On the Evolution of the QE II Storm. I: Synoptic Aspects

Abstract

The hurricane-force winds and heavy seas which battered the liner Queen Elizabeth II on 10 and 11 September 1978 were associated with an extreme example of a meteorological ?bomb? as defined by Sanders and Gyakum. Despite the existence of surface buoys, and the relatively high density of mobile ships in the North Atlantic, real-time weather analyses, subjective forecasts, and numerical prognoses all erred in the intensity and track of this storm. In this study, deficiencies in the real-time surface analysis were compensated for by the addition of Seasat-A surface wind fields and previously-discarded conventional ship reports. This paper examines the synoptic aspects of this case with emphasis on physical mechanisms most likely responsible for the development. The cyclone originated as a shallow barocline disturbance west of Atlantic City, New Jersey, and explosive deepening (?60 mb/24 h) commenced once the storm moved offshore, and in association with cumulus convection adjacent to the storm center. The hurricane-force winds, a deep tropospheric warm core, and a clear eye-like center, all characteristics of a tropical cycline, were associated with this storm at 1200 GMT 10 September. A diagnostic assessment of batoclinic forcing reveals that, although the cyclone formed on the anticyclonic shear side of the 500 mb flow, a shallow lower tropospheric layer of cyclonic thermal vorticity advection existed over the surface cyclone center. Calculations using a diagnostic, adiabatic, inviscid quasi-geostrophic model, which can approximately replicate the shallow baroclinic structure of this cyclone, yield instantaneous vertical motion and deepening rates far less than those observed. It is suggested that the convection associated with this cyclone during its explosive deepening played a substantial additional role, as in tropical cyclone formation, in this cyclone's evolution.