Junuary?

Remarkable aridity and mild temperatures continue in the Sierra and California. Badger Pass (Badger Grass?) Ski Area is closed, the Valley Stables have opened. We've been in and out of Red Flag Warnings (fire danger) since late December. The Merced River has flatlined at around 20 cfs (at Pohono Bridge) whereas the average flow for late January is almost seven times that!

Incense cedar pollen is flying now, producing allergic responses in some locals and visitors. Indian Paintbrush was reported in bloom above El Portal but it's too dry for most flowers to emerge. There are only a couple waterfall buttercups blooming near Ned's Gulch where there were hundreds a year ago. Bears are still active in the Valley (as some can be every other winter in recent years); I saw one yesterday. Surprisingly a trace of snow is accumulating in the high country at this moment.

For Martin Luther King, Jr. weekend, I roamed the site of Camp A. E. Wood, where African-American troopers were stationed for the summers of 1899, 1903 and 1904. These Buffalo Soldiers patrolled Yosemite National Park from this base in Wawona. Among their many accomplishments was the 1904 establishment of what's believed to be the first formal interpretive facility in the entire national park system: the Yosemite Arboretum. Boundary changes the next year removed the Arboretum from Army stewardship and this promising start at educating and inspiring visitors was abandoned. Very faint remnants of the Buffalo Soldiers' interpretive work can still be discerned.

Here's another valuable interpretive effort from long ago: Yosemite Nature Notes, the precursor of this blog and of Steve's excellent video series. What creative efforts of ours will be abandoned or sustained for the next hundred years?

A Winter's Solstice

The extra cold that the West had last week, was surely felt in Yosemite. Snow fell well below the park boundary and still persists in the shady parts of El Portal. The Merced River has frozen over in much of the Valley and the southern cliffs are streaked with frozen waterfalls. We did not get enough snow to open the Badger Pass area to skiing, etc.

The Merced is running at less than 30% of normal volume, and the watershed still has a way to go to recover from two dry winters.

Yesterday's Christmas Bird Count featured a frosty cold morning then comfortable warmth in the afternoon (unless you were in the shadow of the south wall). Compiler Sarah Stock organized quite a large group of birders, and the birds responded. It's a good year for the colorful varied thrushes, a species that migrates here for the winter, though it doesn't come every year. Early efforts turned up quite a few owls, too: pygmy, screech and great-horned.

Solstice happens on Saturday, when the long, cold night dominates the Sierra. Have a closer look at Yosemite's winter on one of our snowshoe outings. Here's hoping for a snowy new year.

Shakin' It

The Clark Range, within the southeast corner of Yosemite National Park, has been seismically active in recent years. Many nearly imperceptible earthquakes occur here each year. There was a series of 4 shakers last night, some of which were noticed on the west side of Yosemite. The park community of El Portal sits astride the boundary of the granitic batholith and the older metamorphic belt. The way ores can concentrate near a contact like this, vibrations may, as well. Deep but slender barium mine excavations at the igneous/metamorphic boundary may serve as sound boxes where the resonances of the earth can surface.

When the Merced River is low, El Portal is a pretty quiet place, especially at night. Some of us heard at least some of the four 1.0-2.2 magnitude temblors as deep roars, lower pitched and shorter in duration than a passing jet. I noted the time of the clearest roar, at 2:54 a.m., and there it was on the USGS website, as a restless moment east of Gray Peak, and 15.9 km deep.

Aspen on the East Side and in small pockets within the park, are past their peak color, but still bright. In the Valley, the sugar maple has gone bare, but there's lots of color remaining.

Dogwoods are red,

The sky is blue.

The oaks are all golden,

And maples are, too.

Autumnal Equinox

We are about a week from when the length of day and night balance out. It's still warm in much of Yosemite, especially in our northwest corner, where smoke and burned ground are the rule. That part of the park will be interesting for many years, while it recovers from the Rim Fire. Egret seen in the Valley. Gaylor basin's pikas weren't shy while gathering winter stores of bilberry, etc. Grindella still adds floral color to the canyon in El Portal, while dogwoods, dogbane and other foliage is turning autumn colors in mid-elevations. The Conservancy's Fall Gathering event is coming up soon, and there's still space in our one-day field seminars with either author Suzanne Swedo or photographer Chris Loberg that first weekend of October.

I've had such a busy season in the office and out on the trail; Yosemite has too much good stuff to get it all in. Now I look foward to Orion overhead, chlorophyll breaking down, the frost line descending, and more square mileage per person in the park.

Cumuli

We've had 4 days in a row of afternoon thunderclouds and rain in the high country.  Locals are reminded of the August monsoons.  We expect Yosemite Valley temperatures in the low 90's, with continued thunderstorm possibilities.

