The mountains around Turnagain Pass, Portage Valley and Girdwood Valley got a healthy dose of new snow during the past 48 hours. We have seen between 10 and 20 inches of new medium density snow at the high elevations and around 6-10 inches of wet snow below treeline. There was little visibility yesterday but we did see one wind slab and initiate a few wet sluffs in steep terrain. See video below.
The main concern for today, and heading into Monday and Tuesday, will be how this new snow sheds off the slopes with our spring-time weather. As the sun comes out and warms the surfaces, especially at the upper elevations, watch for wet slabs and potentially large point releases to initiate. Expect wet slab depths to be in the 10-20″ range and point releases to entrain all the new snow. These types of avalanches can be very unmanageable due to the heaviness and momentum of the debris.
Cornices formed during the storm are suspect for breaking off in the next couple days. Not only are they a concern alone, but they will have the potential to trigger wind slabs or wet avalanches below.
The strong Easterly winds that have been relentless for two days now will slowly begin to decrease through today. Ridgetops are expected to average in the 25-35mph range which will be enough to continue loading slopes. Yesterday, wind was making it well into the trees and forming slabs above 2,000ft; below 2,000ft the snow was too wet for the wind to transport. We saw one natural cornice fall that triggered a wind slab off the CFR ridge on Tincan (~2,500ft elev. SW aspect) – nothing too surprising with 10″ of new snow at that point and strong wind.
For today, wind slabs and drifts will be found at the upper elevations. These are likely to be fairly stubborn to trigger due to the higher density ‘stickiness’ of the new snow. However, they are 1-2ft thick (possibly thicker), dense and would be hard to get out of if released. Letting the new snow settle out a day isn’t a bad idea if you are headed to large or committing terrain. Keep in mind that these wind slabs can re-activate during the first day to two of intense sun and warming – possibly today, Monday or Tuesday.
A look at yesterday’s conditions during the height of the storm:
A wet, warm and windy storm continued to impact the mountains yesterday. Skies were obscured and rain fell below 1200ft with wet snow above, becoming drier with elevation. Winds were out of the East averaging 30-40mph with gusts to 71 at the Sunburst weather station. Temperatures have held steady in the mid to upper 20’s F on the ridgetops and upper 30’s F at 1,000ft.
Mid elevation snow totals:
Last 24 hours Storm Total (beginning Friday morning)
Center Ridge SNOTEL (1880ft) 4″ (.7″ water) 12″ (1.5″ water)
Alyeska Mid (1700ft) 1″(0.2 water) 7″ (.9″ water)
Summit Lake (1400ft) 2″(.3″ water) 2″ (.3″ water)
Today, Sunday, this system will slowly move out and cloud cover should break a bit. There is still .1-.2″ of rain expected below 2,000′ with 1-2″ of snow above treeline. Ridgetop winds are forecast to remain from East in the 25-35mph range and temperatures warm to 45F at 1,000′ and up to the 30’s F on the ridgelines.
For Monday and Tuesday we should see a return to partly cloudy skies and warm spring-time temperatures.
|04/19/21||Turnagain||Avalanche: Triangle, Seattle creek||Will Morrison|
|04/18/21||Turnagain||Avalanche: Turnagain Pass Road Obs||Andy Moderow|
|04/18/21||Turnagain||Observation: Seattle Ridge, approximately 300 yards south of the up track||Brent Byrne|
|04/17/21||Turnagain||Avalanche: Road obs||Johnston-Bloom / Moderow Forecaster|
|04/16/21||Turnagain||Avalanche: Seattle Ridge||Wendy Wagner Forecaster|
|04/16/21||Turnagain||Avalanche: Turnagain Pass, non-motorized side seen from Seattle Ridge||CNFAIC Staff Forecaster|
|04/16/21||Turnagain||Observation: Sunburst||Lance breeding|
|04/15/21||Turnagain||Observation: Tincan||Schauer/ Rothman Forecaster|
|04/13/21||Turnagain||Observation: Turnagain Pass Road Obs||A Schauer Forecaster|
|04/12/21||Turnagain||Observation: Tincan||Johnston-Bloom / Latosuo Forecaster|
|Area||Status||Weather & Riding Conditions|