Tam McArthur Rim

One could make the argument that the terrain along the Tam McArthur rim is the best in Oregon. Located NE of Broken Top, and more or less due East of the Three Sisters, the Tam rim offers some of the most sustained steep pitches in Oregon. Given the steepness of the terrain, much of it is highly avalanche prone, and can only be skied in prime conditions. We headed out there the day after Christmas. Unfortunately for us, we did not hit prime conditions. Nonetheless, the views alone were worth the six mile approach.

Approaching from the North, the Tam rim rises abuptly from the rolling foothills below. It is geological feature that would look more at home in the Tetons than the Cascades. The approach begins at the Three Creeks Snowpark, outside of Sisters. The fastest way out to the rim is via snowmobile along the unplowed Three Creeks road. Bring your own sled, or you can arrange a dropoff from a number of guiding groups in the Bend/Sisters area. However, the approach is totally skiable, and that was the option we selected.

We left the snowpark a little before 10:00 a.m. with the plan of overnighting at the base of the rim for a night or two. A recent storm had made us hopeful that we would would find a solid layer of fresh snow on top of the rain crusts that formed the third week of December. Loaded down with a pulk, it took us around two and half hours to hike a little over five miles to Three Creeks Meadow. There we found a nice spot to camp and dropped our overnight gear. We continued with our daypacks toward the rim.

The easist approach to the rim is along the East side, right before you reach Three Creeks lake. A trailhead marker will indicate where to begin. As we ascended, we did not find the fresh new snow we were hoping for. In the protected areas, there were around four or five  inches of faceted snow sitting on top of the rain crust. On top of the facet layer was a thin layer of surface hoar. While it looked pretty, the top layer of  snow offered little buffer between our skis and the rain  crust below. The open steeps were just a rain crust.

By the time we reached the top of the rim, we had more or less ruled out skiing any of the bigger lines. Our decision was confirmed when we got a full visual of the rim. It appeared that nearly every slope along the rim had slid out during the rain storm. Much of the skiable terrain looked to be disrupted by avalanche debris.  We skied down through the trees, doing our best to enjoy the granular surface and runneled rain crust  underneath. Given the overall low snow  quality and plunging temperatures, we opted to hike out that night and enjoy some warm food and beds at David's cabin in Black Butte. Now that we know Tam is doable in a day, next time we probably won't mess around with overnight gear.

A note on the snowpack:

Since our trip to the rim, another 8 inches or so of snow has fallen. My guess is that the new snow is sitting on top of that faceted layer, and that faceted layer likely has not bonded to the rain crust beneath. The result is likely a highly unstable layer 8-10 inches deep, with the greatest instability in the protected east facing slopes. I have not had a chance to confirm this suspicion...but anyone who goes out there should be particularly careful.