Upcoming El Niño (continued), Tucson winter

In a post eight weeks ago, I showed a scatterplot of the combined total September plus October precipitation at Tucson airport for each of the last 65 years versus the Oceanic Niño Index (ONI, defined by the Climate Prediction Center) for October of each year. This year the airport has had 2.40 inches in September (and more to come next week), which already puts this year's September-October total well above the median for the last sixty-five years. So far this year's September-October total is in the middle of the pack relative to the eight years that had an October ONI greater than +1.0 (as this year is almost sure to have).

The plot in this post is similar to the earlier post's September-October plot, except that now in this plot the Tucson airport rainfall is totaled for the five successive winter months of November through March, and the ONI is for January (the middle month of the five-month period). Selected years are labeled (the year is for the end of the five-month period).

I'm still no fan of drawing a straight line through the data points. Instead, the important consideration for this upcoming winter is that, of the eight previous winters for which the January ONI was greater than +1.0, all eight of those years are in the upper one-third of the five-month precipitation totals. No matter who in the Southwest gets clobbered this winter, Tucson will at least get decent pieces of the action. It's easy to forget that last winter's November through March total (the point labeled 15) was already the 12th-wettest among the past 65 years. If this coming winter were only to match last year's total, it would still be a respectable showing for a moderate-to-strong El Niño winter.

I'm a contrarian in going with a 5-month winter, but that's the way it is in Tucson. Freezing temperatures can occur in November and March, although they are more common from December through February. Winter weather patterns can bring rain to Tucson in November and March, although on average they do so more often from December through February. It's important to bear in mind that even El Niño winters are feast or famine—there can be periods lasting weeks, even a month or more, when the jet stream gets locked into a pattern unfavorable for rain in the Southwest. During the 1972-1973 El Niño most of Tucson's winter rain, 3.5 inches, came in November and March, while only 2.27 inches came in December through February. Similarly, 1957-1958's November plus March outperformed December through February. Conversely, and more typically, of the 10 inches in the five-month winter of 1965-1966, 9 inches came during December through February.

Budapest Flooding

On Monday evening Budapest received over three inches of rain in one hour. The results are characterized in online news articles as apocalyptic and tsunami-like. Those Budapest scenes look a lot like Tucson at this time of year in most years, although not so much so far this year. Hopefully in Budapest they've recovered in time for Hungary's national holiday today. Coincidentally, today is also Tucson's 240th birthday.

Upcoming El Niño Seasons

Here in Tucson the rain for the past week finally met expectations. But already, even before the monsoon begins to wane, attention is turning to the upcoming El Niño seasons. It will be interesting to see if the consensus outlooks hold for a strong El Niño to develop and persist through the winter. Whatever the strength of El Niño may turn out to be, the evolution of the weather patterns will be fascinating.
I was preparing to update a five-year-old plot and accompanying rant concerning winter precipitation variability here in Tucson, which I had made back when a La Niña was on the way. But a few days ago the local paper had a tantalizing story discussing the prospect of an active tail-end to the monsoon this year, because El Niño.
So I decided to see what the actual numbers look like. Traditionally September rains would be considered the tail-end of the monsoon, and a tropical system in early October would be beyond the monsoon. Actually, that's still the official definition. Instead of trying to separate the two, I totaled the precipitation for the two months of September and October. The precipitation data are from the Western Regional Climate Center. I used the latest, official definition of the calculation of the Oceanic Niño Index by the Climate Prediction Center. There are a total of 65 years on the plot. Selected specific years are labeled.

I hope that nobody tries to fit a straight line through the plotted points. If this year's October ONI is greater than +1.0, as present trends and most projections suggest, what does history tell us about what to expect? On the plot, there are eight years with an October ONI greater than +1.0 (the right one-third of the plot). For seven of those eight years, the combined total September-October precipitation was at least 1.7 inches. In contrast, the left two-thirds of the plot contains 57 years with an October ONI less than +1.0. Of those 57 years, nearly half had less than 1.7 inches, and two of those years had no measurable rain in either month. So this year, bet on more than 1.7 inches in September-October, because you will have a very good chance of not losing that bet. But another way to summarize the right side of the plot would be to say that in six out of those eight years, precipitation was within plus or minus one half inch of the 65-year mean, which is 2.21 inches. On the other hand, one might choose to go with a persistence forecast, imagining that whatever factors contributed to last year's, i.e. 2014, September-October precipitation performance, those factors are only better this year, and thus the decade of the 2010's might join the 1970's as star contributors toward the upper right quadrant of the plot.
Citing 1972's disastrous tropical system Joanne as the kind of thing that could happen this year would at least be the right analogy--both years with oncoming strong El Niños. Citing 1983's September-October disastrous sequence of events as an example of what can happen in an El Niño year, while discussing this year's high and rising ONI's, is mixing apples and oranges. The 1983 data point would support imagining a big September-October next year. That data point is the only big year making the argument for a lagging effect in September-October from the previous winter's El Niño. But then 1972 is the only data point arguing for a big September-October this year. Certainly the possibility of disastrous flooding triggered by tropical systems in September and early October is a concern, but it should be a concern most years. Dangling the notion that that concern should be higher in Tucson this year because a strong El Niño is developing is not supported by the data.

