Title: On the Role of Upper Tropospheric Jet Streaks and Leeside Cyclogenesis in the Development of Low-Level Jets in the Great Plains
Abstract:A review of 13 cases of low level jets which developed in the Great Plains and which have been previously discussed in the literature is presented.The review notes that boundary layer processes were e...A review of 13 cases of low level jets which developed in the Great Plains and which have been previously discussed in the literature is presented.The review notes that boundary layer processes were emphasized as causative factors in the development of the low level jet ( LLJ) while upper tropospheric features were not considered and the importance of synoptic kale processes were generally minimized _ For i' out of the 1: cases.a systematic upper level flow pattern was isolated which includes the existence of a trough over the southwest united States and the propagation of upper level jet streaks from the Rocky Mountains toward the Great Plains.This flow pattern is responsible for lee-side cyclogenesis or lee-side troughing that produces the pressure gradients needed for the development of the LU_ For the other three cases, a blocking ridge existed over the Great Plains and the upper level flow was relatively weak.It is during these situations that the "classic."diurnal osJli ting LU was observed.A more detailed review of four cases which used a special PIBAL network indicates that the subsynoptic scale forcing associated with the upper level jet streak 's forcing of lee-side cvcloeenesis could be an important factor in the development of LLJ 's in the Great Plains.The review does not discount the importance of boundary layer processes which lead to the observed diurnal oscillation of the LU. but does question the notion that a retrogression of the subtropical high provides the increased pressure gradient force needed for the development of the LU in the Great Plains region.Read More