February 14, 2017

The West Coast Will Face An Extraordinarily Wet Period

Northwest Weather Workshop:  Open to AllThe Northwest Weather Workshop, the big annual weather gathering in the Northwest, will take place on March 3-4, 2017 in Seattle (NOAA Sand Point Facility).   Everyone is welcome.  For more information and to register, go to https://www.atmos.washington.edu/pnww/
Northern California is experiencing its wettest winter on record, with reservoirs full, the ground saturated, and many of the rivers at or near flood stage.

Oroville Dam, northeast of Sacramento, is on the brink of failure and downstream residents have been warned to evacuate.  Water is being released through the emergency spillway in a desperate attempt to save the dam.

During the past two weeks, immense amounts of precipitation has fallen over the West Coast (see image), with some locations in the Sierra and coastal mountains getting more than 20 inches of water.

Considering the last 60 days, large sections of California, Nevada, Utah, and southern Oregon have received 200-400% of normal precipitation, with limited areas exceeding 400% of normal.  Generally, Washington State is slightly drier than normal.

Folks, it is not over yet.  Although a ridge of high pressure temporarily has dried things out the last few days, the fire hose of rain will be returning on Wednesday.

Here is the forecast precipitation total for the next 9-days from the U.S. GFS model.  Nearly all of the Cascades, Sierras, and coastal mountains will get 5-10 inches of additional precipitation.   This includes the last hold-out from serious wetting, the mountains behind Santa Barbara.

The forecast for nearly the identical period from the European Center model shows a similar story.   Very wet conditions along the entire West Coast.

A number of rivers are now at flood stage in California (red dots on map below from the California/Nevada river forecast center) and they will be pushed higher during the next week.

There are a number of individuals and groups that talk about drought in California being a threat from global warming.  But heavier precipitation during major precipitation events during the winter is perhaps a more probable expectation, as atmospheric rivers become more potent as the earth warms. Warm air can "hold" more water vapor than cold air.

The atmospheric river that will approach the Northwest on Wednesday will be a strong one (see map, blue colors indicate very large water contents), and will then head towards California.  And more atmospheric rivers are to follow.

An historic wet winter and one that was not forecast last fall.  My profession has a lot to learn about seasonal forecasting, assuming it is possible.


  1. I hope they come out OK. They had a choice ten years ago to spend billions to properly repair their decaying levee system. Instead, they spent it on a train to nowhere.

  2. Clarification: the dam itself is not in danger. The potential failure is with the emergency spillway itself (and there is damage to the main spillway as well). If the emergency spillway is undermined it would still be catastrophic, with 30 feet of reservoir draining, but it is an important distinction. The desperate measures were to increase flow through the damaged main spillway to lower the reservoir as much below the (ungated) emergency overflow as possible before the next series of storms.

  3. Walter, what stops the erosion of the hill side beneath the Auxiliary Spillway if it is used again? In addition, what stops the erosion if the Auxiliary Spillway collapses? One has to assume that the 30 foot below the surface of the reservoir point is very hard bed rock - and I suppose there is a geological report stating that somewhere.

    I'll just be hoping you are right and that the whole structure, spillways et c, can make it through he next 20 inches of rain.

  4. @Walter Kolczynski

    If the emergency spillway failed, most of the hillside below it could erode and pretty much equate to the dam failing.

  5. The issues with the damn are man - made and were entirely preventable. Take a look at CA's recent submission to the WH in advance of the massive infrastructure bill - the Oroville damn is nowhere to be found on their lengthy wishlist. Now people's lives and property are being negatively affected, and it could get even worse (although I sincerely hope not).

