Discussion: During November, eastward surges of tropical convection across the equatorial Pacific occurred due to the La Nina climate starting to weaken. The daily southern oscillation (SOI) index was the best indicator of that regime showing a choppy day-to-day character and averaging +0.47 for the month which is just below the La Nina threshold for the first time since January.
The Nino SSTA regions remain steadily cool within the La Nina threshold EXCEPT for the Nino12 region which is off the northwest coast of South America and warmed significantly last week (Fig. 1). The warmer shift may widen to the Nino3SSTA region next week.
In November, subsurface equatorial Pacific waters remain cooler than normal to fuel the ongoing La Nina. However, a warming trend is underway (Fig. 2).
The NCEP FCS V2 Nino34 SSTA forecast continues an aggressive trend that indicates ending of La Nina early in 2023 followed by a shift into El Nino middle of 2023 (Fig. 3). ECM is indicating a much stronger El Nino developing middle of 2023 (Fig. 4). Climate Impact Company will issue a new ENSO forecast for 2023 late this week!
Fig. 1: The 12-week Nino SSTA observations. Note the much warmer change off the northwest coast of South America.
Fig. 2: Monthly subsurface equatorial Pacific Ocean temperatures for the past year. A warming trend has initiated.
Fig. 3: NCEP CVFS V2 Nino34 SSTA forecast indicates El Nino by middle of 2023.
Fig. 4: ECM Nino34 SSTA forecast indicates a strong El Nino ahead for 2023.