Winter Rain

Here is an update of a figure that I have posted and discussed several times over the past nine years or so. The running total for this 2019-2020 winter, which when it ends will be in a new decade, is off to a good start. As of mid-December this winter has already surpassed the entire, disappointing, strong El Niño winter of 2015-2016.

This winter's ONI is expected to remain on the warm side of neutral territory, just less than the +0.5 threshold that is used to categorize El Niño. This winter's data point may end up shifted a little to the right or left, but probably not by much--the consensus of dynamical model forecasts of (sea surface temperatures that go into calculating) ONI has verified well over the last few years. The only question is how far the point will move up on the vertical scale of precipitation. It would be a shame if this winter ended clustered with the red data points from the 1950's and 2000's. Instead, given the head start, I'll be optimistic that by the end of March this winter will be comparable to 2018-2019.

Hot July

Hot July

In a few days the Weather Service in Tucson will issue a summary specifying, to the nearest tenth of a degree Fahrenheit, exactly how much the average high temperature this July exceeded the current 30-year average. While that number alone should make eyeballs pop, consider also the frequencies of the highs that will have contributed to this month's average. At the Tucson Airport through July 28, the number of days with high temperatures: 1-110, 1-109, 3-108, 1-107, 3-106, 4-105, 2-104, 6-103, 1-102, 3-101, none exactly 100, and only 3 days less than 100. That distribution occurring in June would still be a bit on the warm side for that month, but not so unusual. And in June it is a dry heat, with a good cool off at night. In contrast this month's humidity has been at monsoon levels for the last few weeks. But the rain amounts have not.

When averaged over the years the monsoon daily rainfall peaks this week, and then begins to taper off, slowly at first and then more rapidly toward the end of August. But this July when the upper high has been in its good position to the north it has been too broad--too warm aloft and on most days not enough vertical wind sheer to support organized lines of storms sweeping across the area. Things may change for the rest of this week.

The fact that on average the monsoon peaks about now may not be entirely coincidental with the fact that today, July 29, is Rain Day in Waynesburg (where I was born), Pennsylvania. Don't think they've had any rain yet today. But a sprinkle just before midnight tonight would count, and they may get that.

This Tucson Winter

During this El Niño winter with each storm Tucsonans have been reminiscing about winter rains (and mountain snows) of long ago. People say that this winter is like when I first moved here or when I was a kid. But we need only go back four years to find a winter similar to this one in Tucson.

The scatterplot above is almost the same figure presented and discussed in my post five months ago, but now with this winter included. This November through March five-month period is not complete, and so this winter could yet creep past the one four years ago. Either way, this winter and the one four years ago are the two wettest winters for Tucson since the winter of 1997-1998. Together this decade's three above-normal winters (all El Niños, two of them with ONIs qualifying as weak El Niños) rank 12th, 13th and tied for 16th wettest out of the last 70 years, making up somewhat for the dud strong El Niño winter three years ago.

This year's running total for Tucson Airport for the five-month period November through March stands at 144% of normal. Adding in last year's very wet October, Tucson's running total for October through March stands at 180% of normal. That latter number can be more easily compared with the real-time water-year analyses for the entire Colorado River Basin (under that site's tab Monthly Precipitation; March so far has been very good to the areas in Colorado and New Mexico that missed out earlier).

Fascism

Several months ago I downloaded from Apple a free sample of the 2018 book by Timothy Snyder titled The Road to Unfreedom: Russia, Europe, America. On television I had seen Professor Snyder being interviewed about the topic of his latest book, and I had previously been engrossed by excerpts from his earlier works. But reading through the free sample of the first chapter my eyes glazed over. That first impression was wrong; I would now like to be an evangelist for The Road to Unfreedom.

My change of heart started with the latest issue of the PennStater alumni magazine. In the latest issue the new editor has put his stamp on the PennStater with an interview of a retired Penn State history professor. The interview article is titled Defending Freedom Is Not Easy. The PennStater article includes a sidebar with a list of books for additional reading, among them The Road to Unfreedom.

