El Niño is a universal solvent in popular discussion of weather. Before global warming came along, and if an El Niño was on the prowl, the latter was always blamed by weathercasters and the great unwashed (eg reporters) for almost any meteorological oddity that came along. In 1997 I wrote a half-satirical newspaper story on this telling readers "Shanked a golf shot? Blame El Niño." This year for awhile, looks like, we'll have two fall-guys to choose between and blame for all heat waves, floods, droughts, fish die-offs, strange marine animals in unexpected places, monsoons, atmospheric rivers, and cyclones across most of the world.
This week at its official site the Nat'l Oceanic and Atmospheric Administration's Nat'l Weather Service and its Climate Prediction Center posted its latest diagnostic discussion on ENSO (El Niño-Southern Oscillation, a reference to the whole cycle). It says, some 17 years after the last really big one, that the Pacific Ocean appears to be brewing up another, maybe a big one. Odds for onset this summer are now put at well over 50-50. Some say we have about 2/3 chance of it (there are many models. That is a rough but informed guess).
Here is one of the more excited, perhaps over-excited, news accounts:
- Slate – Eric Holthaus (also, picked up by Mother Jones): El Niño Could Grow Into a Monster, New Data Show ; Text is somewhat more temperate than the hed. Still, just referring to a monster El Niño, no matter the word "could," is on the rash side. Still, maybe it will.
The story uses a pastiche of weather terms and diagnostic events to make the case. These including blasts of reversed trade winds in the central equatorial Pacific, blowing west to east rather than the usual other way around, and a mid-surface plume of anomalously warm water sneaking toward South America. This is a lot of warm water, Holthaus writes,enough to cover the US 300 feet deep. If it reaches the surface as it nears South America the full expression of El Niño will be on, it says here.
I must say this does not ring quite right to me, and have left a message at NOAA's Pacific Marine Environmental Laboratory in Washington State asking about it. For sure, the NOAA website does say that anomalously warmth appears progressively farther east down hundreds of meters prior to and during El Niño, influenced in part by slow-moving shifts in sea level called Kelvin waves. I am unsure however that, as the Slate article implies, this water surfaces already-warmed-up and is the direct trigger for cascades of changed weather from the Indian Ocean to the Atlantic's hurricane incubation sites. I thought the prime reason that waters off Peru and thousands of miles westward warm up during ENSO's high phase is that, without the driving force of the usual trade wind, the upwelling of frigid deep water stalls in the eastern Pacific and allows surface waters to warm up. Will let you know if that is correct or if Holthaus has it exactly right. Maybe neither of us does.
(*AMENDED IN BOLD)- THE ANSWER: Reached NOAA oceanographer William Kessler. He says, indeed, that already-warm surface waters in the central and eastern Pacific near South America pile up to greater depths as the thermocline, or boundary between surface and colder deeper waters, descends while El Nino sets in. Therefore upwelling no longer reaches down into cold, deep water to mix it in with shallower waters and thus allowing the surface to warm in the sun. The red blob in plots of the water column along the equator do not represent deep waters moving in from great distances or warming up – but only that the thickening surface layer extends its existing warmth deeper. He also cautions: "There are many factors here. We may not get a big El Niñ0 at all much as I'd like to see one." *His motive, he added, is to have a larger range of data to help refine forecasting methods. (Amended to clarify that he is not rooting for a big El Nino). Admittedly, while Holthaus may not have things quite right, this stuff is complicated and defies usual intuition.
Other stories on the big stirrings in the tropical Pacific:
- Los Angeles Times – Tony Barboza: Chance of El Niño this year is increasing, forecast says ; Hmm. 66 percent is just so precise. But it is a guess. Its looseness would be suggested better by calling the odds about two-to-one. Barboza nicely sums up how the chances have risen over recent weeks, and quotes an Australian bureau at putting it at 70%. For drought-stricken California, a tendency of wetter rainy seasons with El Niño makes it good news, so Barboza leads with that. He does not mention that Australia and other western Pacific nations associate it with damaging drought. This story also points out that these are just odds – there is still a chance of nothing, or even its opposite phase, La Niña.
- Grist – John Upton: El Niño could raise meteorological hell this year ; These things ARE normal, so the raising hell thing makes it sound like something is amiss. Upton writes "monster" in the lede. The story lifts, with credit, verbiage from the next item down to explain the technicalities.
- Mashable – Andrew Freeman: Unusually Intense El Nino May Lie Ahead, Scientists Say ; Very nice physical description of both the unusual waves that alter sea level across the breadth of the Pacific and the trade wind mixups – plus a good metaphor: "The Pacific Ocean exists in a constant state of unease, like an ocean badly in need of a mood stabilizer." Freeman is an old hand at such stories.
- Salon – Lindsay Abrams: Why an El Niño is this year's extreme weather event to look out for ; Based on the Australian Bureau of Meteorology's prognosis, similar to NOAA's but a few days earlier. The story also samples extensively stories from other outlets, fully credited.
- Wash. Post Capital Weather Gang – Jason Samenow: Bet on El Niño says NOAA ;
- USA Today – Doyle Rice: El Niño likely later in year, could help Calif. drought ;
- San jose Mercury News – Paul Rogers: California drought: El Niño could bring big storms next winter, new report says ; Nice choice, he puts the odds at 2-in-3 rather than an overly fussy 66 percent. Also, however, refers to the warm water in the upper layers of the Pacific as "flowing" east to west. Some is, but mostly it is warming more or less in place due, I just learned, to a deepening thermocline. Overall very detailed and historically informed story.
Grist for the Mill: NOAA ENSO Diagnostic Discussion ;