I have been watching Northwest weather for a long time and I have never seen anything like what we have experienced during the last month:
An extended and intense minimum temperature heat wave.
Something amazing has been going on this fall, and for some reason the Ebola-crazed media hasn't picked up on it. But that is why we have blogs. Gardeners know something weird is happening. Vegetable plants are not dying. Tomatoes are still ripening.
There are movies about this issue.
Here are the temperatures at Seattle-Tacoma Airport during the past 4 weeks, with the average high (red) and lows (blue) shown. Only ONE day in that entire period has seen the temperature dropping to the average low. For most days, our minimum temperatures have been 5-10 degrees above normal. Our minimum temperatures last night were close to the average maximum for the date!
And this is not Seattle alone, here is the same trace for Bellingham. Same thing. Bellingham cooled to 59F last night!
A close-up over Washington State shows some areas are 8-10F above normal.
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And the latest NOAA Climate Prediction Center extended forecasts show no end in sight
to the warmth:
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Now why is this happening? This is an important question because one can expect some folks in the media and advocacy groups to start saying this is a "sign" or "consistent with" global warming due to mankind's emissions of greenhouse gases. There is no reason to think that is true.
There are two main reasons for the warmth and they are both associated with the anomalous atmospheric circulations we are having.
Reason #1: a persistent area of low pressure over the eastern Pacific. The figure below shows the sea level pressure anomaly (difference from normal) for the past month. There is an area west of us with pressures well below normal. Such anomalous low pressure is associated with stronger than normal southerly and southwesterly winds over us that blow in warmer than normal air.
This is probably the major cause. Then there is something else, something I have talked about in previous blog: the warm water BLOB off the coast.
Below is the sea surface temperature anomaly map for the past week. You see the orange and red colors off the coast that indicate temperatures 2-4F above normal? The BLOB still lives. So air passing over the eastern Pacific is exposed to warmer than normal water. Me like BLOB, BLOB is good.
As I noted earlier, the BLOB has little to do with global warming but was produced by anomalous high pressure over the Pacific last winter and year.
So our ridiculously warm temperatures this fall are being produced by an unusual combination of high pressure a year ago that produced the blob and low pressure this fall that is bringing up warm air from the south.
There is no reason to think that these circulation anomalies are caused by human greenhouse gas emissions. And remember that the eastern U.S. has been colder than normal.
Well, time for me to go out to my garden to harvest some more red tomatoes.
I thought it was a little strange that my tomatoes are still ripening. I thought I was just really that good at growing them.
ReplyDeleteYes, but are the persistent low and the blob at all caused by anthropogenic climate change? I thought there was a recent study showing that the blocking patterns in the jet stream were related to climate change?
ReplyDeleteOcean water has a high thermal coefficient, so the blob is where some of the "missing heat" is. It'll help keep us cozy of awhile.
ReplyDeleteI wonder if this also explains the vine maple that usually turns brown and is beautifully colored this year with oranges and reds.
ReplyDeleteI don't care WHY, but, am so happy. This has been a summer and, now, fall for the record books. It's wonderfully nice, and I'm so happy. Thank you weather gods.
ReplyDeleteCliff says that he has been watching PNW weather for a long time, and now he sees something he has never seen before, the "extraordinary minimum temperature heat wave," and then throws his customary cold water on climate change as a potential cause for the anomaly. At some point the growing number of anomalies are going to need a scientific explanation.
ReplyDeleteHere is a link to a blog describing a study that concludes that the conditions for the anomalous high pressure cited by Cliff is much more likely under climate warming.
ReplyDeletehttp://www.weatherwest.com/archives/tag/ridiculously-resilient-ridge
And the best part? (aside from still ripening tomatoes) The house was 70F this morning and I have yet to turn on the furnace for the year. A normal year we are heating the house by the end of September.
ReplyDeleteOf course this unusual warmth isn't a sign of warming!!!
ReplyDeletemola mola,
ReplyDeleteThe situation the last month is exactly the OPPOSITE of that...we have had TROUGHING not ridging over the eastern Pacific. And I should note that there are major problems with the Ridiculous Resilient Ridge paper....major technical flaws that I would be happy to describe...cliff
Cliff, very interesting observation. And yesterday, October 19th we set a DAYTIME record high. This kind of weather is unprecedented in my experience here over roughly the last 50 years. Also, apparently rare in the hundred or so years we have been keeping temperature records. But to put in perspective, there have probably been a lot of climate swings in this area prior to human fossil fuel burning as glaciers ebbed and flowed. Nevertheless, your statement above seems a bit absolute: "There is no reason to think that these circulation anomalies are caused by human greenhouse gas emissions. And remember that the eastern U.S. has been colder than normal." I am not sure our ocean/atmosphere/climate/weather models are robust enough to rule out human greenhouse gas emissions as a contributor to our current anomalous weather, hot or cold. I would say something like, "Our current models do not indicate a clear link between this unusual run of warm weather in the west and human greenhouse gas emissions." But if you said that, you wouldn't receive fan mail from people like me.
