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.
The western third of the North Island should be slightly above normal and the rest of the island near normal.
Almost all of the North Island should be normal to only slightly above normal.
Near normal to slightly wetter than normal across nearly the entire island with slightly wetter parts of the East Cape through Hawkes Bay down to Wellington.
Near normal across nearly the entire island with slightly drier parts in far eastern Northland and East Cape through Hawkes Bay.
Almost all of the South Island should be slightly above normal except the east coast and plains that should be near normal.
Almost all of the South Island should be slightly to moderately above normal.
Slightly drier than normal on the West Coast and the remainder of the island near normal.
Most of the island should be near normal.