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PROFESSIONAL OBSERVATION FORM
 Start Date: 03.13.18 End Date: 03.13.18 Name: Savage Operation: SAC
 Drainage/Route:  Beaver Ck area (recreational trip) Observed Terrain:  7300-10200', all aspects Zone/Region:  Smoky & Boulder Mountains
WEATHER OBSERVATIONS
 HN24: HST: 12-15cm Sky: Precip: Temps:
 Ridgeline Wind: Light
 Blowing Snow: None Snow Available for Transport: Small amounts
 Comments: 3/13: warm, crusts forming on solars, becoming OVC by 1900hrs 3/14: rain to 8500', more significant rain crust below 8200', then 10cm snow 3/15: 2cm new overnight, 2-3cm during the day 3/16: winds calm the prior 2 days but increasing this morning
AVALANCHE OBSERVATIONS
 No. Location Date Size Type Trigger Aspect Elevation Comments
 1 9800' peak SW of Vienna Peak Yesterday 1 L AS N 9350 steep terrain over 45*
 many Beaver Ck Older than a week 2.5 SS N W 8800-9400 At least a dozen D2-3 slides, 2-5' thick crowns, some soft slabs and some hard slabs, failing on 2/14 during March 1-2 storm. Activity focused on W/NW aspect.
 Comments: We triggered a few smaller dry loose slides on shady aspects >40*.
SNOWPACK OBSERVATIONS
 HS: 220-260cm 9000-9500' 
 Upper Pack: above 9000': 10-15cm PP and DF, sun crust (formed 3/14 PM) on W-S-SE, generally well graded rounds with faint 3/1 interface about 70cm down
below 9000': 1-5cm PP above rain/temp crust on all aspects to 8000' with crust turning into razor crust around 8200' and stout sun crust on solars, then spring snowpack matrix of crust/melt freeze/RG on solars and 1F consolidated DF/RG on shady side
 
 Middle Pack: above 9000': 2/14 at 90-110cm from surface, didn't really investigate much below this
below 9000': 2/14 60-90cm from surface 
 Lower Pack: Not observed 
AVALANCHE PROBLEM ASSESSMENT
Avalanche Characteristics
Character/Avalanche Problem:
Dry Loose

Layer/Depth:
10-15cm

Likelihood of Triggering
Sensitivity:
Reactive

Spatial Distribution:
Specific
Terrain
  Primary Concern Comments: Had to be over about 40* on shady slopes to get it moving and sluffs were small.
 
Avalanche Characteristics
Character/Avalanche Problem:
Persistent Slab

Layer/Depth:
90-110cm

Likelihood of Triggering
Sensitivity:
Unreactive

Spatial Distribution:
Widespread
Terrain
  Problem 2 Comments: Widespread cycle on W/NW aspects around 8800-9400' during the last big storm, but we saw no signs of instability in 3 days of traveling.
STABILITY TESTS
 Stability Test Results: ECTN, 20's on 2/14 layer about 90-110cm down
SNOW STABILITY
 Snow Stability Rating for your observed area: Good Confidence: HIGH Trend:
 Comments (aspects and elevations of instability, etc): Dry loose problem was easy to manage. Persistent slab problem appeared to be dormant in this area, but would need more observations to confidently state this. Wind was a non-issue through Friday morning (today, 3/16) but was starting to blow and likely form small wind slabs this afternoon after we left.
BOTTOM LINE
 Comments: I hadn't been in this area in a long time, so we traveled fairly conservatively at the beginning of the trip. We did not see any new wind slabs or wind transported snow. We did not observe any signs of instability (recent avalanches, cracking, collapsing). By the end of day 3 (Thursday evening), we felt comfortable skiing all N-facing slopes with clean runouts. We minimized our time in steep, W/NW terrain where the previous persistent slab natural avalanche cycle was focused. Solars were dust on crust (some supportable, some breakable); we mostly avoided them due to ski quality rather than stability concerns. Increasing winds today (Friday) were probably changing the stability equation.
FILE ATTACHMENTS

20180315_BeaverCk_D1sluffAS.jpg
Sluff on N aspect near 9400', AS.

20180315_debris chunks.jpg
Debris chunks from natural hard slab avalanche that likely released around the March 1-2 storm.