Ghost Town Notes

It's astonishing to have Yosemite Valley empty of all but a few hundred staff residents at this time of year. No traffic, no buses, no parking issues, no crowds on trails. It's just running water, greening plants, singing birds. Is this a glimpse of what it was like in the historic past? Or might it be a vision of a future when most people visit Yosemite through virtual reality?

The paved roads are still here, all the built environment of hotels, shops and all the housing for 1500 employees and their families is here. The infrastructure stands ready to host 4 million visitors - so this is very different from what Hutchings or Monroe would've seen for a Valley without lines of cars and acres of parking. The Valley is most like a ghost town now; all but abandoned in what should be busy season. The isolated community is getting out a bit on trails and its fun to see families biking around the safe, quiet roads.

The Valley has been populated by the usual suspects who've slipped past the gates: tanager, oriole, peewee, MacGillivray's, grosbeak, violet-green, etc. After a rainy April, then a hot stretch, the Merced River peaked at healthy 3500 cfs on 30 April, and it's dropped back to average now. This weekend's heat will bump it up again, but the usual annual peak for our river is the third week of May; can't say for sure yet, but we seem to be early. Tenaya Creek went around both sides of the footbridge near North Pines, partly due to a big logjam just downstream. Sentinel Creek flows in just 3 of its potential 8 channels, Eagle Creek and Horsetail Creek are dry on the Valley floor. Indian Creek flows only in its main channel, with none of its common leakage in the Village. Ribbon Creek flows in all four culverts under Northside Drive but isn't leaking into El Cap Meadow. Wosky Pond is quite small, only 15-20m long. Bridalveil Creek flows strongly, and all but overcomes the noise of machinery working on the access improvement project there. The 1 May snow surveys show 54% of average snowpack water content in the Merced watershed and less in the Tuolumne. The spring rains at lower elevations have produced an exceptionally thick growth of grass and forbs - which will be come a lot of fast fuels in another month.

Clarkia has started blooming west of the park and dry canyon slopes mean that the foothill growing season is tapering off. The corona pathogen hasn't reached into the park as far as we know and it is not at all tapering off in the state. There are only guesses about when Yosemite will reopen for visitors and what limits on visitors there might be. We'll all need to be patient for a while before re-populating this ghost town.

Wet Spring

After another very dry winter, Yosemite has had a bit of recovery with a wet spring. We had warm storms in March and April and are now enjoying a string of about 10 days of cool, cloudy afternoons. The first weekend of April we had the markedly unusual experience of a very late, warm, winter-scale storm. This atmospheric river brought high elevation rain instead of snow, a flood forecast, and a successful pre-emptive evacuation of Yosemite Valley. Sure enough, the Merced River came up through the campgrounds, over the roads, through Housekeeping Camp, and filled the meadows. NPS has nice footage online. There's a persistent myth that these 'Pineapple Express' storms melt a lot of snow, but they really don't. It's the high elevation rain over thousands of acres of bare rock and thin soils that fills the river. This flood event wasn't from a 'monster' rainstorm, just a pretty big storm up high. Lower elevation side streams barely rose, compared to what the river did.

Because of the poor winter and the late-season rains, our springtime runoff peaked a month ahead of normal. The Merced and the waterfalls are already declining in volume, especially with the cloudy conditions we've been having. The clouds are delaying our minimal runoff a bit, which will help waterfalls last and forests to stay watered a bit further into the summer.

The park is still busy felling hazard trees, the small portion of our dead trees that might fall on people/roads/infrastructure. This year's below-average precipitation and above-average warmth will continue to stress Sierra forests (over-thick with trees due to decades of fire suppression) and we'll see more of the weak trees succumb to native bark beetles. Despite changes in Washington, D.C., the NPS in Yosemite is sticking with science and is not dodging the reality of climate change in its training of new rangers. The climate IS changing, it's changing NOW, in ways more rapid than ever, it is because of OUR hydrocarbon use, and it'll have serious consequences for US. It's disappointing that some political leaders think they know more than NASA or the National Academies of Science. Among other things, our fire season is longer, more severe and is costing us all more money to deal with. I'll be heading up to Lyell and Maclure Glaciers with Yosemite Conservancy groups in August and I expect to see those small ice bodies closer to leaving Yosemite entirely glacier-less.

