Last night a cold moist air mass brought a several inch refresh to the Girdwood and Portage Valleys (4-6″), yet only an inch or two for Turnagain Pass. Water weight was only in the .25 – .1″ range, but most of us will take what we can get to cover the crusts at the lower elevations! With that said, until we see more weather, snow, rain, etc, our avalanche problems on the surface remain on the small side (see below) and our main concern still lies with a much larger, but stubborn avalanche problem.
Deep persistent slab avalanches remain our primary concern, which exist in the high elevation terrain above 3,000′. On these upper elevation slopes, there is a dense hard slab sitting on a variety of weak layers in the mid pack (buried surface hoar) and old November facets near the ground. Triggering a deep slab is becoming more and more difficult, but still possible. The most likely trigger spots are thin areas in the snow cover, often near rocks, or where the slope rolls over. High peaks, that see wind, can also be thinner and more likely to find a deep slab.
Again, here are a few points that keep sending home with our current snowpack set up:
– We have a ‘low probability, high consequence’ situation at the upper elevations for deep slab avalanches
– Obvious signs of instability are not likely to been seen before a deep slab is triggered (such as whumpfing and cracking)
– Remote triggering is possible
– Last, this issue can simply be avoided by sticking to terrain below 3000’ (which is a good portion of terrain at Turnagain) or choosing low-consequence terrain in the alpine
Photos of old avalanche debris from the Seattle Headwall area. Last week’s warm storm initiated very large avalanches on many slopes, yet many still remain intact and did not avalanche.
Ridgetop winds bumped up slightly last night into the 10-15mph range from a generally Easterly direction. This isn’t much for wind, but with such loose surface snow existing right now, it could be enough to form shallow wind slabs along ridgelines. Watch for recent wind texturing on the snow surface and feel for stiffer wind packed snow over softer snow or a crust. If you happen to find a fresh wind slab, expect it to be quite touchy.
Again, the loose surface snow is quick to sluff and has been running far on steep slopes. Hence, watch your sluff on the steeper slopes. Any additional new snow from overnight will add to the volume of these and could catch a person by surprise.
Photo of loose surface snow (near surface facets) over a stout crust in the mid-elevations. Another crop of surface hoar (on the top of the snow in photo below) grew last weekend and now sits under the little bit of new snow from last night.
Mostly cloudy skies filled the area yesterday with a few snow flurries region wide. Snowfall increased overnight and the Girdwood and Portage Valley areas picked up 4-6″ at the mid-upper elevations while Turnagain Pass looks to have seen only around an inch. Ridgetop winds from the East, Northeast bumped up slightly overnight, blowing 10-15mph with gusts into the 20’smph. Temperatures have warmed at the high elevations into the low 20’sF, while valley bottoms remain around 10-15F this morning.
Today, mostly cloudy skies are expected with a snow flurry or two (little to no accumulation). Ridgetop winds are slated to remain light from an Easterly direction, 5-10mph. Temperatures should warm to the mid-upper 20’sF in valley bottoms and remain near 20F along ridgetops.
For tonigh night into Tuesday morning there is another chance for a few inches of snow to sea level, possibly up to 6″ in favored areas. Winds look to remain light to moderate with this pulse of moisture and temperatures look to remain in the teens to 20’sF. Stay tuned.
*Seattle Ridge anemometer is rimed over and not able to collect wind data.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||11||1||0.1||54|
|Summit Lake (1400′)||7||0||0||15|
|Alyeska Mid (1700′)||12||4||0.23||47|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||15||*n/a||*n/a||*n/a|
|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: email@example.com
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