Good morning. This is Wendy Wagner with the Chugach National Forest Avalanche Information Center on Monday, March 5th 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 generally LOW this morning but will rise to MODERATE through the course of the day with the approach of a weak storm system. Newly developed wind slab avalanches will be possible to trigger above treeline on slopes with recent, or current, wind loading. Additionally, small to medium sized human triggered sluffs will be possible on slopes near 38 degrees and steeper. Areas without wind effect and below treeline will continue to have a LOW danger.
What a brilliant day in the backcountry yesterday. Patchy clouds and cool temperatures kept the full strength of the sun at bay in many areas until the afternoon, leaving cold settled powder in most locations. A new sun crust has formed on more southerly slopes but seems to be fairly scattered and most widespread on southwest aspects. Avalanche activity was relegated to natural wet point releases in rocky south aspects as well as plentiful human triggered dry sluffs and a few small isolated wind slabs.
Today we should see a shift in the weather as light snowfall and moderate wind is expected to move in through the day. With that we can expect an increase in avalanche potential.
Primary concern: Wind Slab
With the bounty of loose dry snow on the surface available for transport, as well as a couple additional inches of light snow today, moderate winds should not have a hard time forming soft wind slabs on leeward slopes. These are likely to be small to medium size, occurring mainly above treeline near ridgelines and be VERY touchy as they will be sitting on very loose powder. Keeping an eye out for areas where the winds are increasing, snow is being moved and deposited onto slopes, and cracking in the snow around you will be key to avoiding a freshly formed slab.
Secondary concern: Loose Snow
Dry snow sluffing should continue on steep slopes that did not form a sun crust yesterday. In addition to today’s expected 2″ of snow, the single digit temperatures overnight likely kept the older surface quite loose and sluffing in this older snow still probable.
There is a slight chance we could see sun induced moist point release avalanches on east and south aspects in the case the clouds and wind do not move into our area until later today.
Partly cloudy skies cleared to mostly sunny by the afternoon yesterday as temperatures stayed chilly (mid 20’s below treeline and the mid-teens on the ridgetops). Winds were calm to light on the peaks and ridges, gusting to 10mph, from the north and west.
Temperatures have plummeted overnight with the clear skies and we are in an inversion this morning for the first time in a month or more. Sea level temperatures are in the -5 to -10F range with 4000′ near 10F above zero. Burr.
Through the day today, the low pressure system spinning in the Bering moves in from the west and our clear skies should begin to fill in by mid-day. Snowfall is expected in the afternoon with around 2″ accumulating by this evening. Winds will shift from the north to a southerly direction this morning and are expected to increase and blow in the 15-20mph range with gusts near 30mph. AnCNFAIC Staff 3-6″ should fall tonight with snow and wind tapering off tomorrow.
CNFAIC Weather Page and the NWS forecast
Graham 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.