South Columbia

The recent storm snow is being re-distributed by winds at upper elevations.  Watch for freshly wind-loaded areas and pay attention to how the storm snow has bonded to the old crusts.

Moderate - Wind effect is extremely variable

THURSDAY: Mostly cloudy. Ridge wind light to moderate, west. Alpine temperature near -5. Freezing level 1600 m. Snow beginning late afternoon.FRIDAY: Flurries. Accumulation 10-20 cm. Ridge wind moderate to strong west. Alpine temperature near -5. Freezing level 1500 m.SATURDAY: Mix of sun and cloud. Ridge wind light, west. Alpine temperature near -4. Freezing level 1700 m.

A widespread natural avalanche cycle to size 2.5 was reported on Tuesday, all aspects at tree line and in the alpine. On Monday, backcountry skiers triggered a size 2 wind slab near the Asulkan cabin on a northeast aspect near 2050m. The slab's thickness varied from 40-60cm. See the MIN report for more details.On Sunday several natural and skier-triggered storm and wind slabs to size 2 were reported, on southeast through northeast aspects between 1900m and 2600m. Some ran on the March 18th layer, buried 25cm in that location.On Saturday we received reports of several wind slabs and storm slabs to size 2.5, mostly on northerly aspects above 2200m. Also on Saturday, a wet loose size 1.5 avalanche injured a skier in Glacier National Park on a west aspect near 2000m.

Storm snow amounts from Tuesday's storm vary widely across the region and range from about 30- 60 cm.  This new snow has fallen with moderate to strong southerly winds switching to northerly near the end of the storm. New snow amounts taper with elevation and below 1900 m, reduced accumulations have buried a supportive crust on all aspects.  At higher elevations the new snow lies on a crust on solar aspects while on northerly aspects old wind slabs and surface hoar have been buried.Deeper pockets of surface hoar (buried March 18th) have been reported between old storm snow layers on shaded aspects at higher elevations and may be found approximately 60-80 cm below the surface. Deeper persistent weak layers from January and December are generally considered dormant, but could wake up with a surface avalanche stepping down, large cornice fall, or a human trigger in a shallow or variable-depth snowpack area. These layers consist of sun crust, surface hoar and/or facets.