Mammoth Crest - Cloudy day, lower elevation warming on treed slopes

Afternoon tour up from Tamarack to Mammoth Crest near Blue Crag (~11,100').  Warm, but cloudy day, occasional light gusts over ridgetops.  Clouds caused some greenhouse effect, leading to some shallow surface melt on all aspects.  At 3pm at 9,500' on due north 25° slope in an open area between trees top 4-5cm of snow was moist, but dry under that.  On similar slopes, except in denser trees, melt was much more extensive due to warmth radiating from trees, but still quite supportable on skis (ski pen ~10cm).  Ideal pinwheel snow on these lower elevation northerly treed slopes, with snowballs rolling down the slope getting to beach-ball size quickly.  The transitional state of these northerly facing slopes which have been developing surface facets over the previous days was much more pronounced than slopes with more solar aspects which have been going thru melt-freeze for quite a few days now (transitional: i.e. some stickiness, vs. larger melt-freeze grains).  Northerly facing slops above treeline had some slight surface warming today too, making areas of firm windboard more edgeable and pleasant.  Moderately sized cornices over many NE facing slopes.  No signs of instability other than the pinwheels we caused in isolated steep treed areas.  Tamarack x-country trails at 3:30pm were still quite supportable, not sticky, but a bit slow.  Mostly pleasant skiing throughout.