Strong southwesterly winds over the past couple of days have transported snow to leeward, NW to NE facing slopes. Though not much snow was available for transport prior to Monday, wind gusts in excess of 80-90 mph were able to pick-up hard-packed snow and scour windward facing slopes, creating sensitive wind slabs on the leeward slopes below ridgelines, cross-loaded slopes, and gullies. Wind slabs likely formed on Monday with strong winds and a foot of new snow near Leavitt Lake. With the heavy snowfall predicted tonight through Thursday, combined with wind gusts up to 80-100 mph, NW-N-NE-SE facing slopes will load rapidly and natural and human triggered avalanches will be likely.
Heavy snow is expected to begin again in the BWRA this afternoon lasting through Thursday, with total accumulations between 34-56", on top of the 12" recorded Monday at Leavitt Lake. Temperatures will rise through the duration of the storm, which will increase snowfall densities leading to an upside down snowpack, increasing the avalanche danger on all slopes. Additionally, the new snow will fall on a weak snow surface consisting of near-surface facets and surface hoar on north facing sheltered locations and a slick melt-freeze or sun crust on southerly aspects. The new snow will not bond very well to the old snow surface leading to dangerous avalanche conditions. For the next couple of days, natural avalanches will be likely and human triggered avalanches will be very likely on slopes steeper than 35 degrees, though sheltered areas with intact surface hoar and facets on the surface could produce avalanches on slopes as low as 30 degrees.
My partner was out yesterday in the BWRA and reported a foot of new snow and strong winds, creating whiteout conditions on Leavitt Lake. Snow totals dropped off dramatically further down the road. He also reported road conditions were treacherous due to ice and long sections of bare pavement below 8000'. Until we get snow down to the trailhead (which should be soon!), it will be tricky getting up to the BWRA.
Over the previous 24 hours, the Leavitt Lake SNOTEL station reported 14" of new snow/1" new SWE. A potent winter storm will impact our area beginning this afternoon through Thursday, here are the details:
New Snow: 15-25" / New SWE: 1.4-2.3" / Snow Density:9.3%
New Snow: 16-24" / New SWE: 1.7-2.5" / Snow Density:10.6%
New Snow: 3-7" / New SWE: 0.4-0.8" / Snow Density:12%
Total New Snow: 34-56" / Total New SWE: 3.5-5.5"
Temperatures will being to warm into the upper 20's/low 30's and winds will be strong out of the SW with gusts up to 100 mph in the most exposed locations. The storm will move out of our area by Thursday night with clearing skies and colder temperatures on Friday. This break in the weather will be short lived as a potentially stronger system, an atmospheric river event, will move into our area by Saturday afternoon. Right now, models are predicting this system to be warmer with snow levels up above 8000 ft and snowfall totals potentially in the range of 4-5 ft through Monday. This means the BWRA could potentially see a total of 7-9 ft of new snow over the next week! Stayed tuned for updates to this potentially epic event over the coming days.
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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