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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Sunday, February 3rd 2013
Updated: Feb 3rd 9:49 am
Created: Feb 3rd 6:44 am
2 Moderate Above Treeline
Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern. Likelihood of Avalanches: Natural avalanches unlikely; human-triggered avalanches possible. Avalanche Size & Distribution: Small avalanches in specific areas; or large avalanches in isolated areas.
1 Low Below Treeline
Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. Likelihood of Avalanches: Natural and human-triggered avalanches unlikely. Avalanche Size & Distribution: Small avalanches in isolated areas or extreme terrain.
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The Bottom Line

We continue to have a MODERATE avalanche danger above treeline for wind slab avalanches, cornice falls and deep slab avalanches. Strong easterly winds, with 3-6" of snow overnight, will form soft wind slabs which could be fairly sensitive to human triggers. Girdwood Valley has seen 6-10" and if precipitation does not back off this morning as expected, the avalanche danger will increase in the Girdwood area.  These slabs will be most likely found near ridgelines, rollovers and cross-loaded in gullies. Below treeline we have a LOW avalanche danger where light rain has been falling on a wet and crusty snowpack. There is a possibility of wet avalanches below treeline in areas outside the Turnagain Pass zone where higher amounts of precipitation has been recorded such as Girdwood Valley and Portage Valley.


Primary Concern

There were two skier/snowboarder triggered avalanches on Tincan yesterday, Saturday 2/2. There was no other avalanche activity seen or reported. It sounds like these were soft wind slabs formed on a rollover overlying a hard crust. Today similar conditions remain as winds have continued to blow moderate to strong from the east overnight, though should be on a decline through the day. 

If skies clear enough today for travel above treeline, wind slab avalanches and cornice breaks will be the primary concern. Watching for areas with current or recent wind deposited snow will be key. These are likely to be found in the usual places: lee sides of ridgelines, rollovers and cross-loaded in gullies and sub-ridges. In areas around treeline where an old melt-freeze crusts sits under the snow that has accumulated the past few days, these slabs could be quite tender still as was seen yesterday. Slabs could range anywhere from 6” to 2’ and sussed out by watching for smooth rounded surfaces, stiff feeling snow and shooting cracks.

Below treeline, intermittent rain has been falling on snow for two days and today will be the third. Small wet loose avalanches were seen Friday with no new activity noted yesterday. The Turnagain Pass and Summit areas have only seen ~.5” of rain below 2,000’ during the past 48 hours while the Girdwood Valley has seen double that, ~1” in 48 hours. In valleys such as Girdwood and Portage, with higher amounts of rainfall, wet avalanches are possible.


Secondary Concern

It has been nearly three weeks now since the last known deep slab avalanche occurred. However, the weak early season snow still resides at the bottom of the pack and therefore the deep slab problem still resides in the bottom of our minds. Triggering one of these large and dangerous avalanches is low but the consequences are high. keeping to safe travel practices remains a must.


Mountain Weather

Off and on rain and snow showers associated with a warm southeasterly flow has been dominating our weather the past two days. Conditions at 1,000' on the Pass have been quite soggy. Temperatures have been in the upper 30's F below 1,000' and in the upper 20's F at 3,000'. The easterly flow on the ridgetops has been averaging 25mph with gusts in the 50's. As far as precipitation, the rain/snow line has been hovering around 1,500' with water numbers listed below.

Rundown on water numbers:
                                                         24hr totals            48hr totals
Turnagain Pass (1880’)                           .3”                       .5”
Girdwood Valley (1700’ / 2800’)            .7 / 1”                  1.3 / 1.9”
Summit Lake (1400’)                              0”                        .2"

Today, we can expect the rain snow line to drop slightly with .25" of rain below 1,000’ and 2-5” of snow above. Precipitation should begin to taper off through the day but skies look to remain cloudy with low visibility (could be a great day for watching the Super Bowl). Temperatures should decrease slightly to 32F at 1,000' and mid 20's at 3,000'. Winds are forecast to abate today to the 10-30mph range and shift to a more southerly direction.

 


Fitz will issue our next advisory tomorrow morning, February 4th.

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: Oct 11, 2014 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedClosed as of April 23rd.
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: Closed
Snug Harbor: Closed
South Fork Snow River Corridor: Closed
Summit Lake: Closed

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 regarding CNFAIC operations or winter recreation management, please email wendy@chugachavalanche.org
© 2014 Chugach National Forest Avalanche Information Center. All rights reserved.
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