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PROFESSIONAL OBSERVATION FORM
 Start Date: 04.08.19 End Date: 04.08.19 Name: Savage Operation: SAC
 Drainage/Route:  Beaver Creek Observed Terrain:  7200-10000', mostly W-N-E except also solars below 8500' on 4/10 Zone/Region:  Smoky & Boulder Mountains
WEATHER OBSERVATIONS
 HN24: 1-2cm HST: 0-12cm Sky: OVC Precip: Temps: 20s to lower 30s on 4/10
 Ridgeline Wind: Moderate and Gusty from the NE
 Blowing Snow: M Snow Available for Transport: Small amounts
 Comments: 1.25" precip from Mon 2PM through Tuesday morning. Probably 1.5-2" storm precip. Almost all rain below about 8700', transition to snow 8700-8900', but wet surface (from some rain) beneath the new snow up to at least 9500' on all aspects. Cecent freeze overnight on 4-9/10, formed crusts. Moderate to strong, erratic NE winds on ridgelines on 4/10.
AVALANCHE OBSERVATIONS
 No. Location Date Size Type Trigger Aspect Elevation Comments
 6 Beaver Creek Within past week 2 SS N 8400-9400' Focused on NE aspects, but some on solar slopes too. 1.5-2.5 feet thick, failing on dry crust+FC formed in early March. Largest was about 500' wide, most 100-150' wide. Most activity appeared to fail where is was mostly snowing and not raining.
 many Beaver Creek Within past week 1.5 SS N 8200-9500' Many smaller slabs in the D1-1.5 range.
 Comments: Natural activity occurred Monday and Monday night. Mix of dry and wet slabs.
SNOWPACK OBSERVATIONS
 HS: 150cm at 7800' in flats. 260-350cm at 9200'.  
 Upper Pack: Free water from rain made it down >60cm at 7800', 30cm at 9200', not that deep at upper elevations. 8-12cm crust formed at surface Tuesday night from 7800-8300', and crust thinned and was less brittle as new snow depth increased above the wet surface. In alpine terrain above 9000', upper pack was dense wind blown snow and exposed crust on shady slopes today. Above 8300', most slopes still had wet snow below the crust and a "greasy" interface between the wet and dry snow.  
 Middle Pack: Mixed bag depending on elevation, but dry round grains on shady slopes above about 8700' and wet/damp melt freeze grains at lower elevations.  
 Lower Pack: Not observed except for wet snow around 7800' during rain event Monday night. 
AVALANCHE PROBLEM ASSESSMENT
Avalanche Characteristics
Character/Avalanche Problem:
Persistent Slab

Layer/Depth:
50-80cm

Likelihood of Triggering
Sensitivity:


Spatial Distribution:
Widespread
Terrain
  Primary Concern Comments: During precip event, several slides failed on crust+FC layer formed in early March. Wet slab, persistent slab, take your pick: the crowns were above where most of the rain fell. Stability markedly improved by Tuesday afternoon.
 
Avalanche Characteristics
Character/Avalanche Problem:
Wet Slab

Layer/Depth:
15-40cm

Likelihood of Triggering
Sensitivity:


Spatial Distribution:
Widespread
Terrain
  Problem 2 Comments: Rain induced wet slabs, fairly shallow. Problem ceased by Tues afternoon.
 
Avalanche Characteristics
Character/Avalanche Problem:
Wind Slab

Layer/Depth:
10-30cm

Likelihood of Triggering
Sensitivity:
Stubborn

Spatial Distribution:
Isolated
Terrain
  Problem 3 Comments: We didn't get into much upper elevation terrain. The few wind slabs we saw Tuesday were not very touchy. Wind was moving snow today and building slabs, especially above about 9500'. I would expect the new generation of wind slabs to be more sensitive than the ones that formed Monday night.
STABILITY TESTS
 Stability Test Results: Tuesday 4/9 at 9200' NE and NW: ECTP16, ECTP24, ECTNmodx2 on March 4-5 layer buried 50-70cm down. Conflicting results on PST's.
OBVIOUS SIGNS OF INSTABILITY
 Marked with checkmark if observed:
 Cracking (isolated) Depth: 10-30cm Length: less than 20 feet, shallow new wind slabs
 Collapsing (isolated) Depth: uncertain but likely 50-70cm Length: 100-200 feet
 Comments: 3 notable collapses on Tuesday afternoon (4/9) from 9200-9700', shady and solar aspects.
SNOW STABILITY
 Snow Stability Rating for your observed area: Poor Confidence: MODERATE Trend: Improving
 Comments (aspects and elevations of instability, etc): Danger/hazard peaked Monday afternoon and night. Stability improved beginning Tuesday morning. Good to very good stability today (Wednesday 4/10) where we traveled (7800-9200').
BOTTOM LINE
 Comments: Although we got 1.5-2" of rain below 8400', we didn't see that much in the way of wet loose or classic wet slab avalanche activity. The most activity occured where we think a mix of rain and dense snow or only dense snow fell (approximately 8400-9400'). Stability was steadily improving since the end of the heavier precipitation (Tuesday morning). The crusts that formed Tuesday night were supportable for skiers above about 7900' and a mixed bag for snowmobiles.