A Diagnostic Comparison of the 1980 and 1988 U.S. Summer Heat Wave-Droughts

Abstract

Abstract Observational analyses are performed to examine the roles of remote and local forcing in the evolutions of the extreme U.S. summer heat wave-drought cases of 1980 and 1988. At early stages, both events are associated with anomalous stationary wave patterns. Wave activity flux analyses suggest that in the 1980 case anomalous wave activity propagates southeastward from an apparent source region to the south of the Aleutians. The flux pattern is more complex in the 1988 case but suggests two possible source regions, one over the central North Pacific to the north of the Hawaiian Islands and a second located over the far western Pacific. The 1988 analyses show no anomalous wave propagation out of the eastern tropical Pacific, although this result does not necessarily preclude a role for tropical forcing in generating the anomalous wave train. In both cases the anomalous wave trains and associated wave activity fluxes become very weak by early July, indicating that remotely forced anomalous stationary...