20171230 East Side Snow Talk- First Edition

Temperature forecast for the last hours of 2017...The East Side difference is clear. Brrrr!

We continue the pattern of high pressure followed by a walloping, then high pressure followed by a walloping. I like. The last walloping 12/17-20 featured 2-4" of h20 and decreasing density snow, with diminishing winds. A decent snow producer for the E Side, but not great. 8" higher density snow in Dertown...

The one ending today (12/30) appears to be more like 2-3" h20 and kinda sloppy with flip flopping temps. The reason for this was;

1- The upper airmass temperature came in mild then slowly warmed, slowly cooled, then warmed, then cooled. 

2- Cold air pooled on the E Side of the Mtns remained in place during most of the precipitation, but then was scoured out by strong Westerly flow at about the same time as the second warm up in the airmass described in 1.

The result: Not a perfect pow ski setup...depending on location of course, but a great snow producer for the E Side...about 16" for Dertown. The storms final warm up created variable upper snowpack conditions ranging from a thick wet snow layer to a thin breakable rain crust. This is likely to be found 5-15cms beneath the surface. The trend is that further south, like Blewett Pass this layer will be thick and wet... and probably supportable, once it freezes that is. Blewett is still a no go in my book due to lack of coverage. As one goes north this crust will diminish in thickness. Trinity, the remote mining village at 3,000ft picked up nearly 20" to their overall HS, now at 54"! Mazama and the NE Cascades may have been spared altogether. So has Dertown and likely other low valleys. E Side valleys and access roads have plenty of snow to recreate. Closer to the crest like E Side of Stevens Pass will probably have that breakable, shin slicing, pizza cutting crust that I'm talking about. 

Oh, and the winds ripped from the West last night. Luckily they are beginning to slow down now and should taper as the day goes on. Check out that gust of 118mph up at Mission Ridge at 1am!  

As the storm finishes up we're headed back to the high pressure/inversion. Ice climbs should be coming into shape, the snowpack will need some time to settle out fresh wind and storm slabs. The potential remains for deeper weak layers like the funky Solstice crust/NSF and 12/15 SH. Assess, then step out there my friend, step out cautiously. Happy Deep Winter and 2018!