Bad planning and hyperbole
Posted on | January 21, 2010 | 6 Comments
Photo: Bob Chamberlin / Los Angeles Times. Click on the image to be taken to the paper's storm photo gallery.
Contrary to forecasts, including the one repeated here, there were neither particularly heavy rains nor gales in Los Angeles yesterday. “I’m sympathetic with a blown forecast,” says Bill Patzert, an oceanographer with the Jet Propulsion Laboratory in Pasadena.
Having carried it, this writer is too, but only to a degree. It gives rain a bad name.
But when wrong news is good news, why gyp? Moreover, there is more good news in a place with such bad zoning that even the best-behaved showers throw the city into chaos.
As reported in The week that was, and repeated here for good measure, last week, the Los Angeles Board of Public Works passed a Low Impact Development Ordinance that will require new construction to retain more rain water on site to reduce flooding caused by over-development. Click here to read about it from Mark Gold.
But the glow at the blog of the President of Heal the Bay was short-lived after normal rainfall yesterday once again triggered flooding, mudslides and mayhem in coastal and foothill communities. To read why, click here.
Elsewhere on the subject of wetness, to the mind of Patzert, nothing about the recent rains enforces predictions that Los Angeles will enjoy a bumper El Nino rainfall year. At just over three inches in January for downtown Los Angeles this morning, we are still below average for the month, he says, though the steady showers falling today seem capable of putting us into normal range. As for the year, we will need to hope for much the same kind of weather / self-imposed disasters in February to reach our average of 14 inches.
For a TreePeople guide to how to capture rainwater on your property, click here.
Update: In the best for last department, here near downtown Los Angeles, at 6:57 pm, we are finally getting some of the bluster predicted for yesterday. See Comments for the remark of someone who argues that the storm packed plenty of wallop yesterday.
This post has been repeatedly updated.
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6 Responses to “Bad planning and hyperbole”
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January 21st, 2010 @ 6:48 pm
A reader wrote in:
Actually, it did materialize in the south bay.
It rained sideways. I was outside briefly and I can
attest to that. Then something blew into my coworkers window.
Right now, it is calm. Different story at 2:30.
January 21st, 2010 @ 10:13 pm
Emily –
I’m hesitant to question Dr. Patzert, given his expertise in this area, but the National Weather Service* as of midnight last night (the 20th) reported 3.4 inches of rain for downtown LA for the month, which the NWS says is 1.4 inches above normal for the first 20 days of the month. And a tour of other weather stations around the area show some big numbers: Burbank is almost double normal for the first 20 days of January, all of that coming in just the last four days. Camarillo is double, Long Beach is triple, with 2.5 inches of that coming yesterday.
I don’t think this invalidates your underlying point, because even if events like these are only once-a-decade occurrences, that is sufficient frequency that the urban landscape has to be able to accommodate it.
* http://www.weather.gov/climate/index.php?wfo=lox
January 22nd, 2010 @ 6:09 am
Out here in Santa Clarita, the rain came down rather heavily in the morning. Around 1:30 or so, the rain came down so heavily, it was hard to see the house across the street. It was very loud, all the noise of the rain coming down. It rained like that for 20 minutes.
January 22nd, 2010 @ 9:32 am
Hi John, Chris — Don’t blame Patzert. Shoot the messenger, but first allow her to defend herself. Patzert was talking about the Jan 20 forecast, which if you read it, called for sustained gales, which didn’t happen, sudden downpours aside. This made it not too much more than a rather rainy day, which at just over 1 inch here in Los Angeles, was really not that special within rain events. What makes it special is that it’s part of a series of storms and nobody argued that. Now, with monthlong totals, we are not anyplace special for January, a second point. The third being that the promised El Nino might or might not deliver us the much anticipated mana.
January 22nd, 2010 @ 9:51 am
I should add, gale-wise, for most of the day, it was hard to see leaves moving in the numerous palms in my neighborhood. Not a record stormy day in the Look Outside The Window school of weather reporting. But as a third generation Californian, I can say this: Everyone with any history in the place knows that our rain comes in the winter. Divide the average of 14 or so inches by three, even four months, and you have a reasonable expectation of heavy rains during those months of three to four inches. So planning for them is not unreasonable. And planning for how rain behaves near the coast is not unreasonable. Or, given the foothill fire ecology, planning for how heavy rain behaves near burn areas is not unreasonable. I love it here, I live here, but LA fails on all those counts.
Re: Patzert. He’s funny so reporters call him. But the reason I call him is that he’s been the only one to predict correctly a prolonged drying out of the Colorado River system. He did it when no one else believed him, and he was right. He’s been pretty much right ever since.
January 22nd, 2010 @ 1:52 pm
“…to the mind of Patzert, nothing about the recent rains enforces predictions that Los Angeles will enjoy a bumper El Nino rainfall year.”…”we will need to hope for much the same kind of weather / self-imposed disasters in February to reach our average of 14 inches.”
Agreed! And let’s be pedantically clear on the statistical significance of our monthly and season-to-date rainfall figures taking this month as an example.
Data from the last several decades shows that in January we have a 50% probability of receiving between 3/4 and 4 inches of rain (in round numbers.) In terms of cumulative rainfall we have a 50% chance of having between 1 and 9 inches (again, round numbers) at the end of January.
We’re close to the top of that range of cumulative rainfall by my accounting. (I show 8.32″ in my back yard as of yesterday afternoon, but in that range I typically measure less rainfall than the official LA weather report).
The point here is that there’s huge variation in “normal” and indeed, there is nothing to suggest yet that we have had or will have an exceptionally high rainfall year. With about a 50-50 chance of being where we are right now, we’re sitting at “typical” in my book.
As an aside, mean rainfall figures (I have mean total seasonal rainfall at 12″ for LA rather than the 14″ quoted above) aren’t really as insightful as median rainfall figures (I have the LA median total rainfall at about 7″). This is because rainfall is not symmetric on either side of the mean.