Just as the unwritten rule states, after three consecutive warm nights in the mountains with no re-freeze at the ridgetop elevations, wet avalanches start running. Yesterday was the first of these days and in fact, several wet loose and shallow wet slab avalanches ran naturally. These occurred on all aspects, with North and West aspects seeing the majority of the activity at Turnagain Pass. What about today and tomorrow? Although stormy weather with slightly cooler temperatures have moved in, we can expect similar wet avalanche activity.
This morning wet snow is falling above 2,000-2,500′ and rain below this. Only a few inches of snow is expected and this should stick well to the wet and warm old surface. That said, winds are blowing in the 20’s mph along ridgetops, which is enough to move the new snow into shallow wind slabs at the higher elevations where the snow is drier, such as 4,000′. Most of our terrain however is lower and wet snow issues will remain the main concern.
WET SLAB, WET LOOSE and CORNICE FALLS:
As the snowpack continues to loose its strength with the springtime melt-down, several different wet avalanche concerns are present. Things to keep in mind if you are headed out:
Wet loose and wet slab avalanches on the West face of Magnum, occurring Monday, April 24th
Wet loose avalanches in the North chutes of Tincan
Wet loose avalanches in the North chutes of Cornbiscuit
Similar to the wet issues above, glide avalanches are also occurring with the springtime melt-down. Glide cracks are opening up and releasing on many slopes in the region – steer clear of any slopes harboring glide cracks. Check out the photo below from the motorized up-track. This slope is notorious for producing glide avalanches. Additional glide avalanche activity is expected today and through the week.
Photo below: A comparison of the glide avalanches on Seattle Ridge during the past couple days (top photo from Saturday, April 22nd, bottom photo from yesterday, April 24th). The glide that released yesterday sent debris over a portion of the Turnagain Pass motorized up-track.
Upper elevation Northerly aspects have now warmed to the degree the surface layer is wet and saturated. How deep the wet snow exists varies, but what this warming does is weaken the snowpack and increases the stress on underlying weak layers. There are several buried persistent weak layers in the snowpack; ranging from buried surface hoar 2-6′ deep, mid-pack facets and facets near the ground. Shallow snowpack zones such as the Summit Lake area harbor depth hoar near the ground. As the upper elevation North, West and Easterly snowpack warms up, these weak layers could re-activate and large natural slabs are possible along with the increased chance for a person to trigger a slab.
Cloudy skies and light rainfall were over the region yesterday as a moist Southerly flow continued across Southcentral, AK. Around .1″ of rain was seen in general with higher amounts in the Portage area. Over the past 24-hours ridgetop winds have averaged 20-25mph from a generally East direction at Turnagain Pass. Temperatures climbed to the low 30’sF along ridgetops and near 50F at sea level before cooling off last night into the upper 20’s along ridgetops and near 40F at sea level.
Today, Tuesday, another wave of moisture is headed our way. We should see .1-.2″ of rain below 2,500′ and 1-3″ of wet snow above this. Ridgetop winds are expected to be in the 15-25mph range. Temperatures will hover in the upper 40’sF at sea level and the mid 30’sF along ridgelines.
For tomorrow, Wednesday, rainfall along with ridgetop winds should tapper off. Temperatures on the other hand are expected to increase a few degrees with cloud cover remaining over the area. There could be some patches of clearing sky on Wednesday before another wave of moisture moves in.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||40||Rain||0.1||56|
|Summit Lake (1400′)||40||0||0||16|
|Alyeska Mid (1700′)||38||1||0.09||51|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||No Data||SE||15||34|
|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|
|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|
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.