Good morning backcountry travelers. This is Wendy Wagner with the Chugach National Forest Avalanche Information Center on Sunday, February 27th 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).
The avalanche danger is MODERATE on any slope with wind deposited snow in the past several days. There also exist isolated pockets of CONSIDERABLE danger for recent and/or significantly wind loaded steeper terrain. These can be found on all aspects, both on and off ridgelines and in cross loaded areas. In addition, a MODERATE danger remains for triggering a deeper avalanche that breaks into the older weak layers in shallow snow cover areas.
There was one avalanche report from yesterday. This was a snowmachine triggered slide in Seattle Creek and believed to be across from Triangle Bowl on the west side of the valley. Currently details are limited but two people were caught with one able to ride it out on their sled while the CNFAIC Staff was carried down with the debris off their sled. CNFAIC Staffwise, over the past week, there has been widespread natural wind slab activity with the most recent events occurring Friday. A few of these wind slabs have taken out practically entire bowls as well as breaking down into the deeper facets near the ground, creating larger and more dangerous slides. This natural activity was most pronounced in the interior Kenai region.
Today, wind slabs continue to be the primary concern. The winds have been pummeling our tired snowpack for a week now and though they did decrease this morning the forecast is for continued strong gusts today. Fresh wind drifts will likely be the most sensitive but stiffer older drifts and slabs are still a concern, though potentially more difficult to trigger. Slopes may be loaded well off of ridgelines by the strong winds or in gullies/sub-ridges by cross loading winds and in areas different from the usual suspects. There is still snow available for transport, even if it has blown from one side of a ridge to the CNFAIC Staff and back again. Stiff slabs may be harder to trigger but could pull out larger, above you or knock a person down somewhere they don’t want to go. Smooth snow surfaces, wind pillows and hollow feeling drifts are what to look for as well as any cracking or collapsing.
We can’t forget that deeper weakness still exist in the snowpack. Triggering this type of larger and deeper avalanche is still possible by a human, snowmachine or the weight of a wind slab running over it in just the right spot, and can break well above you. Most suspect regions have a total snow depth less than 2 meters. This is mainly in the Crow Pass/Raggedtop area above Girdwood and the interior Kenai south of Turnagain Pass. Travel in thin snow cover areas deserves a heightened level of attention and avoiding steeper slopes is advised, especially where wind loading has occurred.
Below: A look at what a week-long beating from the ruthless winds has done to the mountains…
The sun may have shone yesterday but it was cold (temperatures in the single digits) and the winds were blowing (northwesterly gusting over 50mph). Overnight winds have decreased and this morning are around 10 mph with gusts into the 20’s from the northwest. Temperatures have remained cold and are currently in the single digits at most locations. Today will be a similar story. Skies will be clear with winds forecast to increase into the 20’s with gusts over 40mph. Temperatures will likely hover in the single digits.
ANNOUNCEMENTS An APU student is conducting a survey on backcountry skiing group dynamics. Click on the link to participate in research on avalanche safety. Click here to take survey
The Forest Service is installing winter use bridges across Granite creek in Turnagain Pass. Be aware of an ice road from the Lyon creek bridge south towards Johnson Pass on the West side of the highway. Heavy equipment will also be used in the area.
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-
500 AM AKST SUN FEB 27 2011
…STRONG WIND THROUGH THIS MORNING NEAR SEWARD AND WHITTIER…
.TODAY…SUNNY. HIGHS 15 TO 25. NORTH TO WEST WIND 15 TO 30 MPH
WITH GUSTS 40 TO 50 MPH NEAR SEWARD AND WHITTIER.
.TONIGHT…CLEAR. LOWS 5 BELOW TO 5 ABOVE INLAND AND 5 TO 15
ABOVE ALONG THE COAST. NORTH TO WEST WIND 10 TO 25 MPH. GUSTS
TO 40 MPH NEAR SEWARD AND WHITTIER.
.MONDAY…SUNNY. HIGHS IN THE 20S. NORTH TO WEST WIND 5 TO 20 MPH.
GUSTS 25 TO 35 MPH NEAR SEWARD AND WHITTIER.
.MONDAY NIGHT…CLEAR. LOWS ZERO TO 15 ABOVE…COLDEST INLAND.
NORTH TO WEST WIND 10 TO 25 MPH. GUSTS TO 35 MPH NEAR WHITTIER.
.TUESDAY…MOSTLY SUNNY. HIGHS IN THE 20S. NORTH TO WEST WIND
TO 15 MPH
TEMPERATURE / PRECIPITATION
SEWARD 20 12 26 / 0 0 0
GIRDWOOD 23 7 28 / 0 0 0
WEATHER STATION SUMMARY for Turnagain Pass:
-3800′ Sunburst Wx Station-
Temperature 2 degrees. NW winds 5-10mph, gusting to 20.
-2600′ Seattle Ridge Wx Station-
Temperature 4 degrees. NW winds in the teens gusting into the upper 20’s.
-1800′ Center Ridge Wx Station-
Temperature 8 degrees. No new snow recorded.