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Tuolumne
Meadows Winter Conditions Updates
by
Bruce & Tracey, 2004-05 Winter Rangers WEATHER: (from March 17 to March 23) SKIING CONDITIONS: Back to trail breaking conditions. With five feet of new snow it will be awhile before we see the return of last week’s spring conditions. The new snow can settle fast this time of year although new snow depth may vary widely with altitude and aspect (see avalanche discussion). AVALANCHE/SNOW CONDITIONS: (above 8,000’) Avalanche danger is CONSIDERABLE and avalanche consequences are also very considerable with five feet of new snow on a firm base in the last few days. Be extremely cautious of wind loaded slopes formed during strong SW winds. If you only consider the steeper wind loaded slopes the avalanche danger would be HIGH. DISCUSSION: Two storms over the last weekend and early part of this week left us with five feet of new (not so light) snow. Strong SW winds also accompanied these storms leaving some wickedly deep wind loads on lee slopes. On Monday the 21st (the only break in this storm series) we found some 5-6 foot wind loads at tree line on Unicorn Peak. Some of the steeper roll over areas (change in slope) had so much blown in snow they appeared much smoother than before. We also saw evidence of several sizable slab avalanches off the lee side of the Cathedral Range with crown fractures of 5 feet or more. At about 10,000’ on a N aspect and 37º slope we tried isolating shovel size columns of snow which either collapsed in the digging or failed after one finger tap on a shovel. The failure took place 2 ½’ deep at the interface between the old snow surface and the newly fallen snow. Now add another 3-4 feet of heavy new snow on top and you have present conditions, yikes. WILDLIFE: Just before this storm cycle we spotted our first Violet-green Swallows winging their way westward. They were low to the ground as they zipped past us on top of Pothole Dome. Another pre-storm report from Bill who was staying at the ski hut: he saw several Gray-crowned Rosy Finches bathing in the snow surface melt water near the summit of Mammoth Peak. I guess they knew about the coming storm and that it would be awhile before their next bath. SKIING CONDITIONS: The snow has gone through a major transition this last week turning isothermal (32º F or 0º C) throughout the snowpack on all but the north facing slopes and well above tree line on all but the most southern aspects. What started out as rotten afternoon snow earlier this week has turned into solid melt/freeze conditions. The snow is icy in the mornings but generally firm or sun-kissed as the day goes on. It does sound like there is fresh snow on its way this weekend and early next week. AVALANCHE/SNOW CONDITIONS: (above 8000’) Avalanche danger is MODERATE to LOW with increased potential for slides during and just after warm day time temperatures. HIGHER avalanche potential is present in granite dome and slab areas with snow instability lingering well past the heat of the day. DISCUSSION: Several days ago much of the snow in the Tuolumne area turned isothermal. Water moves much more freely in a snowpack that is all hovering around freezing, particularly when the air temperature is above freezing. Avalanche activity off of granite slabs and domes has been steady but slowed down considerably when the daytime temperatures cooled. We have had reports of slides off Olmsted area. It sounds like there is snow in the forecast for the upcoming week. The isothermal snow will warm the new snow quicker but there is also a tremendously hard sliding surface for the new snow to fall upon. So prepare for quick changes and transitions in the new snow as well as the snow surface. New snow and warm weather could also bring a return of surface snow rot (water running down into the snow pack leaving air filled snow) but only for a short time. WILDLIFE: A couple weeks ago we reported on a flock of Canada Geese which spent some time in Dana Meadows. At about the same time our nearest neighbors at Tioga Pass Resort also had a water fowl encounter, such a close encounter that they named the Eared Grebe which landed near a pile of backpacks in front of the lodge “Trooper”. Diving duck’s legs are set far back on their bodies so they need a stretch of open water to take wing. So Trooper spent the night in the bathtub then was transported down Lee