It’s been almost a week since the Valentines Day storm dumped 2-3’ of heavy snow on top of a weak surface (surface hoar and/or near surface facets.) On Saturday several human triggered avalanches occurred on Seattle Ridge, and luckily there were no reports of anyone being caught. Poor visibility over the last two days has made travel into the alpine challenging and has limited traffic and observations in this zone. The good news is with time, the slab has been adjusting to the weak layer below, making it more difficult to trigger. However the consiquences remain high, meaning it is still possible to trigger an avalanche large enough to bury, injure or a kill a person. Be aware that no red flags may be present (whumphing or cracking in the snow) and the pack could have a general “it seems fine to me” feel before someone finds a trigger point. Trigger points are often where the slab is thinner, near rocks or scoured areas. Also keep in mind, these slabs can break above you, release after several tracks are on a slope and be triggered remotely. The trickiest part about our current snowpack is how difficult it is to assess due to the spacial variability of both the weak layer, the slab, and even the bed surface in some places. Some steep solar aspects (S-SE) may have a slick sun crust bed surface/buried surface hoar combo. Be aware that snow pits and stability tests may not be representative of the actual slope you are trying to assess.
This snowpit from yesterday on a West aspect of Taylor Pass shows all of the weak layers described in both the Persistent and Deep Slab poor structure. This location did not produce any conderning results, but its still good example of the difficulty in assessing these avalanche concerns.
Human triggered avalanche that was reported second hand on Saturday in Seatte Creek on JR’s, Southern aspect. If anyone has info or details about this avalanche please submit an observation HERE. Photo taken on Monday, 2/20/17 by Bryan Pfaender.
WIND SLABS: There is 3-6” of very light weight fluffy snow on all aspect throughout our region and ridgetop winds 5-15mph are in the forecast today. If this is the case expect small isolated wind slabs to be easy to trigger on leeward features. Be aware that Northwest winds can funnel through some terrain in Turnagain Pass in more of a Southwest direction, causing an unusual loading pattern. Although these slabs are not expected to be very dangerous, don’t let one catch you off guard in a the wrong place. Watch for blowing snow and identify steep features where the snow may be loading.
LOOSE SNOW: Sluff will also be easy to initiate on steep features and could be fast moving
CORNICES that grew last week could still be teetering on the balance and could break further back than expected
GLIDE AVALANCHES: There is a new glide crack above the flats along Seattle Ridge, just looker’s left of the up-track and Repeat Offender slide path. Avoid hanging out under this crack and any others you may see – these release without warning and are very destructive.
SUNSHINE? Although winds are expected to keep the surface cool today, be aware of solar warming that may trigger loose snow avalanches in steep Southerly aspects.
At the bottom of the snowpack are various layers of facets with varying degrees of strength. In the Summit Lake zone and some areas in Girdwood Valley and Johnson Pass depth hoar has been found as well as some areas in Turnagain Pass. Last week’s storm cycle tested these layers and only a few avalanches that we know of broke in them (Girdwood Valley, Portage and Summit Lake). These layers will be tough for people to trigger, but possible in shallow snowpack zones. The more likely case is where an avalanche occurring in the upper layers of the pack has the potential to step down and release the entire snowpack. If this does happen the volume will be large and could run long distances.
Yesterday temperature dropped into the single digits. Skies were obscured and snow flurries left several inches of fluffy low density snow throughout our region. Ridgetop winds were calm. Overnight a similar pattern continued.
Today skies will start out mostly clear becoming cloudy be this afternoon as a front moves into our region. Ridgtop winds are expected to increase 5-15mph from the NW throughout the day with winds increasing to the mid 20’s from the SE by this evening. Temperatures are also expected to warm up into the teens F by the afternoon. Snow flurries are in the forecast and 1-3 € of snow expected by this evening.
Tomorrow night into the Thursday a second warm front is expected to bring more snow and warmer temperatures. There is much uncertainty as to how much accumulation will occur in Turnagain Pass zone.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||11||trace||0||67|
|Summit Lake (1400′)||12||trace||0||31|
|Alyeska Mid (1700′)||12||1||.1||65|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||6||n/a||n/a||n/a|
|04/21/21||Turnagain||Observation: Sunburst||Schauer/ Behney Forecaster|
|04/19/21||Turnagain||Avalanche: Triangle, Seattle creek||Will Morrison|
|04/18/21||Turnagain||Avalanche: Turnagain Pass Road Obs||Andy Moderow|
|04/18/21||Turnagain||Observation: Seattle Ridge, approximately 300 yards south of the up track||Brent Byrne|
|04/17/21||Turnagain||Avalanche: Road obs||Johnston-Bloom / Moderow Forecaster|
|04/16/21||Turnagain||Avalanche: Seattle Ridge||Wendy Wagner Forecaster|
|04/16/21||Turnagain||Avalanche: Turnagain Pass, non-motorized side seen from Seattle Ridge||CNFAIC Staff Forecaster|
|04/16/21||Turnagain||Observation: Sunburst||Lance breeding|
|04/15/21||Turnagain||Observation: Tincan||Schauer/ Rothman Forecaster|
|04/13/21||Turnagain||Observation: Turnagain Pass Road Obs||A Schauer 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|
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.