Why global warming made it rain last night in the Central Valley

If you live east of the Rockies you probably don’t see anything strange with rain this time of year. But here in the Central Valley of California summer rain isused to be an oxymoron.

In non-drought years (a whole ‘nother story) we would get plenty of precipitation, but 90% of it came during November through March, and 99% of it came between October and May. Back east dams are for flood control and hydroelectric power. We use them for that too, but they are also essential for irrigating crops and residential use as well.

Before the white man came the Central Valley was a mosquito filled swamp in the spring and a desert in the summer. The Native Americans would come down to hunt or gather acorns and then skedaddle back into the hills (proving that while they may have been ignorant savages they were no dummies.) When the white man arrived he started building dams and irrigation canals so he could farm during the dry summer months.

It’s summer, so why is it raining outside my house right now?

The answer is global warming. Yeah, yeah, I know the climate change deniers would say just the opposite, but they’re idiots. Let me give you a little geography lesson.

The Central Valley is separated from the Pacific coast and the San Francisco Bay by a low mountain range. If you’ve never been out here but you watch shows like Baywatch you probably think the Pacific coast is nothing but a series of sunny beaches filled with surfers and bikini-clad babes. That impression provides lots of entertainment for the locals when we get to watch scantily-clad tourists turning blue from the freezing winds.

Remember that alleged quote from Mark Twain?:

“The coldest winter I ever spent was the summer I spent in San Francisco.”

Mr. Clemens never actually said it but he could of. That’s because the prevailing winds here come from the northwest – from the Gulf of Alaska. Not only that but the water is pretty cold too.

When we move into summer the land heats up faster than the water. This warms the air over the land which causes it to rise. When the warm air rises it is replaced with cold moist air coming in from over the ocean.

That’s why most places along the west coast (like San Francisco and Monterey) are cold and overcast this time of year, with chilly gale-force winds blowing in from over the water. (Tourist tip: By late summer/early fall the water is warmer so the temperature differential is smaller and the coastal weather is much nicer.)

Normally the coastal range blocks that cold moist air from the Central Valley, and we enjoy sunny, dry days in the low nineties. But because of global warming we have been getting unusually high temperatures early in the year. (Last week it went over 100 degrees for several days in a row.)

This heats the air and causes it to rise which literally pulls the cold, moist air in over the coastal range. Once that cold mist air gets here it warms up, rises, and then cools. This causes the moisture to condense and turn into rain drops.

And that is why it is raining in the Central Valley again for the umpteenth time this month.

BTW – Usually by this time of year most of the wild grasses and weeds have stopped growing and turned brown. Farmers, homeowners and road & fire crews have cut them down or back to prevent fires. These late season rains will have them growing bigger and/or re-growing in places they were already cut down. August and September should be a real hot time around here.

Watch this climate change ad from Greenpeace (ironically, it’s via Hot Air):

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12 Responses to Why global warming made it rain last night in the Central Valley

  1. ralphb says:

    Great ad! Most of the people I know who are not convinced that climate change is caused by humans still think it’s occurring. In other words, it’s a problem no matter why it’s happening so we should try and solve it. Not to mention that renewables and conservation are good in any case.

  2. Three Wickets says:

    OT if I may. I don’t really know what Matt Yglesias is mumbling about here, but it sounds like he’s trying to say feminism has been one reason for the decline of education standards in America. What the hell..

    At any rate, while I don’t want this to be taken the wrong way, I think the cause of the problem here is the intersection of feminism and capitalism. Prior to 1970 or so, overwhelming social and politician coercion was brought to bear on women to overwhelmingly focus their time on childrearing and to severely limit the range of occupations they could enter. One of those occupations was, of course, teaching. This all constituted a giant implicit subsidy to the school system. In some countries, such as Sweden and Finland, the feminist turn was accompanied by big-time family leave policies, big investments in preschool, and substantial structural reforms to K-12 education. But America just kind of welcomed women to the world of competitive labor markets and left it at that. Under the circumstances, I think it’s slightly surprising that we’ve managed to avoid actively backsliding in educational attainment.

    • myiq2xu says:

      Matt should tell Pat Sajak he wants to buy a clue.

    • ralphb says:

      Do you think that Matt realizes he just gave a ringing endorsement to completely voucherized K-12 education with total choice of school by the student?

      In Sweden, each child receives the amount spent per year in their district and can take it to any school they wish to attend be it public or private or whatever.

  3. Miq is right. I lived on the north coast of CA for a while and that is how it worked. When the interior got hot, that pulled fog in from the ocean and we had cold foggy weather. Almost like a thermostat. 😉

    • PS. There’s more to it. We got cold foggy Julys on the coast because the ocean and the ocean air were cold, like Miq says. Now the oceans and the air are warmer, so more water is evaporating into the air, so it’s full of moisture, so it’s got all that moisture to drop inland as rain.

      And the oceans are still rising because the polar ice is melting.

  4. Lola-at-Large says:

    This post didn’t get a lot of comment-action, but I wanted you to know I read it and appreciated it. You’re as good when you’re serious as you are when you’re being snarky. Why aren’t you getting paid to write?

  5. WMCB says:

    That was a great ad.

  6. djmm says:

    Excellent post, myiq. This is an important issue, in my view, and the consequences of doing nothing are truly dire.


    • myiq2xu says:

      It’s not just a matter of inconvenience. There are some crops that can be badly damaged by unseasonal rain – grapes and cherries for example.

      I already mentioned the increased fire dangers.

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