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Thu, January 8th, 2015 - 7:00AM
Fri, January 9th, 2015 - 7:00AM
Graham Predeger
Avalanche risk The Bottom Line

The avalanche danger is MODERATE today at all elevations above 1,000.   With rapidly warming temperatures overnight and in-coming moisture, the trend will be for increasing danger throughout the day.   If we see an inch or more of rain and ridgetop temperatures continuing to climb north of the mid-30’s, the danger may rise to CONSIDERABLE by late in the day.   Wet slabs and wind slabs up to 2 feet deep will be possible for a skier to trigger above 2,500′, particularly later in the day as the storm ramps up.   Large avalanches in isolated areas could be possible in these upper elevations as a wet slab could step down into a buried weak layer.   The rain/ snow line is expected to be somewhere in the 2,500 €“ 3,000′ band today.

Below 2,500′ small, wet-loose snow avalanches will be possible to initiate in steep terrain, (>35 degrees) particularly later in the day on your egress back to the parking lot.  

Make no mistake before driving to the trailhead; today appears to be a warm, wet and windy storm day, making for less than pleasant conditions in the backcountry.

Special Announcements

Join us for our final  Fireside Chat this Thursday, January 8th,  in Anchorage! Topic: Mountain Weather and Snowpack.   CNFAIC forecaster and resident meteorologist Wendy Wagner will be taking a close look at the current state of the snowpack at Turnagain Pass along with a look into “when is it going to snow?”.   You won’t want to miss this, and the best part is that it’s FREE!!!

Do you ski or snowmachine in Hatcher Pass?   The Hatcher Pass Avalanche Center (HPAC) and the Alaska Avalanche School (AAS) are leading an Observer’s Workshop for backcountry enthusiasts who are interested in submitting snow and avalanche observations to the HPAC.   More info can be found by clicking here.  

Thu, January 8th, 2015
Above 2,500'
2 - Moderate
Avalanche risk
2 - Moderate
Avalanche risk
Below Treeline
Below 1,000'
0 - No Rating
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. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential. 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
  • Wet Loose
    Wet Loose
Wet Loose
Wet Loose avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
More info at Avalanche.org

Today marks a significant pattern change in our weather from the cold, dry high pressure of the last several days to another warm, moist air mass spilling into south-central Alaska. The two factors effecting stability the most today will be rapidly rising temperatures and rain; potentially up to 3,000’.

Wet slab avalanches will be possible to trigger as yesterday’s dry surface becomes saturated at elevations below the rain/ snow line.  These may be up to 2’ deep and conceivably could step down into buried weak layers that we know exist throughout the Turnagain and Girdwood Valley zones.  Below 2,500’ our snowpack is strong and lacks energy.  That being said, the surface has already seen rapid warming at this elevation band and as it becomes saturated with rain later in the day, skiers will be able to initiate wet loose ‘push-alanches’ and point releases in steep terrain, though a cohesive slab will be unlikely at this lower elevation band. 

Perhaps more concerning for today; temperatures began their climb across the forecast area yesterday with some dramatic upticks in the mercury this morning (9 deg F in 12 hrs @ Center ridge, 18 deg F in 12 hrs @ Grandview and 28 deg F in 12 hrs at Granite!).  This is a big red flag as rapid warming such as this leads to a loss of strength within the snowpack. Though not as dramatic yet (7am) at ridgetop locations, if temps continue to increase throughout the day, particularly in the upper elevations, expect avalanche danger to follow suite with wet slabs becoming more likely.

Temperatures, winds and RH are all on the rise today throughout the forecast area.

Avalanche Problem 2
  • Persistent Slabs
    Persistent Slabs
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
More info at Avalanche.org

Today’s new load is unlikely to be enough to tip the balance and initiate a persistent slab.  However, the warming trend over the past 24hrs is acting to decrease the strength of buried weak layers.  Rapid warming combined with the potential for a skier-triggered wet slab to step down into buried weak layers has us continuing to keep an eye on this avalanche problem.  

Additional Concern
  • 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

With very little snow available for transport, wind slabs today will be relegated to the upper elevations and comprised of new snow.  These will grow throughout the day above the rain/ snow line and expect them to become increasingly sensitive to human triggers as the storm progresses. As of 6am this morning ridgetop winds are gusting to 60mph in advance of precipitation.

Thu, January 8th, 2015

Yesterday was the end of a period of high pressure and temperature inversions.   Clear skies, light winds, and temps in the low teens at 1,000′ (mid- 20’s at ridge tops) have dominated the region for several days now.   Make way for our latest warm-up €¦.

Today we can expect warm, wet and windy conditions in the eastern Turnagain arm area.   As of 6am this morning the temperature at Turnagain pass is 41 degrees with rain just beginning to show up on the radar.   At ridgetop locations, temperatures are in the low-30’s now and will likely see mid-30’s by late in the day.   Ridgetop winds will be from the east in the 30-60mph range.   The rain/ snow line will be hovering around 3,000′ with .6 €“ 1 € of water forecasted by late tonight.  

Unfortunately more warm, unsettled air is on tap for south central Alaska this weekend and into the latter half of next week.   Now may be a good time to book that last minute trip to Hawaii or Jackson Hole, depending on what you’re in need of more!

PRECIPITATION 24-hour data (6am – 6am)

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 33    0 0   32  
Summit Lake (1400′)  24  1  .2 7  
Alyeska Mid (1700′) 30    .5 .06   25.5  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 31    E  16  65
Seattle Ridge (2400′)  31  E  17  49
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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.