A sneaky storm overnight produced an estimated 10-20” (0.5”-1.0” water weight) of low-density snow across our region and ridge top winds increased into the 20-40mph range last night. This snow started out with light wind and single digit temps, but temperatures suddenly bumped into the 20F’s along with a spike in Easterly winds. This means storm slabs in the alpine could range from 1-2’ deep, have an upside down quality, and could be easy to trigger. This snow fell on 5” of low density snow that was covering a widespread layer of buried surface hoar and near surface facets. Below 2000′ these layers are sitting on a slick bed surface crust. Bonding along these older interfaces is expected to be poor. Triggering a storm slab could be big enough to bury a person, but will depend on how deep the snow in the area you are traveling. The deeper the new snow the bigger the consequence. Clearing skies combined with high quality skiing/riding conditions may be hard to resist. Evaluate snow conditions as you move up in elevation and avoid terrain traps and being on or underneath larger steep slopes. Triggering a storm slab could run farther and faster than expected, which is the nature of cold snow. Shooting cracks, ‘whumpfing’, and any avalanche activity will be obvious clues that the snow is unstable. Be aware of other groups of people in the same area and practice safe travel protocols.
Notice the sudden spike in temps and winds last night. This combined with an estimated 10-20″ of new snow are all red flags warning signs that avalanche danger is elevated.
Web cam at DOT weather station is one of the only views of how much snow has accumulated overnight at Turnagain Pass. 24 hr snow water equivelent was not reporting at this site this morning.
In places protected from the winds loose snow avalanches ‘sluffing’ will be likely on steep terrain features. Similar to a storm slab, this dry loose snow could run faster and farther than expected. This hazard could bury a person in a terrain trap or underneath a large slope.
Unfortunately, the snowpack structure above 3000′ is composed of a hard slab (3-8 feet thick) sitting on a variety of weak layers in the mid pack (including buried surface hoar) and old November facets near the ground. Deep persistent slab avalanches remain a concern on these upper elevation slopes. Triggering a deep slab is becoming difficult, but is still possible. The most likely trigger spots are thin areas in the snow cover, often near rocks, or where the slope rolls over. South of Turnagain Pass the snow cover is thinner, triggering a slab in this area could be more likely as well. Remember, this is a ‘low probability, high consequence’ situation. This issue can simply be avoided by sticking to terrain below 3000’ (which is a good portion of terrain at Turnagain) and is secondary to triggering a storm slab avalanche today. Choosing low-consequence terrain in the Alpine is recommended.
Yesterday a storm brought an estimated 10-20 € of snow across our region. Center Ridge weather station picked up 0.5 € of water and Alyeska Midway, 0.7 € water, and Portage Valley (at Bear Valley) had 1.1 € of water. This storm also started light winds and single digit temperatures. Yesterday evening temperatures suddenly increased into the 20F’s and Northeasterly ridge top winds picked up into the 15-40mph range yesterday evening and overnight.
Today ridge top winds are expected to decrease, but could range from 5-20 mph from the East. Skies could range from partly cloudy to overcast and temperatures are expected to be in the 20F’s. Scattered snow showers are expected this evening.
Snow showers are expected through Saturday morning with only a few inches of accumulation expected. Temps will be in the teens (F) and moderate to strong winds are in the forecast for the weekend. In the long term forecast there is talk of warming temps and a chance for more precipitation mid week.
*Snow totals are estimated from the Center Ridge Weather Station. They could be deeper, but snow depth sensor was not reading depths as of 6am.
Web cam at Bear Valley in Portage. Looks like almost a 1.5′ of snow in Portage overnight.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||11||*10||.5||*67|
|Summit Lake (1400′)||6||7||.3||22|
|Alyeska Mid (1700′)||10||12||.7||59|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||3||E||8||21|
|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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