Observation: Avalanche Professional

Advanced Information

Weather Summary

Fluctuating temps hovering around freezing during the storm. S-4 at times, break in the storm 1/08 around 4pm with precip. starting up again overnight. On 01/09 there was about 6" of consolidating F+ hard storm snow capping 10" of low density precipitation particles.

Persistent buried SH layer (01/02?) -seems very connected in the fortune creek zone (with how much whumpfing we experienced and signs of persistent style propagating avalanches) with an overlying Storm Slab and/or Wind slab in exposed terrain.

Snowpack Observations

My partner and I spent, Monday through Thursday skiing around Iron Mountain and Campfire Girls Bowl. In our time in the valley, we logged about 30" of new snow during the first storm, falling mainly from 01/08-01/09, with about 16" (at 3800') falling overnight on the 8th. With more snow falling Thursday (S2-S3), 1/11 on our way out.

Touring on 1/8, (Iron Mountain 3800' - 5200' W- SW, obscured skies) we experienced several whumpfs while moving through less than 30 degree forested and benchy terrain. We avoided avalanche terrain.

Touring on 1/9, (Iron Mountain 3800' - 5200' W- SW forested glades, obscured sky) we noticed any convexities or unsupported slopes exceeding 30 degrees had slid naturally (~2' deep crown, with propagation consistently to the full width of the steep terrain feature). Low visibility beyond the terrain we traveled in. CTV and CTM SC 60cm down, failing on buried SH atop a weak MFcr. Consistent hand shear results on the same layer. Ski pen of 16" with 6" of firmer snow near the surface, made for difficult trail breaking and challenging flotation for skiing.

Touring 1/10, (Ingalls Pass 5700', partly sunny) visibility cleared and we had the opportunity to visualize some of the natural cycle results -- crowns semi-visible yet filled in/blown in. Of the crowns we could make out, they were mainly on unsupported slopes. Exact size and depth was difficult to assess since snow had kept falling after the main cycle released, and wind continued to move lots snow around in the aftermath. We felt okay traveling through avalanche runouts since the cliffy, unsupported slopes we would be traveling underneath already slid and there was little volume in the start zones overhead. Notable settlement in the upper storm slab (see photo). 6" ski pen most of the day, made for pretty fun skiing.

Touring 1/11, (Iron Mountain, 3800' - 5100', up to 31 degrees forested glades, SW-W aspects, obscured skies) Near freezing temperatures and the beginning of the next storm cycle. Natural avalanches could be heard releasing up valley in unknown locations. The storm slab was now supportable to skis and riding conditions in low angle terrain were fast and fun!

Avalanche Problems

Problem	Location	Distribution	Sensitivity	Size	Comments
Persistent Slab	N E S W	Unknown	Unreactive Stubborn Reactive Touchy	D1 D1.5 D2 D2.5 D3 D3.5 D4 D4.5 D5	Layer Depth/Date: 60cm +, 20230102 SH? Comments: We did not observe this layer on other aspects, but signs of old crowns from the storm across valley seem to indicate more widespread distribution.

Snow is becoming more supportable and thus, the persistent layer felt more difficult to trigger with skis, however we still experienced active avalanching on this layer with continued snowfall/load.