Vining Canyon to the folks at Mono Lake Committee who released the Grebe at Mono Lake with its brethren. WEATHER: (from March 3 to March 10) SKIING CONDITIONS: The sun rules with high temperatures affecting all aspects. Although corn snow has not really appeared in abundance yet the seeds have been planted on sun angled slopes at or below tree line. Icy morning snow has been turning to afternoon wet snow as the snow surface melts. Above tree line snow is generally firmer except on north aspects where last weeks powder has turned heavy. It sounds like conditions may cool off next week. AVALANCHE/SNOW CONDITIONS: (above 8000’) Avalanche danger is MODERATE to LOW with increased potential for slides during and just after warm day time temperatures. HIGHER avalanche potential may be present in granite dome and slab areas. DISCUSSION: After steadily increasing temperatures and three days in the low 60’s we have seen many small wet rollies and sloughs off trees and rocks. We have not been in the granite dome areas just west of Tuolumne in the last few days but it is very likely that some larger slides associated with the warm-up occurred. Lembert Dome has been shedding snow the last few days with some small streams at its base running day and night. Be particularly careful around these granite faces until they are snow free. WILDLIFE: More signs of migration. Along with the appearance of other winged insects we saw the very first Painted Lady Butterflies heading west on their annual trans-sierra migration. Higher in the sky several ski parties have seen flocks of Gulls heading east high above Tioga Pass. It seems most likely that these white specks are California Gulls heading to Mono Lake. February 22, 2005 SKIING CONDITIONS: Lots of fresh snow for trail breaking. Snow gets much deeper (unconsolidated) with elevation particularly on north slopes. AVALANCHE/SNOW CONDITIONS: (above 8000’) Avalanche danger is CONSIDERABLE particularly on steep north slopes with deep, unconsolidated snow. Also expect avalanche action off domes and granite slabs as temperatures warm up. DISCUSSION: Nearly 4’ of new snow in the last week at Tuolumne Meadows It also sounds like our everyday snowy periods may slow or end for a few days. Watch for increased wet slides from granite domes, slick rock and any steeper solar exposed area. Remember route finding is your best avalanche defense and very short slopes can have a huge amount of snow on them, especially this winter. WILDLIFE: Daily snowfall keeps the animal tracks fresh which in reality may show that hours or days will go by before an animal passes by any given area. It does allow us to observe how much area different critters cover. February 17, 2005 SKIING CONDITIONS: Fresh but heavy snow for trail breaking. On Wednesday the 16th ski penetration was generally knee deep in the morning and calf deep by evening, although snow is predicted for the next few days. AVALANCHE/SNOW CONDITIONS: (above 8000’) Avalanche danger is HIGH. With wide spread evidence of natural avalanches on all aspects. DISCUSSION: A foot and a half of heavy new snow Tuesday (15th) and early Wednesday (16th) has set off soft slab avalanches on all aspects visible in the Tuolumne area. Most slides occurred on steep terrain or started in steep areas and ran on mellower slopes. Shovel tap tests on this new snow showed unconsolidated snow which disintegrated with every tap. A Rutschblock test was much more graphic and mirrored the nearby avalanches easily producing a 22” deep soft slab of new snow which slid after several deep knee bends. These tests were done on a N aspect at 9,900 ft. on a 36º slope just north of Johnson Peak. WILDLIFE: Early last week we heard, then spotted, a lone Canada Goose flying north high over Glen Aulin. It was the first such sighting this winter. A week later we heard, then saw, a flock of about 50 Canada Geese flying high over Quarry Peak from the west then turning north. Migration? WEATHER: (from Feb 3 to Feb 8) SKIING CONDITIONS: Three inches of new snow have softened the variable conditions. AVALANCHE/SNOW CONDITIONS: (above 8000’) Avalanche danger is generally MODERATE, be aware of wind slabs which may have formed in last week’s steady NE winds. DISCUSSION: Other than possible wind slab development waiting for a little more weight to break up and slide, conditions appear to be relatively stable. WILDLIFE: With the usual coyote songs