Luckily, because we are causing the current rapid changes in climate, we should have some influence over it. Let's work to reduce our mistake and bring back snowy winters.

Post-winter Recovery

Springtime is making its way uphill in the Sierra with redbud peaking in El Portal now while unfathomable snow persists above 7000 feet. It can hardly be said enough: WHAT a winter we've had here! Storms were repeated with good frequency and lots of Pacific moisture, leaving us with a tremendous snowpack. The snowline was a bit higher than historical averages; not much accumulated in Yosemite Valley (though we had lots of rain runoff), but higher elevations have had fantastical quantities. The central Sierra has 175% of usual water content in the current snowpack. Picture the meadows and forests in the May Lake area buried by 6-7 feet of water (not 6' of snow, but 6' of standing water) - that's the nature of how much mature, dense snow is covering the tens of thousands of acres of Yosemite's upper elevations.

<-Bridalveil in flood.

Storm damage has been considerable in/near the park, with Hwy. 41 having been closed for a month by a washout, and crews working hard to repair slope movement on the Big Oak Flat Road below Crane Flat in hopes of getting it re-opened before Memorial Day. Trails at and above the Yosemite Valley level have a lot of downed trees; trail crew sawyers will be very busy for much of the summer to get those cleared. When you visit the Valley, check out the fragments of bark-less logs below Bridalveil or Yosemite Falls from trees that were uprooted and thrown over the falls this winter. Since December there's been a huge deposit of frazil (wist) ice below Yosemite Falls, and we're now in the month when one is most likely to be able to observe wist ice flowing.

The excitement isn't over. Because of the closure of the Big Oak Flat Road, Hwy. 140 has been handling much more traffic. This past Saturday, visitors were waiting over 2 hours in a 3.5 mile-long line of 800+ cars just to get through the stoplight at the Ferguson rockslide detour west of the park. (Easily avoided by coming in before 9am on weekends.) Because of the road construction in the Valley, the main parking at Yosemite Village will be closed for the next two months, and detours are confusing to both new and veteran visitors. It's going to be a very nice improvement once it's completed, but parking and navigating can be challenges on spring weekends now. Half Dome Village and the new lot by Camp Four are best bets. The road crew is already working to clear Glacier Point Road.

But, wait, there's more. The Merced is running almost 4x average flow today. All that snow in the high country seems likely to bring us some degree of 'high water incident' between now and mid-June (sure to cover some Valley trails at least), depending on how the warming progresses. Yosemite explorers should expect a delayed start to summer, with Tioga Road opening late, trails covered by snow and fallen trees, and creeks difficult to cross.

High Water 2017

I am quite impressed with NPS preparations for anticipated flooding in the next couple of days; this is much different from the surprises of 1997's flood. Forecasting has been honed and there's institutional memory of the last big one.

As of last evening, all visitors have been evacuated from the Valley. Staff housing in the Half Dome Village area has been evacuated and all other locals are being told to stay put as of tonight. Peak flow is expected late in the day on Sunday. Projections are for about 17,000 cfs at Pohono Bridge, where the Merced exits the Valley. Average river flow for this time of year is about 100 cfs, and because of this week's rain the river is carrying 572 cfs right now. Again, that projection is for the river to increase to 30 times the current flow by tomorrow evening. We had a flood warning in mid-December but the river didn't quite reach 5000 cfs; it needs to get to about 7000 cfs before the water comes up on to a road in the Valley. The river would first gently back up on to pavement at Wosky Pond on Northside Drive.

