Pondering Snow & River Crossings

[Wandering Daisy]

I have done Lucifer's Pass twice, Big Shot to Bench and the reverse. It is slabby from Big Shot to a nice valley then talus to the pass (slabby rock to the right, but it looked quite steep). Snow on the slabby part could be unstable this year early season. But I think solid snow on the talus would actually make it better if one were experienced on snow. The worst conditions would be unstable snow in the melt phase with post-hole conditions in the talus. I did the pass July 12, 2013 and do not recall any snow. But that was a dry year.

[jmherrell]

I have a photo of Post Corral Creek at the trail crossing where the Hell for Sure Pass Trail starts. I went there on 7/8/2011, another big snow year, just to have a look not expecting it to be fordable. The water was probably waist deep at the trench in the middle. The ground next to the creek was wet and clean for half the width of the creek so it might have been twice as wide a few days before. What you can't see from the photo is that the water is moving very fast.

[fpb56]

I am leaving for a 7 day backpacking trip and leaving out of Yosemite. Im starting on the Chilnualna Falls trail. After we get to the top we are continuing out towards Chain Lakes. I am concerned that Chilnualna Creek is not passable above the falls. Has anyone seen it or done it this year? There is an alternate way around it and only have to cross the tributaries above the falls so it should be safe. Are there any trees down across the river or has anyone crossed it lately? Thanks

[dbargaehr1]

For those who aren't tracking it, here's how i've been keeping track of snowmelt for my trip in late July. This is as of today. The reference lines are 1982-83 and 2016-17.

Seems like the melt has really started in earnest.

The site can be found here (and is regularly down, so be patient)

https://cdec.water.ca.gov/snowapp/swcchart.action

The other thing I've been using to get more localized (besides Sentinel Hub Satellite Imagery) is the station map and looking at river flows in the areas I'm considering.

https://cdec.water.ca.gov/webgis/?appid=cdecstation

This year being what it is, I have 4 separate routes at various elevations to account for the inevitable road washouts, potential cross-country snow issues, uncrossable creeks, etc. Planning this year is certainly a new challenge!

[fpb56]

It sure is

[frozenintime]

yeah i was wondering about the rapid melt in the data.
it has been unseasonably cold along the coast this entire spring -- has it been unusually hot inland?
the angle of the southern sierra line is so steep compared to even recent years like 18/19.
(though we are still at nearly 400% for the date, ha)

[dbargaehr1]

yeah i was wondering about the rapid melt in the data.
it has been unseasonably cold along the coast this entire spring -- has it been unusually hot inland?
the angle of the southern sierra line is so steep compared to even recent years like 18/19.
(though we are still at nearly 400% for the date, ha)

Screen Shot 2023-05-31 at 4.25.54 PM.png

I haven't been tracking the weather as much as the snowmelt, but it does seem like it's really melting fast in the Southern Sierra in particular.

There's a bit of good and bad there….

Good because my late July trip my first two choices are in the 10K+ elev range and involve XC over passes and hopefully a summit or two. I'd like the lakes to be iced out for fly fishing and the creeks to be calm enough to fish.

Bad because if the runoff is that heavy the forest roads/bridges to access some of the planned trailheads may be completely impassable even with a high-clearance 4WD.

[Wandering Daisy]

The CDEC graphs are for large areas, with the data weighted so that the total melt matches what ends up available, most stored in reservoirs. CDEC is designed as a water resource tool, not specifically for we backpackers. Since the higher altitude snow is a fairly small percentage of the total snowmelt, these graphs are not that good to determine snow up where most of us backpack. You have to go to the individual snow sensors which unfortunately some of the higher ones are not working properly. Arial radar measurement are also being used to get better CDEC coverage, but that data is not available to us (at least I have not found it). Be careful with sensor data, often an individual day or so is an invalid measurement.

The USDA snow depth map is quite useful but on a fairly coarse pixel scale. Honestly, one of my favorite "data" is the web cam on the top of Mammoth Mountain! It looks towards the Minarets. There are a lot of other web cams out there too.

As for stream flows the kayak blogs and web-sites track that a lot. The CDEC daily reservoir reports are also informative. And of course, thanks everyone for posting photos on HST.

[michaelzim]

Yes, the melt has been fast in the south. Those photos I posted of the river level at the S. Fork of the Kern bridge are kind of extraordinary, in that the level 3.5 weeks prior was exactly the same almost a month later. That tells me the melt has been long, steady and high, but without getting Armageddon high. So far there has not been any massive flood at levels I was almost expecting at the beginning of May. I was worried that the bridge could get inundated in the near future, but the bank evidence last week showed no such rise in the intervening weeks.

Snow levels backed off a full 1,500 feet in those 3.5 weeks too! From full snow cover of all slope aspects at 8,000 ft. (around 2 ft. deep on average) to the equivalent last week, almost a month later, at 9,500 ft. That is an impressive retreat in my book, seeing as indeed it has been a cool May here where I live.

Just maybe we will get away with high flow creeks but not mega-flow creeks?! I guess we will see, as with 3 bridges down or damaged from the excessive snow, would be good to not have more blow out from huge flooding.

M.

[dbargaehr1]

Yes, the melt has been fast in the south. Those photos I posted of the river level at the S. Fork of the Kern bridge are kind of extraordinary, in that the level 3.5 weeks prior was exactly the same almost a month later. That tells me the melt has been long, steady and high, but without getting Armageddon high. So far there has not been any massive flood at levels I was almost expecting at the beginning of May. I was worried that the bridge could get inundated in the near future, but the bank evidence last week showed no such rise in the intervening weeks.

Snow levels backed off a full 1,500 feet in those 3.5 weeks too! From full snow cover of all slope aspects at 8,000 ft. (around 2 ft. deep on average) to the equivalent last week, almost a month later, at 9,500 ft. That is an impressive retreat in my book, seeing as indeed it has been a cool May here where I live.

Just maybe we will get away with high flow creeks but not mega-flow creeks?! I guess we will see, as with 3 bridges down or damaged from the excessive snow, would be good to not have more blow out from huge flooding.

M.

I was looking at historical river flow at some local stations in the Southern Sierra, and it seems like peak flows tend to happen in mid-June in recent higher snow years. In lighter snow years it tended to be mid-May to the first week of June. So I wonder if the highest runoff is yet to come.