Tag Archives: california climate

Rain, 2014 Style

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There it is: what you might refer to idiomatically as the sum total of Berkeley rainfall — or at least the rainfall we have seen here in the North Berkeley flatlands — for the entire month of January so far. When the drizzle started coming down last Saturday, I grabbed the camera and ran out to take a picture. It was just enough to moisten the pavement or the bottom of a rain gauge or, as above, to bead up on windshields.

And from what the weather forecasters, the paragons of prognosticatory pessimism, are saying, this is the only rain we can expect to see through the end of the month. Which means we’re starting 2014 with the driest January on record. Here’s a brief synopsis of where the rain season stands from the National Weather Service’s Bay Area forecast discussion:

SAN FRANCISCO`S CURRENT WATER YEAR TOTAL IS 2.11" WHICH IS NOW THE
THE DRIEST WATER YEAR TOTAL TO DATE ON RECORD. THE OLD RECORD WAS
2.26" THROUGH JANUARY 15TH SET BACK IN 1917. SAN FRANCISCO IS
RUNNING AROUND 9" BEHIND AN AVERAGE YEAR. IF NO ADDITIONAL RAINFALL
IS RECORDED BY THE END OF THE MONTH, SAN FRANCISCO WILL BE 11.50"
BEHIND NORMAL.
SAN FRANCISCO AVERAGES AROUND 8 DAYS IN JANUARY WHERE MORE THAN A
TENTH OF AN INCH OF RAINFALL IS REPORTED. THIS YEAR WE HAVE HAD
ZERO DAYS SO FAR. IF THAT HOLDS, IT WILL MARK THE FIRST TIME IN SAN
FRANCISCO`S HISTORY THAT AT LEAST ONE DAY IN JANUARY DID NOT PICK
UP MORE THAN A TENTH OF AN INCH.

And that, friends, kinds of puts things in perspective. What we’re seeing now hasn’t been seen since 1849, the beginning of San Francisco’s rain record.

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California Water: Is the Drought Over?

Is California’s drought over? OK, let me take a step back. Yes, I realize one could debate whether the last three years in California actually constitute a drought. But that’s a discussion for another time. For now, I think everyone can agree that we’ve had lower-than-average precipitation for the past three years.

The only reason to ask the question is that, after the first half of the wet season delivered only spotty rain, we’ve had a pretty solid week of downpours. Water is sluicing into our reservoirs, and the hills are greening up. All of that is a sign of what we think winter should be here. ( My favorite water statistic of the week: when the storms were at their heaviest around Lake Shasta, California’s biggest reservoir, water was flowing into the lake at about 500,000 gallons per second. That’s 1.5 acre feet, or about enough for three “average” households for a year, every second.*)

Amazing numbers like that aside, the people who get paid to think about whether the drought is over say “not yet.” The San Jose Mercury News published a good summary of the situation a couple days ago: “It’s soaking. But the drought’s not over just yet.”

That story does contain one bit of typically odd California thinking about rain and water, though. It quotes a very knowledgeable local meteorologist, Jan Null, about where we stand in terms of normal rainfall. He says: “”We need February and March to be wetter than January to really end the drought. You have to look at the long game here. This is a great start, but we need to keep it going.”

The last sentence stopped me: “This is a great start, but we need to keep it going.”

Of course, Mr. Null recognizes better than most that the amount of rain we get and when we get it is out of anyone’s control. Still, “we’ve got to keep it going.” Maybe he’s a professional rainmaker.

Once you understand the importance of water in California, once you get how crucial the winter rains are, there’s a score-keeping aspect to weather-watching here. It becomes second nature to study the rain gauge and the seasonal precipitation table as an index of performance, a reflection on whether a great collective goal is being attained. Lots of rain means we’re doing well (and that we can put the complexities of water supply out of our minds). A dry spell means we’re failing (and that there will be hell to pay, or at least the strong possibility of stringent conservation measures).

But in reality, there’s no performance going on. The rain is the rain, and the climate is the climate. California’s rainfall is famously variable. Dry spells can be counted on, and the current run of dry years is the third we’ve had since I arrived in Berkeley in the ’70s. My first California winter, 1976-’77, was bone dry and was in fact the second year of the driest two-year period ever recorded here. A decade later, from roughly 1986 through 1992, we had another run of dry years. And if our winter rains were to stop now, we’d be in the fourth year of drier-than-normal years. In between these periods we’ve had average years and very wet years and years that didn’t quite hit the average. That might not be too different from anywhere else. The reason it’s a bigger deal here than it might be in, say, central Wisconsin, is that we have a six-month dry season, we need to store water to get through that, and we have 37 million people and millions and millions acres of farmland that need water whether it’s falling from the sky or not. Thus the need to believe we can wish the rain to keep going during the wet season and the tendency to feel disappointment when the winter turns into a string of dry, sunny days.

