Turnagain Pass Avalanche Forecast RSS

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Wed, December 14th, 2022 - 7:00AM
Expires
Thu, December 15th, 2022 - 7:00AM
Forecaster
Wendy Wagner
Avalanche risk The Bottom Line

Although avalanche danger has decreased to MODERATE today, another storm rolls in that should increase the danger once again late tonight. For today, watch for those lingering wind slabs formed from the strong winds two days ago. These could be up to several feet thick in the upper elevations and possible for us to trigger. Additionally, triggering a sluff on steep slopes in the 2′ of soft settled storm snow will also be possible.

SUMMIT LAKE:  Around a foot of settled storm snow exists that has also been blown into wind slabs above treeline. Additionally, various weak layers of snow sit under the new snow and extra caution is warranted in these more shallow/interior snow zones for an avalanche to break deeper in the pack.

LOST LAKE / SEWARD / SNUG HARBOR:  Very limited information exists for these areas. Cautious travel in avalanche terrain is recommended and please let us know what you see if you head to these zones!

Special Announcements

Chugach State Park:  Tonight’s storm system is looking to bring more snow to Anchorage’s front range than to Turnagain. A Winter Storm Warning has been issued by the NWS. Expect avalanche conditions to increase late tonight into tomorrow in areas seeing heavy snowfall.

Forecaster Chat #1: Come join forecaster John Sykes tomorrow (Dec 15, 7-8pm) at Alaska Mountaineering and Hiking! He will be discussing current conditions, how to submit quick and quality observations, and decision-making during complex snowpack conditions. Admission is free and all are welcome!

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Wed, December 14th, 2022
Alpine
Above 2,500'
Moderate (2)
Avalanche risk
Treeline
1,000'-2,500'
Moderate (2)
Avalanche risk
Below Treeline
Below 1,000'
Moderate (2)
Avalanche risk
Alpine
Above 2,500'
Avalanche risk
Moderate (2)
Treeline
1,000'-2,500'
Avalanche risk
Moderate (2)
Below Treeline
Below 1,000'
Avalanche risk
Moderate (2)
Danger Scale:
No Rating (0)
Low (1)
Moderate (2)
Considerable (3)
High (4)
Extreme (5)
Avalanche Problem 1
  • Wind Slabs
    Wind Slabs
  • Aspect/Elevation
  • Almost Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic (D4-5)
    Very Large (D3)
    Large (D2)
    Small (D1)
    Size
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Aspect/Elevation of the Avalanche Problem
Specialists develop a graphic representation of the potential distribution of a particular avalanche problem across the topography. This aspect/elevation rose is used to indicate where the particular avalanche problem is thought to exist on all elevation aspects. Areas where the avalanche problem is thought to exist are colored grey, and it is less likely to be encountered in areas colored white.

Likelihood of Avalanches
Terms such as "unlikely", "likely", and "certain" are used to define the scale, with the chance of triggering or observing avalanches increasing as we move up the scale. For our purposes, "Unlikely" means that few avalanches could be triggered in avalanche terrain and natural avalanches are not expected. "Certain" means that humans will be able to trigger avalanches on many slopes, and natural avalanches are expected.

Size of Avalanches
Avalanche size is defined by the largest potential avalanche, or expected range of sizes related to the problem in question. Assigned size is a qualitative estimate based on the destructive classification system and requires specialists to estimate the harm avalanches may cause to hypothetical objects located in the avalanche track (AAA 2016, CAA 2014). Under this schema, "Small" avalanches are not large enough to bury humans and are relatively harmless unless they carry people over cliffs or through trees or rocks. Moving up the scale, avalanches become "Large" enough to bury, injure, or kill people. "Very Large" avalanches may bury or destroy vehicles or houses, and "Historic" avalanches are massive events capable of altering the landscape.

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
More info at Avalanche.org

Until this next round of storms moves in tonight, avalanche issues will continue to be lingering wind slabs in exposed areas and sluffs in steep terrain. In the higher elevations, the 1.5 – 2.5 feet of new snow from Sunday night has been hit by winds from the northwest, to south, to east. If getting into zones above treeline, be sure to feel for stiff snow over softer snow and watch for any cracking or collapsing. Slabs could be anywhere from a foot to several feet thick and could be on the more difficult side to trigger.

In sheltered areas away of any wind effect, the new snow is slowly settling and bonding, but still quite soft. If getting onto the steeper slopes, even short steep slopes in the trees, sluffs could be triggered if the slope is steep enough. Tree wells are also getting larger and something to keep in our minds. A good reminder to always keep an eye on our partners.

 

 

The big news is the storm system that should bring some light snow showers this afternoon, then more snow and wind late tonight into tomorrow morning. This event looks to favor the Anchorage area and Hatcher Pass regions while here in Girdwood and Turnagain Pass we are looking at 6-8″, maybe up to 12″ if we’re lucky. It will be a warmer storm and a rain/snow mix may be seen in Girdwood. Stay tuned for tomorrow’s forecast and be sure to check hpavalacnhe.org for Hatcher Pass’s Thursday morning forecast!

 

Weather
Wed, December 14th, 2022

Yesterday:  Overcast skies with a few sucker holes midday. Light snow flurries added 1-4″ of new snow with little water weight. Winds were light from the southeast (5-10mph) along ridgetops and temperatures were in the teens to 20’s.

Today:  Another system is headed in that will bring light snow during the afternoon and peak tonight. Around 1-3″ is expected this afternoon with another 3-6+” overnight. Temperatures are warming and we could see the rain/snow line rise to 500′ or so briefly tonight before cooling back off tomorrow morning. Ridgetop winds will be light and variable until they pick up tonight into the 30’s mph from the SE.

Tomorrow:  Skies should start clearing and temperatures drop as precipitation ends tomorrow morning. Ridgetop winds will be shifting to the NW and expected to blow in the 10-20mph range. Mostly clear and quiet weather is expected Friday through the weekend.

PRECIPITATION 24-hour data (6am – 6am)

Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 25 2 0.1 41
Summit Lake (1400′) 18 1 0.1 31
Alyeska Mid (1700′) 26 4 0.25 43
Bear Valley (132′) N/A 2 0.1

RIDGETOP 24-hour data (6am – 6am)

Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 20 SE 9 29
Seattle Ridge (2400′) 22 SE 7 13
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Riding Areas
Updated Fri, January 06th, 2023

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: mailroom_r10_chugach@fs.fed.us

Area Status Weather & Riding Conditions
Glacier District
Johnson Pass
Open
Opened Dec 13th.
Placer River
Closed
Closed Jan 5th due to lack of snow (holiday storms rained away the snow at sea level).
Skookum Drainage
Closed
Closed Jan 5th due to lack of snow (holiday storms rained away the snow at sea level).
Turnagain Pass
Open
Opened Dec 13th.
Twentymile
Closed
Closed Jan 5th due to lack of snow (holiday storms rained away the snow at sea level).
Seward District
Carter Lake
Open
Opened Dec 13th.
Lost Lake Trail
Open
Opened Dec 13th.
Primrose Trail
Open
Opened Dec 13th.
Resurrection Pass Trail
Closed
Closed to motorized use for the 2022/23 winter season per Forest Plan. Open next season.
Snug Harbor
Open
Opened Dec 13th.
South Fork Snow River Corridor
Open
Opened Dec 13th.
Summit Lake
Open
Opened Dec 13th.

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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.