Tahoe Backcountry Snow

0430 temp. at 6350′ in Carnelian Bay: 37.3 deg. & 80% RH

0515 temp. at 8650′ Tamarack TH: 27 deg. w/ graupel and mixed precip.

Backcountry obs.:

The much-advertised storm had just started to arrive this morning in the Mt. Rose backcountry with strong SW winds, dense fog, and waves of mixed precip. (graupel, icy snow, riming mist and freezing rain). Despite temps. being well below freezing, frozen droplets accumulated on my skis while skinning up in the parking lot and added a light sheen to snow surfaces. My car was covered in a textured glaze of graupel and freezing rain when I returned around 0700.

Much like Mon. 2/26, crusts reigned on all aspects of the zone with only a few isolated stashes of cold powder in true north facing trees. Accumulating graupel and whatever else remained available for wind transport whipped through the forest and along ridge lines with each blasting gust. Wind gusts on adjacent Slide Mtn. not surprisingly flirted with hurricane force (75 mph) throughout the early morning. The jet like roar of winds raking Galena Peak accompanied my entire tour.

Any new snow today is falling mainly on crusty surfaces or old, cold powder in north facing chutes and heavily sheltered, forested areas. The mixed bag coming out of the sky early in the storm may help bond new snow to the old surfaces, but regardless, the amount of anticipated new snow will create avalanche cycles throughout the event.

Weather and forecast thoughts:

It’s pretty remarkable how little has changed in the forecast for the storm over the past few days, especially in the last 24 hours. Take a look at yesterday’s post for the play by play breakdown.

In short, from now until Sun. AM, expect between 3-5′ in Tahoe communities around lake level. 5-10′ can be expected above 7000′ with greatest amounts along the crest and NW of the lake. (It will be very interesting to see what the Central Sierra Snow Lab reports on top of Donner by Sun AM.)

Whatever mixed precip. may be falling currently below 6500′ will transition to all snow and intensify throughout the day and into tonight. Snowfall rates may peak at 5″ per hour Fri.-Sat AM, before dropping back to more civilized 1-3″ per hour rates through Sun/Mon.

A break looks likely for the beginning of the week until another system moves in from the NW around midweek bringing renewed chances for more snowfall. Signals for the midweek storm are not nearly as strong as the current system, but do bear watching.

For now, it’s time to watch the snow fall.

0600 temp. at 6350′ in Carnelian Bay: 27.0 deg. & 80% RH

No backcountry obs. today

Weather and forecast thoughts:

Today is the last calm day before the big storm comes in tomorrow. Expect sunny skies with highs in the 30’s and 40’s from the lake to the backcountry. Winds and clouds may be on the increase this afternoon and into tonight as the most significant storm of the season approaches.

It’s been a tough year to get excited about incoming storms. That said, it’s time to get excited. Models are in remarkable agreement that the largest and most impactful storm of the season will hit the Sierra starting Thurs. and continuing through the weekend, maybe beyond. The most intense period of heavy snowfall will be Fri night into Sat morning with snowfall rates of 3-5″ per hour along with strong winds that will create blizzard conditions. Expect snow totals of 2-4′ at lake level with 4-8′ above 7000′, especially along the crest.

Whereas model agreement throughout the season has been so rare, forecast models for this storm sequence are in great agreement across the various suites and from run to run. It’s this consistency that gives some pretty solid forecaster confidence in the fact that we’re going to get hammered.

For example, the Euro ensemble for total accumulated precip. from Thur.-Tues. at midnight shows 6-7″ of liquid precip. for the NW side of the Tahoe Basin. The GEFS (American model) ensemble shows 5.5-6.5″ of total accumulated precip. for the same area. I haven’t seen that sort of agreement, not to mention amounts that high, all season. To convert that amount into snowfall, use a 12:1 ratio just to be safe. That comes out to 6-7′ by storm’s end, and that’s with a conservative snow/water ratio.