*500,000 gallons per second. Here’s the arithmetic: California Department of Water Resources figures (here: http://bit.ly/6HzIuu) show that in the hour between noon and 1 p.m. on Tuesday, January 19, the net inflow into the lake was 66,288 cubic feet per second. That’s the highest inflow figure for any single hour all week. One cubic foot equals 7.48 gallons. 66,288*7.48=495,834.24 gallons. One acre foot=325,851 gallons. And 495,834.24/325,851=1.52 acre feet. Per second. For the entire 24 hours of the 19th, Lake Shasta’s inflow averaged just over 1 acre foot a second.

Bonus feature! KQED’s latest California Reservoir Watch map, updated earlier today:


View KQED: California Reservoir Watch in a larger map

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California Weather Art

The top image is the current National Weather Service radar mosaic for California (yellow and orange splashes represent areas of heavier rain). The image below that is the quantitative precipitation forecast from the California Nevada River Forecast Center.

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Watching Water

I’ve become preoccupied the last two or three months with the level of water in California’s reservoirs. If you’re inclined to, here’s where you can join in the fun: The state Department of Water Resources’ California Data Exchange Center. The cliche to describe a collection of information like this is “treasure trove.” For example, here’s one report that I’ve taken to taking a look at just about every morning: The Sacramento/San Joaquin Daily Reservoir Storage Summary. It’s a quick look at about three dozen state’s biggest storage facilities: how much water they’re holding, how many acre feet have flowed in or out in the past day, and–especially interesting–how much water they hold compared both to the average for this date and to the amount held a year ago.

There’s a story in the numbers, though I’m still puzzling out what it is. For instance, the state’s current drought is not a drought everywhere. Although rainfall and the mountain snowpack are generally below average, some reservoirs hold more than average for this time of year and much more than they did a year ago (which was an even worse year, precipitation-wise). But the numbers are just one dimension of a complicated picture. All that water has a lot of work to do. We count on it not just for irrigating the Central Valley farms and bringing drinking and lawn water to the citiies and suburbs, but for providing electricity, too. And in recent decades, the state and federal water managers have even been made conscious of another function the water might perform: preserving wildlife–especially the once-magnificent salmon runs in the Sacramento and San Joaquin watersheds.

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Snow Again

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Here’s what that Friday morning snow in Mount Shasta looked like. Not sure when it started, but it was over by 10 a.m. By noon, it was turning into a nice day. I spent the afternoon on a ranch north and east of town, and it was dry and warm there.

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Big Bathtub I: The Acre Foot

An acre foot is the amount of water it would take to flood an acre to a depth of one foot. An acre is, ballpark number only, a patch of land 100 feet by 400 feet. If you were standing on that patch of land with water about halfway up to your knees — well, you’d be having a direct experience of the acre foot.

An acre foot is 325,000 gallons. If you pay a water bill that shows how much you use, you can figure how long that much water would last you. The rule of thumb, that we journalists borrowed from “water experts” here in California was that an acre foot was enough to supply two average households for a year. That’s for use inside and outside the home for three or four people say, and it comes out to about 460 gallons a day for each household. Of course, there’s a lot of variation. An inner city apartment dweller uses a lot less than someone whose lawn looks like a fairway at Augusta National. Someone in a cool coastal area — Berkeley, for instance — uses less than someone in a much hotter area on the other side of the hills, lawn or no lawn.

The acre foot is a basic unit of life in California. Yes, weather people and water management officials count inches of rain and snow in the winter. But those units are incidental in a place that needs to capture and store an immense amount of water to irrigate roughly 15,000 square miles of crops and to supply 36 million people. The acre foot is the fundamental currency of reservoir storage and water delivery.

Up and down California, the federal government, the state government, electric utilities, county and city water companies, and irrigation districts have built reservoirs. They’re big bathtubs that together hold something like 42 million acre feet; that would be enough to submerge the entire state of Wisconsin under a foot of water. They reservoirs are expected to fill up in the winter and spring with runoff from the rains and melting snow running down from the Sierra Nevada. Then the water is pumped out during the dry season to help the fields and orchards thrive and to keep the showers and garden hoses flowing. Some water is even set aside for the fish that swim in dwindling numbers through the maze of waterways between reservoir, farm, and town.

A wet winter here–what people like to think of as normal, with nature’s tap switched on when we get into the middle of autumn–keeps our big bathtubs full and the water running where it’s needed. But there are other kinds of winters, too. Very wet ones, where the system simply can’t hold all the water coming down the rivers. And dry and very dry ones, where the water level in the reservoirs falls and keeps falling if two dry years come back to back.

We’re in what appears to be our third dry–or drier than “normal”–year in a row. Three of the biggest federal reservoirs in Northern California– Shasta, Oroville, and Folsom–all fell to critically low levels in December and January. Together, the three reservoirs can hold about 9 million acre feet; that’s about enough to supply a year’s worth of household water for New York, Pennsylvania, New Jersey, Massachusetts, Connecticut, Rhode Island, New Hampshire, Vermont, and Maine. That’s every U.S. resident east of the Great Lakes and north of the Mason-Dixon Line.

Remember,: that’s the capacity of just three reservoirs. There are dozens of others. During the last five weeks, copious rains have fallen and the water has started to rise in some of those big bathtubs. More about that later.

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