From the L.A. Times: Why L.A. is having such a wet winter after years of drought conditions. (Warning: they’ll let you look at their site for a while, then cut you off like a barkeep when closing time approaches.) Haven’t looked at the article yet, but I’ll fall off my chair if the answer doesn’t contain global warming/climate change.
But I have some ideas of my own. Historical data on seasonal rainfall totals for Los Angeles over the last 140+ year is readily available on the web. I took that data, and did a little light analysis.
Average seasonal rainfall in L.A. is 14.07″. 60% of the time, rainfall is below average; 40% above. Percentage of seasons with:
- less than 75% of average rain: 32.62
- between 75% and 125%: 39.01
- over 75%: 28.37
“Normal” rainfall covers a pretty wide range, one would reasonably suppose. Getting a lot or a little seems somewhat more likely than getting somewhere around average. This fits with my experience growing up in L.A. (18 year sample size, use with caution.)
The last 20 years look like:
| Season (July 1-June 30) | Total Rainfall, Inches | Variance from Avg |
| 2017-2018 | 4.79 | -9.91 |
| 2016-2017 | 19.00 | 4.3 |
| 2015-2016 | 9.65 | -5.05 |
| 2014-2015 | 8.52 | -6.18 |
| 2013-2014 | 6.08 | -8.62 |
| 2012-2013 | 5.85 | -8.85 |
| 2011-2012 | 8.69 | -6.01 |
| 2010-2011 | 20.20 | 5.5 |
| 2009-2010 | 16.36 | 1.66 |
| 2008-2009 | 9.08 | -5.62 |
| 2007-2008 | 13.53 | -1.17 |
| 2006-2007 | 3.21 | -11.49 |
| 2005-2006 | 13.19 | -1.51 |
| 2004-2005 | 37.25 | 22.55 |
| 2003-2004 | 9.24 | -5.46 |
| 2002-2003 | 16.49 | 1.79 |
| 2001-2002 | 4.42 | -10.28 |
| 2000-2001 | 17.94 | 3.24 |
| 1999-2000 | 11.57 | -3.13 |
| 1998-1999 | 9.09 | -5.61 |
14 years out of 20 (70%) are under average; 6 above. Those 5 years in a row stand out, as does the 9 out of 11 years under from 2005-2006 to 2015-2016. (That 22.55 inches in 2004-2005 also stands out – very wet year by L.A. standards.)
Wow, that does look bad. So does this stretch, with 7 out of 8 under:
| 1924-1925 | 7.38 | -7.32 |
| 1923-1924 | 6.67 | -8.03 |
| 1922-1923 | 9.59 | -5.11 |
| 1921-1922 | 19.66 | 4.96 |
| 1920-1921 | 13.71 | -0.99 |
| 1919-1920 | 12.52 | -2.18 |
| 1918-1919 | 8.58 | -6.12 |
| 1917-1918 | 13.86 | -0.84 |
And this one, with 10 out of 11:
| 1954-1955 | 11.94 | -2.76 |
| 1953-1954 | 11.99 | -2.71 |
| 1952-1953 | 9.46 | -5.24 |
| 1951-1952 | 26.21 | 11.51 |
| 1950-1951 | 8.21 | -6.49 |
| 1949-1950 | 10.60 | -4.1 |
| 1948-1949 | 7.99 | -6.71 |
| 1947-1948 | 7.22 | -7.48 |
| 1946-1947 | 12.61 | -2.09 |
| 1945-1946 | 12.13 | -2.57 |
| 1944-1945 | 11.58 | -3.12 |
Or this, with 6 out of 7:
| 1964-1965 | 13.69 | -1.01 |
| 1963-1964 | 7.93 | -6.77 |
| 1962-1963 | 8.38 | -6.32 |
| 1961-1962 | 18.79 | 4.09 |
| 1960-1961 | 4.85 | -9.85 |
| 1959-1960 | 8.18 | -6.52 |
| 1958-1959 | 5.58 | -9.12 |
This last cherry-picked selection is also like the most recent years in that annual rainfall is not just under, but way under. This last sample shows more than 6″ under, in 5 out of 6 years. In the recent sample, 5 out of the last 7 years prior to this year were more than 6″ under, and one over 5″ under.
