Good morning. This is Wendy Wagner with the Chugach National Forest Avalanche Information Center on Monday, March 12th 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 remains LOW in the core Tunagain Pass area. The snow has seen little change over the past few days but when there is snow on the ground avalanche concerns are always present. Today, human triggered dry sluffs are possible in steep terrain as well as sun initiated wet loose sluffs on southerly aspects. Stubborn wind slabs in isolated areas remain possible as well. On the periphery and outside our core zone areas of MODERATE danger may exist.
AnCNFAIC Staff nice day in the backcounty with sunny skies and virtually no wind kept sluffing in the top few inches of loose snow the name of the game for those ramping up their slope angle to over 40 degrees (steeper than a typical black diamond run which is around 35 degrees). For those riding in the lower elevations (e.g. Placer Valley and Twentymile, natural wet loose slides have been occurring during the past week as the sun heats up those steep south facing rocky aspects above. An observation came in from Saturday about a skier triggering a small slab in the Silver Tip area (just south of our core forecast zone) – details HERE. Also, one small wind slab was triggered on the west face of Magnum yesterday (rough estimate: 10-20′ wide, running ~100′ and 10-16″ deep).
Today is the 11th day of light winds and little snow accumulation. Our riding surface is becoming variable with loose recrystallizing powder on west, north and east aspects and this same loose powder with scattered sun crusts on the southerly faces. The wind has moved the snow around at the higher elevations a bit during the past week in some locations but not all. This combo of recrystallized snow and crusts are suspect future weak layers, more on that HERE.
Primary concern: Loose Snow
Both dry and wet point release avalanches continue to be a concern on very steep slopes. Dry sluffs are likely to be triggered on very steep (over 40 degree) slopes and all aspects that sport loose snow. These can run quite far in places with sustained steep slope angles and being aware of where the sluff will run, how big it is and have an escape route planned is necessary for those committing to high exposure/extreme terrain. Though most slopes have already had the impact of the sun for two days now, continuing to avoid areas under south facing rocky/vegetated slope is advised as wet point release avalanches may still be possible in these southerly facing aspects with today’s sun in store.
Secondary concern: Wind Slab
The small wind slab triggered on Magnum is proof that lingering wind slabs still can be found in isolated areas, this one was small and we believe inside our core zone any CNFAIC Staff will be small. Keeping an eye out for any cracking around you, or hollow feeling snow, is part of the ‘normal caution’ routine. The most suspect area to find one of these is just off ridges or rollovers where winds have drifted the snow as well as slopes that are unsupported below (e.g, slope above a cliff).
Clouds broke up yesterday to allow for a mostly sunny day with nearly no wind at the mid and upper elevations (0-5mph, variable direction), gusty winds were seen at sea level near Turnagain Arm. Temperatures were quite pleasant, 20-25F below treeline and in the teens above. Overnight temperatures have dropped dramatically under clear skies and an inversion has set in with minus single digits at sea level and positive single digits on the ridges.
Temperatures are cold this morning but with calm wind and sunny skies they should rebound to near 20F below treeline and the mid-teens above. Skies should be sunny today and wind will shift from the north to the southeast and blow around 5mph.
It looks like we might have snow on tap for mid-week so we may finally get a nice re-fresher.
CNFAIC Weather Page and the NWS forecast
I will issue the next advisory Monday morning. If you get out in the backcountry we want to know what you are seeing. Please send us your observations using the button at the top of this page or give us a call at 754-2369. Thanks and have a great day.