Synopsis: El Niño is expected to remain strong through the Southern Hemisphere summer 2015-16, with a transition to ENSO-neutral anticipated during late autumn or early winter 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. 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. The subsurface temperatures in the central and eastern Pacific, while still well above average, decreased slightly due to the eastward push of the upwelling phase of an equatorial oceanic Kelvin wave. 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. 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 Southern Hemisphere summer 2015-16, followed by weakening and a transition to ENSO-neutral during the late autumn or early winter. 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 Southern Hemisphere summer 2015-16, with a transition to ENSO-neutral anticipated during the late autumn or early winter 2016.s
PNG and the Solomon Islands, and Vanuatu New Caledonia are all expected to be slightly to moderately warmer than normal. Fiji should be near normal to slightly cooler 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 and Kiribati and Nauru.
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. Kiribati and Nauru also are drier than normal.