Following that recommendation, I'm rereading the Snyder book from scratch. The words fascist or fascism appear 33 times in the first chapter of The Road to Unfreedom. The name Ivan Ilyin, a fascist philosopher, appears 125 times, thus the glazing over on my first pass through that chapter. After a second pass I now appreciate that, unlike philosophers whose ideas were later distorted to justify Hitler, there is no misunderstanding Ilyin's prescription of fascism for Russia. Snyder makes the case that the Soviet Union had already entered a politics of eternity during the Brezhnev era, which prepared Soviet citizens for Ilyin's view of the world.

The Ilyin playbook is not just about Russia. The same plays (big lies about past and present, false and eternal crises, artificial enemies, loyalty to the immoral leader) are being used in other countries. For outrageous examples in Hungary, see Hungarian Spectrum and Hungarian Free Press. Putin and Orbán, birds of a feather.

Variability—Elephants in the Room

Yesterday morning at 3:15 I awoke to rain, accompanied by occasional faint rumbles of thunder. My dream had ignored the thunder, but had not been able to reconcile the sound of the rain pelting down outside.
The PBS/NPR stations in Tucson spent the day reporting that, National climate experts are still waiting to see whether an El Niño weather pattern will develop. I don't have any idea who may be their source for that statement, but there are multiple problems with it. First of all, national climate experts have been expecting for at least a month now (see links in my previous post) greater chances for above normal precipitation in Tucson this winter, based mostly on the high chance of El Niño being present this winter. The Climate Prediction Center's outlooks are couched in terms of probability over a certain period of time (as are, or should be, almost all weather forecasts of precipitation). It is not a matter of waiting to see what happens. It's true that an official call on the actual presence of El Niño won't be made until a monthly update; the next monthly update will be on December 13. But El Niño being present (as defined by ocean temperatures) is not the same as a particular weather pattern being present. In every season, in every winter, in every El Niño winter there are a variety of weather patterns. One pattern gives way to another. Sometimes a pattern persists for weeks or even a month; sometimes a pattern lasts for less than a week. Over the course of a five-month winter there might be only a dozen or so pattern shifts. When it looks like an established pattern will never change to something else, it seems that's just when it does. Some patterns tend to return more frequently or last longer during an El Niño winter, and those patterns, averaged with the patterns that return less frequently or last for a shorter period of time in those years, result in what is a departure from an average winter. But every El Niño is different. There is no single El Niño weather pattern that develops and then lasts the rest of winter. As surely as some expert will eventually decree that such a pattern has arrived this winter, that decree will be followed by a shift to a dry pattern for a few weeks.
So every El Niño winter is different, and every non-El Niño winter is different. But intra-seasonal variability is not the whole story behind the scatter. The figure below simply repeats the data points plotted in the previous post. But now the color labels are different for the plotted points.

The entire period, beginning with the winter of 1949-1950, amounts to 69 years. In this figure, unlike the one in the previous post, for an approximate middle half of the period, the winters 1965-1966 through 1997-1998, amounting to 33 years, are plotted as green circles. There is a different distribution for the green years compared to the earlier and later periods. In 7 of the 33 green years the January ONI was greater than 1; 4 of those 7 were whopper winters in terms of precipitation. But also, of the 20 green winters that were not in El Niño territory in January, 4 of those winters were also whoppers. (I've always been skeptical of studies that purport to establish a lagged correlation between El Niño and rainfall. The lag works, until it doesn't. It is interesting to notice that 79 and 93 lagged 78 and 92 by one year, and 68 and 85 lagged 66 and 83 by two years. But most of the time a lag fails miserably, even in the green years.)
The end of the period of green years coincides with a shift from a warm to a cool phase of the Pacific Decadal Oscillation. But the start of the green years was near the middle of a cool phase of the PDO.
Although the El Niño winter three years ago was disappointing for Tucson, we've had a couple of winters this decade that nudged into green-year territory. It will be interesting to see what this winter may bring. We'll have to wait and see what will develop.

El Niño and Tucson Winters

The scatterplot below is an update of a similar figure presented in my post three years ago.

