Environment and Natural Resources Service
FAO Research, Extension and Training Division
On average, May values of the Southern Oscillation Index, a measure of El Niņo strength based on atmospheric measurements, continued to decrease over the previous month (figure 1), thereby indicating an increased likelihood of an El Niņo taking place around the end of this year.
Note that the curve describing the development of the 2002-2003 season is close to the average of the intense El Niņo, which is still rather different from the strongest El Niņo of 1981-82 or 1997-98.
Some leading monitoring centres give mixed interpretations because: