The Formation of a Forward-Tilting Cold Front with Multiple Cloud Bands during Superstorm 1993

Abstract

Abstract A mesoscale-model simulation is used to examine the evolution of the cold front and accompanying cloud bands in eastern Mexico associated with Superstorm 1993 (12–14 March). The simulated cold front differed in structure and evolution from a classical cold front, in agreement with evidence from observations and European Centre for Medium-Range Weather Forecasts analyses. The surface cold front, as defined by the leading edge of strong northerlies and cold advection, initially possessed a rearward tilt with height over southern Texas. Within 6 h, the leading edge of the front moved equatorward and developed a large-scale forward tilt of greater than 200 km in the horizontal from the surface to 700 hPa. This forward tilt occurred as a mid- to upper-tropospheric baroclinic zone arrived from over the Sierra Madre, descended into eastern Mexico, and interacted with the surface cold front. Embedded within this large-scale forward tilt was a locally enhanced horizontal potential temperature gradient tha...