So Autumn

The fall glow in the Range of Light is especially remarkable in Yosemite Valley these days. We are at that point in the sun's apparent migration in the sky when it sets very low in the west, in the skyline notch that is the Merced River Canyon. It's the analog sunset point to that which produces the 'firefall effect' at Horsetail Fall. That photogenic phenomenon happens about 7-8 weeks after Winter Solstice; we are now 7-8 weeks before solstice. The low sunset lets a more colorful sunlight into the Valley at the end of the day. (Horsetail Fall is just trickling now so won't produce the volume of mist/water that catches the light in February.)
In mid-summer the sun sets well to the north of the Merced's exit point, so is high over the canyon rim; in winter it sets high over the canyon wall to the south - in both cases setting when the sunlight is still whiter.
During the day, the sun is traversing a lower angle than in summer, too, but still reaches more of the Valley floor than it does in mid-winter. The Valley's deciduous plants are ending their growing season with the decay of chorophyll that allows other leaf pigments to shine before leaves drop to the ground. Big-leaf maples put on the biggest color display now, and these bands of yellow highlight their preferred wetter, shady habitat in ways that may not have been apparent all summer. The one sugar maple in Old Yosemite Village turned more yellow than red this year, and the afternoon up-canyon breezes have this tree already about 20% bare now. Black oaks are going brown-yellow but many leaves have dropped from some. Dogwoods are still largely green, but showing their startling pink in places. Black cottonwoods are mostly bare now. The brightest plant in the Valley now is dogbane or Indian hemp (Apocynum) - their radiant gold almost hurts one's eyes.
The meadows are a light brown, the fallen pale leaves cover darker ground, more sunshine reaches the ground through branches that are baring. Even ponderosas participate in this season, browning and shedding some of their needles after the dry summer. It all adds up to a lighter albedo. Though the days are shorter and the sun is lower, Yosemite Valley is reflecting more light and is brighter than it is all summer. Only the winter snow will raise the Valley's albedo beyond this dreamy, pale glow of autumn.
Incense cedars are raining their helicopter seeds now. Gray squirrels have been shredding pine cones for a few weeks and their litter of cone scales is everywhere. Been seeing more chickarees than usual in the Valley, also working over the ponderosa cones. Down canyon a bit, Torreya has been dropping its strange green fruits.
The Merced is running at about 80 cfs at Pohono Bridge and dropping since our last storm on 5 October (average for this date is around 33 cfs). Last evening the Valley rim was entirely mantled in a cloud layer that built just at sunset.

Foliage change

Rain ten days ago really swelled the Merced River. The historical average flow for last week was below 30 cfs. It had been running closer to 100 cfs, then leapt to over 600 after the rain. That the high country got snow showed in the nice 24-hour cycle of melt ebb and flow shortly after the storm. Our waterfalls are again looking exceptional for this time of year.
Ladybird beetles are on the move in this warm (moist) weather, with many swarming in El Portal the past couple of days.
A red-shouldered hawk, and a pair of great horned owls were heard in the volunteer campground in Yosemite Valley. A Say's phoebe was seen in Rancheria Flat.
Orion and Canis Major dominate the morning skies if you're out early and have a view to the south.
The sugar maple in old Yosemite Village has just started to show a tiny touch of color. At the Valley elevation, other than dogbane and some bracken, most color has not yet appeared. Alders skip the show and just start dropping their green leaves into the river when they're done, which is now.
Higher up you'll find aspen and bilberry being more colorful now. It should be a good weekend for getting out in the park.
Half Dome cables are down for the winter, Backpackers, Yosemite Creek and Crane Flat Campgrounds are closed for the season now.

