El Niño Update
A moderate-to-strong El Niño continued during February 2010, with sea surface temperature (SST) anomalies exceeding 1.5oC in parts of the equatorial Pacific Ocean at the end of the month (Fig. 1). Weekly values of the Niño-3.4 index remained steady at +1.2oC during February (Fig. 2). An oceanic Kelvin wave was initiated in early February, which acted to increase the subsurface heat content anomalies (average temperatures in the upper 300m of the ocean, Fig. 3), and to strengthen subsurface temperature departures (exceeding +2oC down to 100-175m) across much of the equatorial Pacific (Fig. 4). SSTs were sufficiently warm to support deep tropical convection, which strongly increased across the central and eastern tropical Pacific, while remaining suppressed over Indonesia (Fig. 5). Equatorial low-level westerly wind anomalies also strengthened during February, while upper-level easterly wind anomalies weakened slightly. Collectively, these oceanic and atmospheric anomalies reflect a moderate-to-strong El Niño episode.
Nearly all models predict decreasing SST anomalies in the Niño-3.4 region through 2010, with the model spread increasing at longer lead times (Fig. 6). The majority of models predict the 3-month Niño-3.4 SST anomaly will drop below +0.5oC by May-June-July 2010, indicating a transition to ENSO-neutral conditions near the onset of Northern Hemisphere summer. However, several models suggest the potential of continued weak El Niño conditions through 2010, while others predict the development of La Niña conditions later in the year. Predicting when El Niño will dissipate and what may follow remains highly uncertain.
El Niño impacts are expected to last through the Northern Hemisphere spring, even as equatorial SST departures decrease, partly in response to the typical warming that occurs between now and April/May. Expected impacts during March-May 2010 include drier-than-average conditions over Indonesia and enhanced convection over the central and eastern equatorial Pacific Ocean, as well as coastal sections of Peru and Ecuador. For the contiguous United States, potential El Niño impacts include above-average precipitation for the Southwest, the south-central states, and Florida, and below-average precipitation in the Pacific Northwest and Great Lakes region. Above-average temperatures are most likely across the northern tier of states (excluding New England and the Northern Plains), while below-average temperatures are favored for the south-central and southeastern states.
[Source: Climate Prediction Center, National Centers for Environmental Prediction, NOAA/National Weather Service, Camp Springs, MD 20746-4304]
Download ENSO Cycle: Recent Evolution, Current Status and Predictions Update prepared by Climate Prediction Center / NCEP - 8 March 2010 from link below (PDF)