Observation: Porter Fork

Observation Date
1/3/2016
Observer Name
Greg Gagne and Tom Flaherty
Region
Salt Lake » Mill Creek Canyon » Porter Fork
Location Name or Route
Porter Fork
Weather
Sky
Broken
Wind Direction
South
Wind Speed
Light
Weather Comments
Temperature inversion in place with cold air pooling in drainage bottoms and much warmer temps at higher elevations. Southerly winds were noted on ridges above about 9500'
Snow Characteristics
Snow Surface Conditions
Dense Loose
Faceted Loose
Wind Crust
Melt-Freeze Crust
Snow Characteristics Comments

Widespread damage from New Years Days winds. Sun also beginning to take a toll on solar aspects. HS today up to 9600' in Main Porter is 75-90 cms (2.5 - 3')

Avalanche Problem #1
Problem
Persistent Weak Layer
Trend
Same
Problem #1 Comments

From what I have seen this week throughout Little and Big Cottonwood, as well as Millcreek Canyons, it is difficult to gauge how the basal facets are gaining strength. If I had to generalize, I would say that the faceted layer in the cottonwoods (where the snowpack is deeper) overall seems to be stronger. Two tours this week in Millcreek were showing inconsistent results, but I would say the facets overall seem to be weaker.

Comments

(Human error on my part - no photos or videos submitted with this observation. Might as well read it over a teletype printer.)

General observations from today's tour:

- Although the surface snow is faceted, it is not as weak as I was expecting. Was finding weak faceted snow Friday and Saturday in both LCC and BCC due to cold and clear conditions, but today in Millcreek at similar elevations and protection from the wind, the snow is not as weak. Cloud cover and warmer temps may be helping slow down the faceting near the surface.

- Was finding 5-20 cm (2-8") pencil-hard wind drifts from the New Years Day SE wind event. (If you close your eyes when saying this, it sounds like a sales special being run at some store.) As others have noted, there is a layer of weak faceted snow underneath many of these drifts. However, today we jumped on all sorts of these wind drifts and they were not sensitive at all, at most only cracking right around your skis. If you were on a steep, wind-loaded slope that did break out around you, it is likely to be a very small avalanche.

- Much of the ridgeline from Mount Raymond west had avalanched, likely during the 12/23 natural cycle. Many of these paths had filled in somewhat, and skiing one today ("Sox's" on Wasatch backcountry ski map) showed only a 15-45 cm (6-18") snowpack, with numerous rocks and stumps underneath. (Was sort of missing those early-season conditions.) Quick hand pits were showing much of this thin snowpack has faceted. Following the Christmas storm cycle, people began venturing onto steeper slopes only if they had avalanched. (This is pretty good terrain management.) Am now thinking that paths that slid before Christmas will be especially prone to avalanching once they get any new loading of snow and/or wind as the overall snow structure is weak and thin.

- Despite the wind, sun, warm temps, and numerous tracks throughout the range, there is still plenty of soft snow to be found.

From what I observed today (and the past few days although I did not submit observations), most of the terrain has a Low danger, with a Moderate risk of triggering an avalanche in upper elevation aspects that were wind loaded from SE/E winds. Deep slab remains a problem, but likelihood is very low.

Today's Observed Danger Rating
Moderate
Tomorrows Estimated Danger Rating
Moderate