North Atlantic storminess forecast for winter 2004/5

Interannual variability in winter storminess over the North Atlantic and Europe causes significant risk and uncertainty. North Atlantic storminess over the main storm track region is predicted to be below average during the upcoming winter 2004/5. Only two hindcasts in the last 32 years have given fewer winter days with windspeeds of at least Beaufort Force 7 in this region. The forecast spans the period from 1st December 2004 to 28th February 2005. The prediction is made using a weighted ensemble of two separate forecasts made with prior June/ July northern hemisphere subpolar surface air temperature and prior June/July northern hemisphere snow cover (Saunders et al., 2003). This model anticipates the correct anomaly sign for winter storminess in ~80% of winters 1972/3-2003/4 and explains around 50% of the variance in storminess over this period. Deterministic and tercile probability forecasts for storminess levels in winter 2004/5 are given below.