Wednesday, October 21, 2015

Merced Nadir

Rain and snow over the weekend have brought the Valley's waterfalls back from the dead. Bridalveil, Staircase, Royal Arch, Snow Creek, and Yosemite Falls went from trickles or dry rock to photogenic surges overnight. On Sunday, some of us witnessed Mirror Lake going from dry sand basin to reflecting Mt. Watkins in a matter of moments as thousands of gallons per minute poured into the lakebed in a flash flood. There are six inches of new snow along parts of the Sierra crest.

The Merced River is typically at its lowest point for the year at the end of September. Until these rains, it was continuing to drop, running at about half its normal low flow. The river and waterfalls are dropping again now as the rainfall runs off; the Merced is very muddy due to erosion from steep areas that have burned in the past two seasons.

Despite catastrophic blazes elsewhere in California our fire season in the park was mild; several early July lightning fires crept slowly along the forest floor for months at healthy low intensity. A few human-caused fires were contained before they got too far. A good stretch of the Valley floor's south side continues to smolder from last week's prescribed ignition.

The San Francisco Chronicle featured Tom Stienstra's cover story about the disappearing Lyell Glacier last Sunday; the best version is online only for subscribers but you can see a PDF of the print edition here. It'll be interesting to see what sort of layer this El Nino winter brings to the glacier; even if it's huge, it'll only delay the terminal decline briefly. I look forward to bringing a group (or two) of very fit backpackers up there late next summer to have a look.

My summer was VERY busy with lots of good stuff (Lyell Glacier, Switzerland, Half Dome, etc.) but now I look forward to resuming more frequent posts here.

Wednesday, June 10, 2015


Spring came early after our non-winter. So far, 2015 is California's warmest year on record, and the Sierra has one of its weakest snowpacks. Light storms over the past two months have left recent snow at the Sierra crest, have kept the Merced from bottoming out, and have delayed the blue-skies-til-October summertime that we expect for Yosemite Valley and below.
In the past two weeks I've enjoyed being rained on, snowed on and hailed on. These storms are not overcoming general drought effects, however: the Merced is flowing at about 1/5th of average volume and dead ponderosas greet visitors ascending from the foothills.

While you may read simplistic headlines that beetles are killing trees, they can only do this because the trees are weakened by drought and in some cases had been further stressed by a history of fire suppression. Preventing periodic ground fires allows too many trees to mature, each challenged by competition with too many neighbors. Regular low-intensity fires thin out young trees so that survivors are stronger and more resilient to drought and therefore to beetles.

On top of a precipitation deficit, warmer temperatures and an increased proportion of dead trees, these intermittent moderate storms have grown more light fuels - the kind that dry quickly and burn fast. Indications for an active fire season are worrying. For the moment, the wildflowers are still nice up and down the Merced corridor: globe gilia, LOTS of Clarkia, blazing star, tarweed, Datura, etc. Buckeyes are fading. There are still a few bright dogwoods in their highest, shadiest locales (Tuolumne Grove, Chinquapin).

Looking further ahead, strong El Nino conditions are shaping up in the Pacific and though there's no guarantee, we may have a wet winter coming.

Wednesday, March 4, 2015

Candy Weather

We can call it 'candy weather' because it is yummy/nice in the moment but we know that in the long term this dry, warm, sunny winter isn't good for us. We had a couple small, warm storms in the past two weeks but it's almost a month since our biggest storm (rain). Up on Clouds Rest(9960') the other day there were no clouds, no crowds and almost no snow. This photo from near the summit shows two snow-free roches moutonees on the left and some other dome.

Buckeyes are green, redbuds are pink in the Merced Canyon west of the park. More flowers are blooming and there are a couple of slopes with hundreds of poppies out.

The Merced River has slowly dropped back below average flow after the storms of 6-8 February and it continues to shrink. Yosemite Falls looks good, but at this rate it won't be much in July. Vernal was 3 modest strings yesterday and some ground squirrels have already been active at the top of Vernal for at least a week.

March 1 snow surveys show the Merced watershed's snowpack with 12% of normal water content. Candy is good; candy is bad.

Monday, February 9, 2015


The park has had good wet storms the past several days, but they brought much more rain than snow. Snow levels barely dropped beneath 7000' and not much more than slush was deposited below 8000'.

The rain runoff from up to 8000' in the watershed is departing the Sierra, rather than lingering in the ecosystem the way snow and snowmelt do. The Merced River leapt from a paltry 55 cfs at Pohono Bridge to an exceptional 2500 cfs last night, and is dropping as quickly as it rose. The current river volume from the high elevation rain is larger than any flow in 2014. Unless there is more snow in the next couple months, we wonder if this warm storm might be 2015's high water mark. A splash of mud and rock from the area of last summer's Dog Rock Fire closed Hwy. 140 above El Portal for a few hours this morning. The Merced and the South Fork are both turbid brown. Yosemite Falls is BIG, but there's no snow cone.

