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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Jon Gellings  
Wednesday, March 23rd 2011
Created: Mar 23rd 6:57 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.
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The Bottom Line
Good morning backcountry travelers. This is Jon Gellings with the Chugach National Forest Avalanche Information Center on Wednesday, March 23rd 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 danger remains at LOW. We have received 1 inch of snow overnight, making this the 2nd largest snowstorm in the past month. This new snow, coupled with strong winds into the 30s, has started to fill the divots in the surface snow caused by wind, but we are still a ways away from having a continuous, trigger-able slab on top of the various crusts, near-surface facets, and surface hoar.

AVALANCHE DISCUSSION
Normal hazard conditions continue in Turnagain Pass, but we are watching anCNFAIC Staff concerning set of instabilities emerge. There is still an isolated chance of breaking off an old wind slab on steep unsupported slopes, and cornices could fail if stressed too much by sun or weight, which could become a problem for a person travelling beneath or on them.

The conditions we will be monitoring closely over the next while will be mostly confined to how the new snow and old snow bond together. With observations of surface hoar, near surface facets, and all around hard snow surfaces, I am skeptical of how nice this new snow could become. With strong winds pushing around 1 inch of snow at 1800 feet, the likelihood of deeper snow on top of these surface features exists at higher elevations in wind-loaded start zones. Isolated pooling areas for this snow could start becoming reactive to human triggers if the snow keeps falling.

The recent Hatcher Pass avalanche brings back thoughts about how dangerous a weak and shallow snowpack can be in areas that usually get more snow. Turnagain Pass is currently at 60% of its normal SWE, Summit Lake is at 78% (though inherently thin on a good year), Alyeska Resort is at 55%, and Hatcher Pass is less than 50% of its snow water equivalent, loosely signifying a snowpack less than its usual height. Thin snow tends to mean weak snow, and weak snow should be thought of as guilty until proven innocent. Summit Lake has shown signs of a shallow snowpack all winter, so any new stresses to the old snow could reinvigorate any currently dormant instability. Isolated spots in steep, rocky, unsupported terrain of Turnagain Pass have also shown signs of a shallow snowpack, so this local terrain is not out of the woods yet. New precipitation can help us test this hypothesis.

Encyclopedia of avalanche terms.

WEATHER ROUNDUP
Winds are forecasted to be similar to yesterday, reaching into the 30 mph range again. Temperatures should be similar to yesterday, approaching the freeze threshold in the afternoon if the sun comes out. New precipitation is forecasted at over 50%, making it likely to NWS personnel. These weather factors could start increasing the avalanche danger in Turnagain Pass, so we will see if the forecasts actually become verified.

Kevin 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 WED MAR 23 2011
.TODAY...SNOW SHOWERS IN THE MORNING...THEN NUMEROUS SNOW AND RAIN
SHOWERS IN THE AFTERNOON. SNOW ACCUMULATION 1 TO 3 INCHES. HIGHS IN
THE MID 30S TO LOWER 40S. EAST WIND 10 TO 25 MPH.
.TONIGHT...NUMEROUS SNOW SHOWERS. SNOW ACCUMULATION 1 TO 4
INCHES...HIGHEST AMOUNTS AT HIGHER ELEVATIONS. LOWS IN THE 20S. EAST
WIND 10 TO 20 MPH.
.THURSDAY...NUMEROUS SNOW SHOWERS IN THE MORNING...THEN NUMEROUS
SNOW AND RAIN SHOWERS IN THE AFTERNOON. SNOW ACCUMULATION 1 TO 3
INCHES. HIGHS IN THE MID 30S TO LOWER 40S. EAST WIND 10 TO 15 MPH.


TEMPERATURE / PRECIPITATION
SEWARD 39 28 39 / 80 80 70
GIRDWOOD 37 25 37 / 60 50 60

WEATHER STATION SUMMARY for Turnagain Pass:
-3800 Sunburst Wx Station-
17 degrees. East wind 18mph gusting to 25mph.
-2600 Seattle Ridge Wx Station-
21 degrees. Southeast wind 11mph gusting to 14mph.
-1800 Center Ridge Wx Station-
24 degrees. 1 inch new snow.

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: Apr 28, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: ClosedSKOOKUM DRAINAGE CLOSED TO MOTORIZED USE ON APRIL 1 annually as per the Chugach National Forest Plan document.
Turnagain Pass: OpenOpen thru May 14th.
Twentymile: Closed
Seward District
Carter Lake: OpenClosed May 1.
Lost Lake Trail: OpenClosed May 1.
Primrose Trail: OpenClosed May 1.
Resurrection Pass Trail: ClosedClosed for 2016/17 winter season. This is a non-motorized season. This alternates every other year and will open again during the 2017/18 winter.
Snug Harbor: OpenClosed May 1.
South Fork Snow River Corridor: OpenClosed May 1.
Summit Lake: OpenClosed May 1.

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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