05/11/2023, 1:54 pm EDT

May 2023 ENSO Outlook: ENSO forecast trend is stronger with 2023 El Nino followed by a flip back to La Nina later next year.

Executive summary: Currently, ENSO is in neutral phase. However, due to an expected eastward shift of anomalous convection associated with the Madden Julian oscillation (MJO) across the equatorial Pacific Ocean over the next 2-3 weeks, trade winds will shut-down and may shift into a westerly direction allowing ample anomalous warm subsurface water to up-well and cause El Nino to initiate in June. The global climate pattern which is just leaving La Nina will shift more slowly to El Nino, likely in July. The Climate Impact Company constructed analog (CIC-CA) ENSO phase forecast for 2023-24 has changed. The new forecast is more confident, yielding 4 very similar results. The CIC-CA forecast indicates El Nino onset by June, peak intensity late this year, mature phase during Q1/2024, and dissipation during Q2/2024 (Fig. 1). Later next year, the CIC-CA forecast indicates La Nina will return. The previous forecast was less aggressive at developing El Nino in 2023 and lingered warm ENSO through 2024. Consequently, the stronger El Nino for 2023 and flip to La Nina later next year represents a significant change. The Pacific Ocean SSTA environment is filled with interesting regimes (Fig. 2). Most notable is the El Nino warming in the far eastern equatorial Pacific likely to shift westward over the next few weeks. The cool phase of the Pacific decadal oscillation (-PDO) remains in-place. The -PDO regime continues to enhance cool water flow into the tropics south of Hawaii via the California Current. The 30-day change analysis indicates this pattern is starting to weaken (Fig. 3). The semi-permanent Northeast Pacific marine heat wave (NEP22A) shifted west toward the Dateline during this past winter season, but warming is appearing near the West Coast of North America as the MHW is expected to shift eastward later in 2023. Foreshadowing El Nino ahead is the arrival of anomalous warm water in the Pacific Ocean subsurface to the east of the Dateline (Fig. 4). The cool water support for La Nina has clearly ended. El Nino climate is intact for Q3 and Q4 of 2023. Historically, El Nino produces a warmer than normal national climate with a wet bias for the East-central U.S. during Q3 (Fig. 5) shifting to the Mid-south and East U.S. for Q4 (Fig. 6). Fig. 1: The Climate Impact Company Nino34 SSTA forecast to determine ENSO phase through 2024. El Nino is ahead reversing to La Nina later next year. Fig. 2: The latest daily SSTA analysis across the tropical and northern Pacific Ocean and regions of interest to North America climate. Fig. 3: The 30-day SSTA change to the tropical and northern Pacific Ocean. Fig. 4: Subsurface equatorial Pacific Ocean temperature anomalies defining upper ocean heat indicates a warm flip east of the Dateline supportive of El Nino ahead.   Fig. 5-6: NOAA historical JUL/AUG/SEP temperature and precipitation anomalies during El Nino. Fig. 7-8: NOAA historical OCT/NOV/DEC temperature and precipitation anomalies during El Nino.