While heat waves are local extreme weather events, a planetary Rossby
wave pattern is statistically related to the occurrence of heat waves
events in the U.S. However, whether such planetary wave patterns cause
the enhanced statistics of local heat waves or as a coincidence is
debatable. In this work, we hypothesize that the atmospheric
climatological state dictates the slowly propagating wave pattern, which
sets up a conducive large-scale environment for local US heat waves. We
implement an idealized dry dynamic core model with an iterative approach
to simulate the realistic North American summer climatological state. As
the model can generate similar large-scale planetary wave patterns
propagating throughout North America, significantly more heatwaves are
generated, and the statistics of heat waves become consistent with that
estimated in reanalysis products. The slowly propagating Rossby wave
packets with a timescale of 20-30 days can serve as a new source of
intraseasonal predictability.