February 13, 2008 Good morning backcountry travelers this is Matt Murphy with the Chugach National Forest Avalanche Information Center on Wednesday, February 13th at 8am. This notice will serve as a general backcountry avalanche advisory 5 days a week (Wednesday-Sunday) for the Turnagain Arm area, local variations always occur. Weather Observations In past 24 hours: The Center Ridge weather station at 1800 feet in Turnagain Pass recorded 2 inches new snow and .2 inches of water. It snowed a total of about 5 inches on Monday-Tuesday at the highway elevation and about 7 inches up near the ridges. Total snowpack depth is 84 inches (one inch more than yesterday) The temperature this morning is 26 degrees F (2 degrees colder than yesterday). Sunburst weather station at 3800 feet in Turnagain Pass is recorded strong wind this morning averaging 34-46 mph out of the NE with gusts to 69mph. Even the DOT weather station at the highway in Turnagain Pass is recording moderate winds at 17mph with strong gusts to 31mph. Mile 43 Peak at 3300 feet along the railroad tracks is reported gusts to 65mph. Ridgetop temps currently range from 18 to 21 degrees F (4-5 degrees colder than yesterday). There is a huge storm over the Aluetians right now. It is getting weaker (940mb-950mb), but it is pulling up a lot of precip from the south that you can see plastered to the Prince William Sound and Kenai Peninsula radars. 26 foot seas are forecasted on the outer coast today. Bottom Line (Primary Avalanche Concerns) The avalanche hazard has increased since yesterday due to wind. Natural avalanches will be possible and human triggered avalanches probable on steep rollovers. Plus, there are isolated pockets where human-triggered avalanches are possible on slopes greater than 35 degrees. 1. Wind slabs 2. A layer of BURIED SURFACE HOAR 2-3 feet deep is still something to think about. It’s been difficult to find this layer, but it does exist in isolated pockets on slopes and bowls protected from the predominate winds. Avalanche and Snowpack Discussion (More detailed info…) The wind has been increasing at all weather stations this morning; so, there will be windslabs out there. Yesterday, we found an eggshell crust from the highway to the ridge on Tincan. It was probably formed by supercooled water droplets from the clouds that were hanging around. Those same droplets kept freezing to the lens of my goggles. The crust was dry with a rough texture. We went hunting for those deeper layers of surface hoar on a chute on the northern aspect of Tincan. We did not find any buried surface hoar, but we did find a clear shear on a density change about 2 feet down. There is nothing too remarkable to say about that layer, because it took excessive force to get it to pop out. The 5-7 inches of new snow had not bonded completely to the old snow interface, but it held together well with ski cuts. I hope this storm hammers our snow pack to give some of those buried weak layers a good test. Make sure to manage your terrain today; since, the winds are cranking and forming wind slabs as we speak.