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Observation: Mary Ellen

Observation Date
3/17/2016
Observer Name
Zimmerman-Wall
Region
Provo » American Fork » Mary Ellen Gulch
Location Name or Route
American Fork/Mary Ellen Gulch
Weather
Sky
Scattered
Wind Direction
Southwest
Wind Speed
Strong
Weather Comments
Interesting wind and cloud cover today. Started off the day socked in at ridgetop with strong WSW winds and ceiling at 10k. Lots of wind transport and crossloading, which kept warming at bay on the upper elevation slopes, regardless of aspect. Below 9500 feet, the cloud deck was more scattered and some serious solar was taking aim at the East aspects starting around 10am. By 1400, nearly all clouds had moved eastward, but winds remained moderate gusitng to strong along the highest ridgelines.
Snow Characteristics
New Snow Depth
12"
New Snow Density
Medium
Snow Surface Conditions
Powder
Wind Crust
Damp
Snow Characteristics Comments
High elevation sheltered terrain offered best ski quality and most predictable surface texture. Boot top deep settled powder was the order of the day. However, as we moved around the drainages, we found a variety of wind board, damp powder, and some variations in between. New snow had bonded pretty well to the old snow surfaces, whether it was decomposing temperature crust, melt freeze boilerplate, or settled dense snow with some surface faceting.
Red Flags
Red Flags
Recent Avalanches
Heavy Snowfall
Wind Loading
Cracking
Collapsing
Rapid Warming
Red Flags Comments
Saw and heard about a lot of recent activity since the storm abated on 3/16. Wind loading was prime culprit. Sustained winds transported snow along ridges and cornices were growing before our eyes. Cracking was noticed among pillows and cross loaded wind slabs in exposed/open terrain. Warming temps out of the wind zone on solar aspects resulted in easily initiated push-a-lanches and rampant roller-balling. HST 35cm/ HS Avg in upper AF 190cm
Avalanche Problem #1
Problem
Wind Drifted Snow
Trend
Same
Problem #1 Comments
Observed some of the weirdest loading patterns we've ever seen in the upper AF canyon. MEG was channeling wind in every conceivable direction and even the top loaded slopes were also cross loaded. Cornices were sensitive to hard ski cuts and often we felt collapsing further up the ridgeline from the trigger point. Stiff wind pillows were easily spotted, but harder to provoke. That being said, we avoided pushing them around in any consequential terrain.
Avalanche Problem #2
Problem
Wet Snow
Trend
Same
Problem #2 Comments
Below 9500 feet, the solars were really picking up the heat, especially the Easts, which were out of the cloud deck from the get go. Rollerballs from rock bands and tree islands were indicative of the new snow seeing heat for the first time. We also got several small push-a-lanches to go on steep open terrain, but they were slow moving and only involved the new 10-12" of snow. Maximum 50 vertical feet.
Comments
New snow, up to 30cm in most areas. Well bonded.
Wind loading/cracking on leeward, mid elevation terrain in MEG.
Push-a-lanche on steep East facing below 9500
Strong winds along the Y-Not Buttress.
Today's Observed Danger Rating
Moderate
Tomorrows Estimated Danger Rating
Moderate