Confidence: High. Distribution: Widespread, especially wind loaded NW-N-NE-E aspects. Reactiveness: Touchy.
The last few days brought 20-40″ of new storm snow, and it came in upside-down. This means that the new snow is weak underneath and quite prone to failure. Avoid slopes 30 degrees and steeper, where Human triggered avalanches remain likely. This new snow needs a little more time to heal and bond.
If you venture into avalanche terrain, reduce your exposure by traveling one-at-a-time across suspect slopes, and be mindful of any terrain traps below you where all this new snow can pile up extremely deep.
Any slides in the upper snowpack are likely to step down to deeper weak layers in the midpack. See the Deep Slab problem below…
The layers seen in the image below are all now buried beneath 10-20cm of new storm snow.
Confidence: Low. Distribution: Widespread. Reactiveness: Stubborn.
Given the large amounts of new storm snow, and known weak layers in the mid pack and below, you will need every tool in your toolbox:
We currently have three buried persistent weak layers:
Persistent weak layers below wind slab closer to the surface will be reactive or touchy for human triggered avalanches. Persistent layers in the mid-pack likely are to behave stubbornly, or unreactive.
Again, remember your tool box to reduce risk and travel safely:
Image and wisdom is from IFMGA Guide Joe Stock’s Website https://www.stockalpine.com/posts/.
The layers seen in the image below are all now buried beneath 50-80cm of new storm snow.
Finally, we have Two DEEP persistent weak layers:
Deep Slabs require either a heavy trigger, like cornice falls and snowmachine drops. Or an avalanche in the upper layers of the snowpack that steps-down. You are also more likely to initiate a fracture from the thinnest part of the slope into a much thicker part. Think about how wind distributes snow to thin and fat zones.
These deepest weak layers have been unreactive, or very stubborn but do exist in the landscape. Continued load such as settlement, wind, new snow, rain, or rapid temperatures changes will increase the hazard. Any slabs that break this deep are likely to be deadly. South aspects are known to have poor structure and are getting baked by strong solar radiation when the sun comes out, which weakens the snowpack. Upper persistent slab avalanches could step down, release sympathetically, or remotely trigger deeper layers (see Persistent Slab above).
We are in the most deadly time of year in Haines. Early March has historically brought tragic accidents with large avalanches that break much wider than expected.
Last weekend was calm and very cold with strong NW winds. This week brought a heavy storm cycle with 1.5-3.5″ of new SWE (20-40″ of new snow). Snow showers will taper off Friday, leading to some clearing Saturday. The next storm comes in Sat. night – Sunday with low snow levels and light to moderate accumulations.
( *star means meteorological estimate )
—The Mt. Ripinsky weather station is completely buried and no longer reporting.—
Practice like you play. Make sure all your rescue gear it is fully functional and your beacon has full batteries. Make sure 1) everyone in the group has a functioning beacon, shovel and probe 2) knows how to use them and 3) has trained in companion rescue in the last year. Keep your skills fresh. If you head into the hills, watch out for red flag avalanche conditions, natural avalanches, whoomphing or collapsing, and shooting cracks.
Education Video Links:
Click the + Full Forecast link below for each zone to read more. BOTTOM LINE THIS WEEKEND: Hazardous conditions exist. We still have a complex snowpack, keep your safety margin wide. Heavy recent snowfall is adding stress to buried weak layers. Solar radiation weakens snow and can trigger avalanches naturally.
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