A large storm slab avalanche was seen in Girdwood yesterday morning, on the lower east face of Raggedtop. There was also a slide reported on the Goat Mtn shoulder (southerly facing) that was a deeper slab and may have broke in a weak layer under the storm snow (this is the unusual slab seen in the Girdwood Valley). Otherwise, several shallow slab avalanches and sluffs were seen yesterday morning composed of the 6-8″ of new snow from Wednesday night.
Natural slab avalanche that occurred sometime overnight on Dec 14th (Wednesday night) and seen by several folks. This photo was from H Johnston, taken from the chairlift at Alyeska. 12.15.22.
Avalanches up Crow Creek drainage in Girdwood on the southerly face of Goat Mtn. The slab on the left appears deeper, which is suspect for a breaking in a buried weak layer, as opposed to just the storm snow avalanche type seen on the right. Thanks to George Creighton for the photo. 12.15.22.
Very shallow, but wide, avalanche in Main Bowl on the backside of Seattle Ridge. Likely released also overnight on Wednesday with 6-8″ of new snow and some wind. 12.15.22.
Evidence of 2 older wind slab avalanches on the SW face of Sunburst. These are thought to have occurred several days ago during the storm on Sunday night (12/11). Photo by Sarah Heck on 12.15.22.
|Signal Word||Size (D scale)||Simple Descriptor|
|Small||1||Unlikely to bury a person|
|Large||2||Can bury a person|
|Very Large||3||Can destroy a house|
|Historic||4 & 5||Can destroy part or all of a village|
Around midnight last night the NW outflow winds finally slowed down. For today and into the weekend, it looks as though clear and cold conditions will prevail. The winds should also stay relatively light and variable. That’s good news for the snowpack to start stabilizing.
For today, wind slabs should be the most likely kind of avalanche to trigger. From our field day on Seattle Ridge yesterday, the wind slabs already seemed to be bonding, but this may not be the case for all wind slabs. Slabs could be soft or quite stiff depending on how much wind the area saw. They could also allow a person out onto them before releasing. Watching for wind loaded slopes and any signs of cracking around us will be key. Additionally, having an escape plan in case a wind slab releases and making sure our partners are spotting us will good ways to stack the odds in our favor.
Loose Snow Avalanches: Sluffs on steeper slopes should be expected within the loose soft surface snow.
A look at Seattle Ridge yesterday with winds transporting snow in the upper Girdwood area in the background. 12.15.22.
After seeing the photo on the Goat Shoulder (pictured above) and hearing reports of some weakness near/above the Thanksgiving crust in the Girdwood Valley, there could be some funny business below all the storm snow from this month. From our data points so far, it appears this issue could be just in the Girdwood Valley.
On another note, outside our forecast zone to the south in Summit Lake, we know weak faceted snow exists under the storm snow. Folks traveling in the Summit Lake zone or places the snowpack is much thinner than Turnagain should be on guard for the potential for a slab breaking deeper in the pack. An extra cautious mindset is required for these shallow areas.
Yesterday: High clouds were over the region with sunshine poking through. Ridgetop winds were NW to west averaging ~10-15mph with gusts in the 40’s+ in favored areas. Temperatures were in 20’s to teens in most locations.
Today: A mostly clear sky day is on tap with lighter winds. Ridgetops should see averages ~5mph with some gusts in the 20’s in favored locations. Temperatures are cooling off and should be in the teens most areas to even the single digits in some valley bottoms.
Tomorrow: Mostly sunny skies are expected for the weekend. Ridgetop winds look to be light and variable with temperatures cooling to the single digits at all elevations.
PRECIPITATION 24-hour data (6am – 6am)
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||23||0||0||42|
|Summit Lake (1400′)||15||0||0||33|
|Alyeska Mid (1700′)||20||0||0||48|
|Bear Valley (132′)||20||0||0||–|
RIDGETOP 24-hour data (6am – 6am)
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||19||W||6||17|
|05/22/23||Turnagain||Avalanche: Tincan||Nick D'Alessio|
|05/12/23||Turnagain||Avalanche: Tincan, Sunburst, Magnum, Cornbiscuit||Heather Thamm|
|05/07/23||Turnagain||Observation: Tincan – Bear Tracks||CNFAIC Staff|
|05/05/23||Turnagain||Observation: Seattle Ridge||AS/ WW Forecaster|
|05/02/23||Turnagain||Observation: Cornbiscuit||Schauer/ Sturgess Forecaster|
|05/02/23||Turnagain||Observation: Seward Hwy Turnagain Pass||Joel Curtis|
|04/30/23||Turnagain||Observation: Magnum||Ayla, Kit Crosby, Barton|
|04/29/23||Turnagain||Observation: Tincan||John Sykes|
|04/28/23||Turnagain||Avalanche: Taylor Pass/Pastoral||Schauer/ Creighton Forecaster|
|04/28/23||Turnagain||Avalanche: Tincan||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.