0615 temp. at 6350′ in Carnelian Bay: 23.4 deg. w/ 79% RH
Backcountry Obs.:
Not much changed to backcountry conditions over the long holiday weekend in the Mt. Rose area. Touring throughout the area on 1/20 revealed a cold, dry snowpack that’s becoming increasingly brittle and – tracked out -as this dry spell marches on.
While coverage above 8000′ remains solid, there is now evidence of slow retreat beginning as sun angles slowly begin climbing ever higher on the horizon. Previously obscured stumps and larger rocks now break the snow surface. On recent warm and windless days, solar aspects have also begun softening into creamy, spring-like snow for short periods. Above treeline, wind-exposed aspects host a combination of crusts, windboard, sastrugi, and generally challenging, unpleasant snow. It’s really starting to look and feel like a drought year.
Luckily, the dry spell has been fairly cool, with pulses of very cold and dry air, interspersed with short periods of average temps. This is having some interesting effects on snow in sheltered areas on N-E aspects, especially above 8500′: recycled pow. The snow is becoming increasingly unconsolidated as the cold, dry air mass sublimates moisture out, turning the surface into loose facets. Even crusts that a week ago caused annoyingly difficult combat turns, have now metamorphosed into delicate, 1/2″ thick agglomerations of cold grains that shatter into loose fragments at the slightest ski contact.
While most popular zones are skied out, the tree skiing on N-E aspects is cold, powdery fun, for now.
If/when this weak, brittle snowpack gets covered with new snow loads, expect widespread instability to become an issue in Tahoe.
Weather and forecast thoughts:
There is some hope on the horizon for a break in the seemingly impenetrable dry pattern into next weekend. The rest of the work week will be dry and mild with temps returning to slightly above normal values starting today (1/21). Highs could climb into the 40s above 8000′, especially mid to late week, under mostly clear skies. The airmass will remain dry as well, so there is hope for snow to remain cold in shady zones. Lows each night will cool quickly below freezing in basins and depressions, while inversions will develop for higher elevation peaks and ridges with temps. not falling much below freezing, if at all, especially during the warmest part of the coming week. Inversions and above freezing temps on the summit if Slide Mountain are already showing up this morning.
Models are in good agreement of a pattern change next weekend, but the specifics are still uncertain. Quite a few models show a cutoff low developing along the eastern Sierra which, along with a renewed cold airmass, could create a period of prolonged snow showers throughout the weekend. The system could produce modest amounts of accumulating, snow surface-refreshing snow.
What does look most certain is a return of colder temperatures – perhaps the coldest of the season – with highs in the backcountry in the upper teens to lower 20s Sat – Mon as a Canadian airmass overtakes the region.
The pattern shows mixed signs of trending towards a more active state later next week and into February, but confidence remains low.
Dry January has left its mark.
Tahoe Backcountry Snow 