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.
All the Ricky mountain States and to the west should be slightly to moderately warmer than normal. The plain States should be slightly to moderately cooler than normal\ and the area east of the Mississippi valley should be slightly warmer than normal.
All of Washington should be slightly drier than normal. Most of Oregon, California and Nevada are likely to be slightly wetter than normal. Only far south central California should be considerably drier than normal. The Ricky mountain region and southwest should be slightly to moderately wetter than normal. The northern plains should be drier than normal as well as the eastern gulf states and Florida and Georgia which should be moderately drier than normal. The rest of the east should be slightly drier than normal except for the Appalachian region that should be slightly wetter than normal.