High pressure entrenched over the Southwest since 3/7/17 has brought spring-like weather to the eastern Sierra. This has rapidly transitioned the snowpack from cold winter-like snow to spring-like snow conditions on most aspects (W-SW-S-SE-E above ~ 8000 to ~11,000, below ~8000 the range expands to include NW and NE aspects) with the accompanying melt/freeze cycles, on solar aspects as the sun races toward the spring equinox (March 21). Warm temperatures Saturday softened the snow on solar aspects with the upper 30 to 45 cm of the snowpack becoming wet with small wet point releases reported up to ~9000 reported. Sunday slightly cooler daytime temperatures slowed surface thawing. The recent warm-up has taken its toll on even northerly aspects below ~ 9000’ where the snow hasn’t fully transitioned to corn snow and can become sticky and thick (aka Manky), especially in sheltered trees. Above ~11000’, due to somewhat cooler temperatures, the sun effected surface snow is more narrowly confined to SW-S-SE aspects and has only began to moisten the surface snow, some light crusting possible.
The last snowfall in the area occurred on Sunday (3/5/17) was accompanied by very strong SW to West winds through Monday forming Wind Slabs on exposed W-NW-N-NE-E-SE aspects at all elevations with the mid to upper elevations most heavily impacted. The Wind Slabs that formed during that storm event have had several days to stabilize with spring-like conditions dominating the region since 3/7/17 with above average temperatures and light winds. As temperatures climbed the avalanche focus shifted toward loose-wet point releases on solar aspects in the mid to upper elevations, all but the most northerly aspects in the lower elevations where the overnight low temperatures are near or above freezing.
With spring conditions comes a firm melt-freeze crust on solar aspects in the AM hours (possibly later) and possibly firm wind-board on more northerly aspects. These snow conditions can make an arrest difficult on steeper terrain if a fall occurs (Slide For Life). If these conditions are encountered, crampons, ice ax, or a whippet maybe required to move through steep terrain safely. Caution in complex terrain with multiple aspects due to differential thawing and freezing. Careful snow assessment is recommended, reevaluate your plan as needed, and be prepared to alter your objective as required.
