NOAA El Niño Advisory: There is an approximately 95% chance that El Niño will continue through Northern Hemisphere winter 2015-16, gradually weakening through spring 2016.
During August, sea surface temperature (SST) anomalies were near or greater than +2.0 C across the eastern half of the tropical Pacific. SST anomalies increased in the Niño-3.4 and Niño 3-regions, were approximately unchanged in the Niño-4 region, and decreased in the Niño-1+2 region. Large positive subsurface temperature anomalies persisted in the central and east-central equatorial Pacific during the month, with the largest departures exceeding 6 C. The atmosphere remained coupled to the anomalous oceanic warmth, with significant low-level westerly wind anomalies and upper-level easterly wind anomalies persisting from the western to east-central tropical Pacific. Also, the traditional and equatorial Southern Oscillation Index (SOI) were again negative, consistent with enhanced convection over the central and eastern equatorial Pacific and suppressed convection over Indonesia. Collectively, these atmospheric and oceanic anomalies reflect a strong El Niño.
All models surveyed predict El Niño to continue into the Northern Hemisphere spring 2016, and all multi-model averages predict a peak in late fall/early winter (3-month values of the Niño-3.4 index of +1.5o= C or greater). The forecaster consensus unanimously favors a strong El Niño, with peak 3-month SST departures in the Niño 3.4 region near or exceeding +2.0 C. Overall, there is an approximately 95% chance that El Niño will continue through Northern Hemisphere winter 2015-16, gradually weakening through spring 2016.
Most landmasses will experience average wind conditions for the month. Winds will be less than average in much of the Central 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.
Much of the northern hemisphere including Europe and the USA and Canada should be slightly to moderately below normal. Australia and New Zealand will be slightly to moderately above normal. The Middle East could be below normal. Most of India will be normal. SE Asia to Papua New Guinea should be above normal. The southern inter-tropical convergence zone of the Pacific Ocean will be well below normal as will the north Pacific. Africa should be near normal as well as South America.
Cool outbreaks are limited to parts of eastern Australia, 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 as will be the Nusa Tengarra region of Indonesia. Africa with experience usual low temperatures in the south and usual high temperatures in the north.
Parts of the US Midwest, Rocky Mountains and Sierra Mountains of California and interior parts of Argentina and Brazil near the Andes could have extreme precipitation as well as the Himalayas and West Africa. Papua New Guinea, Indonesia, Southern Malay Peninsula and mainland SE Asia could be unusually dry along with parts of the Amazon Basin and Central America and Caribbean and parts of eastern India.
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 of the USA and southern Brazil and Argentina, coastal Washington State in the USA and British Columbia in Canada all show positive rainfall anomalies as does much of northern and southern Africa. From Vanuatu northwest through Papua New Guinea and the Indonesian archipelago and eastern and western India also some of Central America and the Caribbean, northern South America and the southern coast of Chile there is a considerable negative rainfall anomaly.
The warmer than normal areas include much of California and Alaska and the Northwest Territories across to Hudson’s Bay in Canada. Also the Maritime Provinces of Canada are likely to be warmer than normal and the Gulf States of the USA. Central Argentina and western Brazil should be cooler than normal. Peru and south through Chile should be warmer than normal along with northern Australia and Central Asia and North Africa and the western half of India. Much of the Eastern Pacific ocean area will be considerably warmer than normal as well as large areas in the central Atlantic. Much of northern Africa will be warmer than normal while Central Africa will be considerably cooler than normal. Much of Pakistan and north India across the Himalaya into Southern China will be warmer than normal all the way up to Siberia. The Southern Ocean and areas around Greenland will be well below normal along with the central part of the South Atlantic.