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PROFESSIONAL OBSERVATION FORM
 Start Date: 02.22.19 Name: Lundy Operation: SAC
 Drainage/Route:  Galena Summit - Verlon's Crown Profile Observed Terrain:  8400-9000' Zone/Region:  Smoky & Boulder Mountains
WEATHER OBSERVATIONS
 HN24: HST: Sky: FEW Precip: Temps:
 Ridgeline Wind: Light and Gusty
 Blowing Snow: Snow Available for Transport: Small amounts
 Comments: Variable cloud cover today with BKN thin clouds over the Sawtooth Valley earlier in the day. Most areas seemed to be FEW by late afternoon. A little snow was moving around at mid elevations forming very small slabs
AVALANCHE OBSERVATIONS
 No. Location Date Size Type Trigger Aspect Elevation Comments
 1 Horton Peak Within past week 2.5 N SW ~9600 A few hundred feet wide, ~2' deep, see photo
 Comments: Horton slide looks as though it may have run on the 2/2 crust. Ben saw this a day or two ago.
SNOWPACK OBSERVATIONS
 HS: 8700', ESE: HS = 175. Obs below from Verlon's crown profile performed at lower left crown of slide and from a pit done on the Tweener Ridge with similar aspect/elevation/slope angle to Verlons avalanche 
 Upper Pack: 70-80cm DF, RG F going to P at base of layer (snow since 2/2). This seemed to be about the average depth of the crown, max depth may have been ~1m.  
 Middle Pack: 2/2 MFcr 1cm thick, P hard. Suspect thin layer of FC on top of MFcr but honestly didn't see anything very dramatic even with a lens. Wouldn't have thought there were any FC on the crust had there not been a remotely triggered avalanche there. I dug on a slope on the Tweener ridge that was nearly identical aspect and elevation. It felt like the 1cm above the MFcr was slightly softer but it didn't look significantly faceted beneath a lens. 
 Lower Pack: n/o - but postholing up the bed surface indicated the usual basal FC/DH 
AVALANCHE PROBLEM ASSESSMENT
Avalanche Characteristics
Character/Avalanche Problem:
Deep Persistent Slab

Layer/Depth:
basal, 150-200cm

Likelihood of Triggering
Sensitivity:
Unreactive

Spatial Distribution:
Widespread
Terrain
  Primary Concern Comments: No new obs
 
Avalanche Characteristics
Character/Avalanche Problem:
Persistent Slab

Layer/Depth:
2/2, 70-90cm

Likelihood of Triggering
Sensitivity:


Spatial Distribution:
Isolated
Terrain
  Problem 2 Comments: Growing body of evidence that there is some instability on the 2/2 crust on solars, but still lacking data on reactivity. One pit dug with a similar snowpack layering to the Verlon's slide was not reactive.
 Comments: Saw some very small (less than dinner table sized), fresh wind slabs up to 15cm thick that were touchy.

Evidence pointing to an issue on the 2/2 MFcr are the Verlons ASr avalanche and naturals on Horton, near Mushroom Ridge, and in the E. Fk of the Big Wood. However there was no reactivity in the crown profile pit or in a pit on a similar aspect and elevation. Perhaps this instability was short-lived...? Need more data.
STABILITY TESTS
 Stability Test Results: ECTX on the 2/2 crust at the crown profile. Digging elsewhere on Galena with a very similar aspect, elevation, slope angle, and snowpack layering also yielded CTN, ECTX at the 2/2 I.F.
SNOW STABILITY
 Snow Stability Rating for your observed area: Confidence: Trend:
BOTTOM LINE
 Comments: Surfaces on sheltered/shady aspects don't seem particularly faceted, but solars had a thin crust with 1cm of tiny but very well developed FCsf on top. It may strengthen before a slab develops with the slow but prolonged incoming storm, but definitely something to keep an eye on.
FILE ATTACHMENTS

190222_horton_slab.jpg
Horton Peak slab on SW, 9600'