Record daily +AO value yesterday (CPC index from 1950-present). We use MSLP to calculate the index and find yesterday essentially tied with Jan 14, 1989 (AO=+6.3). This winter (Dec-Feb) as a whole is likely to end in 3rd place for +AO behind 88-89 and 92-93. https://t.co/y7lLmp6m0E

— World Climate Service (@WorldClimateSvc) February 10, 2020