Bring on Weak El Nino for Later 2018

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Using multivariate ENSO index to analog the 2017-18 regime forward through 2018 and into early 2019 yields strong evidence that a weak El Nino is ahead for 2018. There are climate diagnostics present now to support this possibility.


Since the mid-to-late 1990’s the long term cycle of ENSO/Pacific decadal oscillation (PDO) has favored the cool phase while Atlantic multi-decadal oscillation (AMO) has favored the warm phase. Within that 20-year climatology the ENSO regime has produced weak La Nina early in the year on 4 occasions plus 2018 makes five. In each analog year La Nina dissipated quickly in early spring and was followed by weak El Nino by mid-summer according to multivariate ENSO index. The climatology is too strong to ignore

Is there diagnostics present to support this claim? Yes! A strong Kelvin Wave is moving east into the subsurface equatorial East Pacific (Fig. 1) and should dissipate La Nina in April. This is the second Kelvin Wave of 2018. If a third Kelvin Wave follows later this spring into early summer El Nino will form by July. The set of circumstance required to produce El Nino by mid-summer have started and the MEI analogs strongly support the trend toward El Nino.  This change in ENSO philosophy will be applied to all climate forecasts. The U.S. summer outlook will be issued tomorrow to CIC clients.

 Fig. 1: Subsurface equatorial East Pacific ocean temperatures are warming as a Kelvin Wave shifts east.