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ARCHIVED - Forecasts expire after 24 hours.
Issued
Sun, March 12th, 2023 - 7:00AM
Expires
Mon, March 13th, 2023 - 7:00AM
Forecaster
Wendy Wagner
Avalanche risk The Bottom Line

The avalanche danger remains LOW at all elevations. Although triggering an avalanche will be unlikely, we still need to look for signs of unstable snow. If the sun heats up steep south facing slopes enough, small wet loose avalanches could be triggered. Additionally, watch for old wind slabs in upper elevation steep rocky terrain. Give cornices a wide berth along ridgelines and as always, stick with good travel protocol in case you get caught by surprise.

PETE’S / JOHNSON PASS / SILVERTIP: In the southern end of the forecast zone there is a weak layer 1-2′ deep that has shown signs of reactivity. The most recent was an avalanche triggered 6 days ago. This small section of terrain is where triggering a slab may still happen. More on this below in the additional concern section.

SUMMIT LAKE: This area has seen stronger NW outflow winds during the past week. Wind loaded snow has overloaded a weak snowpack and many natural large wind slab avalanches have occurred. Despite calmer winds today, triggering a small or large wind slab on exposed slopes and gullies is possible.

Special Announcements

Turnagain Pass Avalanche Awareness Day – this Saturday!
On March 18th swing by the Turnagain Pass moto lot 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 CNFAIC 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!

Sun, March 12th, 2023
Alpine
Above 2,500'
1 - Low
Avalanche risk
Treeline
1,000'-2,500'
1 - Low
Avalanche risk
Below Treeline
Below 1,000'
1 - Low
Avalanche risk
0 - No Rating
1 - Low
2 - Moderate
3 - Considerable
4 - High
5 - Extreme
Avalanche risk Avalanche risk Avalanche risk Avalanche risk Avalanche risk
Travel Advice Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern. Dangerous avalanche conditions. Dangerous avalanche conditions. Very dangerous avalanche conditions. Travel in avalanche terrain not recommended. Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain.
Likelihood of Avalanches Natural and human-triggered avalanches unlikely. Natural avalanches unlikely; human-triggered avalanches possible. Natural avalanches possible; human-triggered avalanches likely. Natural avalanches likely; human-triggered avalanches very likely. Natural and human-triggered avalanches certain.
Avalanche Size and Distribution Small avalanches in isolated areas or extreme terrain. Small avalanches in specific areas; or large avalanches in isolated areas. Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas. Large avalanches in many areas; or very large avalanches in specific areas. Very large avalanches in many areas.
Recent Avalanches

Over the past week of sunshine and warm weather there have been widespread wet loose avalanches releasing on southerly facing slopes and a couple small glide avalanches. However, with the cooler temperatures the past couple days, these have been much less common. We know of no confirmed avalanches yesterday.

Avalanche Problem 1
  • Normal Caution
    Normal Caution
Normal Caution
Normal Caution means triggering an avalanche is unlikely but not impossible.
More info at Avalanche.org

Another quiet weather day will keep the avalanche danger LOW. Snow surfaces are a mix of sun crusts, old wind crusts, a lot of tracks from the past couple weeks, and some keen folks are finding nice soft surface snow on shady aspects and in the lower angle trees. If you are headed out for a short day or a longer adventure to a new area, be sure to keep up with good habits. These are watching for any red flags (cracking in the snow around us, collapsing/whumpfing in the snow under us) and safe travel protocol (exposing one person at a time, having escape routes planned, watching our partners and posting up in safe zones). The winter mountains always harbor surprises somewhere. Although triggering an avalanche is unlikely, below are some things to keep in mind.

Wet Loose Avalanches:  Daylight savings time started today. This means solar noon is just after 2pm (when the sun is at its highest) and the warmest part of the day tends to be 3-5pm. Hence, if we are looking for the sun crusts to warm and soften, no need to get up early. And, if they soften too much, we could start triggering small wet sluffs. Typically the top 4-5+ inches needs to soften to start triggering these.

Lingering Wind Slabs:  In the upper elevation steep and rocky terrain, there can always be some small pockets of old wind slabs that may still be able to release. This is most likely in areas where a slab(s) is hanging onto steep features and not necessarily supported from anything under it.

Cornices:  As always, give these a wide berth. They can pull back much further than expected.

Glide Avalanches:  A couple small glide cracks have released into avalanches over the past week. Although there are not many cracks where most people travel now, I’m guessing we’ll start seeing more and more open up as the spring progresses. Be sure to limit time under these as they can release at anytime.

 

Sunburst’s much loved SW face with a lot of tracks over the past 12 days of sunny March weather. Photo taken yesterday by Megan Guinn, 3.11.23.

 

Unless the sun heats up southerly slopes enough to soften the crusts, shadier aspects harbor the best snow conditions. This is looking up at Pastoral Peak from Taylor Pass. This photo also taken by CNF Avy Center Intern Megan Guinn yesterday, 3,11.23.

Additional Concern
  • Persistent Slabs
    Persistent Slabs
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
More info at Avalanche.org

As mentioned in the Bottom Line, there is a thin layer of faceted snow buried 1-2′ deep that is still a concern in a very small section of the forecast zone and could extend further to the south. On Monday, 6 days ago, a skier triggered a wide avalanche a little over a foot deep above Johnson Pass in the Bench Pk area. This avalanche released after several skiers had already descended the slope. This is a common sign of a lingering persistent weak layer that may be stubborn to trigger but could still produce an avalanche. The snowpack near the Pete’s ridges to Johnson Pass and toward Summit Lake is different than the rest of the forecast area. The potential for human triggered avalanches big enough to catch and injure us is still low, but not out of the question in this area. We recommend careful evaluation of the snowpack and more conservative terrain selection.

Weather
Sun, March 12th, 2023

Yesterday:  Another brilliant sunny day was over the region yesterday. Ridgetop winds were north to west in the 5-10mph. Temperatures were in the 20’sF in the Alpine and warmed to the 30’s at the lower elevations.

Today:  Some high clouds will be filtering in today from the northwest. Ridgetop winds are again forecast to be light, 5-10mph from the NW. Temperatures are in the single digits in valley bottoms and may not warm quite as much with the clouds, yet should still be in the 20’sF at most locations by this afternoon.

Tomorrow:  Partly cloudy skies with some valley fog is expected tomorrow and into Tuesday. Ridgetop winds look to bump into the 10-15mph range from the NW tomorrow and turn easterly on Tuesday. Temps look to remain in the 20’sF. A chance for a few snow flurries could come on Tuesday into Wednesday. Stay tuned.

PRECIPITATION 24-hour data (6am – 6am)

Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 24 0 0 64
Summit Lake (1400′) 17 0 0 37
Alyeska Mid (1700′) 25 0 0 65
Bear Valley – Portage (132′) 17 0 0

RIDGETOP 24-hour data (6am – 6am)

Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 21 variable 4 11
Seattle Ridge (2400′) 23 variable 1 4
Observations
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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.