If we do get to 17,000, this'd make it the 6th biggest recorded volume for the Pohono gauging station. The bigger events were the floods of 1937, 1950, 1955, 1964 and 1997. Five 'big' floods in a century averages to every other decade or so. What some locals parochially call 'The Flood' of twenty years ago was only a little bit bigger than those other four were, and such floods affect far more than just Yosemite. There was no gauging station in 1862, when the Merced surely exceeded its 1997 size in a mega-flood that wrecked the whole state.

All these high water events happen December-February and are due to warm storms, which bring rain to high elevation instead of snow. There's a persistent myth that the 1997 flood was due to rain melting recent snows, but the science says that rain doesn't melt very much snow. The floods happen simply by high snowline causing tens of thousands more acres of watershed to receive rain. Especially in higher terrain with thinner soils and vast expanses of bare granite, that rain just runs off right away and swells the rivers downstream.

I share Muir's enthusiasm for such events; he witnessed and wrote about the flood of December 1871. While I shelter in place, I look forward to seeing the video record collected by the professionals.

Heat and monsoon

It's been really hot in Yosemite for the past week, with Yosemite Valley temperatures in the high 90's (but only the high 30's for European visitors...)
While it feels like El Portal could just burst into flame at any moment (it's been up to 110 degrees) the park has been having a surprisingly light fire season to date. The Cascade Fire, east of Crane Flat has been burning quietly for two months now and is still not quite 700 acres. There's a small lightning-caused fire at the top of Vernal Fall and another tiny blaze near Porcupine Flat.
Monsoon moisture that's come in with the heat has made for great cloud shows ("higher Sierras" in Muir's words) recently. You can partake via webcam without threat of hail or lightning. The Merced River has actually doubled in volume in Yosemite, right up to a normal/average flow, because of the upstream rains. A bit of rain fell in Yosemite Valley and west yesterday afternoon - what a pleasant change.
We look forward to the southward migration of birds of prey over the next several weeks. Michael Ross will lead a field seminar on September 8 for those who want to observe this annual phenomenon in the high country.

Vernal Equinox

Equinox arrives next week, when day length matches nighttime. Though they were closest on Monday night, it's still worth getting out in the evening to see the close positioning of Venus and Jupiter. They're a bright pair, impossible to miss as long as you have a view to the west for an hour or two after sunset. (You can actually see Venus with the naked eye all day, too, if you know where to look in the blue sky.) Though smaller than Jupiter, Venus is the more brilliant because it is closer to Earth.
Light precipitation off/on in Yosemite this week, with snow level remaining above the rim so far. We expect snow on the Valley floor this weekend. In the Merced Canyon below the park boundary, greenery is soaking up the moisture; great numbers of flowers are in bloom. Dense poppies cover the south-facing slopes in the area burned by the Telegraph Fire of 2 years ago. In contrast, last summer's Motor Fire area is generally not greening up well. Buckeyes are leafing out, elderberry leaves are barely emerging, and redbuds are just starting to show.
The waterfalls are below average in volume now, but it's good that we're adding some fuel this week for later runoff.
Contractors lucked out with dry weather and have re-opened the Big Oak Flat Road (connecting Yosemite Valley to Hwy. 120).
Superintendent Neubacher is contemplating adding more sister national parks - one on every continent is a goal. Asia and South America are already covered. We like the idea of Yosemite having this measure of global significance and await news of coming partnerships (and opportunities for travel to visit new relations.)

