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Mar 2017 SWCO - ENSO Tracker | CLIMAS


Mar 2017 SWCO - ENSO Tracker

Friday, March 17, 2017

Oceanic and atmospheric indicators of the El Niño-Southern Oscillation (ENSO) are currently neutral (Figs. 1-2), and most forecast agencies predict they will remain so through spring 2017. These agencies also forecast that El Niño conditions could return in mid-to-late 2017, but given the uncertainty of ENSO forecasts associated with the “spring predictability barrier,” we can get only a general sense now of the range of outcomes likely later this year (i.e. La Niña is basically off the table). More detailed information about the timing or intensity of a possible El Niño will start to become available in late spring or early summer.

A closer look at the forecasts and seasonal outlooks provides insight into the range of predictions for the rest of winter and the ENSO signal for the rest of 2017. On March 9, the NOAA Climate Prediction Center (CPC) observed that oceanic and atmospheric conditions were consistent with ENSO-neutral conditions. They forecast a 75-percent chance of ENSO-neutral conditions through spring 2017 (March-May 2017), and a 50- to 55-percent chance of El Niño conditions in the second half of 2017 (July-Dec). On March 10, the Japanese Meteorological Agency (JMA) identified a continuation of ENSO-neutral conditions (last month they determined that observed conditions did not meet the JMA definition for a La Niña event). They forecast a 60-percent probability of ENSO-neutral conditions lasting through summer 2017, and a 40-percent chance of El Niño conditions over summer. On March 14, the Australian Bureau of Meteorology moved their ENSO outlook to El Niño Watch, with a 50-percent chance of an El Niño event. They identified warming oceanic conditions as indicating an increased chance of El Niño conditions in 2017. On March 16, the International Research Institute for Climate and Society (IRI) and CPC forecast a 70-percent chance of El Niño by late summer (Fig. 3), but forcasters also highlighted uncertainty regarding model performance given the spring predictability barrier. The North American Multi-Model Ensemble (NMME) characterizes the current model spread and highlights the variability looking forward through the remainder of 2017. The NMME mean is forecast to remain ENSO-neutral through spring, but reaches the threshold of weak El Niño by early summer (Fig. 4).

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