The Bridgeport Winter Recreation Area is CLOSED for the season. Thank you for all the support & we will see you next winter.
At 8770' a measurable 62cm of storm snow was gained & has an upside-down characteristic. Dense snow over loose is the scenario & it is not stable. Settlement cones & rain/wind plastered snow on trees eludes to the recent snow growing more dense. With new snow on the way & cooling temps the strom snow could act as solid unit with a decreasing shear strength. The winds have majorly effected the distribution of the storm snow or erradicated it completely in alpine locations.
Rain profusing through dry surface snow was very evident in our travels. To a depth of 3" on top of loose dry snow was a moist dense layer at 0C. This cohesive layer is peeling off the dryer density change interface in slopes steeper than 35 degrees. Pinwheels show that this layer is acting collectively. The rain weight could increase the potential for surface shearing to the density change.
Although evidence was not readily available on seen slopes, a previously documented instability in old snow could present itself with the recent heavy load. Activity in stability tests has shown an interface in the old wind effected snow to hold a facet layer. This layer can vary in depth (+40cm) & is substantially more reactive in shallow snowpacks. If a traveler was to create this failure in the snowpack the size & destruction of a avalanche could be catastrophic.
Interesting snow dynamic yesterday with the exit of a historically windy storm by Sierra standards. Significant rain on the tail end of this blizzard was apparent as the surface snow was heavy & sticky. Below 7000' rains had deteriorated a lot of the newly fallen snow & turned it into something much less desirable. @ 8770' in our Sonora snow study plot our stormboard measured 29cm, making the storm total for that location 61cm. To complicate matters the dense/wet surface snow sits on dry intact stellars, needles, rime, & broken precip particles that have very low density & high pore space ratios. Tests were propigating 17cm deep with light force within this density change, perfect for pinwheels & push-a-lanches. Furthermore below the new storm snow lies several variable wind packed layers that harbor facets. Persistent in nature the facet layer is activated in stability tests with light to moderate forces 40cm deep in the pack. Elsewhere in the Eastern Sierra front this persistent slab instability is more widespread & obvious, but the evidence of it causing avalanches is inconclusive. Mid-storm avalanches were followed by harsh winds & the spackling of rain & visual clues were lost. Our travel was limited to areas where snow tractors had smushed us a supportable surface, walking was tiresome.
Sometimes after observations & a day in the field there are many more questions, that is our reality here. Straight forward clues & invisible evidence of avalanches has our confidence low. We excersized caution with our travel & were limited visually yesterday.
|0600 temperature:||32 deg. F.|
|Max. temperature in the last 24 hours:||34 deg. F.|
|Average wind direction during the last 24 hours:||SW|
|Average wind speed during the last 24 hours:||moderate mph|
|Maximum wind gust in the last 24 hours:||strong mph|
|New snowfall in the last 24 hours:||trace inches|
|Total snow depth:||44 inches|
Cloudiness & sporatic snow showers are likely today. Later this afternoon the South winds will increase with possible gale force gusts to 90 mph tonight. Wet snow & rain mix may be seen up to 8000'. Wow, a report of 150 mph gust Sunday night, at ridgeline, blowing around the light snow would have been something to see.
This snowpack summary applies only to backcountry areas in the Bridgeport Winter Recreation Area. Click here for a map of the area. This snowpack summary describes general avalanche conditions and local variations always occur. This snowpack summary expires in 48 hours unless otherwise noted. The information in this snowpack summary is provided by the USDA Forest Service who is solely responsible for its content.
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