STAB ASSESSMENT:
WET SLIDE (LOOSE WET) HAZARD REPORT
You have probably ended up here having either observED (initiatED) a wet slide (SKI CUT), SUFFERED HEAPS OF RAIN, RAPID LOCAL WARMING or your ECT TEST did not propAgate.
Assumptions:
You know how to locate and access terrain safely, conduct this assessment, and understand the basic terms and assessment techniques (CT / ECT - Snowform Identification) consistent with your minimum AST2 (Or equivalent) training.
Given the prevailing conditions we are looking for signs of WET SLIDE (LOOSE WET) instability. Notoriously hard to isolate, tricky to forecast. The two things that we are looking for are initiation ( a weak layer) and water saturation (what is the moisture content and how is it distributed within the snowpack). You are looking for natural slides with 'chunky' debris, pinwheels and extended periods without re-freezing and in the event of rain the runnel effect on the surface. If you get these kinds of warnings then we probably already have enough rough intel (Red Flags) about the hazard to raise a RED ALERT.
If conditions are safe enough to permit and / or 'Red flags' have been noted and responded to appropriately, in the process of running this patrol then conduct some pit tests in a suitable (<22˚ incline) aspect. Ideally at an altitude of 1700m or more, although this is not essential.
STEP 1:
Snow Profile & Compression test (CT)
Starting with a simple column test, you will go through the process of isolating any weak layers. Having established extensive moisture captured within the snowpack, looking for weak layers, particularly sheilding interfaces (usually buried crusts) helps outline the scale of the hazard. Similarly understanding capillary ( depth hoar) and percolation effects (Pooling) within the snowpack will also improve our understanding of the likelyhood of the hazard.
Resistant Buried Crusts. Often beneath robust crust layers with significant variations in temperature gradient you will find depth hoar, if a bond is formed with the wet snow and the crust, the whole lot can let loose on this depth hoar interface.
Pooling or percolation on Buried Crusts. If the crust is robust enough to prevent percolation through the crust then water can travel and pool along the buried interface which lubricates the hazard. Let's suss this out now... hope you brought some food dye or gatorade.
STEP 2:
Wet Slab / Slide Pooling Test .
Ok, this is far from an exact science, but we consider it an important part of establishing or eliminating this hazard. Over a 100m area you can get huge variation, so all we need to know is wether the moisture is pooling.
TECHNIQUE
Find a slope, any slope steep enough really, as we are looking at a coverall instability. Avoid standing within of upslope of your test area. You will need a liquid dye, in quite large quantities (2 litres?), we use organic beetroot juice as the most environmentally friendly solution. Pour grid at 30cm intervals (a sauce bottle is a good dispenser). The flow of liquid needs to be generous enough to penetrate to the depth of your crust. An art leant through trial and error. Go big so it looks like a geometric 'murder scene'. Then let it settle for 1 hour.
Once the time is up, excavate the block. Then, cut along the upslope lines to expose the transported dye within the snowpack. You will find either continuous vertical lines (percolating), or a culmination along your crust which means pooling, the hazardous outcome. Either way, take some photos and flip them to us via email: advisory@mountainsportscollective.org.
