A winter storm warning is in effect for the region today. If the forecasted snow totals verify we could quickly start to have storm snow concerns. Initially we could see loose snow avalanches. The new snow will land on weak snow. Surface hoar and near surface facets have formed during the past few days on all aspects and elevations. These could become a very reactive weak layer as the new snow piles up. Winds have destroyed the surface hoar in some areas in the Alpine but unfortunately we will not have x-ray vision to determine exact distribution. The winds have already started to pick up this morning. This combined with the new snow could rapidly create sensitive slabs. Pay close attention to changing conditions. Watch for heavy precipitation intensity, strong winds, shooting cracks and whumpfing. Low visibility will make it hard to see what is above you. Avoid travel in runout zones. If you do venture out today conservative terrain choices are advised.
Yesterday’s snow surface = Today’s weak layer.
The weak snow that formed in early December sitting over the Thanksgiving Rain Crust or old hard snow is now buried under 2-4′ of snow. This combination has been the cause for concern and heightened caution in the backcountry for the past week. This setup could now become overloaded with the additional weight of new snow and wind loading. If avalanches step down into this layer, they could be quite large and destructive.
There have been cornice triggered avalanches during the past week and there are looming sections overhanging slopes today. Cornices will grow quickly with the new snow and may be triggered by the increasing winds. Visibility may make it challenging to see what is above. This is an added reason to stay away from runout zones.
Yesterday was clear in the morning with increasing clouds throughout the day. Winds were light and shifted from W to E. Temperatures were in the single digits in the valleys and the mid-teens at ridge tops.
The winds have picked up this morning and temperatures are warming as the weather system approaches.
NWS Zone Forecast for Turnagain:
…WINTER STORM WARNING FOR HEAVY SNOW REMAINS IN EFFECT FROM
9 AM THIS MORNING TO 6 AM AKST SATURDAY…
* SNOW…13 TO 26 INCHES…HIGHEST AMOUNTS THROUGH TURNAGAIN PASS AND
* VISIBILITY…NEAR ZERO AT TIMES IN HEAVY SNOW AND BLOWING SNOW.
* WIND…EAST WIND 10 TO 25 MPH EXCEPT EAST 40 TO 55 MPH THROUGH
PORTAGE VALLEY AND TURNAGAIN ARM…STRONGEST WINDS THIS
* TIMING…SNOW WILL DEVELOP THIS MORNING THEN BECOME HEAVY THIS
AFTERNOON. HEAVY SNOW WILL CONTINUE THROUGH TONIGHT FOR INLAND
AREAS BEFORE DIMINISHING EARLY SATURDAY MORNING. LOCATIONS ALONG
THE COAST WILL CHANGE TO RAIN LATE THIS AFTERNOON OR EVENING
RESULTING IN LESS SNOW ACCUMULATION OVERALL. The rain/snow line is expected to rise to 500′ tonight.
The storm continues into tomorrow with snow/rain showers and easterly winds. Temperatures will be in the high 20Fs to mid 30Fs.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||15||0||0||49|
|Summit Lake (1400′)||10||0||0||17|
|Alyeska Mid (1700′)||15||0||0||35|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||14||ESE||10||14|
|04/21/21||Turnagain||Observation: Sunburst||Schauer/ Behney Forecaster|
|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|
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.