El Niño is expected to remain strong through the Northern Hemisphere winter 2015-16, with a transition to ENSO-neutral anticipated during late spring or early summer 2016. A strong El Niño continued during November as indicated by well above-average sea surface temperatures (SSTs) across the central and eastern equatorial Pacific Ocean.
This situation is show in Fig. 1. The Niño-4, Niño-3.4 and Niño-3 indices rose to their highest levels so far during this event, while the Niño-1+2 index remained approximately steady (Fig. 2).
The subsurface temperatures in the central and eastern Pacific, while still well above average, decreased slightly (Fig. 3) due to the eastward push of the upwelling phase of an equatorial oceanic Kelvin wave (Fig. 4).
Low-level westerly wind anomalies and upper-level easterly wind anomalies continued over the most of the tropical Pacific.
The traditional and equatorial Southern Oscillation Index (SOI) values remained negative.
These conditions are associated with enhanced convection over the central tropical Pacific and suppressed convection over Indonesia (Fig. 5).
Collectively, these atmospheric and oceanic anomalies reflect a strong El Niño episode that has matured.
Most models indicate that a strong El Niño will continue through the Northern Hemisphere winter 2015-16, followed by weakening and a transition to ENSO-neutral during the late spring or early summer (Fig. 6).
The forecaster consensus remains nearly unchanged from last month, with the expectation that this El Niño will rank among the three strongest episodes as measured by the 3-month SST departures in the Niño 3.4 region dating back to 1950.
El Niño is expected to remain strong through Northern Hemisphere winter 2015-16, with a transition to ENSO-neutral anticipated during the late spring or early summer 2016 (click CPC/IRI consensus forecast for the chance of each outcome for each 3-month period).
El Niño has already produced significant global impacts and is expected to affect temperature and precipitation patterns across the United States during the upcoming months (the 3-month seasonal outlook will be updated on Thursday December 17th).
Seasonal outlooks indicate an increased likelihood of above-median precipitation across the southern tier of the United States, and below-median precipitation over the northern tier of the United States.
Above-average temperatures are favored in the West and northern half of the country with below-average favored in the southern Plains and along the Gulf Coast.
