Regulars here will know that I’ve complained about the Palmer Drought Index before. Why? For the simple reason that it does not compare rain now with historical averages to determine drought, but compares it to temperature adjusted values, and we know the temperature data is fudged and adjusted way too much to compare ‘now’ to the ‘the historical baseline’. It’s just a broken index since the temperature data on which it depends has been buggered. Yeah, still better than nothing, but not by much, and with a load of caveats needed if you use it.
The Palmer drought index, sometimes called the Palmer drought severity index and often abbreviated PDSI, is a measurement of dryness based on recent precipitation and temperature. It was developed by meteorologist Wayne Palmer, who first published his method in the 1965 paper Meteorological Drought for the Office of Climatology of the U.S. Weather Bureau.
So it might have been a good measure in the ’60s when it was developed, but with buggered temperature data it is highly misleading. Why not just say “Average precipitation is FOO cm and now we have BAR where the ratio is 60% of normal, so it is a drought.”?
The Palmer Drought Index is based on a supply-and-demand model of soil moisture. Supply is comparatively straightforward to calculate, but demand is more complicated as it depends on many factors – not just temperature and the amount of moisture in the soil but hard-to-calibrate factors including evapotranspiration and recharge rates. Palmer tried to overcome these difficulties by developing an algorithm that approximated them based on the most readily available data – precipitation and temperature.
In other words: Given the most easy to get data, what simple method can we cook up to make an “answer” even though we don’t have data for the factors that actually matter and don’t know how the system is really working.
Critics have complained that the utility of the Palmer index is weakened by the arbitrary nature of Palmer’s algorithms, including the technique used for standardization. The Palmer index’s inability to account for snow and frozen ground also is cited as a weakness.
The Palmer index is widely used operationally, with Palmer maps published weekly by the United States Government’s National Oceanic and Atmospheric Administration. It also has been used by climatologists to standardize global long-term drought analysis. Global Palmer data sets have been developed based on instrumental records beginning in the 19th century. In addition, dendrochronology has been used to generate estimated Palmer index values for North America for the past 2000 years, allowing analysis of long term drought trends. The Index has also been used as a means of explaining the late Bronze Age collapse.
So we get our nice little tree ring folks in the mix too. I wonder if they are used as temperature proxy or as water proxy, given that tree rings respond to both… (and sun levels and nitrogen levels and …) I note in passing that the Late Bronze Age collapse was the start of what is called the Iron Age Cold Period. We get drought when the world is cold, and at the bottom of an Ice Age Glacial global dust levels rise dramatically in a severe drought. But the Wiki isn’t about to mention that…
Back at California
So California is in a Palmer Drought. From:
Looks pretty grim, doesn’t it?
Well, I took a look at the data for San Jose, California (where we are being told our lawns need to die and we all need to think about skipping the occasional shower – that by law must be using a “gets you slightly damp” water saving showerhead anyway – and can only do ANY outside watering on 2 or 3 days of the week (they keep changing things). From Wunderground and their Historical Almanac, we can get the rainfall for the last “water year” of July to July:
Daily Weekly Monthly Custom
Max Avg Min Sum
Precipitation 3.23 in 0.04 in 0.00 in 13.20 in
So while our historical norm is about 15 inches per year, we got only 13.2 per year. All of about 2 inches shy of average. Given that precipitation can vary by that much in one storm, not exactly what you would think of as drought of historical proportions. In fact, I’d figure that for urban growth planning you would put water availability at one standard deviation below the mean and only call it a drought below that point. Then again, I’m interested in making things work right, not political headlines…
So it’s a drought, but IMHO not by a whole lot.
Yesterday it rained here again. Not much, just a sprinkle, but a bit unusual. I’d say very unusual for a ‘severe drought’, but we’ve had this happening lately. Makes a fellow go “Hmmm….”
Similarly, Texas was shown as being in an End Of Days Drought Of Biblical Proportions… even while it was being flooded…
So why this posting? Well, seems that the “Flooding Drought” has come to California, too. Notice on the map that particularly dark red area in the Sierra Nevada mountains (follow along the Nevada / California border) and the red down near Southern California in the desert areas toward Arizona? Now look at this flood warning map:
Yup, you got it. It’s that Sneaky Flooding Drought again. All along that dark red spine of the Sierra Nevada it is also a dark green flood hazard; and even out in the desert of California. On out to the coastal areas near Santa Barbara too. (Just north of the Los Angeles basin proper).
