Tahoe Backcountry Snow

0430 temp. at 6350′ in Carnelian Bay: 33.8 deg. & 98% RH

0515 temp. at 8650’ Tamarack TH: 31 deg.

Backcountry obs.:

Crust. Thin crust, thick crust, soon-to-be corn crust, and extra tasty, crispy garlic crust: the backcountry has it all this morning!

I headed out this morning to check on refreezes and see how the snowpack is holding up to prolonged warmth. Early morning snow surfaces in the Tamarack area refroze last night in drainages and on ridgetops. Some mid-slope treed areas were a bit softer from trees reflecting energy back into the snowpack. Colder aspects (NW-NE) host variably supportable crusts making turns difficult and unpredictable: combat skiing. Solar aspects are supportable and firm. I did see signs of baby corn snow growing on S aspects, so if you time it right, you might just be able to steal a spring corn run in January.

The current crust/wet snow situation should continue until the arrival of the next storm system late on Weds. Now that the PWL (persistent weak layer) has largely healed in the snowpack, future instabilities will likely depend on how new snow bonds with the current crusts. The old moniker “today’s surface is tomorrow’s weak layer” will be especially relevant.

Weather and forecast thoughts:

Today will be warm and sunny with light winds and highs in the lower 50’s. Expect another night of mostly clear skies, calm winds and lows in the low-mid 30’s. Some valley fog is also possible at night. Rinse and repeat for Tues. and Tues. night.

Weds. begins the great pattern change with winds and cloud cover on the increase ahead of rain/snow starting late afternoon and into the evening. Rain should transition to snow overnight for all elevations, including lake level. Thurs. will be a storm day with snow continuing before tapering off to snow showers overnight Thurs. and into Fri. with temps remaining cold (20s-low 30’s).

Above 7000′, 12-18″ seems like a plausible estimate for this first storm in the pattern. At first glance, this one also looks like it’ll come in right side up with denser, warmer snow starting off, followed by lighter, colder snow towards the end. Down at lake level expect lesser amounts (6-12″), but enough to transform the landscape back into winter. Finally.

The action might mellow a bit over the coming weekend, but temps will stay cold. Residual flow off the Pacific looks to keep snow showers likely Sat. and Sun. Looking at next week, the overall pattern remains conducive to cold, potent, and potentially convective storms with a robust N. Pacific jet just to our south. This keeps us cold while favoring storm development near the central and southern CA coast.

True to form, another potent low began showing up last night in the GFS models for the beginning to middle of next week. This storm would bring another round of significant snow to the Sierra with cold temps hanging on for the duration of the event.

Winter looks like it’s finally making a comeback starting Weds. and continuing for at least a week. Get your sticks ready!

0630 temp. at 6350′ in Carnelian Bay: 34.9 deg. & 98% RH

No backcountry obs. today

Weather and forecast thoughts:

Warm and dry weather is here as an anomalously strong ridge of high pressure builds over our region the next few days. Highs today through Weds. will reach the 50’s throughout the Tahoe Basin under mostly sunny skies. Lows will be in the mid to lower 30’s each night.

Areas of valley fog in valleys, meadows, and along the immediate Tahoe shoreline can also be expected each morning with inversions. As of this writing, temps. are 5-10 deg. warmer midslope (7000-8000′) again today than they are at lake level. High pressure coupled with weak surface winds is inhibiting any mixing in protected basins, allowing cold air from the snow pack to flow downhill and pool, inhibiting the air near the lake from warming as quickly as upper elevation slopes exposed to relatively stronger flow.

Big changes are still holding in the forecast starting Weds. afternoon as the ridge moves out and a strong Pacific jet extension begins sending storms into the Sierra. The first storm comes in late Weds. night starting warm with snow levels up around 8000′, quickly lowering to below lake level on Thurs. and beyond. The bulk of the energy for the first system will be directed at Tahoe and points south, but even without being in the direct bullseye, our region has solid chances of racking up some appreciable snow amounts: a foot or more.

This will not be a one and done storm. Cold and stormy conditions look likely continuing into next weekend and the first full week of February as the jet stream parks itself over SoCal in a position highly favorable for storms to affect our area.

0430 temp. at 6350′ in Carnelian Bay: 35.2 deg. with 98% RH

0515 temp. at 8400′ Incline Peak TH: 36 deg.

Backcountry obs.

Snow in the backcountry is now dominated by various crusts at all elevations and aspects. Expect combat skiing.

This morning a light refreeze on the snow surface made all crusts firm, but mainly breakable. Incline Peak is heavily tracked out and skin tracks are very icy. N facing aspects and sheltered trees tend to have thinner crusts with cold-ish snow beneath, while solar and wind exposed aspects have thicker crusts straddling the breakable/unbreakable line. Even the mellowest terrain has turned into adventure skiing.

Weather and forecast thoughts:

Today through Weds. will be warm and dry with partly cloudy skies. Highs around the lake will approach the lower 50’s, especially Sun. through Weds. while lows hang out in the mid-lower 30’s. Any refreezes on snow surfaces will be minimal. A dramatic shift to colder and wetter conditions takes hold Weds. PM into the weekend bringing snow (potentially significant) to all backcountry zones and elevations.

At dawn high clouds filled the skies with a grey film that has yet to clear by early afternoon. Moisture bumping up along the northwestern edge of the building ridge of high pressure is giving a “dirty ridge” feel to the warm, calm weather. Inversions are in place in the Tahoe Basin with temps. hanging in the low 40’s near lake level with upper 40’s to near 50 in the 7000-8000′ range. Periods of high clouds streaming aloft from now through Wednesday will help keep low temperatures high, adding to the slow bake of the snow pack over the next few days.

It’s a good time to tune up skis and boards for the second half of winter. The warm trend will be short-lived.

Starting Weds. PM, a shift to a more active and cooler pattern begins with the arrival of an initially warm storm (snow levels starting ~7500′) lowering down to lake level by the wee hours of Thurs. AM. Snow looks likely from Thurs., through at least the first half of the coming weekend.

Details of each system within the shift remain hazy this far out. Models continue to play with the idea of a splitting upper jet that favors the Sierra south of Tahoe for heaviest snowfall. In the past day, the idea of AR potential and a subtropical moisture plume phasing with the storm has also begun to look less likely. Despite the hints of these tempering forces conspiring to not wallop our area with multiple feet of snow, the pattern does look highly favorable to rounds of colder, wetter storms through at least next weekend. Looking beyond, ensembles show a strengthening subtropical jet into SoCal, which could bode well for our area being on the colder side of incoming Pacific storms.

Winter is far from over and there’s much reason to hope looking ahead into February.