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It will be possible to trigger a large persistent slab 1-4 feet deep today on all aspects at all elevations.
Small dry loose sluffs will be possible to trigger on steep slopes, on all aspects, at upper elevation in protected locations, and increasing in size throughout the day.
Cornices continue to grow and demand respect as they teeter over most upper elevation leeward aspects. Cornice fall has the potential to trigger a large slab, increasing the size and consequence of any avalanche.
***A Winter Weather Advisory is in effect until 6am Monday and could bring up to 12″ of new snow to HP . Significant new snow and/or wind could overload the persistent weak layer and increase the avalanche danger by Sunday.
This avalanche forecast is brought to you by sponsors at the Matanuska Electric Association.
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. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential. | 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. |
We hypothesize that the SE 9-28 mph winds with gusts 20-53 mph at 4500′ knocked down widespread 3-7 mm surface hoar prior to new snowfall this week.
3/1-3/2 HP received about 12-16″ of new snow and 1.3″SWE.
Several small natural wind slabs were observed up Pinnacle Valley and Archangel Valley.
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 |
You might have thought this problem just disappeared (or at least want it to), but surprise…its still lingering in some cases more than a meter deep. The persistent slab will be challenging to find and stubborn to trigger today, up to D2.5 and 1-4 feet deep. This problem exists on all aspects and at all elevations.
This avalanche problem may fail on slopes as low as 30º in steepness. Either a large load, such as a cornice failure or a snow machine, or a lighter load on a thin spot in the slab, such as a single person on foot, may be able to trigger a large avalanche.
It will be difficult to predict exactly where a person may be able to trigger one of these avalanches. This avalanche problem will let you get well out on a slab before releasing above you, making escape near impossible.
12″ of new snow early in the week 3/1-3/2 ,with some wind, was enough to stress the deep buried January facets, resulting in two sizable natural avalanches on NW and S aspects both at about 3500′. One in particular, on the Punk Spines was D2.5 in size, crown estimated at 3.5 feet deep, with debris running over 1000′. These avalanches likely occurred on 3/3.
Many observers continue to report whumphing at mid elevation specifically, but no cracking or avalanches. The last human triggered avalanche occurred on 3/4. See obs here. We are still dealing with this low probability/high consequence problem.
Use safe travel protocol to increase your safety margin. Traveling one at time, especially on wide open, broad terrain features, utilizing islands of safety, spotting each rider from a safe place, and staying out of the run-out of avalanches from above are all techniques that will increase your safety factor.
Heads up! Another 6-12″ of new snow if forecasted for HP through Monday morning, with the main brunt of the storm on Sunday. It will be possible for this additional snow to overload the persistent weak layer, increasing the avalanche danger by Sunday/Monday.
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 |
More than a foot of new snow early this week (3/1-3/2) combined with colder temperatures will make it possible to trigger a small dry loose sluff on steep slopes above 40°, at mid and upper elevation, on all aspects today, although most likely in wind protected terrain.
Sluff management skills will be key to avoiding getting sluffed somewhere you dont want to go. Skiing one at a time, using safe zones, and clear communication will be aids in mitigating this hazard.
4″ of new snow since 6am with 6-12″ of new snow is forecasted today through Monday morning and could increase the avalanche danger and size for dry loose sluffs. Watch your sluff!
Cornices continue to grow with the ample snow and wind HP has received over the past several weeks. Cornices are teetering over leeward aspects, most notable in Rae Wallace where entry onto slopes can be challenging. We recommend limiting exposure under corniced terrain and giving cornices a wide wide berth at the top. Cornice fall has the potential to trigger the larger persistent slab, increasing the size and consequence of any avalanche.
NWS Rec Forecast here.
NWS point forecast here.
State Parks Snow Report and Motorized Access information here.
A Winter Weather Advisory is in effect from 6am Sat until 6am Monday morning
5-12″ of new snow are expected through Monday morning.