A 25-yr Climatology of Large-Amplitude Hourly Surface Pressure Changes over the Conterminous United States

Abstract

Abstract Hourly surface pressure observations for a 25-yr period (1949–63; 1984–93) for the conterminous United States have been used to map the distribution of large hourly pressure changes defined as falls or rises in excess of 4.25 hPa. Initially, 8431 reports satisfying this pressure change threshold were obtained. After error checking, this number was reduced to 5380 occurrences. Large hourly surface pressure changes are most common over the Great Plains and New England and least common over the Southeast and Southwest. Large pressure falls are confined almost exclusively to the Plains, upper Midwest, and New England, and are virtually absent over the Intermountain West and parts of the Appalachians. A manual (subjective) analysis identified 1038 inertia–gravity wave (IGW) occurrences from the 5380 large hourly surface pressure change occurrences. IGW occurrences are most common across the Plains and from the Great Lakes toward western New England, and are virtually absent across the Intermountain We...