Quick report
- Red Flags
- Poor Snowpack Structure
Snowpack
- Instability Comment
- <p> Objective</p> <p>I intended to ski the northerly, shaded, wind protected lower flanks of Patsy Trees. Ascended via Patsys Ridgeline.</p> <p> </p> <p>Result</p> <p>Fun riding, woohoo!!. Some call today's conditions "Recycled Pow", others "Loud Pow". The fancy call it "diurunal recrystllization" </p> <p> </p> <p> Time for lap two!!</p> <p> </p> <p>Skinning back up the ridge? Felt like walking on a bed of smooth marbles.</p> <p> </p> <p>The extent of the faceting - In excess of at least 1ft (30cm) at times</p> <p> </p> <p> I found very weak, faceted/rounded/rotted snow in two places:</p> <p>- between the thick trees.. falling through to the dirt a few times :( </p> <p>- areas that were once windslabs</p> <p> </p> <p>For the upcoming storm...</p> <p>exercise some caution on what you may consider to be a "Terrain Anchor" as the snow is rotted to the dirt in some areas </p> <p> </p> <p>For you fancy people.. </p> <p>the fancy refer to the "loud pow" phenmonen on it as "diurnal recrystallization" </p> <p>you can get the deets from the 1998 paper <a href="https://www.tandfonline.com/doi/pdf/10.1080/00040851.1998.12002892?needAccess=true">"Near-Surface Faceted Crystals Formed by Diurnal Recrystallization: A Case Study of Weak Layer" (Karl Birkeland, et. al, Gallatin National Forest)</a></p> <p> </p> <p>What is all this "faceting" and "recystallizing" crap? </p> <p>The snow loses it's characteristics (structure, feeling, texture) in a similar fashion that your warm thanksgiving meal loses its texture (and therefore, it's deliciousness) when exposed to differing temperature gradients: from initial preparation, waiting around on the dining table, cut up for serving, then a cycle of refrigeration and reheating for leftovers.</p> <p> </p> <p>Think of "gradient" as "temperature per distance travelled" </p> <p> </p> <p>Like the flow of water, air follows the path of least resistance.</p> <p> </p> <p> "Diurnal" referring to the "daytime" It's a bidirectional temperature gradient. Two directions of changing temperatures. Positive during the day, negative at night.</p> <p> </p> <p>Positive Gradient (Heating)</p> <p> Ambient "heat" from the sun (aka Shortwave Radiation) seeps into the snow surface. The sun's rays contain a lot of energy.</p> <p>Starting from the surface, temperature of the snowpack increases.. The deeper it goes, the less heat there is to work with so there's a limit to just how deep the sun can heat it. </p> <p> </p> <p>Positive gradient during the day , reference to an increase of temperature with an increase of depth</p> <p> </p> <p>Negative Gradient (Cooling)</p> <p> </p> <p>The sun goes away! Where does all the energy from the sun's rays go? </p> <p>It's emitted from the Earth's surface (rises from the snowpack) as the surrounding air cools.. </p> <p> </p> <p>Negative gradient at night, refers to a decrease in temperature with an increase in depth. </p> <p> </p> <p>Max recorded "high" temps at alta @ 45F, Max recorded "low" temp at alta @ 26F. Temps hovering around 32F with +/- 4 in variance. With the Hottest "high" @ 45F being reported Nov 17</p> <p></p> <p> </p> <p> </p> <p> </p> <p>Repeat for two weeks!</p> <p> </p> <p> </p>