  6. Other commenters are correct - the main issue is with the auxiliary (emergency) spillway, although there is significant damage to the concrete lining of the main spillway - which was the reason the lake was allowed to fill in the first place. CA DWR is now putting 100,00 cfs down the main spillway and hoping it will hold - they dialed it back to 55,000 cfs after the concrete damage was assessed. DWR is describing the potential emergency at the auxiliary spillway as "loss of crest control". I have not found credible information on the depth or competency of bedrock at the auxiliary spillway site - 30 feet of weathered regolith seems like a reasonable estimate. The rock is metavolcanics (amphibolite with metagabbro dikes) of the Smartville Complex, and is probably highly fractured from tectonism. Hers's a good recent shot of the eroded headcut near the spillway crest: https://uploads.disquscdn.com/images/4eb74fca71e555936545b3e1cccc4832d304e9d0e87daf1701d178321d054ea1.jpg

  7. Outfield and Joe are correct. The broken spillway has seriously eroded and saturated the earthen dam below the main damn. The primary concern being, if the Spillway is required to be used, or breaks, that the water will continue to erode the earthen support for the main damn.

  8. It should be remembered that these kind of events in California are not unprecedented. The Great Flood of 1862 certainly occurred before any global warming and sounds similar. https://en.wikipedia.org/wiki/Great_Flood_of_1862.

  9. Fred said - "although there is significant damage to the concrete lining of the main spillway - which was the reason the lake was allowed to fill in the first place..."

    The damage to the concrete lining occurred February 7th, one week ago. It is not the reason the lake was allowed to fill to a dangerous level.

    The more likely reason the lake was managed to that level was because water managers have been told, ad nauseum, that California was in a "permanent drought" and they did not want to release water. Google "California permanent drought" and you will get 495,000 hits. The 4th one, from May of 2016 is headlined "Thanks El Nino, But California;s Drought is Probably Forever". And it goes on and on and on.

    Let's hope this does not create the kind of catastrophic physical damage it could.

    But I wonder - just what kind of permanent damage has been done to trust and science by the persistent, loud and entirely wrong declaration that California's drought was "probably forever". It would be laughable if it wasn't so serious.

    And one week ago, it got serious.

  10. QUESTION: Is there a place that explains statistical reporting in weather prognostication? For example, if there is a 50% chance of rain during the 10 o'clock hour and then a 50% chance of rain in the 11 o'clock hour, one would expect that there would be more than a 50% chance of rain for the day. But, no, there is a 50% chance of rain for the entire day. How do I, as a consumer, make sense of this?

    Also, I see there are designations like "rain" and "showers" and then there is "rain showers". How do I interpret that?

    Gary G

  11. There was a study in 2012 and a review in 2005 where the FERC rejected armoring the spillway and emergency spillway. They claimed up and down that the spillway could handle 350,000 cfs, which is insane from an open channel flow angle. It's either corruption at work or really bad math.


  12. "My profession has a lot to learn about seasonal forecasting, assuming it is possible."

    But prognosticating about Climate Change 50-100 years out is considered accurate and irefutable, even though past predictions about today's climate are wrong.

    Yes,your profession has a lot to learn, assuming it is possible.

  13. Go read a similar tale in this (great) book "The Emerald Mile" https://www.amazon.com/Emerald-Mile-Fastest-History-Through/dp/1439159866

  14. Anything is possible. Many people in history are consistent with that thinking.

    This is pretty much most likely going to be the straw that breaks the camels back and water will flood certain towns in California. May we all keep them in our prayers.

  15. .. Just south of me here where I live, in Paradise, CA.. You may have heard, the "evacuation" was lifted at near to 1pm Tues.. If with a warning still in effort. Water levels down due to what actually made it through the "emergency" level "spill way". Expectations being that they will continue to drop. ...

  16. This website (the AGU Landslide Blog) has perhaps the clearest explanation of the emergency a the Oroville Dam. The dam itself is intact but the emergency spillway is not. Built on what looks to be lousy rock that is easily eroded, and only covered with a concrete topping which has failed in places. Gully erosion has started and if allowed to continue, will eventually undermine and compromise the structure there. The photographs in this article show it in excellent detail.

    The Landslide Blog is a great blog to read and follow by the way!