How often does L.A. get rainfall 6″ or more under average? About 22% of the time. So, hardly unusual, and, given a big enough sample (evidently not very big), you would expect to find the sorts of patterns we see here, even if, as it would be foolish to assume, every year’s rainfall is a completely independent event from the preceding year or years. It would make at least as much sense to think there are big, multi-year, multi-decade, multi-century and so on cycles – cycles that would take much larger samples of seasonal rainfall to detect. And those cycles could very well interact – cycles within cycles.
Problem is, I’ve got 141 years of data, so I can’t say. I suspect nobody can. Given the poorly understood cycles in the oceans and sun, and the effect of the moon on the oceans and atmosphere, which it would be reasonable to assume affect weather and rainfall, we’re far from discovering the causes of the little patterns cherry picking the data might present to us. They only tell us that rainfall seems to fall into patterns, where one dry year is often followed by one or two or even four or five more dry years. And sometimes not.
L.A. also gets stretches such as this:
| 1943-1944 | 19.21 | 4.51 |
| 1942-1943 | 19.17 | 4.47 |
| 1941-1942 | 11.18 | -3.52 |
| 1940-1941 | 32.76 | 18.06 |
| 1939-1940 | 18.96 | 4.26 |
| 1938-1939 | 13.06 | -1.64 |
| 1937-1938 | 23.43 | 8.73 |
| 1936-1937 | 22.41 | 7.71 |
| 1935-1936 | 12.07 | -2.63 |
| 1934-1935 | 21.66 | 6.96 |
Not only are 7 out of 10 years wetter than average, the 3 years under average are only a little short. This would help explain why it is so often raining in Raymond Chandler stories set in L.A. – this sample of years overlaps most of his masterpieces.
The L.A. Times sees something in this data-based Rorschach test; I see nothing much. Let’s see what the article says:
Nothing. The headline writer, editor and writer evidently don’t talk to each other, as the article as published makes no attempt to answer or even address the question implied in the headline. It’s just a glorified weather report cobbled together from interviews from over the last several months. Conclusion: things seem OK, water system wise, for now, but keep some panic on slow simmer, just in case. Something like that.
Oh, well. You win some, you lose some. That *thunk* you hear is me falling out of my chair.
Yard Sale of the Mind 
I suppose you can take solace in knowing that when they don’t talk about [insert left’s current political football] they have nothing to say at all.
In the one story where Rex Stout has (NYC) Archie Goodwin fly out to LA, it’s raining too. Archie mentions never seeing the sun the whole visit. I bet it’s in that window of years as well, or at least that Rex Stout was greatly affected by their existence – maybe he visited in a downpour.
Apparently Lancaster (up the 14 from LA) had an exceptionally wet, lush year way back, making it look Eden-like, and that’s why people started living up there in the Antelope Valley on the edge of the Mojave Desert – I wonder if it fell in that bunch as well. That’s fascinating.
Very interesting. This is fun, and I suspect there’s some truth to it. I’ve written in the past about how, in the early decades of the last century, the concern in L.A. was flooding – people built in the wide floodplains of L.A.’s 3 big rivers (Los Angeles, San Fernando and San Gabriel). toodled along for years with no repercussions – and then, it would rain seriously and flood everybody out. Happened enough for the county to eventually pave and wall in almost all of all three river channels so that the water would rush to the sea instead of flooding.
Once, when I was 11 in Whittier, saw streets running like rivers, it was raining so hard. I saw it could happen, but it seemed to me even at that age to be a rare thing.
My sample is too small, and weirdly biased (as all small samples tend to be). When I was 8 – 11 years old, L.A. rain totals looked like this:
Season total over avg
1968-1969 27.47 12.77
1967-1968 16.58 1.88
1966-1967 22.00 7.30
1965-1966 20.44 5.74
On the other hand Singing in the Rain came out in 1952 – the only year between 1944 and 1955 with above average rainfall in L.A.. 😉
Now I’m just free associating…. 😉
I was born in Torrence. But I grew up in hacienda heights. Right next to Whittier
I’m a Puente guy originally.
