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Turnagain Area Avalanche Advisory
Sunday, February 7th 2010 6:43 am by CNFAIC Staff
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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BROUGHT TO YOU BY
The Bottom Line
Good morning backcountry travelers this is Lisa Portune with the Chugach National Forest Avalanche Information Center on Sunday, February 7th 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).

WEATHER ROUNDUP
AnCNFAIC Staff 1 inch of new snow fell in the last 24 hours in Turnagain Pass, bringing our snowfall total for the last 36 hours to around 13 inches of snow and 1 inch of water. Actual amounts vary from 6 inches on the southern end of the pass to 14 inches on the northern end. Yesterday ridgetop winds were ripping, averaging 15-45mph out of the east and southeast with gusts in the 40s, 50s, and 60s. Mountain temps dropped about 10 to 15 degrees to the mid to upper teens by the end of the day. Ridgetop winds died down around midnight last night and are currently light. Sea level winds, however, picked up around midnight and are currently averaging 15-20mph out of the northeast. Temperatures this morning range from 13F at 3800 feet to 24F at sea level. It is currently snowing in Girdwood with an additional 6-8 inches falling last night on top of the 12-18 inches that fell in the last day and a half. A weak low moving into western Prince William Sound may bring an additional 1-3 inches of snow today. Expect mountain temps in the teens with easterly ridgetop winds averaging up to 15-20mph. Skies will clear up tomorrow ahead of the next low that will impact us Tuesday.

AVALANCHE DISCUSSION
Today the avalanche danger is rated CONSIDERABLE on windloaded slopes steeper than 35 degrees. All CNFAIC Staff slopes have a MODERATE danger. Thirteen inches of new snow and strong easterly winds in the last 36 hours means human-triggered avalanches are likely on steep windloaded slopes and cross-loaded gullies. Terrain management is key today as our snowpack adjusts to the new load.

There was no shortage of action yesterday once the skies cleared by midday. Jon and I watched a skier trigger an avalanche on a southwest aspect of Tincan at 3000 feet in an area called the Kitchen Wall. The skier was caught, carried, and partially buried but able to dig himself out. We estimated the slide at 150 feet wide, 200 feet long, 14 inches deep at the crown face, and 39 degrees at the trigger point. The slide failed below a windslab on a possible melt-freeeze layer or sun crust. A second skier immediately skied down next to the first avalanche and triggered a smaller slide but was not buried. Check out our photo and video gallery for a picture of this slide and CNFAIC Staff photos/videos from yesterday. During our tour up Tincan, we got numerous shooting cracks on steep rollovers breaking down about a foot deep and found that any recently formed windslabs (2-6 inches thick) were especially reactive, fracturing 25-60 feet wide on leeward slopes. One of our observers reported seeing numerous small slides on steep rollovers in the alpine in addition to substantial windslabs at the higher elevations. Whumphing was also reported below 2000 feet on Sunburst.

We saw evidence of only a few natural avalanches up at the pass that most likely happened during the height of the storm, the most obvious one being just below the corniced ridge on Tincan (CFR) that ran about 500 feet into the trees. The crown faces were blown in on most of them, so it was difficult to judge the depth of the fractures. Nothing seemed to step down to the buried Jan. 7 rain crust, now buried 2-4 feet deep and even deeper on leeward aspects. Thats not to say its not possible. I think a big enough avalanche could easily step down to this persistent weak layer and create an even bigger slide, especially on the northern end of the pass where we found buried surface hoar lurking on top of this slick crust and clean fast Q1 shears in our stability tests.

Always remember that safe backcountry travel requires training and experience. You control your own risk by choosing where, when, and how you travel.

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.

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

500 AM AKST SUN FEB 7 2010

.TODAY...CLOUDY WITH SCATTERED SNOW SHOWERS. HIGHS IN THE LOWER 20S
TO LOWER 30S. SOUTHEAST WIND TO 15 MPH.
.TONIGHT...MOSTLY CLOUDY WITH SCATTERED SNOW SHOWERS. LOWS 10 TO 20
ABOVE. VARIABLE WIND 10 MPH.
.MONDAY...PARTLY CLOUDY. HIGHS 15 TO 25 ABOVE. LIGHT WINDS. NEAR
WHITTIER...WEST WIND 10 TO 20 MPH BECOMING VARIABLE 10 MPH IN THE
AFTERNOON.
.MONDAY NIGHT...CLOUDY. LOWS 10 TO 20 ABOVE...COLDEST INLAND. EAST
WIND 10 TO 20 MPH. NEAR SEWARD...NORTH WIND 10 MPH INCREASING TO
10 TO 25 MPH AFTER MIDNIGHT.
.TUESDAY...SNOW. HIGHS IN THE MID 20S TO LOWER 30S. EAST WIND
15 TO 25 MPH EXCEPT SOUTHEAST 25 TO 35 MPH THROUGH PORTAGE VALLEY AND
TURNAGAIN ARM.

TEMPERATURE / PRECIPITATION

SEWARD 31 10 19 / 40 40 0
GIRDWOOD 32 24 26 / 40 40 0


WEATHER STATION SUMMARY for Turnagain Pass:
-3800 Sunburst Wx Station-
recorded moderate to gale force easterly winds yesterday averaging 15-45mph with gusts to 68mph. The current temp is 13F (13 degrees colder than yesterday) with winds averaging 8mph out of the east.

-2600 Seattle Ridge Wx Station-
recorded moderate to strong southeasterly winds yesterday averaging 15-30mph with gusts to 53mph. Winds are currently averaging 2mph out of the southeast.

-1800 Center Ridge Wx Station-
recorded 1 inch of new snow and 0.1 inches of water in the last 24 hours. The current temp is 18F (14 degrees colder than yesterday) with a total snowpack depth of 72 inches.

 Show the Complete North American Avalanche Danger Scale
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.

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: Jan 13, 2019 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Open
Placer River: Open
Skookum Drainage: Open
Turnagain Pass: Open
Twentymile: ClosedClosed. Forest Service is monitoring conditions.
Seward District
Carter Lake: Open
Lost Lake Trail: OpenPlease stay on trail to avoid resource damage through forested areas.
Primrose Trail: OpenPlease stay on trail to avoid resource damage through forested areas.
Resurrection Pass Trail: ClosedClosed for the 2018/19 season. Next season will be open to motorized use.
Snug Harbor: Open
South Fork Snow River Corridor: Open
Summit Lake: Open

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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