Turnagain Pass Avalanche Forecast
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There is a MODERATE avalanche danger today as we usher in the first winter storm since New Year’s day. 6-8″ inches of new snow overnight has added .4” of water weight over what was a very weak surface. Storm slabs and fast moving loose snow sluffs will have the potential to be problematic and will gain volume and momentum once initiated, particularly in steep and channeled terrain. Ice climbers take note as these may initiate naturally far above a climb.
SUMMIT LAKE: This region is just out of our advisory area to the south. The snowpack is shallow, composed of several weak layers, and experienced more wind effect and wind slab development. Extra caution is advised for triggering a slab avalanche.
A skier triggered about a 12″ deep wind slab over facets on the far south end of Turnagain Pass yesterday. Overall snowpack was quite shallow and likely more similar to the Summit Lake region.
Signal Word | Size (D scale) | Simple Descriptor |
Small | 1 | Unlikely to bury a person |
Large | 2 | Can bury a person |
Very Large | 3 | Can destroy a house |
Historic | 4 & 5 | Can destroy part or all of a village |
Finally some reprieve today in the form of new snow after a cold, dry start to 2020. A surface low moved into the region late yesterday afternoon providing patient powder-seekers 6-8″ of low density snow overnight and moderately warmer temperatures. New snow fell mostly on a weak, faceted surface and has not had a chance to bond. We may see storm slabs forming today given (relatively) warmer temperatures and moderate wind in the alpine. Any winds today will build fresh, shallow wind slabs given this low density snow and underlying loose facets. A small slab initiated today may gain mass quickly and could entrain a significant amount of loose snow in steep, channeled terrain with potential to run to the valley floor. Ice climbers in Portage Valley and elsewhere need to be particularly cognizant of this avalanche problem today and into the near future.
Close up of weak, faceted surface snow found on Sunburst, 1/18. New snow today will not easily bond to yesterday’s (faceted) surface. photo: Heather Thamm
Loose snow sluffs: Our storm snow last night and today is likely to exacerbate the loose snow sluffing problem by adding volume to an already impressive layer of loose faceted snow near the surface. This will prove most dangerous in steep, channeled terrain as observers have reported sluffs running fast and far. A sluff today may gain enough volume to be problematic for a skier above a terrain trap.
For your reading pleasure, here’s an interesting article on sluff managment techniques from the late 90’s written by some of the Valdez heli ski scene pioneers.
Signal Word | Size (D scale) | Simple Descriptor |
Small | 1 | Unlikely to bury a person |
Large | 2 | Can bury a person |
Very Large | 3 | Can destroy a house |
Historic | 4 & 5 | Can destroy part or all of a village |
Very weak surface snow from the January cold and clear spell and a crust/ facet combo from NYE have persistent slabs still on our radar. An observer yesterday triggered a wind slab over facets in the alpine on the far south end of Turnagain Pass. The water weight of this most recent storm is unlikely to tip the balance for a natural avalanche cycle but it isn’t out of the question to see human-triggered avalanches on an older persistent weak layer today given the .4” of water we’ve just added to our generally weak snowpack.
Yesterday: Mostly clear skies in the morning gave way to diminishing light and obscured peaks by about 4pm. Light snow began falling around 5:30p with winds picking up into the 20’s at some ridgetop locations around midnight last night. Temps at 1,000′ were around 0°F and warming to the mid- teens at higher elevations. We’ve picked up 6-8″ of low density snow overnight, likely more in the alpine.
Today: Another 4-6″ of snow is expected throughout the day at all elevations, tapering off this evening. Winds should stay mostly light from the southeast with temperatures topping out in the 20’s at 1,000′.
Tomorrow: As the current surface low moves out of our area tonight and tomorrow, snow will taper off as another dry air mass sets up over mainland Alaska. This will be a return to ‘cold and clear’ at least in the short term.
PRECIPITATION 24-hour data (6am – 6am)
Temp Avg (F) | Snow (in) | Water (in) | Snow Depth (in) | |
---|---|---|---|---|
Center Ridge (1880′) | 17 | 8-10 | .4 | 47 |
Summit Lake (1400′) | 7 | 1-3 | .1 | 17 |
Alyeska Mid (1700′) | 11 | 10 | .4 | 44 |
RIDGETOP 24-hour data (6am – 6am)
Temp Avg (F) | Wind Dir | Wind Avg (mph) | Wind Gust (mph) | |
---|---|---|---|---|
Sunburst (3812′) | 17 | ENE | 10 | 39 |
Seattle Ridge (2400′) | 20 | ENE | 3 | 12 |
Date | Region | Location | Observer |
---|---|---|---|
05/22/23 | Turnagain | Avalanche: Tincan | Nick D'Alessio |
05/12/23 | Turnagain | Avalanche: Tincan, Sunburst, Magnum, Cornbiscuit | Heather Thamm |
05/07/23 | Turnagain | Observation: Tincan – Bear Tracks | CNFAIC Staff |
05/05/23 | Turnagain | Observation: Seattle Ridge | AS/ WW Forecaster |
05/02/23 | Turnagain | Observation: Cornbiscuit | Schauer/ Sturgess Forecaster |
05/02/23 | Turnagain | Observation: Seward Hwy Turnagain Pass | Joel Curtis |
04/30/23 | Turnagain | Observation: Magnum | Ayla, Kit Crosby, Barton |
04/29/23 | Turnagain | Observation: Tincan | John Sykes |
04/28/23 | Turnagain | Avalanche: Taylor Pass/Pastoral | Schauer/ Creighton Forecaster |
04/28/23 | Turnagain | Avalanche: Tincan | Andy Moderow |
Status of riding areas across the Chugach NF is managed by the Glacier and Seward Ranger Districts, not avalanche center staff. Riding area information is posted as a public service to our users and updated based on snow depth and snow density to prevent resource damage at trailhead locations. Riding area questions contact: mailroom_r10_chugach@fs.fed.us
Area | Status | Weather & Riding Conditions |
---|---|---|
Glacier District |
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This is 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.