the neighborhood sounds have been repeatedly familiar for the past few months. The other day we heard a distinctly different bird sound that was very common last winter but noticeably absent this winter. A flock of Cassin’s Finches were checking out the Lodgepole Pines which provided a variety of seed eaters with a bumper crop of pine cones last winter. WEATHER: (from Jan 27 to Feb 3) SKIING CONDITIONS: Variable conditions from wind blown to wind blasted with plenty of heavy but smooth powder hidden in the trees on shaded aspects. AVALANCHE/SNOW CONDITIONS: (above 8000’) Avalanche danger is generally MODERATE but, with a strong potential for slab avalanches from recently developed wind slabs. DISCUSSION: We received just over two feet of new snow in the last storm series which ended early last weekend (Jan 29). The last 19” of that snow was as light and fluffy as we have seen this winter and it came down with very little wind. Shortly after the snow storm a steady and often strong wind started to blow from the NE and continued day and night for the next five days. Snow banners off the ridges and peaks were common and snow transport was in full swing. The formation of wind packed slabs would be dangerous enough in itself but, in some areas the slabs formed over the initial light snow fall giving the slab something to collapse on, an unfortunate situation for the unaware skier. So look out for these softly supported slabs they come in all sizes. WEATHER: (from Jan 19 to Jan 27) SKIING CONDITIONS: Fresh snow on a firm base. Trail breaking is boot top with some more snow expected before the weekend. AVALANCHE/SNOW CONDITIONS: (above 8000’) Avalanche danger is CONSIDERABLE with just under a foot of new snow poorly bonded to a firm base. DISCUSSION: On Wednesday the 26th at 10,000 ft., NW aspect just north of Johnson Peak our snow pit results showed a weak bond between the 9” of new snow and the previous snow surface which has been basking in the warmth of last weeks high temperatures. Although a crust was not detectable at this spot a density change is obvious producing easy consistent shears with just several taps of the fingers on a “shovel tap test” on a 32º slope. Ski cutting on shorter steeper slopes produced sloughs of new snow. WILDLIFE: A large grey bird caught our attention flying through the Meadows one morning this week. A tiny bit of the river was open and large bird tracks lined its edge solving the mystery: either a teridactyl or a great blue heron. With the Mono Basin blanketed in fog it seemed more likely that a heron would fly up here for some sunshine and a little ice fishing. WEATHER:
(from Jan 13 to Jan 19) SKIING CONDITIONS: Trail breaking is generally boot top or less, heavy snow midday with warm temperatures and probably soon to be crusty but not a deep breakable crust since the snow is so firm. Today (Tuesday the 18th), the snow surface was 32º and a few inches below it was 26º providing an epoxy combo for snow adhesion to ski bottoms. Remember your favorite anti-stick formula and put it in your pack. AVALANCHE/SNOW CONDITIONS: (above 8000’) Avalanche danger is MODERATE with increased risk during and just after warm periods. DISCUSSION: We have seen many rollies and pinwheels off trees and rocks with the warming temperatures but so far very few sizable slides. Many of the granite domes are showing crevasse-like glide cracks indicating the gravity stress of all the new snow. A test pit on Tuesday the 18th near Fairview Dome (NE aspect, 42º slope, 9200’) showed little reaction to a stuff block test (repeatedly dropping a 10 lb. sack of snow on a shovel sized snow column from progressively further heights). In the first 17 days of January there were nine avalanche fatalities in almost as many incidents in the western United States. One was a snowmobiler and the rest were snowboarders or skiers. I suggest that you take a look at the accident reports at http://www.avalanche.org/av-reports/. Many of the big avalanches in the past few weeks involve a similar snow pack layer (old buried faceted snow from November) that exists in this part of the Sierra today. Our milder weather has saved us from wide spread action upon this layer though we will be skiing upon it all winter. Also note the conditions and choices surrounding these accidents. Much closer to home is the story of an avalanche breaking legs but sparing life just outside Mammoth Lakes, see story at www.sierrabackcountry.org . WILDLIFE:
