Abstract

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.