    See http://blogs.agu.org/landslideblog/2017/02/14/oroville-dam-site/

  17. JeffB - You never cease to amaze me. You do realize don't you that forecasting the future lies at the heart of human success? As much as you consider any hint of uncertainty as a sign of failure, history demonstrates repeatedly that humans can indeed function quite successfully in environments of uncertainty, so long as we studiously operate by terms of probability and consequence, nimbly adjusting as we learn more. In fact, if anything, those who reject uncertainty essentially reject all forecasting, dooming themselves to a rigid faith in certainties. It is about as useful, when risk increases, as a dead and rotting albatross around the neck.

    You will note ( I would hope, but I wouldn't put money on it) that Cliff said specifically that his profession has a lot to learn from SEASONAL forecasting. That is, a climate forecast (an average) that is seasonally variable due to weather that is, as always, spectacularly variable. It is a climate prediction that uses a tiny time / data sample size in an environment of high variability. Do you follow me? Do you posses the most basic of skill in statistics? This is the forecast period that is inherently less reliable by many orders of magnitude.

    Conversely - and more important in regard to your miss leading intuitions - the further out in time offers a better reliability. It is counter intuitive, which is why you make your assumption of a linearly decreasing skill in prediction but always remember - beyond a week or so out, it becomes more a climate prediction (averages) not a weather prediction yet the seasonal climate is vastly complicated by natural variability (weather events).

    30 years from now, the averages are actually higher reliability in terms of probability, due to the rule of big numbers smoothing out the perturbations of natural variability. It is true that future perturbations may occur to disrupt the relatively linear warming trend, but those will need to be similarly spectacular in nature to duplicate the disruptive impact seen in seasonal forecasts. Such profound climate perturbations may occur, perhaps by massive geo- engineering projects or possibly by way of the much feared methane releases in the arctic. These scenarios might then be complicated by other climate changers, such as a meteorite strike or an unusually high degree of volcanic activity.

    That is the extent of future uncertainty but even then, what is more probable with what we currently know, warming will continue at its current dramatic rate, which will increasingly become more ecologically destabilizing. That is a generalization that is highly probable, even if it isn't certain.

    Here is a sample of a similarly complicated climate forecast, this one 1 and 2 weeks out. The first one has a history of reasonable reliability while the 2 week much, much less so.


  18. "A 43-day storm that began in December 1861 put central and southern California underwater for up to six months, and it could happen again"

    By B. Lynn Ingram on January 1, 2013


  19. Jeff we all can predict the seasons with excellent accuracy. I feel that looking at a table of past temps can clearly show where the future is headed.. it's not hard for our brains to uncover simple seasonal patterns. Just like we can all look at graph that's climbing, and guess the next few positions with good confidence.

    Jeff why are you so opposed to the idea of forecasting a global warming trend?

  20. @ sunsnow12:
    "The damage to the concrete lining occurred February 7th, one week ago. It is not the reason the lake was allowed to fill to a dangerous level.

    The more likely reason the lake was managed to that level was because water managers have been told, ad nauseum, that California was in a "permanent drought" and they did not want to release water. "

    Incorrect. It is the reason the lake was allowed to fill. As shown here, the lake was being kept at normal levels for a wet year until the main spillway closure:

    That's just a snapshot of the sort of data used for reservoir management, but it gives a very good idea of what their goals are - basically fill to a safe working level that gives you lots of storm capacity as early as you can in winter, than hold it there until late spring when most of the snowmelt is done, before letting it fill the rest of the way to maximize water available in the summer and fall.

    @ DC
    "There was a study in 2012 and a review in 2005 where the FERC rejected armoring the spillway and emergency spillway. They claimed up and down that the spillway could handle 350,000 cfs, which is insane from an open channel flow angle. It's either corruption at work or really bad math."

    The reporting on the 2005 matter has been so bad it effectively qualifies as a lie. It was a Sierra Club attempt to prevent the dam from being relicensed. I read their filing yesterday. They never contested the ability of the emergency spillway to handle 350,000 CFS. They only pointed out it would erode significantly and need repair afterwards, which was known and accepted by the reglators because it was an absolute worst case emergency plan.

    Their objection was almost entirely on the fact that if they're forced to use the emergency spillway, they no longer have the ability to control the flow rate, because there are no gates on the emergency spillway. But they also objected to adding gates. They made some noise about armoring the spillway, but that doesn't actually address their main concern, so it appears their real goal was simply to disrupt the re-licensing process.

