Abstract
The El Niño-Southern Oscillation (ENSO) influences climate variability
across the globe. ENSO is highly predictable on seasonal timescales and
therefore its teleconnections are a source of extratropical forecast
skill. To fully harness this predictability, teleconnections must be
represented accurately in seasonal forecasts. We find that a multimodel
ensemble from five seasonal forecast systems can successfully capture
the spatial structure of the late winter (JFM) El Niño teleconnection to
the North Atlantic via North America, but the simulated amplitude is
half of that observed. We find that weak amplitude teleconnections exist
in all five models and throughout the troposphere, and that the La Niña
teleconnection is also weak. We find evidence that the tropical forcing
of the teleconnection is not underestimated and instead, deficiencies
are likely to emerge in the extratropics. We investigate the impact of
underestimated teleconnection strength on North Atlantic winter
predictability, including its relevance to the signal-to-noise paradox.