Skillful long‐range prediction of European and North American winters

Abstract

Until recently, long-range forecast systems showed only modest levels of skill in predicting surface winter climate around the Atlantic Basin and associated fluctuations in the North Atlantic Oscillation at seasonal lead times. Here we use a new forecast system to assess seasonal predictability of winter North Atlantic climate. We demonstrate that key aspects of European and North American winter climate and the surface North Atlantic Oscillation are highly predictable months ahead. We demonstrate high levels of prediction skill in retrospective forecasts of the surface North Atlantic Oscillation, winter storminess, near-surface temperature, and wind speed, all of which have high value for planning and adaptation to extreme winter conditions. Analysis of forecast ensembles suggests that while useful levels of seasonal forecast skill have now been achieved, key sources of predictability are still only partially represented and there is further untapped predictability.

Winter 2015/16: A Turning Point in ENSO-Based Seasonal Forecasts

“…Temperature swings in SSTs initiate changes in the overlying tropical atmosphere that influence weather patterns around the globe. ENSO is considered the dominant mode of variability in the global climate system and is universally considered the most influential factor in year-round seasonal climate predictions (Barnston et al, 2012;Hoskins, 2013;Scaife et al, 2014). Predictions based on the record-strong El Niño of 1997/98 resulted in one of the most accurate seasonal forecasts to date, and those predictions are considered a major success story (Barnston et al, 1999;Simon et al, 1999).…”

“…It has also been shown to add skill to long-range predictions in some global climate models (GCMs; Scaife et al, 2014). Over the past two to three decades, the Arctic has undergone the most rapid change relative to other regions across the globe, with an observed warming double to triple that of the global average.…”

Seasonal-to-Decadal Climate Forecasting

“…The North Atlantic Oscillation (NAO) is another source of low-frequency variability often attributed to stratosphere-troposphere coupling (Scaife et al 2005) and is known to influence winter temperatures and rainfall over Northern Europe and Central Asia Matthes et al 2006). Recent studies have reported skill at predicting winter NAO from seasonal forecasts using dynamical models (Scaife et al 2014). Evidence of teleconnections between winter NAO and European climate in the following spring has also been suggested based on statistical analyses using observations (Herceg-Bulić and Kucharski 2013).…”

Weather, Climate and the Nature of Predictability

“…As in NWP, the use of ensembles in climate model simulations is common. In this case, however, the ensemble is typically used to sample several different sources of uncertainty 4 : natural climate variability (Deser et al 2012), initial condition uncertainty (Scaife et al 2014), parametric uncertainty (Stainforth et al 2005) or model structural uncertainty (Taylor et al 2012).…”