Steamboat & Flat Tops
AvalancheAustin DiVesta · Mar 12, 2023 · Steamboat & Flat Tops
Weather
The day was warm, with overcast skies and snow flurries. Most of the day consisted of light snow showers, but towards noon heavier snowfall started to happen. Did not notice any snow blowing around with the light to moderate winds out of the west.
Snowpack
Overall, snow depths were well over 2 meters deep on all aspects around Rabbit Ears Pass. The recent storm left around 30 cm of new snow. This recent snow fell “right-side up,” with a denser layer falling on the old snow and finishing with cold, light, and fluffy snow on top. We noted that southerly-facing slopes had a small melt-freeze crust buried about 15cm from the surface. My best guess is that this formed during a brief period of sun on Saturday afternoon. We dug a pit on a west-facing slope below tree line and found a decent about of crusts from the early March warm-ups followed up. I did not find any persistent weak layers in this pit, but I found soft snow, mostly recent snow. An Extended Column Test did produce a hard propagation result (ECTP 30 down 51cm from the surface). It was right below one of these melt-freeze crusts. We did not see any other signs of unstable snow, like cracking or collapsing, but did remotely trigger an avalanche on an open northeast-facing slope. The crown was about 70cm deep. At first, glance, it seemed like it failed on a density change, but on closer inspection, it failed on a layer of buried surface hoar (2-4mm). We could not find this layer on other aspects, but it is something to keep in mind. The slope was only about 31 degrees in steepness.
Avalanche
We remotely triggered an avalanche from about 50ft above the crown of the avalanche. This avalanche broke on a relatively small terrain feature that was only about 31 degrees in steepness. At closer inspection this avalanche was triggered on a layer of buried surface hoar that was about 2-4mm in size. The crown was about 70cm deep and ran about 50-75ft wide.