During the stormy weeks of the New Year we began to feel that there
was very little wildlife out and about. Now after a few snowless days
and much snow settling the snow surface is a mélange of animal
tracks with many stories told or yet to be interpreted. From a mouse’s
last journey ending under owl wing marks to the twists and turns of
a predator following its nose. January
6, 2005 December 29, 2004 SKIING CONDITIONS: Ahh… fresh snow! The snow is finally soft and quiet again after weeks of loud, crusty snow. Expect to be breaking trail in over a foot of fresh snow with more predicted throughout the coming days. AVALANCHE/SNOW CONDITIONS: (above 8,000’) Avalanche danger is HIGH with natural and human caused snow slides likely on most steep slopes. Slab avalanches will likely occur on lee slopes where wind has deposited soft slabs on top of a recrystalized snow layer or hard sun/wind crust. DISCUSSION: At last, some new snow. On Monday the 27th we received a couple inches of new snow. On a midday tour near Cathedral Peak we found lee slopes at tree line up to six inches deep in fresh wind packed slabs with the air full of blowing snow above tree line. Tuesday the 28th we received over a foot more of new snow with some of the same high winds. A snow pit test north of Johnson Peak (late Tuesday) just below tree line showed a clean shear at one of these wind packed layers within the fresh snow. More new snow is expected in the coming days. WILDLIFE: Coyote tracks become more concentrated as the snow deepens and their movements become more conservative. We mentioned earlier that coyote scats seem to indicate a steady diet of Juniper Berries once the snow blankets the ground and many small mammals are hibernating or living under the snow. In November we came across a small back water of the Tuolumne River full of fingerling fish very visible through the clear water. There was a multitude of tracks and the edge of the ice was broken. Often we follow coyote tracks across snowy stream crossings because they are sensitive to weaknesses under paw. WEATHER:
(from
November 24 to December 16) SKIING CONDITIONS: Our feet have seen more sand then snow the last couple of weeks but you can now expect weekly updates the rest of the winter. Ski conditions above tree line are generally firm on some variation of wind packed snow. As you get below tree line the snow varies from sun crust over powder on south slopes to a lighter crust over deeper powder in more protected areas. AVALANCHE/SNOW CONDITIONS: (above 8,000’) Avalanche danger is generally Moderate above tree line. Avalanche danger on steep north slopes near tree line is Considerable with wide spread instabilities and slab conditions. DISCUSSION:
The snow pack at tree line and below shows a very consistent weakness
down 10”-18” were the snow density changes drastically from
one finger/pencil (penetration) hardness to fist hardness (very soft).
This is the layer that has been whumping with some consistency from
tree line down to Tuolumne Meadows as large areas of snow settle around
your skis. This top slab forming layer of snow is very obvious in the
accompanying photo. WEATHER:
(from November 18 to November 24) SKIING CONDITIONS: Ever have one of those Mondays when your party (of two) breaks three ski bindings or the equivalent? Fortunately our tough luck has little to do with the snow conditions. The snow is firm in the open and on south slopes. The firmness is reflected in the fact that our snow stake has only fluctuated 2” in the last 2 ½ weeks. The powder (recrystalized snow) varies from a skiff to over a foot in protected areas near tree line. Above tree line the wind has been at work to leave a very sculpted snow surface with some pockets of wind slab and some very skiable wind crust. Skiers coming up Snow Creek said they hit skiable snow between 7,000’-7,500’ while the Lee Vining approach is patchy until after the Tioga Pass Resort (due to some previous snow removal, not lack of snow). AVALANCHE/SNOW CONDITIONS: (above 8,000’) Avalanche danger is generally Low to Moderate with the possibility of human triggered slab avalanches on steep north slopes particularly around tree line. Look for an increase in avalanche potential with any significant snow fall. DISCUSSION: Several days of strong north and east winds loaded lee slopes around the 20 & 21 of November. In the weeks to come our present snow surface could be a major factor in snow stability. Presently the snow surface on south aspects is a firm sun/wind surface and a wind packed and/or layer of recrystalized snow on near north aspects. We did find a persistent weak layer about 8” down in a test pit on the north side of Unicorn peak at tree line. It was a soft pocket (four finger density) below a one inch ice layer. WILDLIFE:
