Tahoe Backcountry Snow

0430 temp. at 6350′ in Carnelian Bay: 29.3 deg. & 89% RH

Trace new snow

0515 temp. at 8650′ Tamarack TH: 20 deg. under flurries/light snow

4-6″ 36hr. storm total

Backcountry obs.

Overcast skies with light snow started off the morning at lake level and in the backcountry. The 2/1-2/2 storm underperformed with snow totals, but there’s enough of a refresh in the backcountry to make skiing more fun than a frog in a glass of milk!

Light to moderate SW-W winds raked the forests and ridgelines at dawn giving a subtle surface texture to the cold and light new snow. Despite its levity, the new snow still has enough texture to provide cushion and float above the old crust layer. Skinning in steep, traversing terrain provides some challenges: the poorly bonded new snow slides out on the firm crust beneath.

In wind-exposed areas, firm surfaces are forming as windward faces rime in the low clouds and high humidity. Lee zones do have growing drifts with the potential for wind slabs to enlarge modestly as more snow and wind arrive today. No instabilities like cracking, whumphing, or hollowness were noted, but skiing initiated some minor sluffing on steeper terrain.

The wind-kissed, cold pow is just enough to provide consistently soft turns. Turn too sharply and the crust becomes evident, but not problematic. The fun is back!

Weather and forecast thoughts:

Today will be mostly cloudy with some peeks of sunshine in between snow showers. Highs around the lake will stay in the low 30’s with temps in the mountains hanging in the low to mid 20’s. A few inches of accumulation are possible in town while up to 6″ could fall in the mountains, potentially more along the crest and west of CA 89.

Showers will increase in intensity this afternoon as another impulse of energy moves in off the Pacific and aligns with afternoon heating. The combination of lifting from the impulse, with added instability from daytime heating could fire off some heavier, convective showers with short-lived intense snowfall rates.

Tonight through Sat. and Sat. night snow backs off again to just some lingering showers. Temps. remain cold with highs in the low 30’s to 20’s depending on elevation, with low’s into the teens and 20’s.

Sunday the big show gets going. The much advertised “biggest storm of the season” looks to take shape and dump its heavy load on the Sierra from Sun. daybreak through early Tues. An impactful storm is likely with the ability to close roads and create a snowpack at all elevations in the Tahoe Basin. Just how much is still in flux.

As of this morning, models show a strong low combining cold air, dynamic lift, and a robust tap of subtropical moisture moving into the area on Sunday, dumping the heaviest snow Sun. through Mon. AM. An intense plume of moisture looks to arrive from the south and shuffle north during the morning on Sunday. The flow within the fire hose – from the SW – will align well with the topography of the Sierra to create enhanced lift and heavy snow. Highest amounts will be along the crest, but the system will also create efficient spillover into NV and points east.

Today’s model runs trimmed snowfall amounts back a bit for Tahoe and bumped them up for the Eastside to our south, as the plume will likely originate over the Central/Southern Sierra, move north, hang out, then begin moving back to the south before breaking apart into more intermittent snow. Probabilistic models show a 50-60% of 12″+ for Tahoe communities, with 60-80% of 2-3’+ along the Sierra crest. Totals jump up to 4’+ for the crest in Mono County, with 2’+ likely for Mammoth and June Lakes.

Each storm is unique and this one could meet those marks or even overperform. However, considering the trend of models overpromising this season, these amounts may be trimmed back in future forecasts or during the actual event. Time and the atmosphere will tell.

Moving beyond Monday, the active, cold pattern continues with showery, intermittent snow Tues. and Weds., potentially picking up again with another storm arriving from the NW around Thurs. Keep it coming…

Hey winter, it’s good to see you.

0800 temp. at 6350′ in Carnelian Bay: 32.4 deg. & 98% RH with light snow

24 hr. precip: .19″ rain / 1-2″ snow

0530 temp. at 8460′ Incline Peak TH: 30 deg. (falling) with light to moderate snow

2-5″ new snow accumulation as of 0700.

Backcountry obs.:

The much anticipated storm has under performed. Early this morning the changeover to snow did not happen at lake level until around 4:30. Since then, snow has been falling lightly with temps. in the low 30’s. With main band of precip. now to our south and breaking apart, it looks as though the bulk of today’s accumulation has passed. Lingering showers remain.

Precip. shadowing was very evident this morning in the backcountry as Incline Peak only had about 2″ at the TH and around 5″ near the summit at 9500′. During my tour, snow fell around 1/2″ per hour, but pulsed in and out. Winds blew out of the SW in the light/moderate range in open areas and on the summit.

The skiing has vastly improved, but still has a ways to go to recover the soft, bottomless goodness of a powdery mid-winter state. Concrete-hard ruts and tracks from the warm spell are still evident, yet fattened and softened with the new snow. A few more inches should erase them completely. For today expect a heavy dust on crust. The underlying firm surfaces are noticeable with most turns, and especially evident with slipage on steeper, side-hilling sections of the skintrack. The snow has not yet bonded to the crust beneath.

Instabilities noted were confined to loose sluffs running down steeper chutes and gullies, but nothing entraining larger cohesive slabs of snow. At the time of my tour there was not enough snow – except in deposition zones along the lee side of ridge tops – to pose any significant avy risk.

Weather and forecast thoughts:

Some years storms seem to get more potent with each model run in the days preceding their arrival. Then when they hit, they all overperform… That’s not 2024.

Today’s storm arrived late last night with rain at lake level until the predawn hours. An inch or so has fallen as of mid-morning, with Rose zone backcountry amounts in the 2-5″ range. A far cry from 1-2′.

