When Cool Phase Pacific Decadal Oscillation Resists El Nino

Fig: 1-3: Current global tropical SSTA and the SSTA of the East Pacific and 2-week change.  

Discussion: During Q1/2023 a persistent upper trough on the U.S. West Coast has caused amplified cooling of ocean waters off the West Coast of North America (Fig. 1). The cool phase of the Pacific decadal oscillation (-PDO) has intensified. Marine heat wave NEP22A has shifted well to the west and to the north and northwest of Hawaii. The cool California Current continues to arc southwestward bringing cool waters toward the Nino34/Nino4 SSTA regions (Fig. 2). In fact, the cool SSTA in this southwestward trajectory to the west of Baja California has intensified during the past 2 weeks (Fig. 3). Meanwhile, the Nino12 SSTA region off the northwest coast of South America has surged to a very warm daily SSTA of +2.44C. Daily southern oscillation (SOI) has bounced to +2.39 and trade winds have increased in the east-central equatorial Pacific. A Madden Julian oscillation (MJO) pulse is forecast to generate during the next 10 days which should reverse SOI and ease trade winds. But for now, prohibitive El Nino warming off the northwest coast of South America is blocked from westward progression by incoming col waters from the north.