Spring continues to dominate the weather picture with warm daily temperatures and cool nights. A fast moving spring storm is moving through the region today (Mon) thru Tues with moderate to strong winds, cooler temperatures, increasing cloud cover (primarily Mammoth north), and light precipitation over the upper elevations, which will hinder good corn skiing until the sun returns Wed. The last storm to sweep though the region Tuesday (4/18/17) with 3” to 12” inches of new snow reported across the forecast area above ~8500’. However, snow levels fluctuated considerably during the storm with many areas receiving rain Monday before turning to snow in the early morning hours on Tuesday. Snow levels rose once again during the day, Tuesday, with rain up to ~ 9,000’ then easing back down to ~8000’ by Tuesday PM. Loose Wet avalanches were prevalent during the storm throughout the mid elevations as the surface snow becoming saturated with water and internal bonds began to dissolve. Moderate to strong SW winds during the storm formed Wind Slabs in exposed locations throughout the mid and upper elevations, primarily above ~ 9000’ on NW-NE-SE aspects with several avalanches observed. Mammoth Mountain Ski Patrol reported significant results from avalanche control work on Wednesday morning. Most of these avalanches were triggered in Wind Slabs with small hand charges and ski cutting.
Westerly winds continued thru Wednesday and Thursday with snow banners and localized drifting observed from Mammoth south to Rock Creek, forming a new round of Wind Slabs throughout the upper and mid elevations, primarily on N-E-S aspects. Since then, the Wind Slabs have had a couple of days to strengthen but moderate SW winds are forecasted for the upper elevations today (Sunday), which may form very isolated shallow Wind Slabs in the upper elevations on NW-NE-SE aspects where upwind fetches still have snow available for transport. Northwesterly aspects in the mid to upper elevations are starting to heat-up significantly for the first time this season with the dry snow becoming wet, elevating the possibility of loose wet avalanches somewhat on this aspect.