North-south displacements and meridional vacillations of the eddy-driven jet are widely accepted as the dominant cause of variability of the observational zonal-mean zonal wind anomalies (denoted ). In this study, a new idea regarding the primary variability of the observational in the middle latitude troposphere is presented. It is hypothesized that there are two different classes of primary variability of the observational : the poleward propagation of the (abbreviated as PP) and meridional vacillations. To validate this hypothesis, one-point correlation maps of at 200-hPa during the boreal cold season (November–April) of every year from 1957–2002 are used as a criterion. Twelve PP years, in which the PP events are dominant in the variability of , and 15 no_PP years, in which the PP events are recessive and the meridional vacillations are dominant in the variability of , are examined. The results show that the variabilities of are different in the chosen PP and no_PP years. In the PP years, the PP events dominate the variability of ; however, the meridional vacillations are prevalent in the no_PP years.