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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   CNFAIC Staff  
Sunday, January 9th 2011
Created: Jan 9th 6:24 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.
 Show the Complete North American Avalanche Danger Scale
The Bottom Line
Good morning backcountry travelers this is Lisa Portune with the Chugach National Forest Avalanche Information Center on Sunday, January 9th at 7am. This will serve as 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).

BOTTOM LINE
Today the avalanche hazard remains at CONSIDERABLE. The large size of recent human triggered avalanches warrants this elevated danger rating. The 20-30 inches of new snow from last weeks storm fell on an exceptionally weak snowpack littered with multiple layers of buried surface hoar, weak sugary snow, and facets above and below the Thanksgiving Rain Crust (TRC). While natural avalanches are unlikely today, human triggered avalanches still have the potential to go big. The most likely spot to trigger an avalanche today will be in shallow areas of the snowpack where the weak layers are closer to the surface.

AVALANCHE DISCUSSION
You can throw the old wait 24-hours after a storm and all should be good rule out the window when you are dealing with persistent weak layers like we have now. Recent large human triggered avalanches happened a full 60-72 hours after the storm. The most recent reported human triggered avalanche happened late Friday afternoon when a skier remotely triggered a medium sized avalanche on Sunnyside just south of the snowmachine uptrack (see photo below). All of these avalanches failed on either buried surface hoar or TRC facets or both.

477-IMG_3609.JPG

A few folks inched out onto steeper terrain yesterday and didnt trigger anything. Tracks on a slope mean nothing right now in terms of stability. It simply means no one found the trigger spot. The human factor is running high with abundant sunshine and powder, so set limits for yourself and stick to them. We should see a gradual increase in stability over time, but Im still leary of big steep open slopes right now. The trigger spots will be harder to find as the week progresses, but if you do find one, expect a potentially large avalanche. Shallow areas of the snowpack (rocky outcrops) should be avoided like the plague, because that is where you will most likely trigger an avalanche.

Heres a rundown of recent avalanche activity:

Wednesday 1/5
-Large natural avalanches observed on Sunnyside (east aspect), Sunburst (south aspect), Upper Girdwood Valley (south aspect), and Main Bowl (north aspect).

Thurday 1/6
-Skier triggered avalanche on south face of Raggedtop, triggered on buried surface hoar from a chute higher up then propagated down across the face, stepped down to deeper weak layers, crown face 6-8 feet deep at thickest spot.
-Skier triggered avalanche in Warmup Bowl off Seattle Ridge, triggered near some rocks in a shallow area, large propagation across slope, partially buried a snowmachine parked at the bottom of the slope.
-Snowmachiner triggered avalanche on a south facing slope in the Seattle Creek drainage, avalanche released above rider while performing a slope cut.

Friday 1/7
-Full burial of skier in Palmer Creek drainage near Hope. He was the fourth person to ski the slope but took a steeper line. Skier OK with no injuries.
-Skier remotely triggered an avalanche on east face of Sunnyside near snowmachine uptrack.
-Large avalanche on Widowmaker Peak, Seattle Ridge. Unknown trigger.

Encyclopedia of terms: www.fsavalanche.org/Encyclopedia.aspx

WEATHER ROUNDUP
It was anCNFAIC Staff beautiful day in the mountains yesterdaylight winds, temps in the 20s, and abundant sunshine above the low level fog. Our most recent storm that ended 4 days ago dropped 20-30 inches of new snow (2.7 water) over a 5 day period in Turnagain Pass. Skies have been clear since the storm and the winds generally light. A 15 degree temperature inversion exists this morning with Sunburst at 3800 reading 31F and sea level at 15F. Ridgetop winds are currently light out of the north and skies are clear. Expect more of the same today with stronger winds near Whittier.

I will issue the next advisory tomorrow morning at 7am. If you get out in the backcountry give us a call at 754-2369 or send us your observations using the button at the top of this page. Thanks and have a great day.

The NWS weather forecast for:
WESTERN PRINCE WILLIAM SOUND-
INCLUDING...WHITTIER...SEWARD...GIRDWOOD...MOOSE PASS

500 AM AKST SUN JAN 9 2011

.TODAY...PARTLY CLOUDY. HIGHS IN THE LOWER 20S TO MID 30S...COOLEST
INLAND. NORTH WIND 15 TO 25 MPH NEAR SEWARD. WEST WIND 20 TO 35 MPH
NEAR WHITTIER. LIGHT WINDS ELSEWHERE.
.TONIGHT...MOSTLY CLEAR. LOWS IN THE MID TEENS TO LOWER 30S. NORTH
WIND 10 TO 20 MPH NEAR SEWARD. WEST WIND 15 TO 25 MPH NEAR WHITTIER.
LIGHT WINDS ELSEWHERE.
.MONDAY...MOSTLY SUNNY. HIGHS IN THE UPPER 20S TO MID 30S. NORTH WIND
10 TO 20 MPH NEAR SEWARD. WEST WIND 15 TO 25 MPH NEAR WHITTIER.
VARIABLE WINDS 10 MPH ELSEWHERE.

TEMPERATURE / PRECIPITATION

SEWARD 29 22 32 / 0 0 0
GIRDWOOD 20 20 32 / 0 0 0

WEATHER STATION SUMMARY for Turnagain Pass:
-3800 Sunburst Wx Station-
recorded light winds the last 24 hours averaging 5mph out of the west. Temps yesterday ranged from 25F to 30F. The current temp is 31F with light winds out of the north.
-2600 Seattle Ridge Wx Station-
is not recording winds speeds. Temps yesterday ranged from 20F to 27F. The current temp is 26F.
-1800 Center Ridge Wx Station-
recorded no new snow the last 4 days. Temps yesterday ranged from 17F to 21F. The current temp is 20F with a total snowpack depth of 69 inches (2 inches of settlement in the last 24 hours).

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

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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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