It has been two days since a storm with strong wind ended and left behind 1-2 feet of snow across our region. Girdwood, Portage and the Northern side of Turnagain Pass received 18” – 24” and much less on the far Southern end of Turnagain Pass. Rapid warming from the sun, whumpfing, cracking and remote triggered avalanches have occurred over the last two days with most of the activity on Thursday. A handful of storm slabs have been triggered by skiers, boarders and snowmachiners on smaller terrain features in Turnagain Pass. The largest of these slabs released on Thursday on a SW aspect of Tincan late afternoon and may have been remotely triggered from the skin track 300+ feet away. Stability tests on a nearby slope revealed a reactive layer of facets above and below an old sun crust. This structure is present on many Southerly aspects (E – S – SW) and could be more reactive later in the day with warming. A new sun crust has formed on the surface, which is helping stability until it starts to melt today. On North to West aspects where the snow is drier, weak faceted snow sits below the new snow, and triggering a slab 1-2 feet thick will remain possible at any time of the day. Fast moving dry-loose “sluff” is also possible in steeper terrain in shaded areas.
Overcast skies should become partly cloudy by late afternoon. This could be our warmest day of the year with temperature reaching the low-50F’s near sea level, mid-30F’s near ridgetops. It is important to pay close attention to how warm it gets and how wet the snow feels. Ease into terrain with a cautious mind-set and be ready to adjust your plans if you experience collapsing, shoot cracks, or see any avalanche activity.
An avalanche that released between 4pm and 5pm on Thursday on a SW aspect of Hippy Bowl on Tincan. Its unknown if this avalanche was natural or triggered remotely from the skin track.
Several snow pits on Thursday found propagation potential on facets associated with an old sun crust on Southerly aspects in two locations nearby the avalanche above.
SPRINGTIME WARMING: Dozens of small wet loose avalanches occurred on South and Southeast aspects in the afternoon on Thursday, just after the storm ended. Today a thin surface crust will require more energy to break down, but warmer air has already started to move into region and the sun should poke through the clouds by the afternoon. Sun and thin cloud cover can trap the heat and sometimes intensify the affects of solar heating. A thin crust has formed below 1000’ on all aspects and its also present on Southerly aspects (E – SW) at all elevations. If/when this crust softens and becomes moist, its time to avoid South aspects. Natural wet-loose avalanche activity will be possible near rocks and in steep terrain today.
Wet loose avalanches seen on Pete’s North and Pete’s South were visible Thursday evening. Although these point releases are small there is potential for a wet avalanche to trigger a 1-2′ slab if the crusts become saturated.
This new snow fell onto a snowpack with poor structure and several weak layers buried 2-4’ below the old surface. No avalanches have been reported on deeper layers of the snowpack. There remains some level uncertainty around the reactivity of these older weak layers, facets and buried surface hoar. Thin snowpack zones such as the Girdwood Valley and the South end of Turnagain Pass are more suspect for this structure, as well as some Northern and Easterly slopes with a generally thinner pack. Trigger points in this situation are often in thinner areas near rocks, but it is also possible to trigger this avalanche problem from areas along ridges.
Yesterday was overcast with a few sprinkles of rain, but no measurable amounts were recorded. Daytime temperatures were in mid-20F’s near ridgetops and upper-30F’s at sea level. Warmer air and cloud cover kept overnight temperatures in the mid-20F’s in the alpine and low-30F’s near sea level. Northeast winds were 5-15mph most of the day near ridgetops.
Mostly cloudy skies are expected to become partly cloudy this afternoon. Today could be our warmest day of the year with lower elevation temperatures in the upper-40’s to low-50F and upper elevation temps reaching the mid-30F’s. Overnight lows are expected to dip below freezing into the mid-20F’s. Northwest winds could range from calm to 10mph today.
Sunday looks very similar with partly cloudy weather and warmer daytime temperatures. Low temps should dip below freezing at night. Winds are expected to be light and variable. Monday evening through Tuesday there’s a chance for rain and snow showers and moderate winds, but accumulation looks minimal at this point.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||31||0||0||82|
|Summit Lake (1400′)||34||0||0||34|
|Alyeska Mid (1700′)||31||0||0||79|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||28||ESE||9||21|
|01/19/20||Turnagain||Avalanche: south facing aspect on 3800ft bump just northeast of 4940||Anonymous|
|01/19/20||Turnagain||Avalanche: Cornbiscuit & Magnum||Allen Dahl|
|01/19/20||Turnagain||Observation: Eddie’s||Kakiko Ramos-Leon|
|01/18/20||Turnagain||Observation: Sunburst||Ryan Van Luit Forecaster|
|01/18/20||Turnagain||Avalanche: Sunburst||Eric Roberts|
|01/18/20||Turnagain||Avalanche: North end Tincan trees||Heather Johnson|
|01/17/20||Turnagain||Observation: Tincan||Allen Dahl|
|01/16/20||Turnagain||Observation: Lynx Creek||Wagner / Van Luit Forecaster|
|01/13/20||Turnagain||Observation: Tincan||Ryan Van Luit Forecaster|
|01/12/20||Turnagain||Observation: Magnum West face||Levi Oyster|
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.