Tahoe Backcountry Snow

0600 temp. at 6350′ in Carnelian Bay: 35.2 deg.

No new precip.

No firsthand backcountry obs. this morning.

Backcountry obs.:

Based off conditions yesterday and remote sensor readings atop Slide Mountain, I did not head out into the backcountry this morning. High temps. reached 44 deg. yesterday at 9600′ with light to moderate S winds. Lows last night stayed a few degrees above freezing. Conditions are likely cooked and in need of new snow, even at the highest elevations.

Weather and forecast thoughts:

New snow is needed and luckily, that’s what’s in the forecast for this weekend. This morning dawned dreary and a bit warm, signaling the arrival of a warm series of storms slated for the weekend into early next week.

Models this morning are trending a bit wetter for the first system coming in tonight. NWS Reno issued a Winter Weather Advisory last night for areas above 6500′ for 3-8″ up to 7000′,and 8-12″ above 7000′. Because this system will have less potential for spillover, zones along the crest will be favored for higher snow/rain totals. Winds will increase from the SW as the storm approaches, but don’t look to be as strong and intense as those from the last cycle.

Sun. night, the next wave comes in, which will favor areas from Tahoe south into the Eastern Sierra. This system will again be warm with snow levels mainly at 7000′ and higher. There is more convective energy and forcing available with round two, so NWS issued a winter storm warning for the period of Sun. PM to the wee hours of Tues. AM. Snowfall totals for the higher elevations will be between 1-2′ of new Sierra cement. The stronger dynamic of this storm will allow areas east of the crest to get in on more rain/snow action.

The weekend looks promising for a 1-2’+ refresh and base building above 7000′, but around the lake expect another sloppy mix of rain and snow.

Looking beyond the weekend storms, another warm, yet weak disturbance shows up in the models for midweek, followed by a solid signal for a ridge of high pressure building next weekend and holding on for the remainder of January. A ridge would likely warm things up and keep us dry, deflecting the storm track north of us. Could it cook up some late January corn snow?

As we enter February, some models suggest the ridge moving out and a wetter pattern returning. It’s a long way off, but I’m hopeful that winter will return for at least a few weeks. For now, bring on the cement!

0430 temp. at 6350′ in Carnelian Bay: 27.7 deg.

No new precip.

0520 temp. at 8650′ Tamarack TH: 28 deg.

No new snow.

Backcountry obs.

This morning felt like the air mass is beginning to change. Temps. at the Slide Mountain sensor near 9600′ flirted with freezing all night. On the drive up 431, temps. fluctuated between the mid-upper 20’s and low 30’s. At daybreak, skies were overcast.

Most notable this morning was the complete absence of wind. It took me a moment to figure out why the sounds of grooming equipment and traffic could be heard well into the mountains, then it hit me: no wind ripping through the trees. It’s been a while. Also of note was the warmth starting around mid-way up the skin track. Temps. had to be near or above freezing as I needed to shed a layer to not completely sweat through my clothes.

The snow reflected the additional warmth in the approaching air mass. Crusts are now abundant covering more snow than cold soft wind effect. What cold snow remains is becoming ever more dense. Solar aspects hold the thickest crust that’s nearly supportable, while W-NW-NNE aspects in open areas and above treeline host rime-covered pillows and stiff wind board. Do the cardinal math and you can figure out where pockets of soft snow still might be hiding.

Skiing through avy terrain, I observed no red flags or signs of obvious instability.

On balance, the skiing is still fun but becoming a bit more athletic. Good training.

Weather and forecast thoughts:

Today and the first part of tomorrow will be warm and dry due to a ridge of high pressure building over the area. High temps will warm well into the 40’s around Tahoe and with abundant cloud cover, expect the snow to cook as radiation gets reflected back to Earth from the cloud cover.

The weekend forecast for warm storms Fri. PM-Mon. continues to hold. Details regarding timing are emerging, but the theme of snow levels moving between 6500-7500′ throughout the period holds. By Mon. PM, 1-2′ of dense Sierra cement can be expected above 8000′. Lesser amounts east and between 7000-8000′ are a good bet. Little to no accumulation is expected at lake level.

