WeatherTiger’s October modeling has trended modestly cooler this month, with chances of at least a weak La Niña developing by December rising to well over 50%. La Niña is now likely to be strong enough to influence growing season precipitation distribution in South America, and potentially the U.S. winter pattern as well.
El Niño Outlooks
The equatorial Pacific has cooled quite a bit in the last month due to a strong surge in easterly trade winds, and ENSO is beginning to tip into a weak La Niña state.
WeatherTiger’s August modeling shows a solidly neutral ENSO state through year’s end. Major changes to this overall outlook are not expected in the next 3-6 months, as there are seldom large shifts in the Pacific in the latter half of the year.
The latest dynamical ENSO models are showing a strong consensus for continued warm-neutral conditions over the rest of 2017. This is in good agreement with WeatherTiger’s July modeling, which shows a solidly neutral state through year’s end.
After calling for at least moderate El Niño to develop by the summer throughout the spring, dynamical models are still backpedaling in favor of projecting a continuation of warm-neutral conditions. WeatherTiger’s June modeling is cooler again showing solid neutral conditions through year’s end.
The equatorial Pacific remains in neutral ENSO conditions, showing neither a La Niña nor an El Niño state. The uncertainty regarding the evolution of ENSO over the next six months is starting to decrease as evidence mounts that ENSO will remain in a neutral-positive state or only a very weak, marginal El Niño will develop in the next six months.
The equatorial Pacific is officially in neutral ENSO conditions, showing neither a La Niña nor an El Niño state. There remains a great deal of uncertainty regarding the evolution of ENSO over the next six months, but we feel that evidence is mounting that the prospective developing El Niño will underperform expectations.
Technically, the equatorial Pacific remains in a weak La Niña state, which was officially declared by NOAA in early November. However, atmospheric measures of ENSO continue lagging the ocean, and there has been no confirmation of that signal since the declaration. Instead, waters are warming in the central Pacific.
The transition to weak atmospheric La Niña conditions remains possible, but is not particularly expected. The chances of this minimal La Niña ending over the winter of 2016-17 are around 70%, with the most likely outcome as projected by WeatherTiger’s exclusive ENSO Whisperer forecast model three to five more months of continued neutral-negative conditions followed by a spring trend towards true neutral patterns.
Currently, the equatorial Pacific remains in a borderline weak La Niña state. However, the atmospheric measures of ENSO continue lagging the ocean, and though most of them have ticked a bit more towards Niña-like conditions in the past month, continuation of this trend is not certain.