Problem #1: Storm Snow
Location: all aspects and elevations, but especially W-NW-N-NE aspects.
On Wednesday night we received 0.50 - 1.00" of water-equivalent. This is on top of a similar amount that fell 4 days ago. The new storm snow is expected to be heavy, moist, slabby, and wind-affected. It sits over a layer of old facets 30-60cm deep, under Sunday's snowfall. In any wind-affected terrain, expect the new snow to be forming tender soft slabs 30+cm thick. Human-triggered avalanches are likely today on slopes 30-degrees and steeper. Natural avalanches are likely in wind loaded or cross-loaded terrain. Avoid all avalanche terrrain today.
Be mindful of any terrain traps where even small slides can pile up deep.
Problem #2: Persistent Slab
Beneath the new/recent snow, we have two different persistent-slab dangers to watch out for: 1) old facet layers, and 2) buried surface hoar.
1) For the old-facets problem: Location: All aspects, at elevations above treeline where the snowpack is thin/windswept.
One concern is in areas of thin snowpack, where old facets (1-2mm) lurk underneath the wind slabs that sit 30-60cm deep. Our heavy load of new snow may activate these dormant layers. Pole probing can help you map out which slopes contain hard-over-soft layering, a sign of this persistent slab danger. Remote triggering is possible, so keep track of your group and manage your exposure carefully.
2) For Buried Surface Hoar: Location: ALL elevations, clearings in the trees, and specific slopes above treeline (mainly slopes sheltered from NW winds) where surface hoar formed over the last 3-4 weeks and wasn't blown away by NW winds.
There are areas of buried surface hoar lingering at one and three layers down (roughly 50-80cm deep). These dangerous weak layers will persist for several weeks until they can be crushed and flushed out by lots of heavy snowfall. Be sure to dig around in wind sheltered areas to look for "the thin grey line" and clean shears. Assume this weak layer to be present in wind-sheltered areas. Use extra caution in openings around treeline, and avoid wind-sheltered rollovers in the alpine.
Sadly, there was an avalanche involvement at Mumford's (Lutak Zone), Wednesday 3/13 with one fatality. Details are still coming in and HAC staff will be visiting the site Thursday if possible.
5-16" of new snow fell Saturday night - Sunday. Southeast winds were strong, and temperatures warmed up during the storm, raising snow levels to about 1500ft. Another storm hit Wednesday night, bringing 6-12" of new snow above 1000ft. Light to moderate precipitation should continue off and on through the weekend, with snow levels staying around 1000-1500 ft.
Snow Depth [in]
Last 24-hr Snow/SWE [in]
Last 5-days Snow/SWE [in]
Today's Freezing Level [ft]
Next 24-hr Snow/SWE
12" / 1.00
24" / 2.00
2" / 0.20 *
11" / 0.80
18" / 1.40
3" / 0.30 *
3+" / 0.15
8" / 0.60
( *star means meteorological estimate )
If you get out riding, please send in an observation!
Do a rescue practice with your partners. Always carry a beacon, shovel, and probe, and KNOW HOW TO USE THEM.
Practice good risk management, which means only expose one person at a time to slopes 30 degrees and steeper, make group communication and unanimous decision making a priority, and choose your terrain wisely: eliminating unnecessary exposure and planning out your safe zones and escape routes.
Details about Wednesday's avalanche fatality will be updated on our accidents page: https://alaskasnow.org/haines-hac/haines-accidents/
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