Sunday, June 19, 2011

June Skiing

Tioga Road has opened, but summer has not really arrived in the park's high country yet. Tuolumne Meadows is a lake, Tenaya Lake is mostly iced over (with renewed freezing and new ice last night), snow covers a good portion of the terrain above 6000' (north-facing slopes are mostly snow) and meltwater is filling every trail. Skiers still have time to enjoy the slopes near Ellery Lake, False White, Mt. Conness, Mt. Hoffmann, Mt. Dana and more. Backpackers are going to struggle for a while to find trails, to make distance over snow, to avoid wet feet in all the runoff. No facilities are yet open along the Tioga corridor, including TPR, Saddlebag Lake road, White Wolf or anything in Tuolumne Meadows.
Half Dome cables go up this week for those with permits. Walked the west valley loop on Saturday; flowers are looking good: iris in El Cap and Bridalveil Meadows, yellow violets, white Nemophila, Arnica, Senecio, Alumroot, thimbleberry, Linanthus, larkspur near the base of Bridalveil Fall, creek dogwood, Azalea (smells SO good), globe gilia, blue dicks, golden brodeia, silverleaf lotus, Indian paintbrush, pussypaws, catchfly, and more. We saw no snowplants on the loop. One sow bear with two cubs near El Cap's Nose. Slackliners working their art over the icy Merced at El Cap Bridge. Ribbon Creek is running very high in several channels. Birdsong is still plenty active: grosbeak, tanager, Wilsons and yellow warbler, Cassins and warbling vireo, creeper, song sparrow, spotted towhee, etc.
Hotter days are coming this week and the river may hit another peak above flood stage. It is unusual to have such a late peak, such a high peak, and for the river to hover close to the flood level for two weeks like this. What next in this atypical spring/summer transition?

Wednesday, June 15, 2011

High Water is Here

The river gauge at Pohono Bridge is just about tapping the formal 'flood' stage this morning, at 6300 cfs, or a hair under the 10' mark. This is a little lower than the forecasted overnight peak. Tonight's projection is to go over 11' or perhaps 9000 cfs. If it gets that high, the river will be up on parts of Valley roads, not to mention flowing into two campgrounds and Housekeeping Camp. Rangers have been preparing for days for this surge of meltwater, to evacuate people ahead of nighttime peaks as needed and to implement area closures for safety.
There have been lots of cyclists enjoying the delight of pedalling on the Tioga Road without cars for the past couple of weeks; no noise but birds, running water and the whisper of gumwalls. There is still snow at Crane Flat, and lots of deep snow higher up. The avalanche zone at Olmsted Point has been a lingering concern, so that part of the road is closed to cyclists and pedestrians. Road/trail crew personnel have been working on that spot and with this week's heat and clear skies, there is a fair bit of buzz about the road opening this weekend. Nothing is official and the high country route may not be safe enough to open until next week.
From Olmsted Point we can see that Tenaya Lake is still frozen over. Today's San Francisco Chronicle has an item about the park's Tenaya Lake Area Plan, in which the Conservancy is involved for funding.
Tenaya's ice is melting quickly, and washing down-canyon to fill Yosemite Valley with its own transient lakes.

Thursday, June 9, 2011

Yosemite Flood Watch

NWS has issued a Flood Watch for our part of the Sierra starting Friday evening. We are getting warmer weather this week and the Merced River has started rising again, reaching 4000 cubic feet per second (cfs) at Pohono Bridge (the west/downstream end of Yosemite Valley) last night. The average annual high water flow for the Pohono gauge is just 2500 cfs.
As has been said elsewhere, on top of our tremendous snowpack, it's been an unusually cool and wet spring. The normal warming (and therefore snowmelt) trajectory has not happened; there is still a huge quantity of snow in our higher elevations. We have just a little less snow now than what we usually have in April; the combination of June heat and April snowpack suggests powerful possibilities. The rate of Merced runoff may get interesting in the next few days.
We had two spikes of just under 5000 cfs in early May. Then we had another cool stretch and on the typical annual highest water date of May 20, the river was running only about 1800 cfs, 72% of average volume.
NBC Nightly News aired a feature last week about Yosemite's big waterfalls during a period when they were running right about average for springtime. The exceptional flows may have already happened, or may be coming within this next week. Though we're now 3 weeks past the usual highest flow date, we may not yet have seen our biggest water volume for the season. In 2010 we topped out at near 8000 cfs; if it stays warm (like June usually does; our forecast continues warming for the next 5 days) we may surpass that and see the Merced back up through Wosky Pond on to Northside Drive.

Saturday, June 4, 2011

Summer Delayed

Our cycle of stormy weather continues with another cool, wet weekend. We had rain and snow over Memorial Day weekend, but that didn't prevent traffic gridlock in the east end of Yosemite Valley. Glacier Point Road was open for a day before more snowfall closed the road again. It's been open this week, but some snow is likely on Sunday, perhaps below 7000' (= another closure seems likely).
Scott's Oriole was added to the park's bird list last week; another new species to add to the white-faced ibis seen a couple months ago. I saw a Lewis' Woodpecker above Foresta on Thursday - one of the 12 woodpecker species (!) in Yosemite records. Some of us feel that we are short on Pacific Slope Flycatchers this spring. The Conservancy's 'Hawks and Owls' course is happening this weekend and there is a lot going on in the raptor world, with peregrine and eagle nests lining the Merced Canyon. There is still space in the casual White Wolf Botany course and the North Dome Moonrise Photography Backpack Trek in July.
It doesn't appear that the Tioga Road will be open in time for the Mono Basin Bird Chautauqua, but the birds will be there anyway.
Thursday night NBC did a program on the park's big waterfall flow , while the falls have actually been running at average or below average volumes for about half of the past month. We had early peaks on 7 and 14 May, which were higher than the average annual peak flow, but were maybe 60% of last year's high water mark. The slow advent of spring warmth may mean no snowmelt 'flood' this year, just a long period of higher water. Or a sudden spike in temperatures could send us a big pulse of meltwater; that's not in the immediate forecast. The waterfalls should still be strong if the royal couple visits Yosemite in July.