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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Saturday, February 13th 2016
Created: Feb 13th 5:25 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.
2 Moderate Below Treeline / Below 1,000' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
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The John Byrne Family
The Bottom Line

There is a CONSIDERABLE avalanche danger for both wet avalanches and glide avalanches at the mid-elevations (1,000' - 2,500'). This is due to rain-on-snow and warm temperatures that are weakening the snowpack. Above 2,500', in the Alpine terrain, we also have a CONSIDERABLE avalanche danger for storm snow avalanche issues. Human triggered wind slab avalanches and cornice falls are likely in steep leeward terrain. Below 1,000' a MODERATE danger exists where an avalanche in steep channeled terrain could run into this elevation band.

Careful route-finding and conservative decision-making is necessary if headed to the backcountry today.

***Elevated caution is also advised in the Summit Lake area. Please see the Summit Lake Summary for more information and check out the observations page.


Primary Concern

Our primary concern continues to center around glide avalanches. These are popping out both small and large over the past several days. They are mostly in the mid-elevation band and the warm weather has kept them active. The last known glide crack to release on Turnagain Pass that we know about, releasing in areas people recreate, was two-three days ago on Eddies Ridge. The only way to manage this avalanche problem is to limit, or avoid, time under glide cracks.

Photo below: Glide cracks and one release on Peak 3640' just Southeast of Gilpatrick in the Summit Lake zone.


Secondary Concern

Over the past two days we have seen 1.5+" of rain fall up to 2,500, possibly higher in some areas; this is the highest rain line we have seen this season. Yesterday afternoon temperatures at treeline (2,400' on Tincan) reached 34 degrees! The snowpack is slowly decreasing at the mid-elevations, but there is still plenty to ride out this warm spell.

Wet avalanches continue to be a concern. With little visibility yesterday we are uncertain as to the extent of any natural wet activity. As the temperatures remain warm, the rain-on-snow will continue to weaken the snowpack and naturally occurring wet loose, and even some wet slabs avalanches, are possible. These slides can be quite large on sustained slopes such as the East face of Seattle Ridge. Steering clear of runnout zones will be key if you are getting out today.

Left photo: Tincan Ridge, still plenty of snowcover despite the rain.    Right photo: The motorized lot is slick but has been plowed out nicely.
 

 


Additional Concern

At the high elevations where it is snowing (this is above 2,500') there are a variety of storm snow avalanche issues:

Storm Slabs: This warm, wet snow should bond quickly to the surfaces below but the warmer snow over slightly colder snow may create storm slabs. Quick hand pits are a good way to determine if the new snow is sticking to the old snow. 

Wind slabs:  Over the past two days we have received 15-20" of new snow with sustained winds. Although wind slabs are stabilizing quickly with the sticky snow, it may still be possible to trigger a wind slab in steep wind-loaded terrain. Be on the lookout for stiff, pillowed snow and shooting cracks.

Cornices: The fresh snow/wind combination will also add to already large cornices that may be very tender due to warm temperatures. Avoid travel on or below these behemoths.


Mountain Weather

Yesterday was another mostly cloudy day with rain falling off and on at the Pass. Around .5" of rain fell up to 2,500' with ~5" of wet snow above this. Ridgetop winds were strong to moderate through the day from the East and were blowing in the 20-35mph range. Temperatures were warm....up to 35F at 2,000'. This is all due to a series of low-pressure systems moving over us and entraining warm and moist air from the South.

Overnight, light precipitation has continued and temperatures have remained warm. The rain/snow line looks to have dropped slightly to 2,000'. Another shot of precipitation and wind is on tap again today. It has been difficult determining how much precipitation will make it over the mountains from PWS, but so far we seem to get a bit more than forecast. We may see up to .5" today and another .5" tonight, with the rain/snow line between 1,800 and 2,000' (equating to another 5-10+" in the Alpine). The Easterly ridgetop winds should pick up again to the 25-35mph range with stronger gusts.

For Sunday, this warm and wet weather pattern looks to continue. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880')  33  rain  0.5  105 
Summit Lake (1400') 35  rain  0.1  30 
Alyeska Mid (1700') 34   rain  0.6  86 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 27   NE 21  51 
Seattle Ridge(2400') 28   -

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: Feb 09, 2016 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: OpenJohnson Pass is OPEN for motorized use. Please DO NOT park in the turnaroud (near restroom) at the trailhead. Snowmachine access is through the (open) gate down the wagon road. Do not travel on the summer route as this is a non-motorized trail.
Placer River: ClosedInadequate snow at sea level.
Skookum Drainage: ClosedInadequate snow at sea level.
Turnagain Pass: OpenTurnagain Pass is OPEN for motorized use. Early season conditions still exist including creek beds and open water hazards in the flats. Please stay off of "Rookie Hill" (small feature directly out of the parking lot).
Twentymile: ClosedInadequate snow at sea level.
Seward District
Carter Lake: Open
Lost Lake Trail: ClosedDue to inadequate snow conditions and to prevent resource damage, operating or possessing a snowmobile on Lost Lake Trail is prohibited. Conditions will be monitored daily for a re-opening.
Primrose Trail: ClosedConditions are being monitored for an opening.
Resurrection Pass Trail: ClosedConditions are being monitored for an opening.
Snug Harbor: OpenPark in the lot at mile 9. No place to turn a truck around after this parking lot.
South Fork Snow River Corridor: Open
Summit Lake: Open

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
© 2016 Chugach National Forest Avalanche Information Center. All rights reserved.
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