The latest El Niño/Southern Oscillation (ENSO) Diagnostic Discussion is hot off the presses from the Climate Prediction Center

middecember2014plumeofensopredictions

Click here to read the current discussion. Here’s an excerpt:

ENSO Alert System Status: El Niño Watch

Synopsis: There is an approximately 50-60% chance of El Niño conditions during the next two months, with ENSO-neutral favored thereafter.

During December 2014, positive sea surface temperature (SST) anomalies decreased across the central and east-central equatorial Pacific. At the end of the month, the weekly Niño indices ranged from +0.8°C in the Niño-4 region, to +0.5°C in the Niño-3.4 region, to 0.0°C in the Niño-1+2 region. The positive subsurface heat content anomalies (averaged between 180o-100oW) also decreased during December in response to an upwelling equatorial oceanic Kelvin wave. Although the surface and sub-surface temperature anomalies were consistent with El Niño, the overall atmospheric circulation continued to show only limited coupling with the anomalously warm water. The equatorial low-level winds were largely near average during the month, while upper-level easterly anomalies continued in the central and eastern tropical Pacific. The Southern Oscillation Index (SOI) remained slightly negative, but the Equatorial SOI remained near zero. Also, rainfall remained below- average near the Date Line and was above-average over Indonesia. Overall, the combined atmospheric and oceanic state remains ENSO-neutral.

Similar to last month, most models predict the SST anomalies to remain at weak El Niño levels (3-month values of the Niño-3.4 index between 0.5°C and 0.9°C) during December-February 2014-15, and lasting into the Northern Hemisphere spring 2015. If El Niño were to emerge, the forecaster consensus favors a weak event that ends in early Northern Hemisphere spring. In summary, there is an approximately 50-60% chance of El Niño conditions during the next two months, with ENSO-neutral favored thereafter (click CPC/IRI consensus forecast for the chance of each outcome).

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