ReplyDeletethe golf courses on the Peninsula are in great shape!
ReplyDeleteThe problem with your exclamatory statement ("There is no reason to think that these circulation anomalies are caused by human greenhouse gas emissions.") isn't whether or not you're correct -- though I thought you're a meteorologist, so perhaps you should leave such speculation to the climatologists? -- the problem is in your certainty. There's simply no scientific reason to claim that there couldn't be a connection between this anomaly and anthropogenic climate change. Your claim lacks proper skepticism; you can't possibly prove this statement, and I think you should know better. I suspect you wrote it, in bold-print, no less, to provoke, as I imagine it annoys you terribly to see short-term weather phenomena erroneously linked to long-term climate patterns. But please remember the context in which you write your words, as well as the authority with which the public perceives your views. Your voice is a privileged one; rightly or wrongly, people listen to you. To me, this makes your statement reckless and irresponsible. Your petty provocations further muddy the necessary work of shifting our civilization off its carbon-based lifestyle. Please stop this game of yours. Even if your statement could be right, it's just so obviously wrong.
ReplyDeletemycelium,
ReplyDeleteI can't agree with you. Saying that there is no reason to expect such circulations from climate change is completely accurate. I am not saying that it is impossible. Just that every study I have read does not suggest this. I did not say: these circulations are absolutely not due to climate change...then you would have a point...cliff
mycelium,
ReplyDeleteI can't agree with you. Saying that there is no reason to expect such circulations from climate change is completely accurate. I am not saying that it is impossible. Just that every study I have read does not suggest this. I did not say: these circulations are absolutely not due to climate change...then you would have a point...cliff
I studied math in the early 90's and took some classes on "chaos theory" and modeling complex systems on computers. I remember that one of the strong inducements for interest in that study at the time was a result of people trying to model weather systems with simple computer programs.
ReplyDeleteWhen a complex system is disturbed, it often does not nicely lend itself to predictions, but there were expected behavior patterns that one could see in the simple functions that were popular to use at the time. One expected behavior of a disturbed complex system was that it would go through large fluctuations before settling back on a new stability pattern (sometimes called an attractor or soliton). With the systems I modeled I could make a very small change in one of the input variables and there would be absolutely no way to predict where the new stability pattern would go.
Since we have definitely added a disturbance to a complex system, there is some possibility, even a probability that this will create completely new attractors, such as persistent waves. One dramatic example of an attractor in an atmosphere is the red spot on Jupiter. It is a weather system like attractor that has persisted for hundreds of years.
Each time I read of somewhat surprising patterns like the "blob" or this persistent stalled low pressure that has given us unusual September and October weather, I wonder if we are seeing the start of a completely new attractor. We will know for certain only after the fact.
It is pretty hard to tell where this buggy ride is going to go, especially when 7 billion of us have a hand on the throttle.
Actually, you've commented on a study of a longer pattern of northwest heat waves that you were dismissive of using only observations about the placement of a few recording stations. Maybe this strong nighttime warming, consistent with climate models just does not fit your narrative of climate change not showing itself in the northwest yet? http://cliffmass.blogspot.com/2013/07/are-nighttime-heat-waves-increasing-in.html
ReplyDeleteBill Reiswig,
ReplyDeleteI don't have a "narrative." This is not a radiatively forced min. heat wave, but clearly dependent on a circulation anomaly. So it has none of the signs of being forced by increasing greenhouse gases. Just facts...cliff
Overall we are setting way more warm records than cold records of late.
ReplyDeletehttps://www2.ucar.edu/atmosnews/news/1036/record-high-temperatures-far-outpace-record-lows-across-us.
Of course any given period of high temperatures doesn't "prove" global warming anymore than a cold snap disproves global warming.
Interesting also that the IPCC predicted a greater increase in nighttime minimums than in daytime maximums.
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch10s10-es-2-temperature-extremes.html
Our low temperatures the last few days have been around the NORMAL HIGHS. And yesterday broke the record daily high at Sea-Tac Airport. ... lowesthighest.blogspot.com
ReplyDelete