Tahoe Backcountry Snow

0600 temp. at 6350′ in Carnelian Bay: 27.1 deg. & 98% RH

No new snow

No backcountry obs. today

Forecast and weather thoughts:

Inversions are in place this morning with low clouds hanging over the north side of the Basin. Temps. mid slope in the mountains are nearly ten degrees warmer than at lake level, but dewpoints have dropped, likely keeping sheltered snow cold and soft through radiational cooling.

The next system arrives late in the day today. Winds will steadily increase out of the SW and mix out the inversions and fog by midday. High clouds will arrive with the winds, announcing the imminent arrival of more precip. This system is transient and doesn’t have a robust forcing mechanism, but it does have a tap on subtropical moisture. The result will be a warm event beginning this evening and lasting through tomorrow morning. Rain and snow will be heaviest W, dropping off significantly from W to E across the Sierra.

Because of the subtropical moisture tap, snow levels will start out between 8500-9000′ this evening, dropping to around 7000′ by storm’s end. By tomorrow morning, 3-6″ of heavy snow could coat the backcountry. Anywhere from .5″ to 1″ of rain is possible across the Tahoe Basin.

A warm break in the action comes in behind this next system with highs around lake level in the mid 40’s under a mix of clouds and sun.

Fri. pm the storm door opens yet again, with models in agreement showing rounds of rain/snow as a strong Pacific jet takes aim on our area. It still looks like next weekend and the first half of the following week may bring abundant rain and snow, but with snow levels bouncing up and down between 6500-7500′. These storms will all have a subtropical tap to their moisture and with no phasing of cold air from the Gulf of Alaska. We may be in store for a mid-winter rain event in the mid and lower elevations.

On the upside, days of Sierra cement pounding the higher backcountry will continue to fatten up the snowpack and may even overload whatever’s left of the persistent weak layer instabilities that lurk at the bottom of the snowpack. Then we’d just need a cold cycle to load some powder on top and boom: party time!

But back to reality, warm sloppiness is imminent. Do what you can with it.

0430 temp. at 6350′ in Carnelian Bay: 30.4 & 99% RH

No new snow

0530 temp. at 8400′ Incline Peak TH: 24 deg.

No new snow

Backcountry obs.:

When I came out of the backcountry yesterday, there was a mix of clouds and sun and high humidity. The snow at the TH had lost its cold feeling and water rivulets gushed down both sides of the road. With the cool temps. last night, I feared that warmth from yesterday had refrozen into crust on all aspects. I was wrong.

Skinning up Incline Peak I found a mix of breakable crust on any aspect that receives appreciable sunshine, and cold, dense Sierra cement in the trees and on all features facing NW-ENE. It’s still January and the sun angle is pretty low, so aspects receiving little to no sun can still stay cold and soft under the right conditions. If the airmass can dry out a bit over the next 24 hours, with cold overnights, N facing protected snow could still remain cold and crust free.

Incline Peak has been heavily skied, especially through the N. trees and NE side of the E. bowl. Good cold snow is still plentiful though in the right sheltered zones. Coverage continues to improve making for fun descents. Stability also looks to be improving, but the buried persistent weak layer is still out there, so conservative risk management remains prudent.

Forecast and weather thoughts:

The moist airmass left in the wake of Saturday’s storm was apparent this morning as low clouds, heavy hoar frost, and patchy fog adorned the Tahoe Basin. By mid morning, most low cloudiness and fog had burnt off giving way to a sunny, relatively warm day. Highs today are in the low 40’s around lake level. Tonight should cool off again and offer a repeat or close relative of this morning’s conditions as high pressure reigns.

Poor predictability and shifting model forecasts have plagued this winter and this week is no different. Looking to midweek and beyond, the trend towards warm and dry is changing to warm and unsettled.

Tues. will see the arrival of more clouds and rain/snow by Tues. night. Snow levels will initially start very high around 8500′, before falling after midnight and through Weds. am. Precip. will end Weds. am with fairly light storm totals. I wouldn’t expect any more than a few inches of wet snow, even along the crest, due to the warmth and high snow levels. This will be a mainly rain event for areas below 7000′.

The remainder of the work week will be warm and dry with high temps. in the low – mid 40’s around lake level. Sunny skies should prevail from Weds. pm though Fri. pm.

Fri. evening, things begin to shift once again as a train of storms takes aim on us from the Pacific starting next weekend and continuing deep into the following week. Models show these storms coming in on a strong Pacific jet traveling almost directly across the ocean from southern Japan. The mid-latitude placement of the jet will likely draw in milder Pacific moisture to keep each wave of storms fairly warm with snow levels near or above lake level.

This pattern shift is still quite a ways off, but at this point there’s no obvious cold signal interacting with the incoming, juicy subtropical jet, which trends towards a storm cycle of warm storms with higher snow levels. Time will tell as the work week wears on.

0430 temp. at 6350′ in Carnelian Bay: 32.0 deg.

< 1″ of slush accumulated

0530 temp. at 8650′ Tamarack TH: 25 deg.

New snow in Tamarack Peak backcountry: est. 6-8″

Backcountry Obs.

Yesterday’s mix of rain and snow at lake level never transitioned back entirely to snow. This morning a juicy, barely frozen slush coated everything. Driving up Mt. Rose Highway, accumulated snow began around 6800′ and increased with elevation. Heavily-rimed trees suggested a very moist storm overnight. Light snow fell through the morning until 0900.

The dense and heavily wind-drifted nature of the new snow made estimating the new snow amounts difficult: approx. 6-8″? I put in the new skin track through a fresh layer of thick Sierra cement, heavily wind affected into drifts and drummy pillows even in flat open areas. Moderate winds continued to blow from the WSW transporting fresh snow onto N and E aspects. Windward aspects and any snow surface exposed to the winds had a slight rime crust. Sheltered and treed areas were soft and creamy mashed potatoes. The snow did suggest a density change about 4″ from the surface as my skis punched through to the tops of my boots.

The skiing today wasn’t exceptional and the mountains felt precariously warm. Despite that, sheltered areas of fresh snow still offered soft, buttery turns that at speed, didn’t require too much effort. Gullies and boulders are fattening up and softening their lines making for super playful features on which to rip big arching turns. The more speed, the better today.

Hopefully the air mass will cool and dry out this evening to help lighten and dry the first few inches of fresh snow to keep cold softish conditions going.

Forecast and weather thoughts:

Tonight skies will clear with temps cooling to well below freezing in the mountains and at lake level. Expect freezing fog in depressions and valleys too. Tomorrow temps will begin climbing to near and just above average (low-mid 40’s around the lake) with clear skies. The warmth looks to continue at least through the work week.

The next potential storm comes in Tues./Weds., bringing rain and snow. Models show snow levels high throughout the event between 7000′-8000′. Another cement event for the highest backcountry zones. Hopefully the system adds to the base and coverage in areas near and below 8000′. Temps during the day around 6000′ should get into the low 40’s with lows in the low to mid 30’s at night.

After the storm, transient high pressure will clear things out, but keep mild temps. around through the end of the work week. There are signals for a more active pattern starting back around next weekend, but it doesn’t look like any significant cold air will come in with it. Ensembles show a strong zonal jet stream developing with a conspicuous angle towards Hawaii. That usually signals a solid moisture plume, but warm air. Our area may be playing the rain/snow game for a bit.

For now, time to enjoy the soft, creamy turns of classic Sierra mashed potatoes.