Cyclogenesis and Effect of Turbulence on Fronts in the Northern Great Plains: Part I. Cyclogenesis in the Northern Great Plains. II. Turbulence in the Frontogenetical Field

The aim of this paper is to classify certain types of weather developments that arise in the region east of the Rocky Mountains in Southern Canada, Montana, Wyoming, and Colorado, and to correlate their frequency and intensity with various factors which seem most important in their development. After discussing briefly the importance of the Rocky Mountain chain as an air mass boundary, synoptic situations most favorable for fronto- and cyclogenesis are illustrated. The variation of these favorable situations with season is then compared with the frequency of occurrence of the several types of developments which they produce. The dates of initial eastward movement of secondary cyclone developments are correlated with dates of peaks in 14,000-foot pressure over the region. The influence of such wave developments on the buildup and dissipation of the Polar Canadian (Pc) high is studied. Finally, a table of departure from normal temperatures is given for certain East Slope stations, during foehn wind frontogenesis.