Turnagain Pass

Good morning. This is Graham Predeger with the Chugach National Forest Avalanche Information Center on Tuesday, January 24th 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

The avalanche danger today is MODERATE on slopes below tree line. Watch for sluffing of loose, less cohesive snow. Pockets of CONSIDERABLE avalanche hazard exist above tree line in wind-loaded areas where wind slabs have formed.

AVALANCHE DISCUSSION

You know it’s a powder day when you hear of people driving past Turnagain pass toward Summit lake cause there is “less snow in the Summit area”! Storm totals as of yesterday afternoon in the Turnagain pass area were right around 30”. As one observer put it, “too much snow for mellow pitches”.

Below tree line observations are all pointing towards an upper snowpack that is slowly settling and gaining strength. At this point, the storm snow from the previous two days is still relatively light density and lacks the cohesion to form a slab. That being said, an increase in wind at lower elevations or a sudden rise in temperature today would be enough to form a slab. Additionally, it is important to keep in mind what we KNOW is underneath all this new snow. Remember, just two powder days ago we came out of 10+ days of high pressure that formed a thick layer of near-surface facets and sporadic surface hoar, now buried by this latest storm. Whether or not these weak layers become reactive is yet to be determined.

Above tree line there is more uncertainty that exists within the snowpack, specifically size and distribution of wind slabs. What we do know is that the winds have been moderate at ridge tops from the east over the last 48-60 hours. Significant wind texturing was seen yesterday below Seattle ridge as well as ridge top wind plumes south of Turnagain pass. We know that wind slabs are forming, however we don’t know how reactive these young wind slabs will be to a skier or snowmachiner yet. With a lack of upper elevation snowpack observations yesterday, a high degree of uncertainty still exists, lowering my confidence in the snowpack above tree line. Careful snowpack evaluation, cautious route finding and conservative decision-making are essential today as you travel into these upper elevations of our forecast area.

DOT plow drivers are doing their best to remove snow from parking areas on Turnagain pass, though their priority is to keep the highway clear first and foremost. Please keep this in mind today and do not block entrances or exits of parking areas.

MOUNTAIN WEATHER

Everyone seems to be in agreement that this latest storm was a bit of a surprise as it relates to snowfall amounts. Storm totals at Turnagain pass added up to 27″ of snow with 2″ of water equivalent at the Center ridge Snotel site. Temperatures have also risen to a comfortable level, hovering in the teens and low 20’s yesterday.

Overnight, we picked up anCNFAIC Staff 1″ of snow in Girdwood and 6-8″ on Turnagain pass though it quickly tapered off around 3am. Today we can expect intermittent snow showers to continue through the forecast area picking up anCNFAIC Staff 4″ or so of snow with easterly winds in the lower 20’s. Temperatures today will be similar to yesterday. Expect a change in flow tonight and tomorrow with colder air pushing into our area from the north. By Thursday it looks as if colder air will settle in over south-central Alaska once again, though precipitation may persist.

CNFAIC Weather Page and the NWS forecast

Kevin will issue the next advisory Wednesday 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.