Equinox Arrives

Yosemite's weather is still quite warm, but is hinting at autumn. Though mild this week, there has been more frost in high elevation meadows and the bilberry is reddening.
-At the foothill edge of the park, redbud leaves are yellowing and poison oak is going bare. Higher up, dogbane and the green Ceanothus are both going yellow. No color yet in maples, cottonwoods or oaks in Yosemite Valley.
-An osprey has been seen regularly in the El Portal stretch of the Merced for about the past month. The river is running only 23 CFS at Pohono Bridge meaning fish have fewer places to hide. Naturalist Michael R. saw pintails in Tuolumne Meadows last week.

-We've all learned a lot about the epidemiology of the Sin Nombre Virus (Hanta) and about the reactions of people to unfamiliar threats in the past few weeks. It's a most regretable situation.
-The park geologist has measured surface velocities in the Maclure Glacier and the West Lobe of the Lyell Glacier. Though shrinking quickly, both are still living glaciers. The Lyell is moving so slowly that it may grind to a halt in just the next few years; while the surface is still sliding downslope it's possible that the base is already static on the bedrock.
-Though we had such a dry winter, we've only had one real fire this summer: the Cascade Fire, started by lightning in mid-June, just south of Tioga Road between Crane Flat and White Wolf. In 3 months of creeping along the ground it has burned only 1200 acres.
The park's Fire Ecologist Gus Smith will be leading an exploration of the Mariposa Grove on Friday 28 September. This program is open to the public and is sponsored by Yosemite Conservancy. As with all Yosemite Outdoor Adventures courses there is free park entry and free camping.
-Also burning are the stars of Orion in the east before dawn, creeping their way higher into the approaching night skies of winter.

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.

Raccoon Days

Dry 'raccoon days' of July have baked Yosemite. August's 'Dog Days' were named in ancient times when the Dog Star (Sirius, the brightest star in the constellation Canis Major -the big dog) became visible just before sunup. Though we can't see it yet in our deep canyon, this bright star is already rising earlier and earlier before the sun.
Before Canis Major and Sirius rise, the Little Dog, Canis Minor comes up from the east. The bright star in Canis Minor is called Procyon. This is also the genus name of the raccoon. The German taxonomist who gave our raccoon its Latin name in 1780 assigned this animal a ranking slightly preceeding dogs; Procyon means 'before the dog' and this also works with this star rising before Sirius. Therefore, perhaps we can stretch the astronomical story to say that Raccoon Days come before Dog Days. Learn more about the stars in our 10-11 August Tuolumne astronomy program.
As far as terrestrial wildlife, up until recently bears have been relatively well behaved this season; there have been fewer car break-ins than usual.
The Merced River continues to flow about 20% of normal volume. It could keep dropping for two more months but it's already less than half the flow of last year's lowest volume. The photo shows Bridalveil Fall in a wispy state this week.
We have one very modest fire burning in the park. It's near the headwaters of Cascade Creek, just south of Tioga Road and east of Tamarack Flat. Lightning started it in mid-June and it's grown to less than 150 acres over 7 weeks - seems almost as though fire just fits in here...

Interdependence Day

Sierra summer is at its finest now. Heat and blue skies make up our days, the waterfalls shrink, birds quiet down as they taper off feeding young that are fending for themselves, bears with cubs explore opportunities for their own kinds of Yosemite picnics. A little smoke in the air would complete the feel of the season.

The Merced River flows at just over 100 cfs in the Valley - normal for this date is over 600 cfs; a dry winter makes a dry summer and Yosemite Falls is a dwindling presence.
I was up at Summit Meadow along the Glacier Point Road this morning and had that pretty part of the park to myself for a while. Shooting stars, bistort and Bigelow's sneezeweed (yes, that's a fun name to say) are profuse now. Yellow-rumped warbler, Steller's jay, and a Townsend's solitaire added an aural dimension, but the voice of the hermit thrush coming from the dark fir forest is like nothing else in the Sierra. New fencing between the road and the meadow should help protect this sensitive spot.
From the far side of the world: Yosemite's Chinese sister national park, Juizhaigou, reports finding the first fresh panda scat in the park in over ten years. Giant pandas depend on bamboo which blooms, dies off and becomes unavailable for years at a time on a localized basis. Juizhaigou's bamboo has regrown to make it perfect panda habitat again. Perhaps the Conservancy may be taking another group of Yosemite-philes to hike in our two sister parks in China next fall.
Speaking of excitement, we are delighted that legendary Ranger Dick Ewart is leading two Yosemite Outdoor Adventures for people this summer: a 5-day trek from Tuolumne Meadows for experienced backpackers, and an off-trail dayhike to the top of Tenaya Peak. These are special opportunities to experience some of what makes Yosemite such a great place.

