Over the last month, we saw NOAA go out and acknowledge the arrival of El Niño conditions, citing warmer than average sea surface temperatures, warm sub-surface waters, and a westerly wind burst.
These patterns have culminated in increased rainfall and convection in the vicinity of the International Dateline. The Niño 4 Index has exhibited the warmest sea surface temperatures (and anomalies) over the past several months, priming the surrounding regions for enhanced rains and pushing the odds for the MJO to stand in the region. This, overall, signals some ocean-atmosphere coupling.
The “flavour” of the El Niño is much closer to the Modoki (central-based) style than the canonical one.
Over the next few weeks to months, this is forecast to continue. Some dynamical models suggest that the event may transition to a classical event as we head through 2019.
This may contribute to a longer-lasting tropical cyclone season in the Southwest Pacific.
Precipitation anomalies over the last month; note enhanced rainfall around the International Dateline