Regional SSTA Report: Anomalous Warm Gulf of Mexico = Major East-central U.S. Precipitation Events!

Highlight: El Nino in the forecast for mid-year. Warm Gulf of Mexico supports heavier precipitation events for late winter/spring in the eastern half of the U.S.

Fig. 1-2: Australia Bureau of Meteorology Nino34 SSTA forecast is trending more aggressively into El Nino by JUN/JUL 2023. Other models are generally within the NOAA El Nino threshold at that time.  

Discussion: The Australia Bureau of Meteorology updated their ENSO forecast earlier today which more aggressively projects a moderate strength El Nino by JUN/JUL 2023 (Fig. 1). Other forecast models are not as aggressive but generally agree on weak El Nino by June using the NOAA El Nino Nino34 SSTA threshold (Fig. 2). Despite the more aggressive El Nino projections for mid-year, the southern oscillation index (SOI) for January 2023 remains with robust La Nina intensity (Fig. 3). In the equatorial Pacific subsurface, very warm water rests near 160W and westward past the Dateline (Fig. 4). An eastward shift of this warm water would quickly erode La Nina and initiate El Nino. The warm water zone is likely to shift eastward motivated by 2-3 transient Madden Julian oscillation (MJO) events. The first MJO event is on the way during early-to-middle February. Also of interest, regarding ENSO tendencies, is the marine heat wave (MHW) in the Northeast Pacific (Fig. 5) which has split (NEP22A from last year and the new NEP23A) which should shift eastward toward the North America West Coast if El Nino is to generate. If so, the 3-year cool phase of the Pacific decadal oscillation (-PDO) ends. Normally, PDO shifts toward and into the positive phase when El Nino develops. Finally, an ALERT is issued for likely buoyant precipitation events for late winter and spring in the East-central U.S. due to the much warmer than normal Gulf of Mexico implying increased moisture surging northward when southerly flow is induced ahead of storm system (Fig. 6).

Fig. 3: Despite more aggressive El Nino forecasts for middle of 2023, southern oscillation index remains in a robust La Nina phase for January 2023.

Fig. 4: The subsurface equatorial Pacific Ocean features a strong warm anomaly shifting east of the Dateline as a Kelvin Wave. Warmth has appeared off the northwest coast of South America.  

Fig. 5: The marine heat wave in the Central/Northeast Pacific Ocean has split. NEP22A is the 3^rd longest and 4^th most intense MHW since 1982 in this region. A new MHW has emerged west-southwest of California. The warm SSTA pattern will shift toward the coast if El Nino develops by the middle of the year.

Fig. 6: Climate forecasts for the East-central U.S. trend wetter for late winter and spring due to the somewhat warmer than normal Gulf of Mexico SSTA.