There will be two main pulses of energy: Fri. night – Sat. and Sun. pm into Mon. Both systems will tap into subtropical moisture, but the first looks to be weaker, in addition to having a splitting nature as it arrives. Expect less spillover moisture from the crest with the first wave.

The second wave Sun. pm-Mon. will have a stronger cold front and low pressure component creating more efficient forcing as the system hits the Sierra. This one will likely produce the most rain/snow. Snow levels will be high once again with this one, unlikely to produce much, if any, accumulation at lake level, but will deliver a healthy load of cement atop the snowpack. Hopefully another heavy, dense snowfall between 7000-8000′ will build coverage and access to lower elevation backcountry zones.

Expect typical strong SW winds to accompany each storm.

Moving towards the middle of next week, another system takes aim on the region, but it looks to be warm, yet again. Thereafter, models are showing a ridge of high pressure developing over the west for the end of the week and next weekend.

There’s lots of warmth this month, but fortunately there is a snowpack and higher elevation zones continue to build up and deliver good mountain fun.

0430 temp. at 6350′ in Carnelian Bay: 33.3 deg.

Trace new snow / .35″ rain in last 24 hrs.

0530 temp. at 8650′ Tamarack TH: 24 deg.

2-3″ new snow

Backcountry obs.

This morning dawned blustery and cooler with scattered flurries around the area, including at lake level. Only a skiff of new snow coated coated the roads in the predawn. Climbing up Mt. Rose Highway, high winds sent spin drifts airborne, aggressively depositing snow into the roadway and limiting visibility.

In the skin track, 2-3″ of new snow had fallen in more sheltered areas from TH to summit. Any area exposed to the strong WNW winds had been scoured down to the sun and rime crusts created during the warm weather between the 1/13 storm and last night’s disturbance. Soft, high density snow lay in sheltered leeward aspects and in the trees. Areas that did receive new snow wind deposits had a drummy, upside down feel with higher density windblown snow resting on top of lower density cold snow. In sheltered solar aspects, an inch thick, semi-supportable crust, covered lower density cold snow beneath.

The descent skied surprisingly well considering the wind and meager snow totals. Sheltered zones without crust were soft and fun, while more exposed areas featured a mix of crust and fresh wind deposits deep enough for soft turns, but not quite large enough for concerning wind slabs.

The next 36 hours should provide a brief lull in the wind and snow before the next round of systems arrives. Cool enough temps. should prevail to preserve the soft snow.

Weather and forecast thoughts:

Last night’s system dropped mainly rain at lake level before tapering off to a few flurries and a light dandruff coating by early this morning. Low clouds and showers continued to hug the west shore by mid morning today suggesting a continuation of the moist, orographic flow along the Sierra crest.

Clouds and showers will taper throughout the day today, giving way to breaks of sunshine and seasonal temps. with highs in the upper 30’s to lower 40’s around the lake. Tonight, tomorrow, and Friday a transient ridge of high pressure builds back into the area clearing skies and moderating temps. into the mid 40’s Thurs. and Fri. Highs should get near to just above freezing today and tomorrow in the backcountry between 8000-9000′.

Fri. afternoon, the high pressure moves out and the storm door swings back open as a strong zonal Pacific jet is set to bring a parade of systems to the area. Models continue to agree on multiple waves of precip. arriving from the eastern Pacific, each containing a decent subtropical moisture tap.

The first few waves Fri.-Sun. don’t look particularly potent by Sierra standards, but expect periods of rain and snow throughout the weekend. Snow levels will dance between 6500′-7500′, due to the warm subtropical moisture feed with little cold influence from the north. Snow levels will rise each day and fall at night. The wave arriving Mon.-Tues. looks to be the most potent, but still as warm as the waves before it.

Going into midweek and beyond, the GFS ensemble shows the stout Pacific jet stream retreating back to the west with a ridge of high pressure emerging over the west coast and building into the inner mountain west. This would likely usher in a period of warm and dry weather, hopefully not for too long. It’s midwinter and high time for a strong cycle of cold storms.