Monday, 12 January 2004: 10:45 AM
Convection in BAMEX during an active subtropical jet period
An unusually strong subtropical jet (STJ) prevailed during the period 5-14 June 2003 in conjunction with the field phase of the Bow Echo and Mesoscale Convective Vortex Experiment (BAMEX). A noteworthy aspect of this period was the variety of organized convective systems over the southern and central Plains, and the lower and middle Mississippi valley, that appeared to be spawned by transient disturbances embedded within the STJ ("writers" of the storms?). The strong STJ had its roots in an area of active convection in the tropical Pacific to the east of Hawaii. From there, the STJ extended northeast toward the coast of California and Baja, Mexico, where it turned eastward across northern Mexico and the southwestern US before reaching east-northeastwards across the lower Mississippi valley.
The purpose of this presentation is to: (1) determine the large-scale processes that likely controlled the evolution of the STJ, including its observed strengthening and weakening, (2) document the structure and source of the observed transient sub synoptic scale disturbances embedded within the STJ (e.g., via trough fracture and/or convectively generated potential vorticity (PV) anomalies), (3) relate these embedded transient disturbances and PV anomalies to specific observed organized mesoscale convective systems, and (4) to discuss forecast-related problems that arose in response to the STJ-driven convection.