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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Graham Predeger  
Wednesday, February 19th 2014
Created: Feb 19th 6:52 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.
3 Considerable Below Treeline / Below 1,000' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
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Alaska Mining and Diving Supply
Special Announcement

All motorized areas on the Glacier Ranger District of the Chugach National Forest are now OPEN to snowmachines.  This includes Johnson pass (north), Turnagain Pass, Placer, Skookum and 20-mile.  Check the bottom of this page for the latest updates on riding area status and conditions as well as the Chugach National Forest website.


The Bottom Line

A CONSIDERABLE avalanche danger exists at all elevations in the backcountry today. In areas above treeline where a known weak layer has been proving quite reactive to human triggers over the last several days, human triggered avalanches will be likely. Cautious route finding and conservative decision-making are essential ingredients to a fun and safe day in the backcountry.

Below treeline where the persistent weak layer appears to be less of a concern storm snow avalanche problems deserve your attention today.  These are likely to fail at storm interfaces in steep terrain greater than 35 degrees.


Primary Concern

We have received a plethora of snowpack and avalanche observations from the skier side of Turnagain pass over the last several days thanks in part to the Alaska Avalanche School hosting a couple different courses in the Turnagain region over the weekend.  A common theme since Saturday has been parties remotely triggering avalanches that are failing on a thin layer of facets above the January rain crust.  This persistent weak layer seems to be most evident at elevations greater than about 2500’.

With a moderate load of new snow overnight and forecasted through today, this known weak layer will move closer to its tipping point.  Terrain (such as the backside of Seattle ridge, snowmachiner side) that has not seen much traffic this season warrants extra caution today as the weak snow in these areas has not been tested by skiers or snowmachiners like it has in areas such as Tin Can and Sunburst.  Slopes greater than 35 degrees deserve a wide berth when travelling on or underneath, specifically for the possibility of remotely triggering an avalanche.  

For sledders, there is a lot of fun to be had in the flats without exposing your party to avalanche terrain today.


Secondary Concern

Snowfall amounts varied significantly during the last 24 hours across our zone with Girdwood picking up 12-16 inches, Turnagain pass picking up 1-2 inches and for comparison Anchorage accumulated about 6 inches.  The lion’s share of this snow fell during a short but intense period yesterday evening and through the early morning hours though totals fell well short of the forecasted storm.

Storm slab avalanches will be of increased concern in areas that have seen favorable accumulation, spanning all elevations today.  Included in this will be the possibility to trigger a wind slab on leeward slopes or cross-loaded gullies, as there is ample snow available for transport to build tender wind slabs.  Though Turnagain saw less snow than other zones overnight, that area has been favored over the last several days of storms (since Friday).  

Furthermore, loose snow avalanches are likely today in steep terrain above 35 degrees.  Though usually a manageable problem, loose snow avalanches prove most hazardous when initiated above a terrain trap.


Additional Concern

Cornices are growing quite large as of late.  These “backcountry bombs” not only have a tendency to break much further back on a ridge than one expects but also have a great potential to initiate an avalanche on the slope below.  Do not test your luck with cornices today (or ever for that matter!), as a fortunate outcome is highly unlikely.

*Note: The AKDOT webcam is working again on Turnagain Pass!  Keep tabs on snowfall as well as the road conditions with this link.


Mountain Weather

Though yesterday’s winter storm warning was canceled mid-day and we didn’t quite see forecasted snowfall amounts, there was a brief and intense burst of snowfall from about 5PM last night to 2AM this morning.  Areas north of Turnagain pass including Whittier, Portage, Girdwood and Anchorage all woke up to measurable snowfall.

Yesterday in the core advisory area (Turnagain Pass), temperatures reached the mid to high 20’s with winds peaking around noon in the mid-20mph range.  Skies were broken all day during the daylight hours with no snow accumulating during the day.

Today we can expect slightly cooler temperatures in the low to mid-20’s with light winds out of the south east.  2-4 inches of snow is expected throughout the day before tapering off into the overnight hours.  Tomorrow looks to be the best chance for some sunny skies before we return to what appears to be an active weather pattern for the weekend.

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
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