Synopsis:ENSO-neutral conditions are favored to continue through at least the Northern Hemisphere spring 2017, with increasing chances for El Niño development into the fall.
ENSO-neutral conditions continued during February, with near-average sea surface temperatures (SSTs) across the central equatorial Pacific and above-average SSTs in the eastern Pacific. The latest weekly Niño index values were near zero in the Niño-4 and Niño-3.4 regions, and +0.4 and +2.2°C farther east in the Niño-3 and Niño-1+2 regions, respectively. The upper-ocean heat content anomaly increased during February and was slightly positive when averaged across the central and eastern Pacific, a reflection of generally above-average temperatures at depth. Atmospheric convection remained suppressed over the central tropical Pacific and enhanced over the Maritime Continent. The low-level easterly winds were slightly enhanced over the western tropical Pacific and were weaker than average over the eastern Pacific. Also, upper-level westerly winds were anomalously easterly over portions of the western and eastern Pacific. Overall, the ocean and atmosphere system is consistent with ENSO-neutral conditions.
Most models predict the continuation of ENSO-neutral (3-month average Niño-3.4 index between -0.5°C and 0.5°C) through the early Northern Hemisphere summer (May-July). However, some dynamical model forecasts, including the NCEP CFSv2, anticipate an onset of El Niño as soon as the late Northern Hemisphere spring (March-May 2017). Because of typically lower skill in forecasts made at this time of the year, and the lingering La Niña-like tropical convection patterns, the forecaster consensus favors ENSO-neutral during the spring (March-May) with a ~75% chance. Thereafter, there are increasing odds for El Niño toward the second half of 2017 (50-55% chance from approximately July-December). In summary, ENSO-neutral conditions are favored to continue through at least the Northern Hemisphere spring 2017, with increasing chances for El Niño development into the fall.
Much of the country should be slightly to moderately warmer than normal.
All of Washington, most of Oregon and Northern California and Northern Nevada are likely to be slightly drier than normal. Only Southeastern Oregon and Northern Nevada and the far northeast of California could be slightly wetter than normal. The northern plains should be slightly wetter than normal. The southwest through to the Great Lakes region through to the northeast should be moderately to slightly drier than normal. The mid-Atlantic though to the southeast states should be near normal to slightly wetter than normal.