April Flowers Bringing It

The Merced River approaches 'minor flood' stage tonight, with the previous two night's flows being near 5300 cfs, which is roughly double the average peak spring volume. Valley meadows are wet, some trails are under water, some campsites unusable, and it's a great time to be a duck. While exciting, this is the normal and predictable outcome from a winter that brought the Merced watershed 153% of average snowpack water content as of 1 April (and 176% in the Tuolumne watershed). The waterfalls are ripping right now. You may recall that (after vehicle accidents) swiftwater is the number one factor for visitor fatalities in Yosemite; respect the water. April has been warmer than usual (only one day of wist ice [frazil] in its typically most productive month) and we wonder if peak runoff has come 3-4 weeks earlier than the late May average.

There is still a huge quantity of snow at 7000' and above. While we did have some warm storms this winter that brought rain to high elevations, we had far more storms that delivered snow down to 2000'. Several recent SAR call-outs have resulted from people getting up into deep snow where they didn't expect it. Some have been getting their intel from various posts/photos about nice April hikes that others did last year - that was a very dry winter. The Fourmile Trail and the JMT below Nevada Fall (ice cut) are still closed and dangerous. The High Sierra Camps won't open this season. Expect stream crossings to be challenging and snow to persist well into mid-summer in the high country.

Dogwood flowers are at the puppy stage in Yosemite Valley. Tanagers, orioles and grosbeaks are singing and shining brightly. Peregrines are at their eyries. The green dragons are rolling. "This grand show is eternal..."

Post-winter Recovery

Springtime is making its way uphill in the Sierra with redbud peaking in El Portal now while unfathomable snow persists above 7000 feet. It can hardly be said enough: WHAT a winter we've had here! Storms were repeated with good frequency and lots of Pacific moisture, leaving us with a tremendous snowpack. The snowline was a bit higher than historical averages; not much accumulated in Yosemite Valley (though we had lots of rain runoff), but higher elevations have had fantastical quantities. The central Sierra has 175% of usual water content in the current snowpack. Picture the meadows and forests in the May Lake area buried by 6-7 feet of water (not 6' of snow, but 6' of standing water) - that's the nature of how much mature, dense snow is covering the tens of thousands of acres of Yosemite's upper elevations.

<-Bridalveil in flood.

Storm damage has been considerable in/near the park, with Hwy. 41 having been closed for a month by a washout, and crews working hard to repair slope movement on the Big Oak Flat Road below Crane Flat in hopes of getting it re-opened before Memorial Day. Trails at and above the Yosemite Valley level have a lot of downed trees; trail crew sawyers will be very busy for much of the summer to get those cleared. When you visit the Valley, check out the fragments of bark-less logs below Bridalveil or Yosemite Falls from trees that were uprooted and thrown over the falls this winter. Since December there's been a huge deposit of frazil (wist) ice below Yosemite Falls, and we're now in the month when one is most likely to be able to observe wist ice flowing.

The excitement isn't over. Because of the closure of the Big Oak Flat Road, Hwy. 140 has been handling much more traffic. This past Saturday, visitors were waiting over 2 hours in a 3.5 mile-long line of 800+ cars just to get through the stoplight at the Ferguson rockslide detour west of the park. (Easily avoided by coming in before 9am on weekends.) Because of the road construction in the Valley, the main parking at Yosemite Village will be closed for the next two months, and detours are confusing to both new and veteran visitors. It's going to be a very nice improvement once it's completed, but parking and navigating can be challenges on spring weekends now. Half Dome Village and the new lot by Camp Four are best bets. The road crew is already working to clear Glacier Point Road.

But, wait, there's more. The Merced is running almost 4x average flow today. All that snow in the high country seems likely to bring us some degree of 'high water incident' between now and mid-June (sure to cover some Valley trails at least), depending on how the warming progresses. Yosemite explorers should expect a delayed start to summer, with Tioga Road opening late, trails covered by snow and fallen trees, and creeks difficult to cross.

Ice, Ice, Maybe

There's an exceptional accumulation of waterfall slurry ice below Yosemite Falls right now, and the whole amphitheater is closed for safety reasons. The stream of 'frazil' flow meanders dynamically and it'd be possible for someone to get into real trouble with this unstable landscape. We know it's not really 'frazil ice' because this slurry is formed of frozen waterfall mist/droplets, but it's remarkable, whatever we call it.

There's frazil deposition in Royal Arch Creek and Steve B. says there's frazil in Bridalveil and Ribbon Creeks.

There's also a very healthy snowpack at higher elevations, well above average in depth and water content. The Valley has lots of water from recent storms; there's almost a foot of snow on the ground but running water in Sentinel, Eagle, Royal Arch, Ribbon and other creeks. This wet winter bodes well for summertime waterfalls, some groundwater recharge, and perhaps a more normally-timed start to the fire season. We'll have to wait a few months to fully assess the end of the drought.

Meanwhile at lower elevations flowers are blooming in the Merced River canyon: fiddleneck, baby blue eyes, and a galaxy of waterfall buttercups can be found.