Terrain related thermal and dynamical effects have been documented in various studies to determine the strength and frequency of the Great Plains low-level jet (LLJ) through lee cyclonegenesis, diabetic heating, and topographic blocking. We carried out regional model sensitivity simulations in which the height of elevated terrain was reduced gradually to explore simulated LLJ feature changes. The simulations were carried out for a 45-day period during the 1993 flood in the central U.S., when strong LLJs were frequent. The simulations imply significant dynamic effects (lee side cyclonegenesis and blocking) exerted by the Rocky Mountains are important to the formation of low-level jets. Thermal effects (slope induced thermal gradient) by the Rocky Mountains further contributed to the formation of low-level jets. A cyclonic flow perturbation in the lower atmosphere produced by diabatic effects over the mountains is consistent with intensification of the low-level jet.