A simple prognostic model based on Ekman dynamics and available satellite sea surface temperature and wind data is used to estimate rates of frontogenesis and frontolysis in the central North Pacific in the winter of 1977. The computed patterns and rates are compared to those sensed by satellite, and reasonable agreement is found. In the subtropical region, frontogenetic and frontolytic bands tend to occur in pairs, an occurrence which is attributed to a wind stress maximum over the area. Typical observed frontogenetic rates are 0.5--1¿C/100 km per week. The computed rates underestimate the observed ones.