Turnagain Pass Avalanche Forecast RSS

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Fri, March 6th, 2015 - 7:00AM
Expires
Sat, March 7th, 2015 - 7:00AM
Forecaster
Heather Thamm
The Bottom Line

Much of the terrain in Turnagain Pass has a LOW danger where triggering an avalanche is unlikely. However there are areas in the Alpine, above 2500′, where the avalanche danger is MODERATE and triggering a slab 1-2′ is possible. This will be more likely in steep complex terrain, like on large unsupported slopes, around steep rocky features and in steep gullies.  

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Fri, March 6th, 2015
Alpine
Above 2,500'
Moderate (2)
Avalanche risk
Treeline
1,000'-2,500'
Low (1)
Avalanche risk
Below Treeline
Below 1,000'
No Rating (0)
Avalanche risk
Alpine
Above 2,500'
Avalanche risk
Moderate (2)
Treeline
1,000'-2,500'
Avalanche risk
Low (1)
Below Treeline
Below 1,000'
Avalanche risk
No Rating (0)
Danger Scale:
No Rating (0)
Low (1)
Moderate (2)
Considerable (3)
High (4)
Extreme (5)
Avalanche Problem 1
  • Persistent Slabs
    Persistent Slabs
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
More info at Avalanche.org

In the Alpine a slab 1-2′ thick is sitting on a old weak layer of snow, but over the last 10 days triggering this slab has become more difficult with time. Very few obvious signs of instability have been observed over the last week, and inconsistent test results help point towards this weak layer adjusting to its load. On the flip side, we are still finding propagation potential in places, causing enough uncertainty to still encourage conservative slope choices. This problem seems to be more reactive on slopes with more of a Southern aspect where a sun crust/facet interface exists.

Obvious clues such as collapsing/woomphing may not be present and triggering a slab may require steeper terrain or a larger trigger, like several people on a slope. Be sure to practice safe travel habits. Identify safe spots, move between islands of safety one at a time, and always have an escape zone in mind.

Overnight only a trace of new snow fell in Turnagain Pass above 2000’ and another wave of precipitation is expected tonight into Saturday morning. Unfortunately for Turnagain Pass the direction of this cold front looks to be favoring the Talkeetna Mountains. If heading to Hatcher Pass this weekend, be sure to check out the Hatcher Pass Advisory updated once per week on Saturday mornings. 

A stout melt/freeze crust has strengthened the snow pack below 2500’ and has been providing spring-like surface conditions below this elevation. 

Snow may be scarce below 1500′, but a good time can still be found in the the upper elevations.  

Avalanche Problem 2
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
More info at Avalanche.org

 

 

Additional Concern
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
More info at Avalanche.org

Yesterday cloudy skies slowly broke in the morning and by mid-day it was mostly sunny. Temperatures reached the mid 30’s F during the heat of the day, just enough to cause some melting in the 1-2” of new surface snow on sun exposed aspects. Along ridgetops winds were light (5-15mph) mostly from the East.

Overnight temps dipped into the high 20’s F along ridgetops, but at sea level temperatures remained above freezing. There was light rain overnight with rain/snow line around 2000’, up to a few inches of new snow above 2000’. Winds were variable in Turnagain Pass, with Sunburst experiencing a Southerly direction 10-20mph, and Seattle with light Northeasterly winds 5-10mph. 

Tonight another wave of precipitation is expected to move through Western Prince William Sound bringing up to a few inches of snow to upper elevations. Rain/snow line will be around 1000’, with temperatures cooling off late Saturday afternoon as precipitation backs off. Southeast winds are expected to be 20-30mph.  

Weather
Fri, March 6th, 2015

Yesterday cloudy skies slowly broke in the morning and by mid-day it was mostly sunny. Temperatures reached the mid 30’s F during the heat of the day, just enough to cause some melting in the 1-2 € of new surface snow on sun exposed aspects. Along ridgetops winds were light (5-15mph) mostly from the East.

Overnight temps dipped into the high 20’s F along ridgetops, but at sea level temperatures remained above freezing. There was light rain overnight with rain/snow line around 2000′, up to a few inches of new snow above 2000′. Winds were variable in Turnagain Pass, with Sunburst experiencing a Southerly direction 10-20mph, and Seattle with light Northeasterly winds 5-10mph.  

Tonight another wave of precipitation is expected to move through Southcentral Alaska bringing up to a few inches of snow to upper elevations. Rain/snow line will be around 1000′, with temperatures cooling off late Saturday afternoon as precipitation backs off. Southeast winds are expected to be 20-30mph.  

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 35   0   .1   40  
Summit Lake (1400′) 35   0   .1   7  
Alyeska Mid (1700′) 35   0   .14   24  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 28   Var.   12   27  
Seattle Ridge (2400′) 29   NE   11    15
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Riding Areas
Updated Mon, October 26th, 2020

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
Closed
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Closed
Skookum Drainage
Closed
Turnagain Pass
Closed
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Closed
Seward District
Carter Lake
Closed
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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.