Snow showers and cool temps. will prevail today with highs in the low-mid 30’s around the lake, with below freezing temps holding above 7000′. Snow levels will fall to around 5000-5500′ by afternoon. Expect a few peeks of sun in between snow showers, but otherwise skies will remain mostly cloudy. An additional inch or two can be expected in town with slightly greater amounts in the backcountry. Higher amounts will be along CA 89 and on the Crest.

Additional light snow showers will continue tonight and into tomorrow as the moist upsloping flow off the Pacific takes hold. Tomorrow a new, modest impulse swings through in the afternoon, increasing snowfall potential. Another few inches can be expected around the lake, with higher amounts in the mountains and along the crest. This refresh is coming in inch by inch.

Saturday and Sat. night some stray snow showers will grace the region under a mix of clouds and sun, with cooler temps. in the low 30’s during the day and 20’s at night.

The next potential big storm gets rolling on Sun. afternoon and looks to continue through Mon. evening/early Tues. Models this morning show a low developing off the coast that will phase a subtropical moisture fetch with cooler air, bringing another round of snow to the Sierra. Temps will remain cold enough for snow at all elevations – even down into W. Nevada valleys -for the duration of the event. The position of the low near the Monterey Bay is ideal for steering and forcing moisture up against the Sierra to be wrung out as heavy snow.

Probabilistic models this morning have Tahoe Basin communities with a greater than 50% chance of 12″+ and 2-3′ up along the crest. Models are also running a bit wetter today with higher QPF (quantitative precip. forecast) amounts than yesterday. With the storm still a few days out, details on timing and specifics have yet to crystalize and I expect multiple revisions on snow amounts over the next few days. This season has been marked with storms losing their punch as they hit the Sierra, so it’s difficult to see big projections and have confidence that they’ll hold.

That said, the show for this cycle is only getting started and conditions in the backcountry will improve over the next few days: inch by inch at first, then potentially with a big wallop.

0430 temp. at 6350’ in Carnelian Bay: 42 deg. & 50% RH

0515 temp. at 8650’ Tamarack TH: 34 deg.

Backcountry Obs.:

I got out this morning to see what the incoming snow will fall upon and as expected, crusts cover all elevations and aspects from 8600’-9000’ in the Rose backcountry. On windward and solar aspects, these firm surfaces are not even penetrable with the blunt end of a pole. In sheltered areas and NE aspects, crusts are generally 1/2-1” thick and semi supportable. Cold snow lays beneath.

Why does this matter? The crusts create a new bed layer upon which instabilities may form and run in future avalanche cycles. With the early season PWL (persistent weak layer) now less of a concern, most issues will occur from the current surface up.

The big question with the incoming storm today is how well the new snow bonds with the current surface snow. At this point, the storm looks to start warm and finish cold, which in general bodes well for bonding and stability.

The skiing today: hateful, survival combat. A week’s worth of traffic, complete with deep ruts, dinosaur tracks – and who knows, maybe even a mule train or two – on refrozen firm surfaces that occasionally give way, made for a tiring descent. Good thing a fresh start is inbound.

Weather and forecast thoughts:

Today dawned with moderate winds, foreboding skies, and warm temps. Winds ahead of the system have mixed out the inversions of the past few days, improving air quality, but also raising temps and lowering humidities. The storm is already appearing on radar over the North Coast and should begin impacting the Sierra late this afternoon/early evening. NWS Reno issued a Winter Storm Warning yesterday which still remains in effect from 10am today through 10am Fri. Expect a windy day today with increasing clouds, temps in the 40’s, and rain/snow moving into the area late in the day.

Precip. will begin falling as rain around the lake, quickly transitioning to snow and picking up in intensity late tonight through tomorrow morning. Snow levels still look on track to start around 7000′, then fall quickly through lake level and down into the 5500-6000′ range on Thurs. Updated model projections for the storm have trimmed down snow totals a bit for tonight-tomorrow evening to 12-18″ above 7000′, up to 6″ in mountain communities.

The angle of the storm up against the Sierra is a big factor in trimming the snow totals. As the storm hits the range, the flow will be shadowed, meaning more precip. will fall on the western slopes. The crest and areas along CA 89 will get the most, falling off considerably the further east you move.

Behind the opening salvo, a moist flow off the Pacific will promote snow showers continuing Thurs. PM, Fri, and into Sat. Some of these could be convective, giving them an extra punch with some snow bursts freshening up the mountains each day, especially during afternoon hours. A rumble of thunder isn’t out of the question along the crest either.

Looking at the next system, this morning some of the models suggest things getting going Sat. night and lasting into Tues. This one is giving strong signs of being a classic dump machine with the ability to deliver feet to the mountains and maybe even at the lake. There is plenty of cold air in place, so snow will fall at all elevations for Tahoe communities and backcountry zones.

This system is looking pretty complex as it combines a strong AR (atmospheric river) of subtropical moisture phasing with colder air as a closed low drops down the Pacific coast. The strong low will help provide dynamic lift to the moist air as it hits the Sierra, wringing out its contents as heavy snow.

I expect quite a few revisions to the forecast in the next few days. Closed lows are notorious for wobbling about as they travel due to being disconnected from the jet stream and larger upper flow. This makes predictability for specific impacts challenging. Any change in the track of the low a hundred miles one way or another, could significantly alter which parts of the Sierra receive the heaviest snowfall. It’s going to be fun to watch.

For now, snow moves in tonight giving the backcountry a welcome refresh. Never waste a powder day!