The National Oceanic and Atmospheric Administration (NOAA) says while ENSO-neutral conditions continued during March, above-normal sea surface temperatures (SSTs) are developing over much of the eastern tropical Pacific as well as near the International Date Line. In addition to other indicators, NOAA says "they all reflect a clear evolution toward an El Nino state."
"The model predictions of ENSO for this summer and beyond are indicating an increased likelihood of El Niño this year compared with last month," says NOAA. "Most of the models indicate that ENSO-neutral (Niño-3.4 index between -0.5oC and 0.5oC) will persist through much of the remainder of the Northern Hemisphere spring 2014, with many models predicting the development of El Niño sometime during the summer or fall. Despite this greater model consensus, there remains considerable uncertainty as to when El Niño will develop and how strong it may become. This uncertainty is amplified by the inherently lower forecast skill of the models for forecasts made in the spring. While ENSO-neutral is favored for Northern Hemisphere spring, the chances of El Niño increase during the remainder of the year, and exceed 50% by the summer.
Related link: When El Nino Begins Key for 2014 Growing Season
Forecasters we interviewed in late March were in agreement the timing of the El Nino event is critical for the summer weather pattern as it relates to Midwest crop yields. But World Weather, Inc. Meteorologist Drew Lerner said he expects to see El Nino-like conditions in May and June if the trend toward El Nino continues and the event is officially declared later in the summer. El Nino is known as a "friend of the Midwest farmer," reminds Iowa State University Climatologist Elwynn Taylor, as El Nino years increase the odds of trendline to above-trendline Midwest yields.