The National Weather Service's Climate Prediction Center (CPC) says ENSO-neutral conditions are reflected by current oceanic and atmospheric anomalies, but chances are increasing for El Nino to develop in the July to September timeframe.
"Positive equatorial Pacific sea surface temperature (SST) anomalies have grown, exceeding +0.5oC across the eastern Pacific Ocean by the end of June... This warming was consistent with a weakening of the low-level trade winds across the east-central equatorial Pacific, along with a weakening of the persistent pattern of enhanced convection near Papua New Guinea. The observations are consistent with ENSO-neutral, but reflect a likely progression towards El Nino," says CPC.
But models are not in complete agreement toward El Nino. "There continues to be a substantial disparity between the statistical and dynamical model SST forecasts for the Niño-3.4 region. The dynamical models, including the NCEP Climate Forecast System (CFS), largely favor the development of El Nino by July-September 2012, while the majority of statistical models predict ENSO-neutral through the rest of 2012," it states.
"The forecaster consensus largely favors the dynamical model outcome because those models tend to exhibit greater skill emerging from the Northern Hemisphere "spring barrier" (a period of relatively low confidence ENSO forecasts) and also due to the strengthening of observed signals indicating an evolution towards El Nino Overall, the forecaster consensus reflects increased chances for El Nino beginning in July-September 2012," adds CPC.