Using the NCEP/NCAR global reanalysis data for 51 boreal winters, a convective index (CI) for the tropical Pacific is constructed. It is found that the extreme positive and negative events of the CI are connected to the positive phases of the two dominant modes of the extratropical atmospheric variability, i.e., the PNA and the NAO, respectively. The same analysis is applied to the output of a 201-year integration of a global air-sea coupled general circulation model. Results consistent with the observations are obtained.