Turnagain Pass Avalanche Forecast
The avalanche danger is MODERATE above 2500′. NW winds are picking up this morning which could make natural or human triggered avalanches up to 1′ deep possible at upper elevations. We expect these to be isolated to higher elevation ridgelines and areas that are exposed to gap winds like along Turnagain Arm. On the southern end of the forecast zone near Johnson Pass the snowpack is generally weaker and triggering an avalanche on a deeper weak layer is possible. Below 2500′ the avalanche danger is LOW.
SUMMIT LAKE / LOST LAKE / SNUG HARBOR: NW winds picking up this morning will increase avalanche danger in areas with any soft snow remaining that could be transported by the wind. In areas with a thinner and weaker overall snowpack like Summit Lake, this could make deeper weak layer more active again.
Turnagain Pass Avalanche Awareness Day – Mar 18, 2023: Mark your calendars and swing by on your way to or from your backcountry ride or ski!! Test your beacon skills, chow down on hot dogs, and bring your questions for CNFAC forecasters. The Alaska Avalanche School will be there along with a chance to demo snowmachines from Alaska Mining and Diving Supply and Anchorage Yamaha and Polaris. More details HERE!
There were several fresh piles of wet loose avalanche debris observed yesterday that occurred on either Mar 7th or 8th. These were isolated to steep southerly slopes and examples of both natural and human triggered avalanches were observed. The last larger slab avalanche that we know of was skier triggered on Monday in the Johnson Pass area on the far southern end of the forecast zone (see Wednesday’s forecast for a good photo).
Two fairly large wet loose avalanches in the Crow Creek area that released naturally from the rocks and triggered small pockets of deeper slab avalanches midway down the slope. Photo 3.8.23 from Allen Dahl.
Several skier triggered wet loose avalanches that pickup up steam and left some sizable debris piles on the SW shoulder of Max’s in Girdwood. Photo 3.8.23
|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|
The temperatures dipped back below freezing last night after three days of a strong temperature inversion which created some premature spring like wet snow conditions. Today the temperatures are expected to remain below freezing throughout the day at upper elevations which should slow down the onslaught of wet loose avalanches that have been releasing both naturally and from human triggers the past few days. Wet loose avalanches could still be possible on steep south facing terrain in the afternoon but we do not expect them to be as large or widespread as they have been the last few days.
We are currently on the brink of being at low danger at all elevations, but just as the warm temperatures departed a new round of NW winds picked up overnight. Thanks to the prior round of NW winds that impacted the area last weekend the snow surface is already largely wind affected which should limit the amount of snow available for transport today. However, with weather stations already reporting gusts of 30+ mph this morning it is important to have wind slabs on our radar today at upper elevations. Natural and human triggered avalanches up to 1′ deep are possible in areas that are receiving active wind loading. This wind direction commonly has the greatest impact in areas along Turnagain Arm and on upper elevation ridgelines. To identify features with fresh wind slabs you can use small test slopes to check for shooting cracks and look for areas where the snow is visibly being transported by the wind.
Cornice fall is also possible with the combination of active wind loading and sunny skies. Be aware of any large cornices overhead and try to minimize time underneath them, especially if they are being wind loaded or baked in the sun.
Glide cracks have been opening up over the past several weeks. These things have a mind of their own and can release under any conditions, so it is important to be aware of any glide cracks overhead and try to minimize time spent underneath them.
Snow surfaces on shady aspects are already pretty wind affected, so today’s winds might not have as much loose snow to transport into fresh wind slabs. Photo 3.8.23
Areas of the forecast zone with a thinner snowpack, like near Johnson Pass, are still harboring persistent weak layers that could cause a larger avalanche. The last know avalanche on one of these layers was in the Bench Peak area and was skier triggered on Monday. We also have received reports of whumphs and seen some unstable snowpack structure from test pits on Pete’s N in the past week. This area typically gets a lot less snow than most of the forecast zone which can make persistent weak layers last longer and be more easily triggered by the weight of a skier or rider. Extra caution and careful evaluation of the snowpack is recommended if you are travelling in these areas.
Yesterday: Clear skies and unseasonably warm temperatures reaching 40-45 F at mid and upper elevations for the third day in a row as a temperature inversion has been lingering in the area. Temperatures finally dipped back below freezing around midnight on Wednesday as the inversion starts to dissipate. Winds were calm to light during the day but shifted to NW overnight and increased slightly.
Today: Temperatures have dipped down below freezing overnight and are expected to remain in the 20s F at upper elevations today. Winds out of the NW picked up overnight and should increase to 15-20 mph with gusts up to 30-40 mph today. Clear skies are expected again today with no snowfall expected over the next few days.
Tomorrow: On Friday the winds are expected to shift to the NE and wind speeds should remain in the 15-25 mph range with stronger gusts. Clear skies are expected to remain through Saturday with no new snowfall expected. Temperatures at upper elevations should be in the teens to low 20s F.
PRECIPITATION 24-hour data (6am – 6am)
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||36||0||0||65|
|Summit Lake (1400′)||30||0||0||38|
|Alyeska Mid (1700′)||35||0||0||66|
|Bear Valley – Portage (132′)||27||0||0||–|
RIDGETOP 24-hour data (6am – 6am)
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||38||NW||4||24|
|03/30/23||Turnagain||Observation: Magnum/Cornbiscuit||Schauer/ Slesser Forecaster|
|03/30/23||Turnagain||Avalanche: Wolverine, West Flank||James Howery|
|03/26/23||Turnagain||Avalanche: Sunburst avalanche investigation||Schauer/ Cullen Forecaster|
|03/26/23||Turnagain||Observation: Magnum shoulder||Matthew Howard|
|03/25/23||Turnagain||Avalanche: Seattle Ridge backside – several human triggered large avalanches||CNFAIC Staff|
|03/25/23||Turnagain||Avalanche: Seattle Ridge, 3rd Bowl, Rider Triggered Avalanches||CNFAIC Staff|
|03/25/23||Turnagain||Avalanche: Pastoral||Tony Naciuk|
|03/25/23||Turnagain||Avalanche: Eddie’s||James Howery|
|03/25/23||Turnagain||Observation: Eddies lower slopes||Anna Frick Bridget Psarianos|
|03/25/23||Turnagain||Observation: Sunny Side||Peter Wadsworth|
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: firstname.lastname@example.org
|Area||Status||Weather & Riding Conditions|
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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.