November–December mean (ND) (a) Z500, (b) MTPR, and (c) 2mT anomaly correlation (AC) maps. AC between hindcast ensemble mean and ERA-5 is in the leftmost subpanels (darker blue for higher AC). Changes in AC for a selection of members based on having EDJ-2 categories matching ERA5 are in the middle subpanels (purple and green colors for negative or positive changes). Changes in AC for a selection of members based on having EDJ-2 categories matching the predictions of the PCN given the parents set to ERA5 categories each year are in the rightmost subpanels (colors as for the middle). The PCN probabilistic forecast is translated into a single predicted category by selecting the one with the largest relative increase in probability with respect to its climatological occurrence. Black dots show AC significantly different from 0 according to a one-sample two-sided t test at the 0.1 significance level. A stereographic projection is used, and latitudes between 20° and 90°S are shown at intervals of 20°.
Citation: Journal of Climate 37, 10; 10.1175/JCLI-D-23-0425.1
