We are having epic rain in California and that means epic snowfall in the Sierra Nevada Mountains. I wanted to make an interactive and current snowfall visualization to keep track of the amount of water being stored in the mountains. This is an average of snow water content for all of the 120 snow sensor locations in the Sierra. You can also look at specific regions (Northern, Central and Southern Sierras).

The blue/black lines on the graph (from top to bottom) represent the 100th(max), 90th, 75th, 50th (median), 25th, 10th and 0th (min) percentiles of snow water content for each date from 1970 to 2022. The red line is the current water years value.

In general, the snowpack water content to snow depth is about a 3 to 1 ratio so in the image, the average of 22" of snow water content amounts to about 66" (5ft 6inches or ~1.67 meters). It is much more (maybe 10 to 1) when the snow first falls, but over time it settles and also compacts from the overlying snow to get to this lower number.

Here is the interactive and updated daily (sometime in the west coast morning 8-10am) visualization.

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Sources and ToolsData is downloaded from the California Data Exchange Center website of the California Department of Water Resources using a python script. The data is processed in javascript and visualized here using HTML, CSS and javascript and the open source Plotly javascript graphing library.

Utah is having a pretty decent year too, (something like 170% of normal). In other news, parking at any ski resort is a pain.

Its raining on the snow, melting it today. Better than nothing.

Its really good for the drought happening in the west

Thank you for making this! I've been looking for something like this :)

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So big question, between this and Utah’s snow pack, how much can this raise lakes Mead and Powell?

These two reservoirs are on the Colorado river so I don't think California's snow has any impact.

You are welcome. Glad you will find it useful. You can check out the rainfall and reservoir visualizations I've made as well.

Upper Colorado headwaters are currently at 126% of normal snow water equivalent, but that won't really put a dent in Mead and Powell levels.

https://www.nrcs.usda.gov/wps/portal/wcc/home/quicklinks/states/colorado

Nice link! I was trying to see how big of a hole we are in.

Yeah, but how did the snow spend its six figure income last year?

Maybe dumb question...What does it mean that the values go down? Is that the expected amount of rain each month? In that case, should it be more like a column/bar chart? Ir is it supposed to be cumulative? If cumulative, would the values increase monotonically?

To make sure I'm interpreting the graph correctly, there is more snow pack than the median for this time of the year?

If so, I'd think that'd be a good thing to help offset drought to some extent/degree/amount?

Need a Snowky diagram for that

The 100, 90, 75, etc. numbers should be on the graph

I think this is accumulation of snow on the ground. So when it goes down in the spring it’s because it is melting.

Mmmmm that would explain! Thanks!

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Not at all. We need a good decade of above average snow pack in the Colorado Rockies to make any real difference.

I thought that we were in a La Niña year, doesn’t feel like it!

I flew over lake Mead in May; it was really depressing. I wish I knew how to attach a picture. I hope that it recovers.

That's the idea, it's not going to solve the problem but helps a bit. I saw recently that all the rain CA is getting has actually reduced it from very very very bad, to just very very bad in terms of drought.

Likely quite minimal. We want to see cooler summers and continued wet, snow-heavy winters and good monsoon seasons for years to come. This is a nice start though!!

Another downholic mapple what a crap.

Now lets hope this doesn’t cause issues with dams later this year.

Unfortunately the drought is caused almost as much by the over consumption of water as the lack of rain. This will help in the short term to get levels back up, but we're still taking more than nature is putting in.

Sierra snow won't help Lake Mead.

The sad thing is California uses the lion's share of the Colorado River, and their rainfall contributes essentially nothing to it. They consume all the rain falling on their own state, and most of what falls on Utah, Arizona, and Western Colorado.

https://www.usgs.gov/media/images/colorado-river-basin-map

It appears that California should plan on spring-thaw floods and mud slides. Or have I mis-interpreted the data?

Holy hell, 2" of growth in a day and this weather's not gonna let up for another week, to say nothing of possible rain over the next three months. Jeez.

Well, they are in the live site version, I guess they removed it before saving the image.

It's ultimately a temporary reprieve that'll help with water supply for this year and maybe a ripple effect into next year depending on how much melts. The issue is prolonged drought plus overconsumption of water resources has depleted the 'stockpile' of snowpack that usually accumulates year over year, as well as the groundwater reserves. What the state needs is at least several winters with rain/snowfall like what we're getting this winter.

This, we'd need at least a couple years of less-scorching summers with rainy winters before a real dent could be made in the drought, it's hard to overstate how dry and depleted the state is, even after being clobbered by weeks of rain and snow we're still gonna have water problems.

I’m hearing people say the drought will be over this year…like, no dude. Definitely not.

People have very short memories and don’t really understand what a drought is and how impactful it can be.

On top of that, because of the drought we've been depleting groundwater at an even faster rate, and that takes much longer to replenish. So, during the next inevitable drought in the next 10 years or so we're not gonna have as much groundwater to fall back on.

We are, quite simply, using too much of a shrinking resource, and not enough is being done to deal with the problem. We needed to put the screws to the big agribusinesses years ago, that's where all the damned water's going.