Synopsis: El Niño will likely peak during the Southern Hemisphere summer 2015-16, with a transition to ENSO-neutral anticipated during the late autumn or early winter 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 autumn or early winter. 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 Southern Hemisphere summer 2015-16, with a transition to ENSO-neutral anticipated during the late autumn or early winter 2016.
PNG and the Solomon Islands, and Vanuatu and New Caledonia are all expected to be slightly to moderately warmer than normal. Fiji should be near normal to slightly below normal.
Below normal precipitation extends from Papua New Guinea southeastward through most of the Solomon Islands and Vanuatu and slightly less dry in New Caledonia and but moderately dry in Fiji.
PNG and the Solomon Islands, and Vanuatu New Caledonia and Fiji are all expected to be slightly to moderately warmer than normal.
Normal to slightly above normal rainfall returns to a large part of western PNG while most of eastern PNG remains drier than normal along with much of the Solomon Islands and Vanuatu and Fiji with near normal rainfall in New Caledonia.
Parts of northern PNG should be near normal to slightly cooler than normal and the rest warmer than normal and the Solomon Islands, Vanuatu, New Caledonia are expected to be slightly to moderately warmer than normal. Fiji should be near normal to slightly cooler than normal.
Drier than normal conditions return to much of PNG with just the eastern island of PNG returning to normal and moderately above normal rainfall along with much of the Solomon Islands and New Caledonia. Only the northernmost islands of Vanuatu are near normal to slightly above normal for rainfall while the rest of the islands and Fiji remain slightly to moderately drier than normal.