Saturday, March 26, 2011

Yosemite Recovers

Electricity is supposed to be restored to El Portal and Yosemite Valley today (Saturday). Most park roads are now open, though with chain restrictions on all of them. Highway 140 is closed between Mariposa and El Portal by a rockslide near Briceburg; it should be open by Monday or sooner. Badger Pass is closed, but hopes to open for its last weekend of the season, April 1-3. There is over 14 feet of NEW snow at Badger!
The Valley floor has 1- 1.5 feet on it. DNC is using these rare conditions to lead springtime snowshoe walks from the Ahwahnee this weekend. The Visitor Center is fully staffed, and a few visitors are trickling through. It's snowing in the Valley now, but snow isn't sticking much below the 3500' level. Though Hwy. 41 is open, buses are being turned away from the south entrance at the moment. You MUST call 209/372-0200 to check on road conditions before heading to the park.
The Conservancy's annual Spring Forum was supposed to be held today, but conditions obviate that possibility; we'll try again next year. Tomorrow's wildflower field seminar in El Portal is also cancelled; Michael Ross is teaching two other botany courses in the summer where we hope snow won't be a factor.
Warm weather returns to the Sierra next week, with sunny and low 60's in Yosemite Valley. We should see a big spike in runoff by late in the week, with lots of wet meadows, though we probably won't really approach flood level. It's going to be a terrific season for Yosemite waterfalls.

Tuesday, March 22, 2011

Yosemite Closure

An unusually cold and wet storm has delivered a lot of snow, causing extensive tree damage in Yosemite. All roads into Yosemite are closed. Power is expected to be out for 5-7 days. At under 2000' El Portal got 8-9 inches of snow, something not seen in decades. Most of the damage is to live oaks, with hundreds of trees and large limbs down in El Portal alone. The rest of the Merced Canyon has numerous small rockfalls and landslips partly blocking roads between Mariposa and Yosemite Valley. The snowfall took place mostly overnight on Sunday. Skiers exiting Ostrander Hut on Sunday worked as a 20-person team to break trail. They scooped up others along the Glacier Point Road who had dropped from exhaustion pushing against the heavy accumulation. When they reached the trailhead, they couldn't leave Badger Pass; about 60 people spent the night in the day lodge at Badger. Yosemite West has run out of water and all residents and guests have been escorted out of the park. Community meetings later today will tell us more, but it's possible that the park will be closed and all remaining visitors and non-essential employees evacuated. The generators that keep the lights and heat working can only do so much, and they're needed to operate water and wastewater systems, too.
I'll post more when I can.

Saturday, March 19, 2011

Wintery Equinox

Yosemite Valley's mostly bare ground got a few inches of snow overnight and it even accumulated as low as El Portal; most park roads are R2 this morning. Another wave of snow arrives early Sunday morning.
We had frazil ice in the Valley this week, with Yosemite Creek sending frazil into the Merced twice, and Ribbon Creek even fraziling all the way into the river on Thursday. The snow cone at Upper Yosemite Fall is as big as ever. Frazil forecast for the next several days: moderate, best on Monday morning.
Sentinel, Eagle and Horsetail Creeks flow to the river. Wosky Pond is very full.
Varied thrushes, which have not been very evident here this winter, were making their odd squeaks in Yosemite Village yesterday. Karen Amstutz and Michael Ross heard and saw a phainopepla in El Portal earlier. Karen noted a disoriented flock of Canada geese in the rainy nighttime of Badger Pass last weekend, likely drawn to the illuminated slopes.
Tonight's full moon coincides with perigee (the point in its elliptical orbit where it's closest to earth) so will appear a bit larger and about 15% brighter than an average full moon; this happens about every 20 years. Elsewhere in the sky this weekend: vernal equinox on Sunday when the sun rises due East and sets due West, and our day and night are about equal in time. Vernal means springtime, so Sunday is the first day of astronomical spring for the northern hemisphere. Vernal also is a big waterfall that will be running strong this season - given its current name by the first Euro-Americans in the Valley who saw its ferns and moss as springlike. Just upstream was a bigger, but somehow colder-looking waterfall that they named Nevada, meaning snowy.
This weekend is thus both 'vernal' in astronomy and 'nevada' in weather - Yosemite perfection.

Monday, March 14, 2011

The Wearing o' the Green

A lot of the recent snow is now gone from the floor of Yosemite Valley and run-off is picking up. The Merced River is now running at about twice its average volume for mid-March. We got a bit of rain last night and we expect more rain/snow off and on this week. It'll be a grand year for waterfalls with so much wet snowpack in our upper watersheds. Next weekend may also be stormy, with the snow level at or below Yosemite Valley. Frazil ice forecast: low-moderate probability for next weekend.
Meanwhile the foothills and Merced Canyon west of Yosemite are greener and greener with buckeye leaves still emerging. Redbuds are pinking, getting ready for their startling color show soon. Popcorn flower dominates at ground cover level, poppies are coming along, false goldfields and fiddlenecks are looking good. The Hites Cove Trail is well worth a stroll now - yes, even if it's on a rainy weekend; you'll see more newts and hear more chorus frogs singing love songs.
The Ahwahnee re-opens on Thursday, in time for St. Patrick's Day. Meanwhile, we send seismic sympathies to the people of Japan for the blow that the restless earth has dealt there.

Tuesday, March 8, 2011

Quake Noted

A foothill earthquake was heard, not felt, by employee-residents in El Portal shortly before 11 p.m. last night. The hypocenter was nearly 15 miles beneath the Bootjack-Darrah Road-Triangle Road area, west of the park toward Mariposa. This is down in the granite batholith that underlies the western metamorphic belt we see at the surface along much of Highway 49 south of Mariposa. Hearing the earthquake in Rancheria Flat may be helped by its location at the contact zone of the granite and the older metamorphic rock.
The river has been well above average for months now, and the weekend rain has brought the river up again. It was very turbid yesterday. Yosemite Valley got rain and now the snow cover is patchy. The average flow for the Valley's exit in early March is about 300 cfs; it's now running over 500 cfs.
El Portal's flowers are looking good with numerous species found in many sunny locations. Bird activity has picked up, with abundant noisy robins joining vocal titmice, Hutton's vireos, flickers, both towhees and more. Treefrogs are chorusing in various places, even in snowy terrain in the Valley and Foresta.
The summertime's Scorpio is high in the south before dawn. The ISS flies across our sky about 7:30 this evening; STS Discovery has de-coupled for the last time before returning to solid ground tomorrow.

Tuesday, March 1, 2011

Winter is Back

A more usual sequence of wintery storms has returned to the Sierra after so many weeks of dry, mild weather. Wildflowers in the lower Merced Canyon have had to endure extra-frosty mornings and a few doses of snow, even down to 2000.' Today we're in-between snows, with warm-ish, sunny conditions. A few inches of snow still cover the Valley floor, but creeks will come up as the sun converts the snow coverage to run-off. More snow and rain arrive tonight. We expect another set of high elevation snow survey data soon.
Frazil ice continues to appear in Valley locations, with our above average run-off and cold overnight lows. We don't generally see it this early in the season, but this year is different. Maybe its abundant apparitions are a result of the popularity of the video. As April draws closer, we may try to post frazil forecasts here. These can only work 2-3 days ahead, when we get good temperature forecasts from NWS.
Yosemite has come to life indoors, in the form of the Yosemite Renaissance art exhibit in the Museum Gallery, next to the Valley Visitor Center. There were 578 entries submitted, and just the best 42 qualified to be displayed for our enjoyment. Come see the varied pieces between now and early May; pretty inspiring.