PERSISTENT SLAB AVALANCHES (In our current case: Hard WIND SLABS SITTING ON WEAK SNOW): A big wind event that occurred on December 30th has stripped many Southern and Western ridgetops and left an unusual loading pattern for our region; loading Northern and Eastern aspects. This wind event as well as the Christmas snow storm (a week ago) caused widespread avalanching in the area. Several persistent weak layers are buried within the snowpack (facets and buried surface hoar), but strong supportable snow may make it tough to find the right trigger spot.
Some uncertainty remains today with how the warm inverted air temps (approaching 40F) will affect the snowpack in the alpine. Although radiation from the sun at this time of year is minimal, whenever temperatures remain above freezing for 24 hours it is worth keeping in the back of your mind. Be skeptical of supportable and hollow sounding snow on steep slopes. Likely trigger spots will be in thinner areas of the snowpack in steep rocky terrain or on unsupported slopes that haven’t avalanched. Triggering a small isolated wind slab or a deeper slab 2+ feet is becoming more difficult, but is possible for a person or snowmachine to tip the balance. Obvious signs like cracking and ‘wumpfing’ are becoming less common and may not be an early warning sign.
Before exposing yourself to steeper terrain, ask yourself what will happen if the slope slides? Always practice safe travel habits to minimize exposure in avalanche terrain!
A closer view of the natural avalanches that occured on Corn Biscuit’s North facing chutes last Friday (12/30.) Places that haven’t avalanched with similar characteristics (rocky starting zones, top loading and cross loading) remain suspect.
Most of the snow along Southern aspects have blown away making it unlikely to trigger an avalanche in these areas.
Yesterday skies were sunny and clear with light Northwest winds. A large temperature inversion was observed, 12F at 1000′ and 33F at ridge tops, which caused valley fog in Turnagain Arm.
Overnight ridge top temps increased into the high 30F’s Turnagain Pass and low 40F’s in the Girdwood Valley. Valley temps have remained around 10F. Winds have remained light and no precipitation was recorded.
Today expect a similar inverted weather pattern with above freezing temperatures in the alpine and temperatures near 10F in valley bottoms. This will trap dense Valley fog in and along Turnagain Arm.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||33||0||0||38|
|Summit Lake (1400′)||13||0||0||12|
|Alyeska Mid (1700′)||31||0||0||25|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||36||NW||5||16|
|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|
|04/15/21||Turnagain||Observation: Tincan||Schauer/ Rothman Forecaster|
|04/13/21||Turnagain||Observation: Turnagain Pass Road Obs||A Schauer Forecaster|
|04/12/21||Turnagain||Observation: Tincan||Johnston-Bloom / Latosuo Forecaster|
|04/10/21||Turnagain||Observation: north sides||lance breeding|
|04/09/21||Turnagain||Observation: Girdwood to Turnagain Road Observations||W Wagner Forecaster|
|04/05/21||Turnagain||Avalanche: Resort bowl Seattle creek head wall||Clint Kyffin|
|04/04/21||Turnagain||Observation: Center Ridge||Andy Moderow|
|04/03/21||Turnagain||Observation: Repeat Offender – Seattle Ridge||Troy Tempel|
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.