Spring is in full swing with the snowpack mostly consolidated and characterized by Melt-Freeze crusts separated by rounds or decomposing grains closer to the snow surface with a few minor exceptions in the upper elevations where some dry cold snow conditions linger, primarily on Northwest – North – Northeast aspects. Springtime’s warm days and cool nights will continue into mid-week. As a result, avalanche concerns are centered on Loose Wet avalanches and the occasional isolated small sensitive Wind Slabs in the upper elevations. A weak storm moved through the region last Thursday/Friday (3/30/2017 – 3/31/2017) depositing 1” - 4” of new snow throughout the forecast area accompanied by strong gusty Southwest winds, which veered to the North as the shortwave exited to the east. The strong winds associated with this system created isolated small Wind Slabs on all aspects in the mid to upper elevations. As of Sunday, the Wind Slabs have strengthened and stabilized enough that only very isolated small triggered Wind Slab activity Monday and Tuesday in the upper elevations is anticipated. The bigger concern is for Loose Wet activity on solar aspects as the snow thaws under the intense April sun. Low temperatures Sunday night were exceptionally mild (struggled to fall below 32 degrees in many locations) with highs forecasted to climb into the mid 30s to mid and upper 40s Monday (4/3/2017). With such a weak freeze, expect the snow surface to thaw fairly quickly Monday on solar aspects, especially the mid to lower elevations. Monday night, temperatures are forecasted to fall into the teens and 20’s, which will help setup the snow for a hard freeze and slow the daily thaw Tuesday, which will help maintain better riding conditions later into the day. Localized thawing around cliffs, trees, rock features and faces can elevate the hazard of loose wet avalanches.
Lower elevations – the snowpack is disappearing quickly below ~7500 feet and is quickly being confined to sheltered northerly aspects, shaded slopes, terrain features that promote crossloading, or where earlier avalanches spilled into low elevation terrain. The spring storms have deposited limited amounts of snow down low, which quickly melts as skies clear and temperatures rebound. The snowpack fluctuates between weak Melt-Freeze crust at the surface in the AM to fully isothermal by the afternoon.
Caution – Spring Hazards: Avoid riding slopes under cornices (they can fail unexpectedly) and give cornices a wide berth while traveling along ridgelines (can fail much further back than expected). Spring snow can be very firm prior to softening and a slip or fall can result in a slide-for life, even on relatively benign slopes. Evaluate snow, terrain, and runouts carefully. Crampons, ice axe, or whippets maybe required for safe travel, especially prior to the snow softening. Creeks continue to open up with snow bridges beginning to sag and fail.
