Tahoe Backcountry Snow

0430 temp. at 6350′ in Carnelian Bay: 25.5 deg. & 95% RH

0530 temp. at 8650′ Tamarack TH: 19 deg.

Backcountry obs.:

What a weekend marked by transition in the Rose backcountry! Saturday hosted sunshine and cold temps with a stiff NE flow. Cold powder held strong in sheltered and treed zones while the winds did scour NE facing upper bowls and ridges. Sunday brought warmer temps and more sun, heating up the the snowpack on all solar aspects and baking much of the cold snow not shaded or due N facing. By noon on Sunday, all but the coldest aspects on Incline Peak had turned to hot pow, making turns more strenuous and slowing skis not slathered with the appropriate wax.

This morning, cold temps returned to the high country and the higher backcountry zones still have light, dry, unconsolidated powder in sheltered NW – NE aspects. The dry airmass and decently low sun angle have continued to preserve snow keeping smooth powdery turns on offer. Both Tamarack and Incline were hit hard by crowds over the weekend, so completely clean lines are hard to come by unless venturing back aways.

Most terrain near and above treeline is now either sculpted in sastrugi, wind battered into board of varying densities, or coated in suncrust on solar aspects. Last week’s consistent powder up high is now just a memory.

Stability-wise, the snowpack has settled considerably. Most instabilities for the next few days will likely come from warm/wet snow during peak daytime heating, but should still be relatively mild and short lived.

Weather and forecast thoughts:

The ridge of high pressure responsible for the calm conditions over the weekend continues to hold court in the Tahoe Sierra. Today will be partly sunny with high clouds often filtering out pure sunshine. Despite the high cloud cover, temps will reach the low-mid 40’s around the lake, 30’s in the backcountry. Winds will be calm in valleys with some N and E breezes up along the peaks and ridgetops.

Similar fair conditions will prevail for Tues. and most of Weds. before the ridge shifts eastward, opening the storm door for a system to begin nudging into the region from the Pac NW with chances for rain and snow starting Weds. night through the end of the work week.

Thurs. & Fri. a storm arrives to the N. and its southern extent will bring chances for generally light precip. from Tahoe northwards. Models show a fair chance for up to 6″ of new snow in the backcountry. Maybe a nice refresh? This system won’t be particularly cold or warm with snow levels in the 6000′ – 7000′ range.

Sat. – Mon. things get a bit more interesting with the potential for more appreciable snowfall. Models show another Pacific jet extension (similar to what happened during the last storm cycle) approaching the SoCal/Northern Baja Coast bringing in a good fetch of subtropical moisture. Around that same time, an area of low pressure dropping south down the west coast may phase with the subtropical jet, adding enough lift to the atmosphere to wring out some of that moisture as snow on the Sierra. Models have been bouncing around on snowfall amounts and placement of the low for the past 48 hours, so confidence on details is fairly low.

What does this all mean? Expect the warm and dry conditions to last only a few days more before a more active and stormy pattern likely returns to the Sierra. Backcountry snow will continue to offer up a mixed bag of old, cold powder, wind effect, mashed potatoes and suncrusts before hopefully freshening up in time for next weekend and beyond.

0330 temp. at 6350′ in Carnelian Bay: 21.2 deg. & 91% RH

Trace new snow

0430 temp. at 6800′ Jake’s Peak TH: 22 deg.

1-2″ new snow

Backcountry obs.:

I headed out to the West Shore this morning to check out conditions and snowpack. Generally soft snow exists in the trees on sheltered aspects in the Jake’s zone with good – not amazing – skiing. The area has been hit fairly hard with traffic over the past week, so don’t expect a clean line from top to bottom. Surface snow is composed of a few inches of light, dry snow mixed with some surface hoar in shaded areas and on NW-NE aspects. Dense storm snow from last weekend’s cycle lies beneath with a few noticeable density changes.

I observed no signs of instabilities.

On open E aspects, a thin, breakable sun crust has formed, especially on the lower half of the mountain. Higher up, open areas host spotty windboard/crust on windward and solar microaspects. Coverage top to bottom is generally good and skiable, but some sharks still lurk on the lower third, especially in solar and windward zones. Expect to dance with manzanita and white thorn on the lower third of the east face. The upper mountain hosts robust midwinter snow depth with rounded out, playful features.

Weather and forecast thoughts:

Today will be another cool day with mostly cloudy skies and light snow showers developing during the afternoon. Highs around the lake will top out in the low 30’s with upper 20’s in the mountains. NW winds will gently grace the lower elevations with some stouter gusts in the mountains and along ridge lines. Skies will begin clearing tonight, promoting cold lows in the teens and single digits.

Tomorrow will be sunny with temps in the low-mid 30’s as a light NE flow keeps things cool.

Sunday will be sunny and mild with temps warming 5-10 deg. as a ridge of high pressure settles into the region that will likely last through the coming work week. Expect generally sunny skies with seasonable temps in the 40’s during the day, 20’s at night. This doesn’t look like a big, prolonged warm up that will significantly erode the current snowpack. The drier airmass may yet still preserve cold snow in sheltered NW-NE facing backcountry zones.

The ridge shows signs of breaking down towards the end of next week, possibly ushering a new period of storminess with the potential for precip. returning to the Sierra.

Looking more than a week out, models tend to show a robust Pacific jet extension moving towards the California coast next weekend and the following week, then sagging south in a setup similar to what we experienced last weekend. The positioning of the jet will play a big role in how the pattern develops. Should it come in and establish itself into central and southern CA, Tahoe would be in a favorable spot for impactful storms.

For now, enjoy the approaching midwinter bluebird pattern.

0430 temp. at 6350′ in Carnelian Bay: 24.3 deg. & 93% RH

2″ new snow

0515 temp. at 8650′ Tamarack TH: 8 deg.

2-4″ new snow

Backcountry obs.:

Cold, soft snow continues to be the rule in the backcountry. A few inches of cold, light refresh rounded out yesterday’s tracks. In wind exposed and southerly facing areas, the cold snow covered a thicker wind board that was still springy and penetrable, but firmer than the snow found on colder, more protected aspects.

The new snow showed no signs of wind effect. Calm winds and cold temps promoted surface hoar growth over night adding another zippy layer atop the soft pow.

Prime time continues.

Weather and forecast thoughts.:

Today’s cold start will give way to temps topping out in the low 30’s under initially partly cloudy skies that will fill in throughout the day. Another small system will drop in from the NW bringing chances for light snow showers and a reinforcing shot of cold air for tonight and tomorrow. Accumulations will be light: less than 2″. Lows tonight will be in the 20’s around the lake and teens in the mountains. Highs tomorrow will flirt with freezing in mountain communities and remain significantly colder in the backcountry.

A ridge of high pressure finally makes moves on the area starting Saturday. This will bring bluebird conditions to the area with seasonably warm high temps (20’s and 30s for the backcountry, 30’s to 40 around the lake) under sunny skies. Nightly inversions look likely during this pattern, which could promote surface hoar growth on the snowpack in low lying areas: “recycled pow” for some, a future weak layer for others.

The ridge holds on into the next work week, but shows signs of flattening and weakening towards next weekend. This could bring some clouds and brush by moisture as storms begin affecting the PacNW. Further out, longer range models are hinting at a reopening of the storm door going into the President’s Day holiday week. It’s a ways out, but a prolonged, multi-week dry stretch seems unlikely.