Good morning. This is Wendy Wagner with the Chugach National Forest Avalanche Information Center on Monday, March 19th 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).
There is a MODERATE danger today for a variety of avalanche concerns. First, wind slab avalanches are possible with the expected 3-6 inches of new snow and moderate east winds. Second, loose snow sluffing in any new snow will be likely. And third, triggering a slab avalanche that breaks in the buried weak layers still exists in scattered areas predominantly in Placer Valley, Twentymile and Johnson Pass.
AnCNFAIC Staff day of mild weather in the backcounty yesterday kept the hazard steady for our lurking persistent weak layers buried last week. We went on the hunt to find the most notorious of these – buried surface hoar – in the Placer Valley yesterday. Sure enough, we found it on shaded northerly aspects around treeline and it was still reactive 4 days after the storm as we were able to trigger 2 small avalanches (Videos: small avalanche and hang fire). CNFAIC Staffwise, we did not hear of any CNFAIC Staff avalanche activity yesterday.
Today, it looks as though we have a few inches of snow and moderate wind on tap. A possible 3-6 inches is forecast and will fall on a fresh batch of surface hoar that has formed the past couple days (check out these great observations HERE and HERE). This fresh surface hoar layer is widespread from valley bottoms to the peaks and sitting on a mixture of soft to wind hardened snow on northerly slopes and a sun crust on southerly slopes. This layer could become our next persistent weak layer in our pack when buried…
Avalanche concerns for today:
Storm Snow: Wind Slab and Loose Snow
If snow does accumulate today and winds do begin to form fresh wind slabs these will be VERY touchy and easy to trigger as they are likely sitting on surface hoar. With the small amount of snow expected these slabs should be fairly shallow but still not something to mess with. Steering clear of any slope with recent wind loading and watching for cracking in the snow around your snowmaching or boards will be prudent. Additionally, shallow loose snow sluffs will be likely today as well with any new snow. These are likely to run far but not entrain significant snow.
Triggering a slab avalanche on buried surface hoar remains possible today. The addition of new snow, especially on slopes that become wind loaded today, could help to overload this buried weakness. Areas most likely to find this problem are northerly aspects in: Placer Valley, Twentymile and Johnson Pass.
It was anCNFAIC Staff beautiful day in the backcounty yesterday with mostly sunny skies and light winds. Temperatures climbed into the 20’s above treeline and near 30F below. Winds were between 0 and 10mph from the east.
Today, a little bit of snow and some wind is forecast. Clouds have moved in overnight and light snow has starting falling in the Eastern Turnagain Arm region. Winds have bumped up to the teens and gusting to 26mph from the east early this morning. It looks like 3-6 inches of snow could accumulate through the day as temperatures hover in the 20’s at lower elevations and the teens on the ridgelines. Winds are forecast to blow from the east/southeast around 20mph with gusts to 30mph.
CNFAIC Weather Page and the NWS forecast
Chris will issue the next advisory Tuesday 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.