SOI (SOUTHERN OSCILLATION INDEX)

The SOI rose to near normal near the middle of June after a weakly negative April and Mayl. Overall, it has remained near zero since, though recent high pressures at Darwin coupled with low pressures at Tahiti,, has resulted in a small decline in July. The official monthly SOI for July was zero. From January through July, the monthly values of the SOI were + 0.3, - 4.1, - 0.2, - 1.0, -1.2, +0.1, and 0.0. Its 5-month running mean centered on May was approximately - 0.5. With the climate expected to continue remain in a state of ENSO Neutral, the SOI should average near zero for the next three to six months, with month-to-month fluctuations within the range of -1.0 to +1.0.