Solstice Dreams

Yesterday was our longest day for enjoying Yosemite. A thin trace of smoke from the 234-acre controlled burn near Hodgdon Meadow added dimension to the Valley skies - surely a sign that it's summer.
The Merced River would normally be flowing at over 1400 cfs at Pohono Bridge on this date; today is just over 200 cfs. Yosemite Falls is light, but still photo-worthy; it won't be in a few weeks, and it'll completely disappear in August. Mirror Lake still has water in it -as well as people in it, enjoying the gentle flow for cooling off.

Draperia, Azalea and Spicebush bloom in the Valley. Tanagers and both vireos are still singing; grosbeaks are quieter. Saw Vaux's swift over the Visitor Center yesterday. The Conservancy was a sponsor of last weekend's successful Mono Lake Bird Chautauqua - lots of birds and even more great birders.
The museum has a new exhibit in the gallery: historic landscapes that include Ayers, Moran, Jorgensen, Beirstadt and Obata. It's there to the end of September.
There was a 2.4 earthquake 16 miles beneath Crane Flat on Monday afternoon - an unusual place for this, but the Sierra is very much a living range.
Visitation has been busy but not as busy as last year when lots of media attention to above average waterfall flows drew extra crowds early in the summer.

The Conservancy has a wonderful art course coming up in mid-July: "Tuolumne Meadows Pastels" with Moira Donohoe. It's a great chance to improve some skills in a remarkable landscape.

Summer is On

Memorial Day weekend started with snow and road closures.

The holiday weekend featured the predictable crowded roads and difficult parking in Yosemite Valley and at Glacier Point. It's been an interesting experiment to try separate lanes for cars and buses in the east end of the Valley. I was camped near a quiet meadow where I saw no one, but a bear and a great grey owl. Such is Yosemite.

El Portal was in the mid-nineties all week, all grass and forbs are brown. The Merced River is running at 25-30% of average volume. The waterfalls are shrinking noticeably. Sentinel and Ribbon Creeks barely trickle to the river now, Woski Pond is down to about 30' at its widest point.

Birds and flowers are still plenty active. Two vireos, grosbeak, tanager, a few warblers, 2-3 flycatchers, and the hermit thrush are heard as you get up above the Valley. Seems like we've been seeing more Vaux's swifts in the Valley this season. Azalea is perfuming Valley meadows now, cow parsnip is opening. Dogwoods fade, but are still nice higher up. Noticed a monarch in the Valley this morning, as milkweeds are just starting to open. Pale swallowtails are abundant this year.

Tuolumne Meadows hosts artist Moira Donohoe in a pastels workshop in mid-July; should be nice time to get beauty on to paper with her there.

Farewell to Spring

Despite recent warmth, the Merced River has started to decline in volume already; it's running just below average (while the average is still ascending). We are excited to have our new webcam up, showing you Upper Yosemite Falls so you can keep visual tabs on the flows. We expect that by September this year it'll just be the 'Yosemite Wall' webcam.
Indian, Sentinel, Royal Arch and Ribbon Creeks all still run to the river. Eagle Creek has shrunk back from Northside Drive.
The high country along Tioga Road still has snow, lots of soggy trails, no new greenery - it's too early for dry, comfortable hiking that won't leave considerable impacts. People tend to hike outside wet trailbeds, creating new trails and crushing plants as they're trying to get started. Things will be drier in June and it'll be easier to LNT.
Yosemite Valley is alive with birdsong; yesterday's birdwalk included black-headed grosbeaks (plentiful and loud), western tanager, yellow, yellow-rumped, and black-throated gray warblers, Cassin's vireo, white-throated swift, flicker, oriole, Anna's hummingbird displaying in front of the Visitor Center, and more.
In the El Portal area the Clarkia (Farewell-to-Spring) is in bloom, as is buckeye, Ceanothus, and elderberry. Most of the grass and forbs have gone to seed and are browning. The dogwoods in the Valley are glorious right now.
Check out the eclipse of the sun on Sunday at sunset. We were not sure that Yosemite would be a good place from which to observe this spectacle because good western views from places like the Glacier Point Road might not yet be accessible; this year they are. Crane Flat Fire Lookout and Sentinel Dome will be prime spots.
For more enjoyment of the earth sciences: there's still space in our one-day geology course on June 16. Park geologist Greg Stock is a marvelous communicator and will clarify all those questions you have about Yosemite's origins.