Tahoe Backcountry Snow

0400 temp. at 6350′ in Carnelian Bay: 29.1 deg / 12.9 deg dew point / 49% RH

0515 temp. at 8650′ Mt. Rose backcountry TH: 22 deg.

Backcountry obs.:

Dry and stable conditions continued this morning in the Rose backcountry. And it’s not just dry, but anomalously so! This morning at 3:30am, the sensor atop Slide Mountain registered a dew point of -39 deg F. That comes out to a relative humidity of just 4%! Aside from cracking everyone’s lips and cuticles, it’s also having an impact on the snow pack by sublimating out moisture, leading to facet formation on the surface. In layman’s terms: recycled pow.

Recycled pow continues to be widespread throughout shady, tree protected NW-NE aspects in the backcountry above 8000′, while crusts exist on any sun-exposed terrain (E-S-W aspects). Above treeline windboard, sastrugi, and bullet proof ice reign. While cold, protected aspects still host pow, solar aspects with coverage are now beginning to develop soft, mid-winter corn, if you hit it at just the right time: late morning-mid afternoon.

If you know where to look, there’s still fun snow out there despite no new snow in nearly 3 weeks.

Weather and forecast thoughts:

For the first time in weeks, new snow is actually in the forecast for the coming weekend (1/25-26). And with a generous scoop of good fortune, enough may fall to provide a refresh. Beyond the weekend, seasonal temps and dry conditions return as the dominant E. Pacific ridge of high pressure rebuilds for the coming work week (1/27-31). Mixed signals continue to appear in models for the first weekend in February and beyond.

Conditions in the backcountry for today and tomorrow will remain benign with mild afternoons into the upper 30s and low 40s under sunny skies. Lows tonight will dip back to the 20s and 30s, depending on location. High elevation peaks and ridges will stay considerably warmer than depressions as inversions return, especially Thurs. night. Fri (1/24) will be mostly sunny and mild with light winds, increasing by the afternoon heralding the arrival of the coming weekend system.

Late Fri – Sun a system moves in that could produce a few inches of snow. Models depict a modest cut off low developing over the Eastern Sierra on Saturday, then meandering out towards the coast and back inland on late Sunday. The moisture-starved system could produce a few inches of cold, dry powder over the weekend, mainly favoring areas from Tahoe southward into Mono County. The bigger story will be the cold temps and brisk NE winds. Highs in the backcountry on Sat will struggle to reach 20 deg with low 20s at best on Sun afternoon. Brisk NE winds will blow both days, chilling things even further. By the time the system slinks its way out to the east, expect 1-4″ of new snow in the Tahoe backcountry.

Models show a return of the blocking E Pacific ridge next week, bringing another helping of dry, calm conditions and seasonably cool temps. Hopefully the dry airmass preserves whatever new snow falls over the weekend. Expect daily inversions to redevelop across the mountains with ridges and peaks staying 5-10 deg warmer than valley locations each night.

Models are picking up some noise on the horizon as Jan bleeds into Feb, but confidence remains low. Until the blocking pattern in the E Pacific shifts or dissipates dramatically, chances of getting any meaningful snowfall will remain remote.

For now, it’s time to get amped at the possibility of a few inches of blower dust on crust!

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.