Hint of Winter

It's been both a challenging and a welcome return to stormy winter weather over the past several days in Yosemite. Tioga, Glacier Point and Mariposa Grove Roads closed last week, we got rain and snow, and the waterfalls picked up in volume. It snowed a couple of inches in Yosemite Valley yesterday, then clearing sky and swirling clouds at sunset made magic.
Ranger Ryan Hiller was killed by a treefall during the rain and high winds over the weekend. Ryan spent much of last summer patrolling the busy Half Dome trail corridor and was planning to work at our ski area this winter. He was the 10th known person in park history to perish in this manner and his loss is deeply felt by all of us here.
On Sunday night a section of the north canyon wall above the Big Oak Flat Road came loose and wrecked part of that highway between the Merced River and the Foresta turn-off. The slide is below the 3 tunnels, includes a lot of smashed live oaks and some very big boulders. Moving the debris is one thing, but the roadbed itself has been broken through and pushed downhill. NPS has posted pictures on their Facebook site. I'd guess that this will take at least a few weeks to reopen. There is some Sherwin glacial till in that area but this slide looks like all talus and cliff material.
Badger Pass got about a foot of snow and groomers have been working on the slopes. Warm weather the rest of this week will not help retain this base, but -you hear it here first: all Badger Pass operations will open on Thursday.
UPDATE: The Big Oak Flat Road reopens Saturday 28 January! Amazing work by NPS Roads to make this repair. Caution: unpaved gravel surface in the slide area.

Equinox approach

Autumnal equinox arrives Friday, then it's already October at the end of next week. We had 5 days of afternoon monsoons a week ago, a fun change of season, but summer's heat is not done yet. Mts. Dana and Gibbs were quite snow-covered a week ago; Conness is pictured. Hail had piled up at the 8000' level along Tioga Road. A cloudburst in Yosemite Valley left big puddles that haven't evaporated yet, and lots of runoff debris in small channels everywhere. A torrent coming down the Indian Creek fan went into some NPS houses at the edge of Yosemite Creek. The river gauge shows nice spikes from the series of rainy afternoons.
As it has been for most of the past 9 months, the Merced is running above average: at 129 cfs this morning; the average is 32 cfs for today. Yosemite Falls looks like it does in some Julys; not big, but much more than the usual September dribble.
Lessingia's purple blooms on the Valley floor are even visible from Glacier Point. Bears are still finding ripe apples on trees (lots at McAuley Ranch) but it's a weak mast year for acorns in some spots. Migrating raptors are being seen regularly now. A ring-necked snake was seen near Foresta on the weekend.
Another Half Dome fatality yesterday; this time a climber whose rope broke after he pulled a block onto it. Crowds are absent from the Valley most days, though weekends are still relatively busy. Our visitors from other countries stand out more now.

Hecka Weather

We've had a terrific storm over the past few days, with more to come. It started raining Friday and has stayed wet since; Yosemite Valley has had more than 8 inches of precipitation (20% of the year's average total) in the past 4 days. Until this morning, it's all been rain, with high snowline; even Badger Pass got a soaking. This has brought up the waterfalls and flooded the Valley meadows. The gully below Cathedral Spires again surged out into Southside Drive. Sentinel, Ribbon, Eagle, Horsetail and Royal Arch Creeks (but not Indian Creek) are all flowing into the river. Wosky Pond is full and connected to the river. The river itself never approached flood stage, as had been threatened in earlier forecasts.
It was cold enough this morning to have frazil ice forming in Yosemite Creek; unusual for this point in the season. The Valley got over 6 inches of snow today, and Badger's gotten a lot more than that. The picture shown is from a walk up to the Vernal Fall Bridge this morning.
For more than a year I've been looking forward to tonight's astronomical coincidence of the winter solstice and a full moon - with that moon showing a total eclipse over North America. On top of that, the peak totality for our part of earth will be just after midnight, providing the potential for a nice long show. Now it appears that clouds over Yosemite will eclipse the dark orange midnight moon for us. As always, a lunar eclipse only happens with a full moon. A full moon always rises near sunset, is highest near midnight and sets around sunrise. That this full moon (and eclipse) happens during the longest night of the year and with totality close to midnight/overhead is just a happy accident. Whether we see the moon or not, winter solstice means that the days will start to lengthen toward summer - indeed an important date in the calendar.