Alaska. This should bring us light northerly wind and mostly clear skies.


Fitz will issue the next advisory tomorrow morning, April 1st.

Observations
Recent Observations for Turnagain Pass
Date Region Location
11/16/23 Turnagain Observation: Tincan Common
11/14/23 Turnagain Observation: Sunburst/Magnum
11/14/23 Turnagain Observation: Seattle Ridge
11/13/23 Turnagain Avalanche: Tincan Trees
11/12/23 Turnagain Observation: Sunburst
11/12/23 Turnagain Avalanche: Goldpan – avalanche
11/11/23 Turnagain Observation: Tincan Common
11/11/23 Turnagain Observation: Taylor Pass – Sunburst
11/10/23 Turnagain Observation: Tincan
11/10/23 Turnagain Observation: Tincan Trees
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This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area. This advisory does not apply to highways, railroads or operating ski areas.