Other side of hills!
Yeah. The wrong side. ; )
If Whittier is upscale, it sure ain’t by much. 😉
One problem is using average annual rainfall to indicate some kind of normal. There are more below normal years than above normal years for an easy-to-see reason: there is an absolute and practical lower limit to the amount of rainfall possible in a year, and no practical upper limit. There’s already been one year in this century that had time and a half over the average rainfall; there will never be a year that has time and half under the average. Same kind of thing happens, depending on your argument, with average incomes, average tax burdens, average home prices,
Right, of course. Unless you can get negative rainfall (the R&D people are working on it), you would expect most years to be below average, which is what is found. Good point.
I’ve railed against using normal to mean average, as if any deviation from the average is somehow abnormal. Any man under 5’10” (or whatever average male height is these days) is abnormal, as is any man taller. Absurd and misleading.
What is it matter whether or not we have more less rainfall if we start to get storms that are so huge that Los Angeles slides into the ocean as a giant mudslide? Lol
The issue of climate change is not whether it’s raining less or more, and personally I don’t even think it matters whether human beings are the cause of it. I feel like you’re late posts are more addressing whether or not I should feel guilty as a human being because of all the “climate change“ that’s going to destroy the planet or some nonsense.
What I tend to read of your latest posts is a kind of psychological defense that is based in an opposite implication of accusation of my being human, or of your being human in this case.
The simple fact is is that climate changes and we human beings are part of the climate. Everything we do has a climate, reflects acclimate, and changes the climate interactively.
If we look through our his columns of all the various Ice Age is throughout history, I think what we have to conclude is that human beings adapt to the climate, however we do find it.
It just so happens that we are going to have larger storms and that’s going to cost us a lot of fucking money.
Whether or not it’s our fault, recent reports are basically telling us that coral reefs are dying. For many coastal communities who sustenance is based upon the sea, this is going to affect their lifestyle which in turn is going to affect my life style in the middle of the continent in a very drastic way.
Well I do think it is interesting the point you’re making about the rainfall, I somehow feel that the reason that you are making it is very Los Angeles call and everyone is out for themselves, everyone Hass to have the better sports car the more expensive suit it’s got to be hanging out with the in crowd who is more cool than youre in crowd. Etc.
But that’s just my in crowd perception also. Lol. I was born in Los Angeles I partied in Los Angeles it was great fun but then when I started to get some intelligence I was like I’m getting the fuck out of this stupid ass place !
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Sorry for all the lame AutoCorrect. I think you can still See what I’m saying though
“when I started to get some intelligence I was like I’m getting the fuck out of this stupid ass place !”
I’ve got enough intelligence to want to get out, but not quite enough to get out at this point. : )
This is great, fascinating, in fact, for someone who lives in the L.A. area. Really helps me put things in perspective.
L.A. rainfall has fascinated me since I was a kid, how the basic year after year desert would be punctuated by the occasional downpour.
I wish there were reliable L.A. rainfall proxies for the Mediaeval Warm Period, or more generally, over the past 11,000 years since the ice sheets retreated.
In Death Valley, at a visitor center they have a nice exhibit on the periodic flooding and drying of the valleys (Death Valley is one of a series of valleys and plains that were occasionally giant lakes) over the last million years or so, and they mention in passing dramatic changes in climate that appear to have caused it.
But they never really put 2 and 2 together: that California’s climate has been very unstable over many hundreds of thousands of years – rainy, super dry, cold, hot and all over between, with deserts for a few thousand years followed by lakes, swamps, more deserts, and so on. This, before any people were around to have any effect.
Why one would expect it to be stable NOW, when it demonstrably was not stable in the past is a mystery left unspoken.
My wife and I want to move back to Santa Cruz at some point. But I keep thinking in the back of my head “well our friends were putting the drain in their showers so they could use the water for the toilets”. And I keep thinking we’re going to move back to California right when everything dries up and there’s water riots, or we’re going to buy a house just at the point where it washes into the ocean.
Lol. Either way, I feel like right now I live on the best place on the planet.