On some test slopes and steep convexities, I was able to make F- storm slab move down hill (see photo). These all were moving on the new snow/melt freeze crust interface from our February Warming event. None of these small test slopes propagated far or behaved like large, cohesive slabs.
Observation: Hatcher Pass
Location: Japanese Trees Storm Tour
Snow! Well, we finally got some. The system came later than expected but it delivered. If people made it up to Hatcher Pass today, they likely experienced the flipped storm with more snow at lower elevations and less at higher (see “Weather” for more details). Toured up the Glades/Japanese Trees and could hardly believe my eyes; powder. Minimal red flags of instability other than small 2-3ft cracking in storm snow on this limited ob but did see soft storm slabs throughout and wind slabs forming in the afternoon. Watch out for isolated terrain features such as convexities and gullies where the consequences could be magnified by releasing small soft slabs or dry, unconsolidated storm snow.
Observer Comments
Weather
Precipitation barely started yesterday with some graupel and strong southeast winds that clocked around to the southwest by 0800 AM, the classic "Southwest Punch" where cooling temperatures bring increased precip to Hatcher.
Weather stations were showing no snow by 0500 AM, but the webcams begged to differ. The strongest snowfall rates were mid-morning, at times falling at a rate of 2" per hour. This storm seemed to come in "flipped," with about a foot and 1" SWE from 1,500-2,700' and 6-8" and .6" SWE in the upper elevations.
Winds were light gusting moderate in the trees but by 1400, consistently S/SE moderate winds were moving and spindrifting snow.
Snow surface
At the road level and up to 2,500', the trees were pretty dreamy. 10-12" of light new storm snow. At times, it behaved more cohesively, but was mostly light and unsettled. At 2,500' and above, snow was 4-8" deep with some fresh 1cm wind skin and sastrugi forming by 1500 with active wind loading. I did not observe above 2,800'.
Snowpack
Most of the new snow fell on melt feeze crusts of varying strength. In hand sheers, some graupel was observed on top of these crusts (see photo).
Soft (F-) Storm slab
1,800' E @ 1400: Close to a foot of soft and light new snow sitting on our old melt freeze crust.
Finally some powder to ski...Snow surfaces were light and fluffy. On only a few occasions below 2,500' did I scrape on melt freeze crust through the new storm snow. Ski quality felt bottomless.
Government E Glades 2,500'. Higher up, wind transport had clearly diminished storm totals. Most places were 4-8" of new snow over some graupel and breakable meltfreeze crust (see pole).
IMG_6954
Winds clocked around from southeast to southwest. Colloquially the "Southwest Punch," which brings more precip to Hatcher Pass.