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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Kevin Wright  
Friday, April 1st 2011
Created: Apr 1st 6:59 am
2 Moderate Alpine / Above 2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
2 Moderate Treeline / 1,000'-2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
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.
 Show the Complete North American Avalanche Danger Scale
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The Bottom Line
Good morning backcountry travelers this is Kevin Wright with the Chugach National Forest Avalanche Information Center on Friday, April 1st 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
Todays avalanche danger rating is MODERATE for recent snow on top of buried surface hoar and wet slab activity this afternoon. The buried surface hoar is showing unsettling test pit results and deserves some respect. Warm temperatures this afternoon will likely cause some wet slab activity on Southern aspects.

AVALANCHE DISCUSSION
The peak of the recent storm was 3 days ago. Time is a good equalizer for storm snow avalanche problems, but we have some persistent weak layers to worry about. Weve been finding lots of buried surface hoar in our field observations, which is keeping me a little worried about the snowpack.

Primary concern today is storm snow over buried surface hoar. We found 2 feet of settled snow sitting on a very weak layer of frost feathers above the firm March wind hammered snow. Take a look at our pit profile here.

The test results are what really grabbed my attention. The first isolated column failed with the first light tap I gave it, showing very poor strength. The video below shows an extended column test with moderate strength and the possibility for the weakness to propagate.


CNFAIC Staff definitive information about this weakness is the natural and human triggered avalanche activity that happened during and after the storm on Tuesday. There were a number of reported sympathetic avalanches (one avalanche triggering a second disconnected avalanche). This behavior indicates a collapsing weak layer (buried surface hoar) and conditions that can be difficult to manage safely. The surface hoar is widely distributed to the ridgetops and on all aspects. Take a look at anCNFAIC Staff recent avalanche in the photo gallery here.

Secondary concern today will be afternoon sun and rising temperatures. Sunny southern slopes will have a stiff sun crust this morning from yesterdays afternoon melting and cold temperatures overnight. Today is forecasted to be similar with partly cloudy skies and warm temperatures. There is the possibility for all that heat to trigger sluffs and slabs in the same weak layers we are most concerned about. This concern will spike in the late afternoon and only on Southern exposures.

Encyclopedia of avalanche terms.

WEATHER ROUNDUP
An inch of snow fell yesterday morning. Anchorage got the brunt of that squall, while Turnagain arm took the remnants. Temperatures last night dipped into the low to mid 20s. Today, partly cloudy skies with temperatures into the 30s (40s at sea level) and light wind.

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 AKDT FRI APR 1 2011

.TODAY...MOSTLY CLOUDY BECOMING PARTLY CLOUDY. HIGHS IN THE MID 30S
TO MID 40S. VARIABLE WIND TO 10 MPH.
.TONIGHT...MOSTLY CLOUDY WITH SCATTERED SNOW SHOWERS. LOWS IN THE
MID 20S TO LOWER 30S. VARIABLE WIND 10 MPH.
.SATURDAY...SNOW IN THE MORNING...THEN RAIN IN THE AFTERNOON. LITTLE
SNOW ACCUMULATION. HIGHS IN THE UPPER 30S TO MID 40S. EAST WIND 10 TO
15 MPH INCREASING TO 15 TO 30 MPH IN THE AFTERNOON. THROUGH PORTAGE
VALLEY AND TURNAGAIN ARM...EAST WIND 10 TO 15 MPH INCREASING TO 25 TO
45 MPH IN THE AFTERNOON.
.SATURDAY NIGHT...RAIN AND SNOW. LOWS IN THE UPPER 20S TO MID 30S.
NORTH TO EAST WIND 20 TO 35 MPH EXCEPT EAST 35 TO 50 MPH THROUGH
PORTAGE VALLEY AND TURNAGAIN ARM.
.SUNDAY...RAIN AND SNOW IN THE MORNING...THEN RAIN IN THE
AFTERNOON. HIGHS IN THE UPPER 30S TO MID 40S. EAST WIND 20 TO
35 MPH EXCEPT EAST 35 TO 50 MPH THROUGH PORTAGE VALLEY AND
TURNAGAIN ARM.

TEMPERATURE / PRECIPITATION

SEWARD 41 31 43 / 0 20 80
GIRDWOOD 39 29 39 / 0 40 80


WEATHER STATION SUMMARY for Turnagain Pass:
-3800 Sunburst Wx Station-
Currently 20 degrees at 6am. Light West wind.
-2600 Seattle Ridge Wx Station-
23 degrees at 6am. Light SE wind.
-1800 Center Ridge Wx Station-
23 degrees at 6am. 1 inch new snow recorded yesterday.


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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