Surprising? Not in any normal year. This is just the “Flash Flood” hazard, and is directly related to single rain events, while the drought index looks at longer term averages. In any normal year, there’s a significant risk of flash flooding from a single large storm that “dumps a load” and moves on. But I suggest that in a drought of Biblical Proportions, it is unusual. So which is wrong? The hazard map, or the Palmer Drought map? Might this really be an ordinary year, a bit dry but not by much, over hyped by statistical manipulations and over building population centers in a desert climate to beyond the 1-sigma carry capacity? Is there an existence proof that this might be a bit out of the ordinary rainfall?
Part of Interstate 10 Collapses After Heavy Rains in California
Andrew Dalton and Tami Abdollah
AP July 19, 2015 Updated: July 20, 2015 2:39 AM ET
A driver who crashed in the collapse had to be extracted
(LOS ANGELES) — An elevated section of Interstate 10 collapsed Sunday amid heavy rains in the California desert, injuring one driver, stranding many others, and halting travel for thousands by cutting off both directions of a main corridor between Southern California and Arizona.
“Interstate 10 is closed completely and indefinitely,” said Terri Kasinga, spokeswoman for the California Department of Transportation.
A bridge for eastbound traffic about 15 feet above a normally dry wash about 50 miles west of the Arizona state gave way and ended up in the flooding water below, the California Highway Patrol said, blocking all traffic headed toward Arizona.
They also closed the westbound direction as that part of the road, while not collapsed, had significantly been undermined.
For those not in the USA, the Interstate Highway System was built under Eisenhower for military transport. (Back in his day they actually understood the Constitution and it essentially forbid using Federal money for things not ‘enumerated’ in the Constitution… so they had to say these were military roads to legally spend the money). There is a Federal Specification for these roads that requires bridge strength and clearances so that you can drive military transports on them. In San Jose, a chunk of the State highway 17 was renumbered to Interstate 880 and handed over to The Feds for maintenance. That act required inspection and approval of all bridges and clearances for overpasses as sufficient to carry military transports. Basically, this isn’t some half assed road in the middle of nowhere. It’s a world class road in the middle of nowhere ;-)
I-10 is THE major east / west corridor of the USA. Yes, there are others ( I’ve driven all of them at one time or another). I-8 was added south of it to take some SoCal traffic (from San Diego) off of I-10 when it became too popular. I-40 runs north of it (through Flagstaff Az and snow country). Go higher still, you get to I-80 that runs through the middle of Nevada at Reno (and closes when the snow is too heavy in Donner Pass). There’s also an I-70 that splits off of I-80 to Colorado, and doesn’t make it to California, and an I-90 way up in Montana. All of them are important, and carry a lot of traffic (especially in summer when the snows are gone). BUT, in cold weather, it is I-10 that is open and clear and gets the traffic.
Update: Here’s a map of the location of the washout (middle of nowhere Mojave desert) and showing bypass roads north and south of it. Not big enough to carry full I-10 volume (except maybe I-8 to the south) but “enough” to get past. Personally, since I’m coming from far north, I can either take I-80 if staying north, or drop down to I-40 for Dallas and then on to Florida or “wherever”. I’ve often taken I-40 just out of boredom with the “crossing LA” and then I-10 forever. It’s a nice road (at least when it isn’t full of snow and chains required …)
Click on the map for a very big view. “Local” bypass would be highway 62 / 117 to the north (or 62 / 95 for a longer run but with 95 being larger than 117) and alternately 86 / 78 or 86 / 111 / 78 around the bottom (or if ‘going on through’ then 86 / 111 to I-8 or 86 / 78 / 111 to I-8 as I-8 merges back in with I-10 at Casa Grande just south of Phoenix. When returning from Florida last time I took I-10 to I-8 to 85 to avoid Phoenix. Would have been quite happy to just take I-8 on in further and then head north (at about any point).
So not too hard a ‘bypass’ to work out, but a ‘crimp’ for those folks wanting to do a quick 6 hour run from L.A. to Phoenix… Folks not doing the LA/Phoenix thing can easily swing high or low around this.
Sidebar on I-numbers: USA has an interesting numbering system for highways. Odd numbers run North / South, so I-5 runs from San Diego to Seattle. Even runs East West, so the 10, 40, 70, 80, 90 etc. above. Small numbers on N/S are in the West. (So I-3 is in Hawaii. For details on how you can have an “interstate” highway on an Island, see: http://www.fhwa.dot.gov/infrastructure/hawaii.cfm) From that, you can easily guess that I-95 runs N/S on the East Coast. Small numbers on E/W are in the south, so I-8 is south of I-10 (but merges into it just past Phoenix) and I-20 is north of I-10 (and splits off from it in the Middle Of Nowhere Texas headed for Dallas) Three digit numbers are a “bypass’ of some other Interstate. So I-680 is the sixth bypass on I-80 (and connects from up near the Bay Delta down to San Jose). Lately they ran out of single digit bypass numbers so started doing reuse… so you will find 880 in the SF Bay Area and another 880 bypassing Sacramento.
