Because last week’s storm loaded a widespread layer of surface hoar (a persistent weak layer) we are calling this a persistent slab issue and not just a wind slab. The main concern in the advisory area is finding a slope where the snow above the January 21st buried surface hoar is acting like a slab. We are not finding evidence of this below 2500′. Cold temperatures with the inversion have been quickly degrading the snow near and below treeline. Slopes near ridgelines in the Alpine, are where the winds over the weekend affected the snow and changed it from fluffy, low density powder to stiff and consolidated wind crust or slab. There were a couple reports of people intentionally triggering small slabs on wind-loaded slopes Tuesday that failed on the buried surface hoar, one skier triggered and one snowmachine triggered. These are a good reminder that despite the cold and clear weather now slowly faceting away the slabs; there is still the possibility of finding and triggering lingering slabs in leeward terrain today. Remember that there is surface hoar is lurking underneath the recent snow and it’s important to assess areas affected by wind. Slabs can be deeper in loaded areas. Pay attention to slopes where the snow feels stiff, looks pillowed or sounds hollow and watch for shooting cracks. A small slab in the wrong terrain could have high consequences. The easterly winds have picked up this morning blowing into the teens and 20s. Look for changing conditions today if you see snow getting moved around.
Evidence of a natural wind slab avalanche in Ragged Bowl and wind-affected snow. This was likely triggered during the higher winds around the Girdwood area Sunday into Monday morning. Photo: Mike Ausman
Snow pit from Cornbiscuit yesterday. The January 21st buried surface hoar was easy to find but not reactive in this spot.
January 21st buried surface hoar preserved under the slab.
As the cold weather continues to loosen and facet the surface snow, loose snow avalanches (sluffs) are becoming larger and faster by the day. Watch out for and manage your sluff in steep terrain features.
Natural loose snow avalanches and skier triggered sluffs on Magnum.
Triggering a deep slab is becoming unlikely, but is still not out of the question above 3000′. In the high elevation snowpack there are a variety of weak layers in the mid pack and near the ground. Because of this poor structure, there is still a chance of triggering a deep slab if you find the wrong spot. The most likely trigger spots are in thin areas in the snow cover, often near rocks, or where the slope rolls over.
Yesterday the clouds moved out and the skies became clear again. Temperatures were in the teens at upper elevations and single digits in the valleys. Winds were light and easterly. Overnight they picked up a little from the SE blowing in consistently in the teens. Temperatures dropped below 0F in the valley bottoms and were in the single digits to low teens at ridgelines stations.
Today will be clear and sunny. Temperatures will be in the single digits to teens with an inversion still in place. Winds will be easterly 5-15 mph gusting into the 20s.
This sunny, cold weather is forecast to continue into the weekend. There is a chance of snow showers Monday afternoon and a “gradual uptick in temperature.” Stay tuned to see what actually happens with the blocking high that is dominating our weather.
PRECIPITATION 24-hour data (6am – 6am)
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||18||0||0||62|
|Summit Lake (1400′)||3||0||0||17|
|Alyeska Mid (1700′)||11||0||0||51|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||12||variable||7||18|
|12/06/19||Turnagain||Avalanche: Sunburst||Billy Finley|
|12/04/19||Turnagain||Observation: Sunburst||A.Johnston-Bloom/ W.Wagner/ R.Van Luit Forecaster|
|12/03/19||Turnagain||Observation: Hippy Bowl||Nick Langowski|
|12/01/19||Turnagain||Observation: Tincan, All elevations||Eric Roberts|
|12/01/19||Turnagain||Observation: Tincan||Andy Moderow|
|11/30/19||Turnagain||Observation: Tincan Treeline Plateau/ Common Bowl/ Ridge||Eric Roberts|
|11/29/19||Turnagain||Observation: Sunburst Ob #2||Aleph Johnston-Bloom Forecaster|
|11/29/19||Turnagain||Observation: Sunburst Ob #1||Aleph Johnston-Bloom Forecaster|
|11/27/19||Turnagain||Observation: Tincan||Aleph Johnston-Bloom Forecaster|
|11/25/19||Turnagain||Observation: Sunnyside||Graham Predeger Forecaster|
Status of riding areas across the Chugach NF is managed by the Glacier and Seward Ranger Districts, not avalanche center staff. Riding area information is posted as a public service to our users and updated based on snow depth and snow density to prevent resource damage at trailhead locations. Riding area questions contact: firstname.lastname@example.org
|Area||Status||Weather & Riding Conditions|
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