A diagnostic analysis of the Presidents' Day storm of February 1979.

Abstract

A comparison of kinematic, quasi-geostrophic and semigeostrophic vertical motions reveals that the kinematic method best captures the structure in the lower troposphere, indicative of the importance of boundary layer convergence. The semigeostrophic vertical motions are superior to the quasi-geostrophic vertical motions in depicting a sloping updraft and a closer separation of the ascent-descent dipole. Solution of the semigeostrophic vertical circulation equation from Hoskins and Draghici lends some support to the finding of Uccellini and others that the flow around the subtropical jet streak was unbalanced. -from Authors