The lower canyon, west of the park is lush with bright moss and new plant growth. In bloom now: small numbers of shooting stars, poppies, a couple mustards, paintbrush, a saxifrage, more popcorn flower and fiddlenecks and abundant filaree. In favored spots the waterfall buttercups number in the thousands. Buckeye and elderberry leaves are emerging.

It is another odd winter of the new normal.

Wednesday, January 28, 2015

January in Little Yosemite Valley

Mild, dry conditions allowed an easy visit to spend a couple nights camped up in Little Yosemite Valley. Only in shady spots and north-facing slopes was there a bit of shallow (icy, packed) snow; the ground is otherwise bare at 1830m. Nights were below freezing, days became comfortable in shirt-sleeves. There were many interesting things about this trip.

First: there was almost no one in this most popular backpacking spot. The LYV campground has dozens of people in it every night during the Half Dome season; it was a strange delight to experience it when completely empty.

Second: there were tiny frazil ice deposits in several places below Nevada and Vernal Falls, but in Emerald Pool the accumulation was up to 2 meters thick and covered 3/4 of the pool. These flows are remnants of the cold spell around New Years.

Third: last summer's Meadow Fire has completely changed the character of LYV, leaving it open and bare, but for black trunks. The campground area is unburned but a few minutes walk beyond there is a different landscape that's going to be a hot, sunny stretch in the summer, all the way up through Lost Valley.

Fourth: the little-known logjam in LYV has burned. This jam is upriver of the campground area, consists of several hundred tree trunks that have blocked the Merced River for many decades. It's big enough that it stayed in place during the flood of 1997. The jam is still there but the fire must surely have affected its stability.

Fifth: Consistent with the absence of people, there were none of summer's Steller's Jays in LYV.

Wednesday, January 14, 2015

June-uary Again

The autumn's nice sequence of storms has faded to a string of mild, dry weeks. Snow is patchy at 6000' and Badger Pass (or might we be changing it to Munroe Meadow?) Ski Area has just enough snow coverage for a little longer. The storms we had Oct-Dec had high snow lines and our snowpack is less than half of average. The Merced River is also running at about half of average flow. Yosemite Falls is looking good, but the watershed is now burning through what should be March-May runoff. The snow cone beneath Upper Falls is modest and shrinking. The Sierra's drought continues.

Waterfall buttercup is blooming profusely in its usual spots in the lower Merced Canyon. Parts of Scorpio and the Summer Triangle are visible in the pre-dawn skies over the Valley walls. Much media attention is being paid to climbers on the Dawn Wall these days as an extra tricky ascent of El Cap is about to conclude after 2.5 weeks.

The media had also been reporting on the ownership of the names of the park's commercial operations like Curry Village, Wawona Hotel, Yosemite Lodge, etc. It would seem odd to have to buy these names back or to change them. Alas, they're just hotels; they're not Yosemite. Though traditional, the labels on ephemeral infrastructure shouldn't matter too much in the long run. No one worries about the Stoneman House, Camp Lost Arrow or The Cosmopolitan any more and "The Ahwahnee" will not last forever. The real and enduring beauty of these mountains is a gift that can never be taken away.

Thursday, December 11, 2014

Pacific Bucket Arrives

An interesting wave of warm air came up the canyon this morning, ahead of this big storm. So far, just a bit of rain and snow in the park today, but we anticipate a serious pouring tonight. There were light flurries in Mariposa Grove around noon today, but more impressive was (the near absence of visitors and) the strong upslope wind. Sugar Pines bent more than the sequoias did, both species of giants looking like large ships riding out big swells at sea. Clouds move from the south, wind comes from the West.

Some of the media hype makes reference to an Ark Storm [sic] but that's not at all what this is. That term has nothing to do with a big boat; look up ARkStorm and prepare to be unnerved. When it comes (and it will) it's going to cause more damage and destruction than the biggest urban earthquake might. California (and the US) could not possibly be ready for an event like what happened in 1861-62 when infrastructure and population were a fraction of what they are today.

This storm will help add to our surface water and snowpack, but it's relatively warm; snow level may only drop as low as 6000'. We've had a decent sequence of fall storms (like 'normal') but the snow has remained high. The Merced River (and our waterfalls) bumped up to above average flow after last week's weather, but it's back down to half of average volume now.

As a measure of the season's warmth (plus its wetness), the Merced Canyon below the park boundary is nice and green, with several wildflowers in bloom, including cranesbill, Indian paintbrush, tarweed, gumplant, and Shepherd's purse. There's a big patch of fiddleneck flowering unusually early near the Ferguson Slide bridge (west end), and a patch of goldenrod blooming in the El Portal Fire burn scar up the Foresta Road above El Portal.

We expect a dynamic night and tomorrow, especially in the burned areas...