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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Sunday, April 10th 2016
Created: Apr 10th 5:44 am
3 Considerable Alpine / Above 2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
3 Considerable Treeline / 1,000'-2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
0 NO RATING Below Treeline / Below 1,000'
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Silverton Mountain Guides
Special Announcement
  • This will the final week of daily avalanche advisories. Between Monday, April 18th and Saturday, April 30th we will be issuing advisories on weekends and intermittently during the week.

  • The Chugach National Forest has closed some riding areas to motorized use due to snow melting out. Please see the table at the bottom of this page for a complete list. Snug Harbor, Summit Lake and Turnagain Pass (N. of Granite creek) will remain open. 

The Bottom Line

There is a CONSIDERABLE avalanche danger in the backcountry for glide avalanches, wet snow avalanches and storm snow avalanches. Glide cracks continue to release on all aspects under 3,000'. Travel under glide cracks is NOT recommended. At elevations below 2,500', human triggered wet snow avalanches are likely where rain is saturating the snowpack. And last, at elevations above 3,000', naturally occurring wind slab avalanches 1-2' thick are possible. 

If you are headed into the mountains today, expert level terrain management and observation skills are key to steer clear of glide cracks, steep slopes with saturated snow and slopes with recent storm snow.


Primary Concern

As a warm band of moisture moves through the region we contine to see rain between 2,000' and 2,500' and wet snow above this. So far total rainfall during the storm (beginning early yesterday morning) is around 1 to 2" in the Girdwood and Portage Valley areas - lesser amounts have been seen on Turnagain Pass and South. We have another .5-.75" of rain on the way today with snow up high. 

Although we are seeing a storm moving through, the main concern will remain focused on glide avalanches. Two new glide cracks released yesterday in the Turnagain Pass region. One (pictured below) was on the South side of Seattle Ridge and the other was on the North face of Sharks Fin. The fact these cracks keep releasing into avalanches should be evidence enough that avoiding travel under glide cracks remains a prudent rule. 

Glide avalanche from yesterday on Seattle Ridge (South end across from the Bertha Creek campground)

 

Keeping an eye on the Seattle Ridge 'up-track'. The last glide avalanche threathening this popular zone was on Thursday, April 7th.


Secondary Concern

As rain continues to melt and saturate the snowpack from 2,500' and below, wet loose snow avalanches are a concern. At these elevations, triggering wet snow sluffs on steep slopes is likely - if one were to travel on steep slopes in this weather. At the elevation band between 2,500 and 3,000' where wet snow is falling, shallow wet sluffs composed of the new snow are likely to occur naturally. We have not seen the typical springtime large wet avalanches that are compose of the older snow yet, but are watching for this.

Saturated and mostly unsupportable snow exists at the lower and mid-elevations along Turnagain Pass. This photo is near the Sunburst parking lot at 900' in elevation.

 

Rain and warm weather is melting the snow out quickly along the South end of Turnagain Pass. Photo is of the Sunburst parking lot looking West toward Seattle Ridge.


Additional Concern

At elevations high enough to see dry(ish) snow, storm snow instabilities will be seen. At what elevations will this be? Likely above 3,000' and in the upper sections of the starting zones along Turnagain Pass. As of this morning there could be anywhere between 6-16+" of snow that has fallen, the most in areas close to Turnagain Arm (Between Girdwood and Tincan). We are looking at another 3-7" today. With the high winds at these upper elevations, wind slabs 1-2' thick are likely and could release naturally. Cornice falls are also an issue. both these types of avalanches could entrain wet snow on the way down and run quite far in steep channeled terrain.


Mountain Weather

A strong frontal system moving through the region has brought rain, up to 2,500, beginning early yesterday morning. Heavy rain fell in Girdwood and as far South as Tincan but only light rain was seen South of the Pass, from Sunburst and on. Ridgetop winds over the past 24-hours have been strong out of the East, averaging ~40mph with gusts to the 70's. Temperatures are warm, mid 20's at 4,000' and reaching the upper 30'sF at 1,000'. 

Today the storm system will continue to push through and exit the area by Monday. We should pick up another .5-.75" of rain up to 2,500' (possibly higher) with 4-7" of wet snow above this. Ridgetop winds are slated to remain strong in the 30-40mph range from the East. Temperatures should stay warm with highs today around 40F at 1,000' and up to 30F on the ridgetops. Both precipitation and wind should decrease overnight tonight and temperatures cool off.

For Monday and Tuesday, a colder low pressure system moves past to our South that may push snow/rain and wind our way. If this low is South enough in the Gulf we could see relatively nice skies, stay tuned on tomorrow's forecast.

*The Center Ridge SNOTEL is not reporting accurate precipitaiton data. Also, the RWIS Turnagain Pass station is down. Precipitation numbers for Turnagain Pass are estimated at ~1" of water during this storm (past 30 hours).

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 36  not reporting  0.3* (under reporting) 114 
Summit Lake (1400') 39  33 
Alyeska Mid (1700') 35  rain  0.7  101 

 

RIDGETOP 24-hour data (6am - 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 27  NE  41  75 
Seattle Ridge(2400') 28  SE  28  56 

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).

Winter snowmachine use open/closed status and riding conditions updates

Riding status is not associated with avalanche danger. An area will be open to motorized use in accordance to the Forest Management Plan when snow coverage is adequate to protect underlying vegetation. Backcountry hazards including avalanche hazard are always present regardless of the open status of motorized use areas.

(Updated: Nov 18, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedOnly a few inches of snow sits at the motorized lot, not enough to open for snowmachining at this time. Updated Nov. 18, 2017
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: ClosedResurrection Pass trail is expected to open to snowmachine use during the 2017/18 winter season.
Snug Harbor: Closed
South Fork Snow River Corridor: Closed
Summit Lake: Closed

Subscribe to the Turnagain Area Avalanche Advisory:

The information in this advisory is from the U.S. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur. This advisory provided by the Chugach National Forest, in partnership with Friends of the Chugach National Forest Avalanche Information Center.


USFS SNOW AND AVALANCHE HOTLINE (907) 754-2369
If you have comments or questions regarding CNFAIC operations or winter recreation management, please email staff@chugachavalanche.org
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