A transition to ENSO-neutral is likely during late Northern Hemisphere spring or early summer 2016, with a possible transition to La Niña conditions during the fall.
Indicative of a strong El Niño, sea surface temperature (SSTs) anomalies were in excess of 2°C across the east-central equatorial Pacific Ocean during January. The Niño indices in the eastern Pacific declined, while Niño-3.4 and Niño-4 were nearly unchanged. The subsurface temperatures in the central and eastern Pacific increased due to a downwelling Kelvin wave, but toward the end of the month weakened again in association with the eastward shift of below-average temperatures at depth in the central Pacific. Also, low-level westerly wind anomalies and upper-level easterly wind anomalies continued over much of the tropical Pacific. The traditional and equatorial Southern Oscillation Index (SOI) values remained negative but weakened relative to last month. Convection remained much enhanced over the central and east-central tropical Pacific and suppressed over Indonesia. Collectively, these anomalies reflect the continuation of a strong El Niño.
Most models indicate that El Niño will weaken, with a transition to ENSO-neutral during the late spring or early summer 2016. Thereafter, the chance of La Niña conditions increases into the fall. While there is both model and physical support for La Niña following strong El Niño, considerable uncertainty remains. A transition to ENSO-neutral is likely during late Northern Hemisphere spring or early summer 2016, with a possible transition to La Niña conditions during the fall.
El Niño has already produced significant global impacts and is expected to affect temperature and precipitation patterns across the United States during the upcoming months. The seasonal outlooks for February - April indicate an increased likelihood of above-median precipitation across the southern tier of the United States, and below-median precipitation over the northern tier. Above-average temperatures are favored in the North and West, and below-average temperatures are favored in the southern Plains and along the Gulf Coast.
Much of the west and intermountain region should be from slightly warmer to slightly cooler than normal while the Great Plains east and including Minnesota, Iowa and Kansas should slightly to moderately cooler than normal while the Northeast, Eastern Seaboard, far South and Southwest remain considerably warmer than normal.
Most of the western states will be drier than normal with the upper plain states through Missouri and Indiana and the Gulf state to Northern Florida and Georgia being slightly to moderately wetter than normal along with the Appalachian states. The far northeast from including upstate New York and New Hampshire and Vermont should be drier than normal.
Much of the west and intermountain region should be warmer than normal while the Great Plains east and including Wisconsin, Illinois and Missouri and most of Michigan and Indiana should be moderately colder than normal while the far Northeast, Eastern Seaboard, Appalachia and the far South and Southwest remain warmer than normal.
Parts of central Washington state and Oregon and north Idaho and western Wyoming along and eastern Arizona and New Mexico across to Georgia should be slightly to moderately wetter than normal. Much of the western plans from Montana through to Wisconsin should be near normal to slightly drier than normal. The Mississippi and Ohio valleys should be near normal to slightly wetter than normal. The eastern seaboard all way to northern Georgia should be slightly drier than normal.