Hatcher Pass

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.

3/3 D2 Large natural storm slab on S aspect of Sunnyside of Hatch 3500′ . Debris ran all the way to the gully at the bottom of the slope.

3/3? D2.5  Large natural persistent slab avalanche on NW aspect of Punk Spines across from Stairstep 3500′. The bed surface looked like the old January facet layer. Debris ran to the gully and then continued downhill towards the lower alders.

3/3? D2 Large natural persistent slab avalanche on W aspect of Punk Spines at 3100′.

Several small natural wind slabs were observed up Pinnacle Valley and Archangel Valley.

Several small D1-D1.5 Dry Loose sluffs were observed on steep slopes above 40° on all aspects at mid and upper elevation.

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.

Going, going, almost gone!

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.

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.

Large cornices loom over leeward aspects and could break further back than anticipated.