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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Heather Thamm  
Thursday, December 15th 2016
Created: Dec 15th 5:49 am
1 Low Alpine / Above 2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1 Low Treeline / 1,000'-2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
 Show the Complete North American Avalanche Danger Scale
Anchorage Snowmobile Club
Special Announcement

TONIGHT: Fireside Chat: Avalanche Awareness and Rescue with the CNFAIC in Girdwood at the Powder Hound Ski Shop! December 15 @ 6:30 pm - 8:00 pm. FREE!


The Bottom Line

A LOW avalanche danger remains in the mountains surrounding Turnagain Pass where triggering loose surface snow could be fast moving, enough to knock you off your feet in steep terrain. Popping out an old wind slab sitting on faceted snow, breaking off a chunk of cornice or triggering a larger ‘outlier’ avalanche are all in the realm of 'unlikely possibilities’ but worth noting. 

*Today pay attention for changing weather conditions and always practice good travel habits; expose one person at a time, watch your partners, have an escape route planned and group up in safe zones. 

 


Primary Concern

If you are headed to steep slopes, pay attention for ‘facet’ sluff (yesterday we received a report that loose surface snow was becoming fast moving and more difficult to manage than previous days.) Also watch out for cornices and old wind slabs near ridges - all of these avalanche concerns are too small to bury a person, but could take you for a ride in an undesirable place. Lastly, be aware of an 'outlier' slab avalanche that could fail mid-pack due to the Nov 16 buried surface hoar, especially in areas that haven't seen much traffic.

Light snowfall is expected to start this afternoon with the possibility of 1-4 inches falling this evening. This is not quite enough precip or the right timing to elevate the danger rating for today. As always be prepared to change your plans should snowfall arrive early and intensity increase beyond what is forecasted. 

As we anxiously await a change in the weather we have been taking inventory of the surface conditions and snowpack structure in our region. It has been just over two weeks since our last snow event left 6-10”, and cold and clear weather has dominated our region. This has been the perfect recipe for creating weak, poorly bonded snow: near surface facets and surface hoar, as well as depth hoar in shallow/thin areas of the snowpack. With a few inches of snow expected tonight and heavier amounts forecasted into the weekend we will see just what the avalanche conditions will do. Should we get significant precipitation be prepared for dangerous avalanche conditions this weekend and into next week. 

 

An observer sent in this photo yesterday of the Eastern facing slopes of Seattle Ridge, with a great question, “Does this count as skier compaction?” Well... don’t get excited yet. It's too soon to tell if the weak surface snow (one of several future weak layers) was disturbed enough in this high traffic area to truly be considered compaction. AND we mustn’t forget about the November 16 surface hoar that is still buried 1-2’ below the surface in some areas. For more discussion on the topic of 'skier compaction' check out the observation HERE. Photo by Andy Milauskas

 


Mountain Weather

Yesterday an inversion persisted with temperatures averaging in the low 20F’s the alpine and single digits (F) near sea level. Skies were mostly clear with valley fog at lower elevations. Ridge top winds were calm and no new precipitation was recorded. Conditions were similar overnight.

Expect partly cloudy skies to become overcast in the afternoon and light precipitation to start falling mid-day. Light winds will shift from the South becoming Easterly and increasing to moderate by this evening. Temperatures are expected to increase into the high 20F’s and 1-4” of snow could fall by this evening.

This is the first major pattern shift in weeks and several low pressure systems are on track to impact Southcentral, Alaska. Right now Saturday and Sunday look to be the more precipitous events for Western Prince William Sound. There is some uncertainty about how warm these next few storms will be, but rain was mentioned near the coast and inland at times over over weekend in the NWS forecast discussion

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 21  20
Summit Lake (1400') 13 
Alyeska Mid (1700') 20   0

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 23  variable 
Seattle Ridge(2400') 22  variable  11 

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: May 16, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedThanks all for a safe and fun season on the Chugach NF! Stay tuned for the 2017/18 season. #playsafe #snowtosealevel
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: ClosedResurrection Pass trail will be 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
© 2017 Chugach National Forest Avalanche Information Center. All rights reserved.
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