The Oceanic Niño Index (ONI) is defined and calculated by the Climate Prediction Center [CPC] as a climate-adjusted three-month average of the sea surface temperature anomaly for the 3.4 region of the tropical Pacific. Thus the January ONIs are already averages over the three months of December, January and February. Historical calculations now use version 5 of the CPC's reconstructed sea surface temperature dataset. The figure that I presented three years ago was from version 4. In some cases the plotted points on this figure have shifted a few tenths of a degree left or right from where they were three years ago. But the overall scatter remains the same. This updated figure includes the last three winters. The last two winters would be labeled 17 and 18, but those two points are packed (unremarkably) among similar years having negative ONI with below average precipitation. (For all 69 years, the mean of the five-month total precipitation is about 3.7 inches; the median is about 3.3 inches; the upper one-third starts at 4.1 inches.) The winter of 2015-2016 (labeled 16) is remarkable because though it is the rightmost point, it is also below average.

Being a three-month running average, the September ONI that will become available at the CPC site tomorrow will lag the latest developments. According to the weekly updates from the CPC the 3.4 anomaly has climbed rapidly in October so that for the latest week it stands at plus 1.1 degrees. The models had correctly predicted the rapid warming in October. If their prediction of a leveling off for the rest of the winter holds, then the January 2019 ONI would be close to plus one, which is the dividing line between a weak and a moderate El Niño. Accordingly the CPC's outlook for the upcoming winter (three months, December through February) issued two weeks ago expects an El Niño pattern across the country. Their outlook puts Tucson's odds into wetter-than-average territory, consistent with the plot above, where of the 24 winters in El Niño territory in January, 15 had above average precipitation, 14 of the 24 were above 4.1 inches. For the 13 weak El Niño winters alone, the two decades of the 1950's and the 2000's are tilted toward below average; the decades of the 1970's through the 1990's, along with so far the decade of the 2010's are tilted toward above average. The fact that the El Niño winter three years ago was below average is unlikely to have ushered in a new era of below average El Niño winters, not anymore than the winters of 1984-1985 or 1967-1968 ushered in new eras of above average La Niña winters. This coming winter's precipitation in Tucson might not be above average, but it more likely will be.

Fall Festival of Rain

Tucsonans don't complain when it rains. Rain makes the actual festivals more fun, more reason to celebrate while packed under the tents. Tucson so far this fall has escaped any serious flooding such as has affected points south, west and north of here.

In a post two months ago, I noted the Climate Prediction Center's odds for El Niño during the upcoming fall and winter, and revisited my rant from three years ago regarding chatter about fall rain in Tucson related to El Niño. Since this fall's rains have been so good, I decided to present a fresh scatterplot for fall. For more explanation about the reasoning behind the scatterplot and for additional sources, follow the links in the previous post.

The Oceanic Niño Index (ONI) is defined and calculated by the Climate Prediction Center [CPC], and won't be available for October until the end of November. For now I'm forecasting 2018's October ONI will be approximated by the latest (mid-October) weekly Niño 3.4 region SST departure. As for this year's fall (September plus October) rain, so far for the period from 1 September through the morning of 16 October the airport has had 3.44 inches; that running total will probably increase by the end of the month. (I've had 4.76 inches for the same period, including 0.84 overnight last night.)

Considering just the last six years (2013-2018), there is a trend toward higher precipitation totals when moving from colder to warmer ONI. The decade of the 2010's has joined the decade of the 1970's in favoring above normal fall precipitation when the ONI is in positive territory. The exceptional years (fall precip well below normal but positive ONI) for those two decades were 2012 and 1979. Fall of 1976 was close to normal.

Considering the wet years appearing in the negative territory of October ONI, with the exception of the decade of the 1950's, in each decade there is one unusually wet fall. These wet falls have followed El Niño fall/winters by one (1964, 1970 and 1983) two (1996 and 2011) or three (2000) years. Certainly it's possible that the climate system sometimes stores somewhere a lingering effect of a previous El Niño, maybe even for a few years, and that that lingering effect influences Tucson precipitation in a specific La Niña fall. But most often any lingering effect does not appear to have an influence. As a specific example, most recently the fall of 2016 does not appear to have been influenced by a lingering effect of the previous fall/winter's strong El Niño. It is as much nonsense to call the fall of 1983 an El Niño year as it would be to apply the same label to the fall of 2016.