Anatomy of Great Plains Protracted Heat Waves (especially the 1980 U.S. summer drought)

Abstract

Abstract The protracted heat wave and drought of the Great Plains during summer 1980 was a manifestation of an abnormal form of the general circulation. An upper-level continental high developed rapidly over the Southern Plains in late May and persisted with only small changes throughout the summer. The associated subsidence, dry soil, lack of cloud and high insolation led to unrelenting heat. Descriptions of several interlocking features are given followed by an attempt to ascribe the development and maintenance of the drought-producing cell to several physical factors. Strong low-latitude westerlies (expanded circumpolar vortex) over the North Pacific, North America and North Atlantic during spring 1980 led to latitudinally depressed storm tracks relative to normal. Combined with normal seasonal forcing this anomalous pattern was stable in spring but unstable in summer after the climatologically dependable northward march of the westerlies. Moreover, normal spring to summer mid-tropospheric height chang...