Synopsis: La Niña is favored to develop during the Southern Hemisphere winter 2016, with about a 75% chance of La Nina during the fall and winter 2016-17.
During the past month, sea surface temperature (SST) anomalies decreased across the equatorial Pacific Ocean, with near-to-below average SSTs recently emerging in the eastern Pacific. The latest Niño region indices also reflect this decline, with the steepest decreases occurring in the Niño-3 and Niño-1+2 regions. The surface cooling was largely driven by the expansion of below-average subsurface temperatures, which extended to the surface in the eastern Pacific. While oceanic anomalies are clearly trending toward ENSO-neutral, many atmospheric anomalies were still consistent with El Niño, such as the negative equatorial and traditional Southern Oscillation indices. Upper-level easterly winds persisted over the central and eastern Pacific, while low-level winds were near average. Enhanced convection continued over the central tropical Pacific and was suppressed north of Indonesia. Collectively, these anomalies reflect a weakening El Niño and a trend toward ENSO-neutral conditions.
Most models predict the end of El Niño and a brief period of ENSO-neutral by early Southern Hemisphere winter. The model consensus then calls for increasingly negative SST anomalies in the Niño 3.4 region as the winter and spring progress. However, there is clear uncertainty over the timing and intensity of a potential La Niña (3-month Niño-3.4 SST less than or equal to -0.5°C). The forecaster consensus favors La Niña onset during the winter, mainly weighting the dynamical models (such as NCEP CFSv2) and observed trends toward cooler-than-average conditions. Overall, La Niña is favored to develop during the Southern Hemisphere winter 2016, with about a 75% chance of La Nina during the spring and summer 2016-17.
Most landmasses will experience average wind conditions for the month. Winds will be less than average in much of the central and western and southeastern Pacific Ocean into SE Asia and and Northern Australia and the Central Atlantic Ocean.
Much of the world should be near normal.
August Temperature Extreme Forecast Index
Much of Central North America and South America are forecast as usually low while similar conditions prevail in much of Africa and SE Asia and China and Central Asia. Warm episodes are limited to Western Europe and the western South Pacific and insular SE Asia and the Arctic region.
In the western hemisphere extreme precipitation events are forecast for Texas, and through Colorado and the western plain States and parts of the northern and eastern Caribbean. The Amazon could have unusually to very unusually low rainfall. Higher than normal rainfall events area also expected in Argentina and Bolivia.
In SE Asia and unusually low rainfall is forecast through the western island portion of the region. In Northeast Asia unusually to very unusually high rainfall events are possible in western and Central China and above normal events in Northeast China. Also in the Central Pacific both above and below the equator and also in Indonesia.
Extreme rainfall events are possible in DR Congo and Angola and also in northeast Africa in Egypt, and also in the interior of West Africa (Mali, Burkina Faso and Nigeria) and eastern Saudi Arabia and Kuwait and southern Iraq as well as eastern Iran and western Afghanistan.
Through much of Europe and continental north Asia usual normal to usual high conditions prevail with extreme rainfall possible in northern Spain and southern France.
Warmer than normal; conditions prevail in the western North Atlantic and near normal conditions elsewhere. In the South Atlantic warmer than normal conditions prevail except along the coast of southern Brazil and Argentina that are cooler than normal.
The Northern Pacific is near normal with ENSO neutral conditions prevailing with cooler waters in the eastern tropical Pacific. The South Pacific is warmer than normal off the South American coast and also in the western South Pacific near Australia and New Zealand while the central South Pacific is near normal.
The Indian Ocean is warmer than normal from north to south in the Central region, South of India and Sri Lanka with cooler than normal water off the coast of Africa and also off the coast of southwestern Australia.
North and South America near normal with slightly wetter conditions in Central North America and also northwest South America and part of western Mexico and norther Brazil into Suriname and Guyana. Drier than normal in central Chile.
Southeast Asia looks to be drier than normal north of the Equator and wetter than normal south of Equator while northern India is wetter than normal and central India is slightly drier than normal along with the west coast of India. Much of Bangladesh and western Myanmar is likely to be wetter than normal and most of China and north Asia near normal.
Much of Africa should be near normal except a belt from Sudan wester to Nigeria and Burkina Faso that should be wetter than normal. The Middle East and western central Asia should be only slightly wetter than normal. Europe should be near normal to slightly wetter than normal.
Much of North America, the Caribbean, and Central and northern South America should be warmer than normal. Only Argentic and Southern Brazil should be cooler than normal.
New Zealand the eastern half and northern part of Australia should be warmer than normal and southwestern Australia cooler than normal and all of east and Southeast Asia should be warmer than normal with norther India and eastern Pakistan cooler than normal. Southwest India should be warmer than normal as well as western China and Tibet.
Central Africa should be cooler than normal and Southern Africa warmer than normal as well as northern Africa. The Middle East and Iran and Afghanistan should be warmer than normal as well as all of northern Asia to the Arctic. Bulgaria through Georgia and Azerbaijan should be cooler than normal. Eastern Spain and should be cooler than normal and most of the rest of Europe near normal.