In addition to the heavy snows, the storm will have sustained high winds throughout the event, bringing blizzard conditions across the range. Traveling during the storm is being discouraged by authorities and the wind/snow combo will almost certainly close passes and bring down trees and limbs, affecting utility infrastructure. With that in mind, today will be a good day to stock up on firewood, whiskey, gas and food (in that order).

So how’s it going to go? Increasing winds this afternoon and tonight with presage the arrival of the storm and increase into Thurs. Snow will move into Tahoe on Thurs. late morning from the NW with snow levels around 6000′. I wouldn’t be surprised if a few rain drops mixed in at the onset, but will quickly transition over to snow. Temps will likely begin falling throughout the afternoon as snow rates pick up into the 1-3″ per hour range. Snowfall will intensify Thurs. night into Fri., then peak Fri. night into Sat. at rates between 3-5″ per hour. Colder air will filter into the system Fri., boosting snow/water ratios through the end of the storm. Snowfall will become more showery in nature into Sun. and Mon., before picking up yet again with another system or two for the middle of the week.

Needless to say, this storm will create a large avalanche cycle with many zones sliding repeatedly with such intense snow loading. The storm appears to come in rightside up with denser snow at the onset, becoming colder, lighter and drier as the event wears on. Despite this, storm slabs and wind slabs will likely initiate unstable backcountry conditions in any areas steep enough for fun skiing.

For now, it’s time to enjoy one last day of glorious Sierra sunshine and pre-storm anticipation. A big one’s en route that might just set this season straight and put us in great position for spring.

0415 temp. at 6350’ in Carnelian Bay: 36.1 deg. & 80% RH

0530 temp. at 8650’ Tamarack TH: 26 deg. w/wind driven flurries

Backcountry obs.:

Gusty winds out of the SW shook the car upon arrival at the TH this morning. On the mountain, strong winds and wind-driven snow graupel provided nice facial exfoliation in the skintrack. Surfaces from the TH to the summit are a mix of crusts, deep ruts and tracks and the occasional stash of cold, soft snow. With the noticeably higher solar angle, snow surfaces are largely dictated by aspect: those with the most southern exposure have the thickest, most supportable crusts, while E and NE aspects hold breakable crusts. Only protected, true N aspects and shaded zones beneath trees hold cold, soft snow.

The warmth and traffic of the past few days has taken its toll on the backcountry and the modest inbound refresh is very much welcome.

Weather and forecast thoughts:

Expect strong and gusty SW winds today with snow showers picking up in intensity through the afternoon hours, tapering off after dark. Highs will reach the upper 30’s in mountain communities and not make it above freezing for most backcountry zones. Total accumulations for the area will be light with a coating to an inch around the lake with up to 4-6″ in the mountains before the system kicks out to the east.

Tues. and Weds. will be fair and seasonably chilly with sunshine and highs Tues. around 40 at lake level, moderating 5-10 more degrees for Weds. Lows both nights will be in the 10’s to 20’s from lake level to the backcountry.

Now the big story: a high impact winter storm looks very likely to move into the Tahoe Sierra Thurs. through through the weekend dropping heavy snows at all elevations. A deep low associated with a strong attendant jet stream will drop in from the Gulf of Alaska Thurs.-Sat. bringing high winds, heavy snows and cold temps. This storm will bring feet of snow to the Sierra – and it’s looking ever more likely that big snows fall at lake level too. This morning’s Euro ensemble shows total precip. amounts through Sun. between 4-6″ of water, which could translate to multiple feet of snow on the mountains through the weekend. Colder temps. will also help to boost snow/water ratios. Models are also very consistent in their representation of the track and intensity of this storm across models and ensembles, quite a different tune from the rest of the 2024 winter.

In addition to the snow, this storm will bring high winds making utility interruptions a real possibility. It might not be a bad idea to stock up on essentials in the coming days.

Bottom line: a big, cold storm reminiscent of 2023 is likely to hit Tahoe this weekend…