Synopsis: El Niño will likely peak during the Northern Hemisphere winter 2015-16, with a transition to ENSO-neutral anticipated during the late spring or early summer 2016.
A strong El Niño continued during October as indicated by well above-average sea surface temperatures (SSTs) across the central and eastern equatorial Pacific Ocean. Most Niño indices increased during the month, although the far eastern Niño-1+2 index decreased, accentuating the maximum in anomalous SST farther west. The subsurface temperature anomalies also increased in the central and eastern Pacific, in association with another downwelling equatorial oceanic Kelvin wave. Low-level westerly wind anomalies and upper-level easterly wind anomalies continued over the western to east-central tropical Pacific. Also, the traditional and equatorial Southern Oscillation Index (SOI) values remained negative. These conditions are associated with enhanced convection over the central and eastern tropical Pacific and with suppressed convection over Indonesia. Collectively, these atmospheric and oceanic anomalies reflect a strong and mature El Niño episode.
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, with the expectation that this El Niño could rank among the top three strongest episodes as measured by the 3-month SST departures in the Niño 3.4 region going back to 1950. El Niño will likely peak during the Northern Hemisphere winter 2015-16, with a transition to ENSO-neutral anticipated during the late spring or early summer 2016.
Most landmasses will experience average wind conditions for the month. Winds will be less than average in much of the central and western Pacific Ocean and North Indian Ocean into SE Asia and across much of Africa and southern South America. Around New Zealand will be stronger than normal as will the western and north Pacific and Atlantic Oceans and Eastern Europe.
Much of the northern hemisphere including Europe and the USA, Canada and Europe should be near normal. Western Australia and Central Africa and southern South America and New Zealand should be slightly to moderately below normal. Indonesia and the Philippines and eastern Brazil and southwest Africa should be above normal.
Cool outbreaks are limited to New Zealand, Papua New Guinea and the southernmost part of South America and eastern Russia. Meanwhile in the Pacific Ocean where the north Pacific through to the equatorial Pacific will be much warmer than normal as will be the eastern Pacific off of South America and the North Atlantic into Europe. While much of North Atlantic will be below normal the Atlantic along the USA eastern seaboard and to the east of the Caribbean will be warmer than normal. Southeast Asia will be warmer than normal. Africa with experience usual low temperatures in the south and usual high temperatures in the north.
Northern Brazil and the western part of the North Pacific Ocean and most of the Philippines and Indonesia should be unusually to very unusually low. Central America and Mexico, southern Argentina and Chile and Western Australia and eastern China and central and East Africa and Central Asia including Iran and Afghanistan should experience unusually high extreme rainfall at some point in the month.
The evolution of ENSO can be viewed through sea surface temperature anomaly maps. The Eastern Pacific is warmer than normal as is the Indian Ocean. The eastern central Atlantic is also warmer than normal. The ocean surrounding New Zealand is cooler than normal.
The Southwest of the USA including California and Northwest of Mexico and across the Midwest and Gulf States of the USA and the Caribbean show positive rainfall anomalies as does much of Central Africa and the Maldives and Sri Lanka. Central Africa and Southern Brazil also show positive precipitation anomalies. From Fiji to Vanuatu northwest through Papua New Guinea and the Indonesian archipelago, the Philippines and north and east South America and the southern coast of Chile there is a considerable negative rainfall anomaly.
Much of Canada down to the Gulf of Mexico are above normal for temperature while the western States of the USA and Maritime Provinces of Canada are cooler to considerably cooler than normal. Central America and the Caribbean and the northern half of South America are above normal as is the Eastern half of Asia and most of Australia and Southeast Asia and India and southern part of the Middle East. Northeast and southern China is much colder than normal along with much of east Africa and the northern part of the Middle East. Eastern Indonesia through Papua New Guinea and the South Pacific should be slightly cooler than normal. While most of the western half of Australia and New Zealand should be slightly to moderately above normal along with New Zealand. Argentina and southern Brazil should be cooler than normal.