Backcountry obs.:

Touring deep on the West Shore this weekend, I found a snowpack closely reflecting the Juneuary weather of the past month.

Below treeline, N-E aspects host a combo of cold, soft snow interspersed with delicate breakable crust: delightful to defensive skiing within a few feet. Shaded valleys and creek depressions have remained well below freezing each night, pooling cold, moist air, perfect for growing delicate surface hoar that in some areas has accumulated multiple inches deep. Ski turns through this recycled pow shatter at once like fine crystal on marble, tinkling as they scatter across the snow surface. It’s a remarkable sound and feeling.

Venturing out into the sun from the cold backcountry hideaways, the snow wears heavy weeks of sun and heat. Breakable crusts atop heated mush are the main story in the trees, while open, due south facing areas hold supportable melt freeze crusts that under clear skies and light winds, have softened into smooth butter each afternoon. Buttery turns aren’t bad.

Up at the highest elevations, despite the warm temps, extremely dry air has kept snow surfaces mostly frozen. Ridges and summits host all forms of sculpted sastrugi, edgeable wind buff and occasional soft, textured, wind deposited snow. Carrying a whippet or axe is a wise idea in high consequence terrain where firm surfaces abound.

It’s a variable thrift shop of conditions out there. Add in the heavy holiday traffic and you’ll find popular zones thrashed with tracks, ruts, dinosaur tracks (snowshoes), and even some lamely poached snowmobile tracks.

As they dry days stack up and extend into the future, the calculus of skiing an ever degrading backcountry snow pack versus doing anything else fun becomes harder to pencil out.

Weather and forecast thoughts:

Looking ahead at the coming week (1/19-1/25) dry and warm weather will continue to exacerbate the growing snow drought in the Tahoe Sierra. No precip. throughout the entire week seems nearly guaranteed. Temperatures look to remain steady with only a few modest variations: edging up a few degrees by midweek, then cooling by a few degrees by the weekend.

Highs this week will generally wobble between the low to mid 40s through the work week and into next weekend above 7000′, under a very dry air mass. Low temps already a bit cooler than last weekend will drop into the low to mid 30s along higher terrain, with temps into the 10s and 20s in valleys and depressions each morning. Expect a bumper crop of surface hoar throughout the week. Shaded aspects should continue to hold onto vintage, dirty powder with the dry airmass.

Yee ole’ persistent dome of high pressure continues to defend the Sierra from any hint of a storm system. Around midweek ensembles do show a cut off low developing off SoCal and undercutting the ridge, but it will then move off into the desert Southwest without much trace for the Central Sierra. A few high clouds and breezes might be the only evidence of its passing.

As noted above, behind the low another ridge redevelops over CA, reinforcing warm, dry conditions going into next week (1/26-2/1).

An interesting, although grim, note about this pattern is its resilience. Looking at a model of the amount of spin half way up in the atmosphere (aka 500mb vorticity), it’s evident how the blocking ridge dissipates and largely deflects any storms that try to penetrate it. The below GFS model spans the North Pacific and goes out until 2/4. Storms are denoted by brighter colors showing areas of greater spin (vorticity). Note the path of disturbances as they approach the CA Coast.

A model going out this far will almost certainly play out differently than depicted above. However, it’s instructive in showing how persistent and entrenched the current pattern is and its ability to stave off perturbations.

Change will come, but it’s not looking likely until at least the beginning of February.