The SMSA are not regularly propagating features.
Latitudinal movement occurs in both northern and southern directions.
Both eastward movement and stationarity are are observed in the zonal direction. The anomalies are episodic, with an episode lasting from 1 to 3 weeks. They require a few days to grow, persist for a few days to two weeks, and then decay over a period of a few days. In addition to the temperature structure, SMSA are found in the zonal wind, meridional wind, and geopotential heights. The SMSA momentum fluxes, both the self momentum flux and that caused by interaction with other scales, are found to be substantial.