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07/10/2019, 8:03 pm EDT

July ENSO Outlook

Borderline Weak El Nino regime continues (limited climate influence) Executive summary: Recent weeks have seen mostly a decay of the 2018-19 weak El Nino. As a result, many lead dynamic forecast models have indicated El Nino dissipation and neutral to weak La Nina for the remainder of 2019. However, there are a few ingredients (warm upper ocean and persistent negative southern oscillation index) remaining that prevent a dissipation of El Nino statement. Warmer than normal ocean waters in the surface and subsurface in the vicinity of the Dateline lingers and is likely to maintain presence of weak El Nino or possibly generation of an El Nino Modoki. The extended-range forecast for later this year is very uncertain. Dynamic models and the Climate Impact Company constructed analog generally agree on neutral ENSO (Fig. 1-3). Discussion: The on again/off again El Nino continues. In recent weeks the eastern equatorial Pacific has cooled to near or below the El Nino threshold while near the Dateline El Nino warming persists (Fig. 4). In the subsurface (Fig. 5) anomalous warm water remains in the upper 75-100 meters of the equatorial Pacific Ocean while deeper waters have cooled (expansively). The southern oscillation index remains El Nino-like but the atmosphere continues to stubbornly not engage the warm equatorial region to ignite an El Nino climate based on persistent multivariate ENSO index. So what does all of this mean? There have been about one half dozen head fakes on the ENSO regime in regard to El Nino the past 1 year. Forecast models have trended away from El Nino in recent weeks however there’s another westerly wind burst near and east of the Dateline now and additional warming of the ocean could regenerate. Expect the ENSO pattern of on again/off again El Nino to continue for the next several months. ENSO Forecasts Fig. 1: The Bureau of Meteorology/Australia calls off El Nino and forecasts neutral ENSO the remainder of 2019. Fig. 2: The NCEP CFS V2 (model) is trending toward La Nina. Fig. 3: The Climate Impact Company constructed analog forecast indicates neutral ENSO ahead. ENSO Observations Fig. 4: Sea surface temperature anomalies for July 1-7, 2019 indicate El Nino Modoki-like conditions near and just east of the Dateline while farther east the equatorial region is closer to neutral. Fig. 5: The deeper ocean in the equatorial Pacific Ocean is cooling but near the surface enough anomalous warmth persists to sustain a very weak El Nino.