The point here being that that particular chunk of road is a Very Big Deal. Gets regular maintenance and inspections. Is built to take very heavy loads (think “tank on a truck”) and stand up in just about any reasonably expected weather. That it’s had a washout is a very big deal and a very big surprise.
BTW, I last drove over that bit of road in the drive back from Florida a few months ago… So I know that chunk of road. I’ve driven it dozens of times.
The TIME article goes on:
“Oh my God, we are so stuck out here,” Browne told the Desert Sun newspaper. “There’s no end to the cars that are stuck out here.”
The rains came amid a second day of showers and thunderstorms in southern and central California that were setting rainfall records in what is usually a dry month.
Rain fell Sunday afternoon in parts of Los Angeles County’s mountains, the valley north and inland urban areas to the east. The city also was expected to get a late repeat of Saturday’s scattered showers and occasional downpours as remnants of tropical storm Dolores brought warm, muggy conditions northward.
“We have a chance of some more heavy rain in LA County this evening, thunderstorms, lightning, possibly some localized street flooding,” said National Weather Service meteorologist Joe Sirard.
The showers forced the Los Angeles Angels’ first rainout in 20 years and the San Diego Padres’ first rainout since 2006.
Saturday’s rainfall broke records in at least 11 locations, including five places that had the most rain ever recorded on any day in July, Sirard said.
Now a ‘one in 20 years’ rainout is NOT a freak event. It’s a 1 in 20 unusual but normal event. What is odd is having a 1 in 20 freak rain event in what is supposed to be a Drought Of Historic Proportions… Thus my complaint about the Palmer Drought Index when used with buggered temperature data.
The “most rain ever” for “any day in July”, however, IS a freak event… Those damn Flooding Droughts can be real sneaky things ;-)
Another story of the event, from a local TV station IIRC what KTLA does, is here and includes pictures of the bridge over the “dry” wash from the side:
Bridge Collapses Amid Heavy Rains East of Indio, Prompting Full Closure of 10 Freeway
POSTED 8:05 PM, JULY 19, 2015, BY JOHN A. MORENO, UPDATED AT 11:43PM, JULY 19, 2015
A 30-foot-by-50-foot section of the eastbound side of the interstate “is washed away and the bridge is gone,” according to an incident report on a CHP website.
A pickup truck went over the side of the roadway in the collapse, which was first reported at 4:43 p.m. and left the driver trapped inside after a passenger got out, according to the Highway Patrol and Cal Fire’s Riverside division.
Other motorists used tow straps to secure the vehicle to a guardrail, preventing the truck from being swept away in the Tex Wash, said Jennifer Fuhrman, spokeswoman for the fire agency.
I’m especially fond of that bit about the “other motorists” taking action and improvising with tow straps an anchor for the truck. Makes me think maybe we haven’t lost all of our “Can Do” attitude and willingness for Citizen Action when and where needed. Damn the legalities and niceties, we need to save that guy’s life… Gotta luv it.
In the side shot from their site you can see that the bridge isn’t very high. It is only to cover a ‘wash’ area for the infrequent desert rains. You really ought to ‘hit the link’ and read their article / see their pictures, but I’m linking to one of their pictures here:
Yeah… rapid water in a sandy desert can erode fast and far. But it’s not usual to get that much water in such a dry wash and the approaches are usually protected with cement or rip rap (rocks and such). You can see some on the left side of the photo, but that on the right has been washed away.
Foreman to DC Boss: “Boss, we gotta get us some bigger rocks…” ;-)
My point here is pretty simple. Say to folks that it’s a Drought Of Biblical Proportions and that rain is a thing of the past and that it’s Perma-Drought from here on out; and they stop thinking about the usual and ordinary flash floods. They certainly don’t start inspection and preparation for the “100 year flood event”.
The result is things like this washout on I-10.
Lying to yourselves (or worse, to others) using statistical manipulations of data, and using bent temperature data instead of actual rainfall amounts to define a “drought” just causes trouble.
But it’s what we have, now, from our Special Interest Owned and UN Operated government in Washington D.C.
So expect to see more “Flooding Droughts” coming soon to an area near you…