It’s happening. The most powerful sub surface warming of the Pacific Ocean on record is continuing to progress into the Eastern Pacific even as it rises toward the surface. As a result, risks for the emergence of El Nino during 2014 are spiking together with the potential for a host of global weather extremes.
Over the past month, trade winds remained weak even as west wind back bursts continued to push against the trades along the Equatorial Pacific. Moderate west winds emerged during mid-to-late April northeast of the Solomon Islands while cyclonic lows produced sporadic west winds in the Central Pacific. By May, consistent west winds were blowing over a large section of the Eastern Pacific.
Upper level easterlies had also emerged reinforcing a general pattern toward El Nino development.
The strong Kelvin wave that, in March, featured the highest sub-surface temperature anomalies on record entered its upwelling phase and began to push more and more of its heat potential toward the surface in the Eastern Pacific. This propagation is clearly visible in the sequence below:
(Kelvin Wave monitoring by NOAA. Image source: Climate Prediction Center.)
As of May 3, 2-3 C above average water temperatures had hit the surface of the Eastern Pacific and 3-6+ C above average temperatures lurked not far below.
The result of this rising warm water pulse was above average sea surface temperatures across the entire Equatorial Pacific with anomalies for the broader region hitting +.62 C on May 8th, 2014. It is worth noting that for El Nino to be declared, Equatorial Pacific water temperatures in the mid to eastern Pacific must remain above +.5 C for two months running. And, at this point, conditions appear primed for just such an event.
(May 7, 2014 Sea Surface Temperature anomaly map shows Pacific Ocean looking more and more like an El Nino. Image source: NOAA ESRL.)
These clear ongoing trends have resulted in yet one more upgrade of El Nino potentials by the Climate Prediction Center (CPC) this week. Chances for El Nino in the current three month period of May, June and July have now been adjusted to about 55% with probabilities continuing to rise throughout the summer and fall. Peak chances for El Nino, according to CPC, are now just shy of 80% by October, November and December of 2014.
All values now show a very high degree of certainty that El Nino will emerge exceeding even the high confidence predictions provided last month by both NOAA and Australia’s Bureau of Meteorology (BOM).
(El Nino Prediction Chart as of May 8, 2014. Image source: CPC/IRI.)
The model predictions of ENSO for this summer and beyond are indicating an increased likelihood of El Niño compared with those from last month. Most of the models indicate that ENSO-neutral (Niño-3.4 index between -0.5°C and 0.5°C) will persist through part of the remainder of the Northern Hemisphere spring 2014, most likely transitioning to El Niño during the summer. While ENSO-neutral is favored for Northern Hemisphere spring, the chance of El Niño increases during the remainder of the year, exceeding 65% during the summer.
When El Nino Comes Early, Risks of a Strong Event Increase
It usually takes until Fall or even Winter for a typical El Nino event to emerge. When El Nino comes early — by late spring or summer — risks increase that the event will be far stronger than normal. In general, such events are thought to be preceded by very strong Kelvin waves like the one we’ve witnessed since January.
Many Ocean researchers such as Dr Wenju Cai, a climate expert at Australia’s Commonwealth Scientific and Industrial Research Organisation, now consider the ocean to be primed for such a strong El Nino event.
Dr. Cai explains:
“I think this event has lots of characteristics with a strong El Nino. A strong El Nino appears early and we have seen this event over the last couple of months, which is unusual; the wind that has caused the warming is quite large and there is what we call the pre-conditioned effects, where you must have a lot of heat already in the system to have a big El Nino event.”
Rising Potential for Very Bad Weather
With the world’s weather already pushed to extreme states by human warming, the emergence of a strong El Nino would likely have increasingly severe consequences. Weather events at both the flood and drought extreme would be further amplified as a portion of hottest ever Pacific Ocean heat content transferred back to the atmosphere. This transfer would push a hydrological cycle already amped by more than 6% due to human-caused warming to a greater extreme. It would also likely result in new global high temperature records worldwide as a Pacific Ocean that had sucked up so much of excess human warming during the past decade and a half again becomes a major heat source.
Hat tip to Colorado Bob