Good morning. This is Chris Engelhardt with the Chugach National Forest Avalanche Information Center on Friday, April 6th 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).
Today, we have a MODERATE avalanche danger for newly formed soft wind slabs above tree line and a MODERATE danger for wet avalanches below tree line. The 2-6” of moist snow from yesterday and last night, coupled with strong winds likely has deposited and cross-loaded alpine terrain with shallow, sensitive soft slabs on north, west, and southerly slopes. The lack of a hard freeze last night along with rain will make for increased likelihood of wet avalanches and an increasingly unsupportive snowpack at lower elevations below 1500′.
The new pasting of snow yesterday along with warm temperatures actually made the skiing decent on smooth surfaces down to 1000′ or so. Below this, the new frosting turned sticky and slow and you could feel the water grabbing at your bases. Wind and low visibility have been the major players the past few days while snow accumulations have lacked much significance. The snow that did fall though was high density and likely filled in pockets, catchment zones and leeward sides of ridges. It will more than likely be easy to trigger as it has fallen on a variety of smooth surfaces on sunny aspects and dry loose powder on north aspects. These tender pockets probably do not extend very far off the leeward of ridges, but if there is enough volume and weight they could potentially step down into the multiple layers of buried surface hoar that reside on northerly aspects.
With the rain level rising and lack of freezing, lower elevations are definitely going to provide for conditions conducive to wet avalanches, not to mention punchier and injury inducing unsupportive snow. Sunny slopes that were locked up previously early in the week will start to once again shed snow and you’re likely to find some nasty little spots on saturated wet gully banks or roll-overs. Small terrain features, such as cut banks on streams or little roll- overs in the woods can be enough to bury a person in heavy wet cement like snow.
Above treeline – Wind Slab, Soft Slab and Persistent Slab
Expect to find shallow wind loaded soft slabs on a variety of aspects today. The primary concern has been the strong winds which even with a small amount of snow can produce dangerous fresh wind slab conditions. The new snow is fairly warm and wet which is good for bonding, but to reiterate, it has fallen on a variety of smooth sun crust surfaces as well as loose, dry, northerly surfaces, so expect some tender conditions today.
Don’t forget about our multiple layers of buried surface hoar above tree line on north aspects. They possibly could become more reactive with a new snow load, so keep it on the radar of things to check for.
Below treeline – Wet Avalanches
Human triggered avalanches will be possible along with natural activity associated with the rain and wet saturated snow. We may not be quite to the threshold of major wet avalanche activity, but it should be calculated into your travel plan. Try to avoid travel on, or below any steeper slopes that are unsupportive. A good way to test this is to get off your skis or snow machine in a safe spot and see how far you sink in. Sinking up to your knees is a pretty good sign of dangerous wet conditions as well as poor riding.
Yesterday saw light snow flurries and accumulations of around 1-2” up to tree line. More than likely there was up to 4-5” on wind loaded slopes at higher elevations, but the extremely flat light kept me next to the trees where I could see. Temperatures were just at or below freezing below 1800ft and it felt sort of like being in a greenhouse on the way up. The winds continued to blow consistently from the east and south east in the high 20mph to mid 30mph range over the ridges and were gusting to 50mph at points.
Overnight, 1-2 inches of snow has fallen at tree line elevations at Turnagain Pass and Girdwood Valley, and temperatures have remained warm, hovering around 29F at 1880ft on Center Ridge. It stayed cooler on ridge tops averaging around 22F on Sunburst. Winds continued to remain consistent from the east and south east in the mid-20mph through 30mph range last night and looked to be abating early this morning.
Today, temperatures are supposed to push higher up and be from 34F-40F at around 1000ft elevations. Rain levels and sticky conditions are also predicted to exist up to the 1000ft mark. Winds are looking to back off to the 12-20mph range from the southeast.
CNFAIC Weather Page and the NWS forecast
Wendy will issue the next advisory Saturday 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.