Pacific Decadal Oscillation/Atlantic Multi-decadal Oscillation Outlook

PDO: When the cool phase of the PDO is in-place with La Nina, the effectiveness of the La Nina climate is usually stronger. Emergence of the northeastern Pacific Ocean “warm blob” in 2013 makes PDO analog forecasts tricky. Presence of the “warm blob” indicates increased risk of an east shift to the North America West Coast to quickly eliminate cool PDO regimes. The 3 most recent -PDO regimes identify the possibilities through next May. The PDO regime during emergence of the 2013 “warm blob” quickly erased -PDO and caused a fast reversal to the warm phase. The 2007-09 -PDO was persistent but before the “warm blob” formed. The current -PDO has been weak but persistent. The average of all 3 potential scenarios indicates weak -PDO through winter and neutral phase next spring. The weaker -PDO may have limited enhancing La Nina effects.

AMO: During the past 2+ decades the North Atlantic basin has warmed and entered the warm phase of the decadal cycle and typically lasts 2-4 decades before reversing. However, the AMO has a different character this year in that western North Atlantic warmth has been moderate and representative of weak +AMO phase but in the deep tropics SSTA has been mostly near normal. Additionally, the North Atlantic Warm Hole (NAWH) south-southeast of Greenland has also weakened the usually stronger +AMO regime. The analog forecast reflects the weaker +AMO regimes of recent years to project the AMO regime into 2022. Revealed is a weak warm phase during the core of the upcoming tropical cyclone season followed by a return to neutral phase for late 2021 and into next spring.

Fig. 1: The Climate Impact Company constructed analog forecast of PDO phase through May 2022.

Fig. 2: The Climate Impact Company constructed analog forecast of AMO phase through May 2022.