    The 2005 objection had nothing to do with erosion working back towards the weir on top of the emergency spillway, it NEVER predicted collapse, and it never predicted a failure of the main spillway.

  21. Iamlucky13 – I am clear on water management. The graph you link (which I have seen), demonstrates the fact they were holding water at a near maximum level, in fact you have to go back 34 years to get there. Not a lot of room for error. And they got error.

    It was far above the historical average. In fact exceeded the very maximum set in 1983.

    I am not trying to second guess this, in fact I think they were put in a very difficult situation. But I don’t think anyone believes now it was a “safe working level”. And my guess is it won't happen again, at least not until we start hearing about a permanent drought again.

  22. Questions for Cliff: How does this wet weather relate to climate change? We have heard that no single weather event can be attributed to climate change... but at the same time I have heard that no weather event is completely uninfluenced by climate change.

    The global average air temperature is higher, warmer air can carry more water. Do these truths help us?

    What are the probabilities of an event such as our current soaking if we had pre-industrial carbon concentrations in the atmosphere? What are the probabilities today?

    Thanks for your work.

  23. California drought? Global warming.

    California rain? Global warming.

    You people are religious fanatics.

  24. @Placeholder

    Anthropogenic climate change is not religion. Religion is defined as belief in the absence of fact. Scientists and the scientific process has many different historical records from different processes to better understand climate change. These scientists used repeatable processes to collect data. These data sets combined and analyzed a number of different ways all peer reviewed to conclusively show a trend that burning of fossil fuels puts CO2 in the atmosphere which is warming the planet.

    If you don't feel that the scientific process is valid then by all means: stop flying in airplanes, using any mathematics or physics, eating modern food, using electricity or the Internet, using medical services, and driving cars, because they were all developed using the same scientific principles and peer review we use for anthropogenic climate change.

    Your phrasing is actually backwards. Climate Change Denial is actually closer to a religion as it is the denial of scientific facts and has not shown to be repeatable. Climate Change Denial serves to preserve a narrative that the facts do not support.

  25. @Placeholder:

    I enjoyed your post - if being disingenuous becomes an Olympic sport, we'll see your face on a Wheaties box in no time at all.

    But just for fun, let's set it straight:

    Extreme, and increasingly common, weather event A? Global warming.

    Extreme, and increasingly common, weather event B? Global warming.

    My trick for spotting religious fanatics: Start at a pointed finger and work your way backwards until you figure out who's attached to it.

  26. How do you define 'extreme' weather? Until you can do that scientifically, it has no meaning.

  27. sunsnow12:
    "I am clear on water management. The graph you link (which I have seen), demonstrates the fact they were holding water at a near maximum level, in fact you have to go back 34 years to get there. Not a lot of room for error. And they got error."

    You are mistaken based on considering also the dry years when they haven't had enough rain to reliably fill the reservoir to target levels. If you plot more than just the three years shown, you will see that they do indeed consistently target the 2.75 million acre feet level, leaving them with 700,000 acre feet, or about 20% of the total capacity for flood management. That's several days worth of some of the worst inflows they've ever had to deal with.

  28. Foo, here's one for you - a religious heretic shunned -


    The climatistas also have been after Richard Lidzen's scalp for years (he's one of the fathers of the field of climatology), for the heretical belief that while the earth may indeed be warming, the causes for it are as yet unknown. So here we have two prominent climate scientists being harassed to the ends of the earth for not going along with the other cultists.

    Now, who exactly are the religious fanatics in this case?

  29. Curry and Lindzen are not "harassed to the ends of the earth". They are criticized. Are you suggesting that they are delicate snow flakes unfamiliar with the standard mosh pit of peer review? I think they would be a little insulted at you suggesting they can't hack what they signed up for.

  30. Every departure from a mythical average weather event is now global warming. This is from the same religious fanatics who once lectured us about the difference between weather and climate.

    You people are your own best parody. No wonder you've lost the political debate outside of your sanctuary cities.


Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

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