Turnagain Pass

No new avalanches were reported or seen yesterday. Continued cloud cover is hampering a good look onto the slopes. However, there’s a chance with all the winds in the high elevations and rain in the lower elevations, some type of avalanche activity is occurring out there. Especially in the Portage Valley zone where the heaviest precipitation is happening.

Portage Valley looking up the Byron Glacier drainage with Portage Lake on the far left. There is a popular summer trail called the Byron Glacier Trail that goes up this valley near an ice cave. The cave is formed from the creek running under avalanche debris that has accumulated for years and does not completely melt out during the summer. This area can be very dangerous due to avalanches releasing above sending debris into the drainage, especially during hot spring afternoons. Thanks to Dan Keeler for snapping this photo during a period of ‘lighter’ rain yesterday. 3.25.2024.

One more day of warm, a little wet, and windy weather. However today should be a bit lighter than the past two days in terms of winds as well as precipitation. There even could be a sliver of sun poke through this afternoon. Over the past 24-hours we’ve seen between 0.1″ of precipitation at Turnagain and 1.75″ in Portage Valley, Girdwood around 0.5″. Here are a few precipitation number from the past couple days:

48-hour precipitation numbers:
Girdwood Valley:  0.5 to 1.2″ of rain up to 1200′, 5-12″ of wet snow above 1500′
Portage Valley:  3″ or so of rain up to 1500′ and 30″ of snow in the Alpine
Turnagain Pass:  0.2 to 0.4″ of rain to 1200′, 2-4″ of snow above this
Summit lake:  Only around 0.1″ of rain to 1200′, an inch of wet snow above

Dry Snow Avalanches – Above 2,000′:  Ridgetop winds have slowed down since the past two days and are currently blowing from the east in the 10-15 mph range and gusting in the 20s mph. A variety of wind slabs have likely formed over the past few days and how big and sensitive they are will depend on location. There has been a couple of feet or more in Placer Valley and a foot or so in Girdwood but only a few inches at Turnagain. Hence the largest slabs will be in the Portage/Placer zones and the smaller ones at Turnagain Pass. As always, keep a close eye out for signs of wind loading, cracking in the snow around you, and any collapsing (whumpfing) in the snowpack. A group found cracking in wind slabs on Tincan yesterday.

Wet Snow Avalanches – Below 2,000′:  Light rain is expected to fall up to 1,000′ or a bit higher through today. At these lower elevations in general we can expect mostly wet snow with possibly some crusts on top where any kind of refreeze was able to happen. Below 1,500′ reports are the snowpack has lost most of its cohesion; meaning the surface and mid-pack crusts have melted and the whole snowpack is becoming one thick layer of wet saturated snow. At this point larger wet avalanches are prime to occur because the pack has essentially lost its strength. We have not seen these large wet avalanches yet, but we are looking for them. It’s good to remember both natural and human triggered wet avalanches are possible on steep slopes with wet snow. These can be more dangerous if they are on bigger slopes where they can gain momentum and entrain more wet snow as they move downhill.

Sunburst webcam yesterday at 4:30pm. Cloudy skies and low visibility! 

Sunburst webcam again at 3:00am this morning. A few snow flurries adding up to what looks to be an inch or so from overnight. 

We are still concerned with a weak layer of facets and surface hoar that was buried just over two weeks ago. The layers seem to be found in most places at Turnagain Pass around 2 feet deep, but less so in other regions. How likely it is for a person to trigger a slab 2-3 feet deep is uncertain, but this would be a big avalanche and something to be wary of. Forecasters are getting into the field today, but there has been little traffic and new information for several days. If you do head onto the steeper slopes, be sure only one person is exposed at a time, have an escape route planned, and watch your partners from safe areas outside of avalanche runout zones.