The subsurface eastern equatorial Pacific continues too steadily warm. A Kelvin Wave moving east across the Dateline during early December reached waters off northwest South America recently while a second Kelvin Wave emerged near and east of the Dateline and is drifting eastward. The atmosphere remains slow to respond as southern oscillation index (SOI) stays positive and 15-day forecasts maintain the positive phase.

GFS indicates a progressive MJO toward the Dateline in the 8-14/11-15-day period. If so, ongoing U.S. warmth continues and could become stronger. Yesterday, NOAA introduced the Relative Operational Nino Index (RONI) which provides a new Nino34 index accounting for the historical general warming of the global tropics. But! Does this new index effectively identify ENSO pattern change and intensity?