February 2016 El Niño update: Q & A…and some Thursday-morning quarterbacking

Good question. The topic of ENSO and climate change is a fascinating one and, just as importantly, an ongoing one. Please check out the several previous ENSO blog posts which have delved into this scientific question here, here and here. A long story short, ENSO relies not just on the central/eastern Pacific Ocean becoming warmer but the contrast between the central/eastern Pacific and western Pacific (which is cooler than average during El Nino events, vice versa for La Nina). This doesn't necessarily match up if everywhere is warming.

There is evidence though that in the future due to climate change, El Ninos will increase BUT there is also evidence they may not. Which is why at this time the consensus is that we have a low confidence on just how ENSO will change in the future but a high confidence that ENSO will continue to exist. 

Around 200 km west of Buenos Aires, there is no signal in our current forecast for the coming 3-month period, and there s;dp is no clear, systematic effect expected form El Nino or La Nina, in general, during the Feb-March period. So it looks like there are equal chances for below normal, near normal or above normal rainfall, which I hope is good news. No preferred tendency toward drought or flooding.

It depends on where you are located. To first order, the expectation is roughtly opposite that of El Nino, although there are some places/seasons where that holds less strongly than others.

It's easier to say the "warmest on record" if you pick a short period, like the first two weeks of February. I doubt we can say the warmest February on record already, although I have not seen the noaa web page you mention. Maybe they actually are taking the forecast for the next week and a half into account and calling this record already. In any case, the odds are still in favor of getting above average rainfall in San Diego in March, due to the El Nino. It would be more of a "miracle" if you got below average rainfall in March than above average rainfall. The climate influence from the El Nino should "show its face" at some point.

There was a strong westerly wind event in the east-central tropical Pacific in January, and we have been on the lookout to see if its downwelling Kelvin wave would raise the Nino3.4, then Nino3, and then Nino1+2 readings. It did serve to stop, temporarily, the drop in Nino3.4, but does not appear to be exerting more than a small influence on the behavior of Nino3 and Nino1+2, at least to date. There is still some chance for an upward move in Nino1+2 in the coming few weeks, but since Nino1+2 has already dropped by a considerable amount, even some rise, or pause in the decrease, will not translate to implications for important rainfall activity along the South American coast -- at least not in the coming few weeks. There is still a moderate amount of subsurface heat in the eastern tropical Pacific, so Nino1+2 would not be expected to return all the way to average in the next month or two. But it does now appear less likely that Nino1+2 will be at very high levels during late February and March.

El Nino is associated with drought in Indonesia, which in turn has led to an increase in forest fire activity in that region. But even without the forest fires, the fact that the rainfall in decreased would change NPP (net primary production), and the ratio of NPP to GPP (gross primary production). Densely vegetated ecosystems have a lower NPP/GPP ratio than sparsely vegetated ecosystems, and during extended drought periods, such as those linked to El Nino, the vegetation would become effectively more sparse. Forest fires would exaccerbate the vegetation decrease still further. While El Nino may not necessarily change the global average NPP/GPP ratio of close to 0.5, it could affect the spatial distribution of that ratio.

Yes, the forecast for the enhanced chance for above-normal rainfall in southeastern South America has migrated to the north as the time has progressed from October or November 2015 through southern hemisphere summer 2015-16, and now autumn 2016. This is the way it should be, because the teleconnection pattern from El Nino does the same thing, if we look at composites of the rainfall observations during El Nino based on the 1950-2014 time period. During southern hemisphere spring and summer, the pattern of above-average rainfall with El Nino is located farther south than it is during late summer and fall. Also, the strength of that response to El Nino decreases between those two times of the year, and I think our forecasts have shown a slight tendency toward this weakening.

Bill, thanks for your comment, but here we keep the discussions focussed on ENSO, not all climate topics, such as climate change (unless it regards long-term change of ENSO). I encourage you to pose your question to to the Climate.gov general mailbox: climate-portal @ noaa.gov (remove the spaces).

Your "opposite rule" sounds smart on an initial take, but when reading farther, it doesn't sound very persuasive or scientific. First, since when can you base a rule on a single case? That is very risky indeed. In 2003-04, the ENSO situaiton was neutral, as you said. In 2004-05 there was a weak El Nino, which would normally lead to a forecast for a tilt of the odds toward above normal rainfall during the winter of 2004-05 in southern California. That is indeed what happened, as rainfall was plentiful during December 2004 and January and February 2005. It makes sense. I don't know why the local water experts would sy that there would not be a full lake level in our lifetimes in Lake Arrowhead. How would they be able to come up with a precipitation forecast going out years in advance? It sounds like a statement made in a very pessimistic frame of mind, not an objective statement. Getting back to your "opposte rule", what is your forecast for this winter? A poor rainfall result this winter despite the El Nino? And a healthy rainy season next winter (2016-17) when there is a chance for La Nina?