After a second dry winter, the park's watercourses are low.  The Merced River is running about 1/3 of average.  Yosemite Falls looks good now, but it's bound to dry up entirely by late summer.  Buckeyes in the lower canyon are browning already.  Clarkia is mostly gone: farewell to farewell-to-spring. 
A pair of wood ducks has been at Mirror Lake, but not seen nesting.  Mallards have their ducklings now.  Our morning birdwalks are still filled with singing tanagers, orioles and grosbeaks.  Several bears have been hit by cars recently, with at least one killed; those speed limits are there for good reasons. 
The new 'Snowplants' Yosemite Nature Notes video is remarkable; watch this space for the new posting in the next few days.
Geologist Greg Stock is sharing his expertise in a one-day geology course on June 15 in the Valley, and the photography course to Waterwheel Fall also has space available. 

Signs of Summer

Cool, wet weather a week ago brought the river level down from above average to below average.  Now the unusual heat has brought it back toward a more typical volume again, a bit below 2000 cfs at Pohono Bridge.  I could be wrong, but the peak flow of the Merced and tributaries may have passed already - 3 weeks earlier than average.  We expect a long and active fire season this year.
The Valley has been humid and green lately.  Oaks and maples are all but fully leafed out.  Dogwood blooms light the forest from within. A cloudburst the afternoon of the 9th caused local flooding and felt like an August monsoon storm.

Otherwise the waters are retreating.  Sentinel and Ribbon Falls are noticably smaller than a week or two ago. Staircase, Horsetail and Royal Arch are just dribbles.  Eagle Creek and Horsetail Creek haven't flowed on the surface of the Valley floor at all this year.  Wosky Pond is no more than 15m across at any point. 
Orioles, vireos, warblers, tanagers, grosbeaks, peewees, and robins sing with energy in the mixed oak/conifer canopies throughout the Valley.  White-throated and Vaux's Swifts have been seen and heard on the Monday/Thursday Conservany birdwalks lately.  A rare yellow-headed blackbird has been observed calmly feeding in Yosemite Village for several days recently. 
Tioga Road opened this weekend; snow cover is obviously light in the high country.  There was a fatal accident at Vernal Fall last week.  Weekends in the Valley are busy now, but weekdays will be relatively calm until more schools get out.
Some of the Conservancy's upcoming courses are full, but there's still space in a one-day, mid-June geology adventure with the wonderful Greg Stock, our Park Geologist.  Some of our Half Dome trips still have space available this summer, too.  Summer seems to be upon us now.

It's not 'frazil ice'

Technically, frazil ice is a slurry of ice particles that forms at the supercooled surface of turbulent liquid water.  Frazil forms in rivers and in wind-blown lakes/reservoirs in cold places.  What we have in Yosemite is a slurry of ice particles that forms as liquid water is aerosolized in a waterfall descending through sub-freezing air.  The end product of each process looks similar, but the way the very different talus and till can look similar or the unrelated heron and a crane look similar, to be proper, frazil and the distinct Yosemite waterfall feature should be distinguished with a different label. 
We might shorthand this frozen waterfall mist as 'wist ice' or a 'wist slurry.'  Because its origin is distinct from true frazil ice, our phenomenon deserves it's own name, though I wouldn't really expect our established common usage of 'frazil' to change.
One line of evidence that tells us that this isn't frazil ice is that when the creek below the waterfall is filling with the slushy mass, there is no ice above the falls.  This photo shows Yosemite Creek just above Upper Yosemite Falls at 7:30a.m. on 16 April, when it was 24 degrees F there.

There are no ice particles above the waterfall, but a dense slurry flow below.  No supercooled liquid is involved.
We've had wist slurries flow in Yosemite Creek and Ribbon Creek the past couple of mornings when temperatures dropped into the 20's.  Near-term forecasts don't look cold enough to produce much wist for the next few days.
Yosemite Conservancy's Monday and Thursday 8 a.m. birdwalks in the Valley have resumed for the next two months.  Orioles and grosbeaks have arrived in Yosemite Valley; we eagerly await our first tanagers.  The first warbling vireo of the year was heard yesterday.
The Hetch Hetchy Road has re-opened after repairs.  Merced River Plan public comments are due April 30.  Tioga Road is melting out faster than usual.  River and stream run-off has been higher than usual for the past two weeks, but it's expected to taper off early.  Seasonal waterfalls should be quite small by mid-summer.
There's still space in Dave Wyman's 'Spring Light Photography' course in mid-May.  Dave is a charismatic teacher with years of experience in Yosemite, and Yosemite always has something to teach us.