Hungary

Tuesday was about all things Irish. But now back to Hungary. The posts at Hungarian Spectrum, along with other English-language sites recommended there, provide comprehensive, detailed and, sadly I believe, accurate analyses of the political situation in Hungary.
If I ever do manage to visit Hungary on a March 15th--their independence day--I would hope to spend part of the day in a particular village in the northeast corner of Hungary. When I drove to Tarpa last summer, a very nice family there patiently listened to my poor efforts at speaking Hungarian, and they repeated slowly over and over until I at least partially understood. I didn't think to write down their names, and I have no idea which political chants they might endorse. But I keep thinking about the town square in Tarpa. I like the memorials there better than the ones closest to the parliament building in Budapest. With Tarpa's Rákóczi, both horse and rider have a calm, alert, dignified, maybe stoical pose. Behind them, on the corner of the town hall, are the names of Tarpa's leaders in the 1956 revolution. Given the event that took place in a Budapest cemetery a little over a month ago, it's nice to know that Tarpa has a wreath honoring the Hungarian side in 1956.

Don't Blame The Models

I happened to notice this news story (only excerpts below) appearing at a variety of online sites this morning (1/27/15).

MOUNT HOLLY, N.J. (AP) — A National Weather Service official says the agency will evaluate its storm modeling after a storm that was predicted to dump a foot or more of snow on many parts of New Jersey and the Philadelphia region delivered far less than that. ... ... says the storm tracked a bit to the east of what forecasting models predicted. ... ... says the agency will evaluate what happened to see how it can do better in the future.

I am a big opponent of the phrase confidence is high because models have converged on a solution. Red alarm bells should go off any time a forecaster starts to use that phrase. Confidence should be high because alternatives have been ruled out, not because a certain number of models have converged on a small subset of the universe of still plausible scenarios.
But yesterday's storm was not even a case of all models having converged on a solution. I remembered seeing the word outlier in yesterday's forecast discussions. This morning I searched for that word in the Mount Holly discussions, but discovered that outlier had been last used by that office on Sunday afternoon. Instead it was in two of yesterday's discussions for New York, NY, where that word appeared.

New York, NY 10:05 AM [Monday] NWP GUIDANCE HAS SHOWN A LITTLE MORE SPREAD THAN ONE WOULD LIKE TO SEE AT SUCH A SHORT RANGE. MUCH OF THE 00Z GUIDANCE LOWERED QPF AMOUNTS FOR MUCH OF THE REGION...WHICH WOULD MEAN LOWER SNOW TOTALS. HOWEVER... ... DID NOT WANT TO MAKE DRASTIC CHANGES TO THE EXPECTED SNOW AMOUNTS AND HEADLINES WITH JUST ONE MODEL CYCLE. IN FACT... ... THE 00Z GFS APPEARS TO BE A FAST NE OUTLIER.

(The omitted sections in the above quote, after however and in fact, are where the forecaster's confidence was being elevated by model output.)

New York, NY 1:34 PM [Monday] THE STORM APPEARS ON TRACK. THE 12Z GFS IS AN OUTLIER FROM THE 12Z NAM AND 12Z ECMWF. HAVE UPPED SNOWFALL TOTALS ACCORDINGLY WITH MOST AREAS IN THE 20-30 RANGE FOR THIS EVENT.

Nobody wants to hear a forecaster be wishy-washy. People want to hear your best shot. At the same time it is possible to communicate what could go wrong. But instead of acknowledging plausible alternatives, the messages to the public (e.g., upgrading watches to warnings 18 hours before the start of the event) were indicating that forecaster confidence was exceeding record highs.
Don't blame the models. Blame policies, procedures, sloppy communications and training.