This past week has seen an extreme range in temperatures and winds. A week ago, daytime temperatures struggled to reach 15 F in the Mammoth Basin, followed by two days of sustained high winds; there was an 8 hour period on Mammoth Mountain when the wind blew 80 mph with gusts over 140 mph. The exposed terrain on the San Joaquin Ridge took on the appearance of an inclined agricultural field with alternating furrows of snow and pumice. A week later, the high pressure ridge is still in place but there are no “inside slider” storms slipping over the ridge to bring meager snowfall or strong north east winds
During the wind event last week, a few inches of new snow fell on sheltered slopes in the trees in the Mammoth Basin. Near surface facets were widespread but no surface hoar was observed. Two December crust layers are the features of interest in a shallow faceted snowpack on north facing slopes in the Mammoth Basin above 9,000 ft. An extended period of dry weather generally promotes faceting if temperatures are close to the mean for early winter but the rapid and extreme changes in the weather this winter means the snow structure could change in unexpected ways.