Predation

Happy, Balanced Equinox.
The Yosemite Facelift is underway and there are hundreds of volunteers deployed all over the park to clean it up. It's a very impressive endeavor, started by Yosemite Climbing Association and successfully grown into a significant success story.
Tony Carlstrom reports observing a California ground squirrel wrestle, subdue and kill a chipmunk atop Sentinel Dome on Tuesday. The chipmunk's body was then dragged off by the squirrel. This kind of gruesome aggression is not something we generally expect from those little snack-beggars. I have observed California ground squirrels feeding on road-killed squirrels in Yosemite Valley.
Rangers at Hodgdon Meadow watched a mountain lion kill a mule deer buck a few days ago. Local bucks are still in velvet but have full grown racks. Lions generally prefer easier prey than large adults males approaching rutting season.
Red columbine still in bloom in the "Ice Cut" on the JMT near Nevada Fall, along with waterfall buttercups.
Afternoon clouds massing from the crest toward the west these past few days.

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.

Shake and Bake

We thought that last Wednesday's little earthquake here was exciting, then we had the Motor Fire come to El Portal on Thursday. The fire started on the highway, on the south side of the Merced River, jumped across to the north and quickly shot to the canyon rim. It moved east toward Incline and El Portal, but a heavy application of brute force firefighting in steep terrain (including use of the mighty DC-10 Supertanker) has contained this in a few days.
Now outside the Conservancy office in El Portal there is fresh handline, just a hint of smoke, and no helicopter traffic. Ground squirrels bark, acorn woodpeckers laugh their maniacal cackles, scrub jays squawk. A tanager was 'br-dip'-ing earlier, and a phoebe 'p-chew'-ing. Grindelia remains in bloom in El Portal and the pale turkey mullein is having a good year. The river is more refreshing than ever as canyon temperatures will remain near 100 for the week.
The Motor Fire is nearly out, but the Avalanche Fire near Badger Pass continues to smolder. Though the park was open and not too smoky, visitation plummeted during the Motor Fire excitement; people may have misunderstood the location/impact of the blaze. Maybe it'll be a somewhat quieter holiday weekend.

Founders Day

The National Park Service was established on this date in 1916, and today's Director is announcing big plans to prepare for celebrating the centennial in 5 years. In Yosemite we are also planning diverse ways to observe the sesquicentennial of the Yosemite Grant in 2014. This was when the US government protected Mariposa Grove and Yosemite Valley (yes, 8 years before Yellowstone).
There was yet another regretable fatality in the park early this week, when a hiker fell from the top of Half Dome, down the face. No official story for how this happened has been released.
Some of us woke to an earthquake yesterday (24 August). After anomalous quakes in the prairie of southern Colorado then near Washington, D.C. in recent days, it was a little more exciting to hear the ground roar then feel it tremble for a moment here. Our event was from a 4.2 shaker, over near Mammoth Lakes on the East Side at 5 a.m. The hypocenter was 10 km beneath the Sierra, between the crest and Mt. Morrison.
The Merced River is low, but not as low as it usually is at the end of August. Yosemite Falls is still relatively impressive - far more people are taking photographs of it than ever do in typical August. Squirrels are shredding ponderosa cones. Bears are finding ripening apples, and though the eat pounds of them, their scat appears to leave a lot of calories untouched.

Smoke and Heat

The Avalanche Fire is putting up a good amount of smoke from just above the western end of the Glacier Point Road and it finally feels like summer in the Sierra. This fire was caused by lightning and is just over 400 acres. It's burning at ground level in a healthy way and managers hope it'll burn at least 2000 acres.
The river and waterfalls are still running at unusually high levels, approximately 4-5 times the trickling volumes normally seen in early August. Yosemite Falls is still worth a photograph and Vernal is still all the way across the lip, and putting lots of mist on to the Mist Trail.
Birdlife has quieted considerably in Yosemite Valley. Orioles and grosbeaks are still around, but they are silent. Mule deer bucks have full, velvety racks now.
Coneflower, some tincture plant, lotus and milkweed are in bloom in the Valley - it's a great year for floral displays. The show has shifted to higher elevations where pentstemon, gentians and others are blossoming. Post-bloom, our native raspberries are ready for harvest in the Valley. Yum!