Observational synthesis of mesoscale structures within an explosively developing cyclone

Abstract

AbstractAn observational case‐study is presented of a rapidly developing UK cyclone on 30 October 2000 to reveal the rich diversity of coexisting mesoscale structures in the vicinity of the cloud head, dry slot and polar‐front cloud band. The mesoscale structures include: multiple rain bands, due to upright convection originating in the boundary layer; stacked slantwise convective circulations at middle levels; cloud‐top striations, due to upright convection originating at high levels above the polar‐front cloud band; multiple sub‐structure within the cloud head; and inertia–gravity waves in the region of the tropopause fold. The emphasis of the analysis (synthesis) is on the inter‐relationships between the various mesoscale structures. Issues raised by this study include: (i) the interaction between upright and slantwise convection, including the effects of evaporation in the dry slot; (ii) the possible roles of inertia–gravity waves and conditional symmetric instability in triggering/organizing the dry‐slot convective rain bands and the sub‐structure within the cloud head; and (iii) the relationship between the dry‐slot rain bands and the multiple structures within the cloud head. This study is limited to documenting these relationships; controlled experiments with high‐resolution mesoscale models will be required to establish cause and effect and to assess their importance. Copyright © 2005 Royal Meteorological Society.