We have seen bear tracks at the upper end of Lyell Canyon and at tree
line on Unicorn Peak. Most of them are several days old but the snow
reveals their presence regardless of the wintery conditions. WEATHER:
(from November 4 to November12) SKIING CONDITIONS: Conditions have varied widely, mostly with elevation, but snow coverage and base is exceptional if you’re looking at the calendar. Early in the week we received 3 inches of soggy snow at Tuolumne Meadows (8,500’) while above 10,000’ the same storm put down about 10” of new snow. We still deal with lots of transitional snow this time of year so don’t forget your nonstick formula for your ski bases, whatever it may be. AVALANCHE/SNOW CONDITIONS: (above 8,000’) Avalanche danger is generally Moderate with the possibility of human triggered slab avalanches on steep slopes. Any dome or slick rock granite areas with measurably snow have Considerable avalanche potential. DISCUSSION:
On the 4th of November we received 9” of new snow. The wind commenced
to blow for the next three days from the east and northeast loading
most west or near west aspects. On the 7th & 8th we received a wetter
storm with winds from the west and southwest with snowfall considerably
deeper above 10,000’ (about 10”). We saw a lot of rollies
and small sluffs as this sticky snow released from steep rocky areas
the following day. We saw one class 2 avalanche from this snow on a
NE slope at 10,400’. A snow profile on the 9th near Johnson Peak
(10,500’, NW aspect) showed a weakness at 8”. A Rutschblock
test produced a uniform 8” deep slide after one jump of a 125 pound
skier on a 33º slope. The weakness occurs at a density change between
snow layers. WILDLIFE: The wet snow fall we had earlier in the week seemed to bring out an abundance of snow bugs. As we skied protecting our faces from wet snow and wind the snow surface was active with beetles, spiders, and long legged insects. We have seen all these crawlies before but it struck us as a harsh time to be cruising the snow surface. Perhaps the pollen and spores that are their food source were abundant on the snow surface but beyond our vision capabilities. Or perhaps nasty weather is a good time to avoid being picked up by a bird. The Rosie Finches we saw last week picking up bugs off the smooth new ice of Evelyn Lake would not have been running around on this blustery snow surface. We also saw a Black Bear print near Mammoth Meadow, a good reminder to keep up your good food storage habits. WEATHER:
(from October 28 to November 4) SKIING CONDITIONS: Warm and cold temperatures have provided a variety of snow conditions from crust to powder. Several days have had periods of “terrible transition” when parts of the snow are thawing and other layers are freezing (a recipe for sticky skis). This morning Nov 4th, our world has changed with 9” of new powder. AVALANCHE/SNOW CONDITIONS: (above 8,000’) Avalanche danger has slipped back up to Considerable this morning with 9” of new snow on thaw and wind crusts. DISCUSSION: If you thought winter came early this year, you were right. Our weather records guru, Bob Gregg, tells us that October was the snowiest and wettest on Tuolumne records including a 24 hour snowfall record. The snow pack is already reflecting this snowy history with layers and events to keep track of. There is a definite thaw crust and in some areas wind crust below this new 9” of snow. The next layer to watch is down about 10” where a change in snow density still shows some shear weakness. The building of cornices and noticeable wind slabs from southwest winds are another part of the early winter snow history. WILDLIFE:
We had several up close and personal sightings this week. One occurred
on our way to vote (absentee). Near Tioga Pass a mouse came scurrying
across the open snow to arrive at Bruce’s ski boot and perch there
for some time before checking out the length of one ski and then the Bruce &
Tracey,
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