Following in step with our unprecedented warm winter, during the past several days we have seen rain falling on snow up to 2,000′, and as high as 3,000′ in places. Water amounts have accumulated to ~.7″ on Turnagain Pass and up to 2″ in the Girdwood Valley since Saturday. Not only has this been raising the snow line (which is currently around 1,500′) but it has more importantly induced a mini wet slab cycle in this small elevation band. Technically, warm temperatures and sunshine has helped to tip the balance for some of these wet slabs after the rain, but regardless, there is a poor snowpack structure in the top 1-2′ and this is why we are seeing wet slabs. Below are some shallow slabs seen yesterday in the Portage Valley – these are similar to the shallow slabs on Seattle Ridge two days ago.
For today, skies have been clearing the temperature dropping which will start freezing the pack from the surface down and decrease the wet slab potential. But, only a shallow re-freeze on the surface should not be mistaken for good stability. Sometimes a shallow re-freeze can act to strengthen the slab enough to increase triggering potential before it does indeed freeze enough to be safe; something to keep in mind when moving through the mid-elevations to get to the drier snow above.
Portage Valley shallow wet slabs likely from Sunday 2/22 (Maynard Mtn, West facing ~2,000′).
In the dry snow, which begins roughly just above 2,500′, we continue to be concerned with the well documented layer of faceted snow that sits under a slab 1-3+’ thick. The slab is highly variable due to the extreme winds seen a week ago. From the little information we have been able to gather, high variability does exist in the slab depth as well as the weak layer depth and strength. This variability can be helpful in breaking up the slab/weak layer combo and minimize the ability for an avalanche to propagate across entire slopes. However, a 3′ slab is nothing to mess with even if it does just release in a pocket and not over an entire slope.
If you are getting out in search of dry snow today:
Partly cloudy skies, some sunshine and intermittent rain showers covered much of the region yesterday. Around 0.2″ of rain fell below 2,000′ with a dusting of new snow above this. Ridgetop winds were 5-10mph from the Southwest while temperatures were in the upper 30’s F at 1,000′ and in the upper 20’s F on the Ridgetops.
Overnight, skies have continued to clear and temperatures have cooled slightly at each station (ridgetop as well as valley bottom). Valley fog is likely today with partly sunny skies above. Temperatures should warm back up to the mid 30’s at 1,000′ and the upper 20’s on the ridgetops and feel quite warm in areas with sunshine. Ridgetops winds are expected to be in the 5-10mph from the East.
We look to remain between storms with mostly sunny skies and light winds through Friday; a low pressure does brush to our South on Wednesday, which should only bring some high clouds and moderate East winds. The weather models are showing our next shot of precipitation on Saturday with another dose of warm, wet and windy weather.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||32||rain||0.1||40|
|Summit Lake (1400′)||30||rain||0.1||6|
|Alyeska Mid (1700′)||33||rain||0.17||22|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||27||N/A||7||18|
|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|
|04/12/21||Turnagain||Observation: Tincan||Johnston-Bloom / Latosuo 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: email@example.com
|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.