Observation: Summit

Location: Colorado

Route & General Observations

Colorado to 2650′

Red Flags
Red flags are simple visual clues that are a sign of potential avalanche danger. Please record any sign of red flags below.
Observer Comments

Previously reported glide cracks and recent glide avalanches are present in the region.

Weather & Snow Characteristics
Please provide details to help us determine the weather and snowpack during the time this observation took place.

From 11 AM - 3:30 PM:
Overcast skies that obscured peaks briefly midday, with periods of light snow with no accumulation
Temps in the 20s, occasional light south to east winds above 2000'

Snow surface

Ski penetration of 3-6" below 1800' and in wind protected areas
2 - 4" above 1800' in areas where recent winds affected the surface
Areas of soft, thin wind skin that didn't affect ski quality along the route


Dug pits in two locations, to look for buried surface hoar and to evaluate facets near the Thanksgiving Crust.

Pit #1: 2250', E aspect, 30 degree slope, height of snow = 105cm.
- This pit was dug adjacent to pits dug on 12/16 and 12/30 to track how the T-Day crust/facets have changed over time. In each pit over prior weeks, the Thanksgiving crust has been well bonded to the bottom of stability test blocks, with the most pronounced faceting occurring in refrozen melt forms just under that crust. The facets were larger today than two weeks ago, 1-2mm in size, and some grains had striations which wasn't noted on 12/16 and 12/30. Stability test results over the weeks have been consistent with results observed today, which included CT 21, 26 SC, CTN x 2, ECTX, and a PST 37/100 END down 65cm in 1-2mm facets.
- Two thin lines were also visible in the top 30cm of the pit, but no buried surface hoar or fragments could be found under a scope, and these layers had no results in stability tests. See photo below for structure/results.

Pit #2: 2650', E aspect, 30 degree slope, height of snow = 120cm
- Two layers of buried surface hoar were present at this wind protected pit location, with the following test results:
- CT 21, 23 RP & ECTN 22 down 20cm in 2-4mm buried surface hoar/bsh fragments.
- CT 23, 25 RP and ECTX down 35cm in 5-10mm buried surface hoar/bsh fragments.
- The Thanksgiving Crust was thinner at this location, buried 80cm down, again with 1-2mm facets under it. Unlike pit #1, the crust/facet combo was well bonded, staying intact when columns were tipped over after a stability test. Test results on the T Day crust facets included CTN x 2, ECTX, and PST 45/100 END down 81cm in the 1-2mm facets just below the crust.

In both pits, the snow at the ground was moist, with evidence of water at the base of the snowpack in the form of ice as pictured below!

Photos & Video
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