Observation: Mill B North

Observation Date
2/10/2019
Observer Name
Bombard
Region
Salt Lake
Location Name or Route
Mill D North Fork
Red Flags
Red Flags
Wind Loading
Cracking
Collapsing
Avalanche Problem #1
Problem
Wind Drifted Snow
Trend
Increasing Danger
Problem #1 Comments
Cornices on ridge line to Peak 9269 above Short Swing, Little Water Ridge, and on the short eastern ridge of the Cone. Underlying wind drifts unresponsive to cornice drops on Peak 9269 ridge and the Cone. Responsive in steeper terrain? This skier stayed far back of the toothy cornices overhanging Fire Water. Didn't get close enough to see fallout from last week's cornice-triggered avalanche-to-ground. (See Hardesty/Staples report.) The dragon could blow fire at the least provocation.
 
Moderate to strong southerly winds with moderate snow transfer on every ridge line this skier visited today. Winds whipping cotton-snow-candy off Reynolds all AM ((bad) pic below).
 
Found three to four inches of wind slab below and above ridge overlooking Short Swing, with short cracking even on low angles (pic below). Responsive on steeper terrain?
 
Sustrugi and windboard on highly exposed southerly aspects.
 
This problem is getting progressively worse with every new storm. No end in sight. Natural- and human-triggered avalanches likely.  Not taking any chances.
Avalanche Problem #2
Problem
Persistent Weak Layer
Trend
Increasing Danger
Problem #2 Comments
Found basal facets almost a meter and a half below snow surface at 9400' on NW aspect low-angle slope. That's a pretty thick slab on top. Reckon this is what's been giving way to-ground on avalanches in non-repeater spots, but suspect it's mostly unreactive under run-of-the-mill skier pressure. Steering clear of the steep stuff.
 
My real concern would be last night's drop of dry powder (5% of six fresh inches) beneath tonight's thick dump of denser snow (4-8.5% forecasted). Guessing we'll have a new persistent weak layer after tomorrow.
Comments
Six inches fresh snow dropped Saturday night.
 
Cornices, cornices, cornices.
 
Photos: 1) Cotton-snow-candy machine on Reynolds; 2) cornices above Short Swing, 3) and after they were dropped; 4) short cracksing on 3- to 4-inch wind slabs on low-angle slope to Peak 9269; 5) the Cone's cornices; and 6) snarling, toothy cornices on Little Water Ridge above Fire Water.
Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
High

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