El Niño–Southern Oscillation (ENSO) serves as a dominant source of the East Asian winter climate interannual variability by modifying the western North Pacific (WNP) atmospheric circulations. Nevertheless, the embedded nonstationarity substantially limits the climate predictability there. Here, based on recent observations, we identify a robust sub-seasonal fluctuation in the linkage between ENSO and the East Asian winter monsoon, which features a remarkable and unique disruption during the mid-January. Further investigations suggest that the breakdown is largely caused by an interference from the ENSO-driven North Atlantic Oscillation (NAO) abrupt phase reversal in the early January. For El Niño cases, the NAO phase transition from positive to negative leads to a rapid adjustment of the midlatitude Rossby wavetrain. The resultant enhanced Siberian High and anomalous northerlies over East Asia effectively offset the southerly anomalies associated with the WNP anticyclone, thus giving rise to the teleconnection breakdown.
 

ENSO,NAO,East Asian winter monsoon