Wednesday, 13 January 2016
New Orleans Ernest N. Morial Convention Center
Understanding the vertical air motions within and the vertical structure of lake-effect systems is necessary to better predict the high-impact weather that often occurs within them. To develop a better understanding of these systems, airborne Doppler radar data were collected by the Wyoming Cloud Radar (WCR) aboard the University of Wyoming King Air (UWKA) in 8 long lake-axis-parallel (LLAP) lake-effect snow bands near Lake Ontario during the 2013-2014 winter season as a part of the Ontario Winter Lake-effect Systems (OWLeS) project. The 15-m resolution of the WCR enables the detection of mesoscale and smaller phenomena within these lake-effect systems, including: Cloud-top generating cells, deep convective updrafts, shallow surface-based convection, elevated convection, gravity waves, Kelvin-Helmholtz waves, and orographic uplift, most notably near the shoreline of Lake Ontario and on the windward side of both Adirondack Mountains and the Tug Hill Plateau. A series of case studies is presented. Contoured frequency by altitude diagrams (CFADs) are utilized to reveal vertical distributions of vertical radial velocity measured by the WCR and to associate the measured vertical velocities to various modes of convection within the LLAP snow bands. Furthermore, an analysis of the commonality of generating cells in LLAP snow bands, including when they occur (night or day), where they occur (over land or water), the synoptic and thermodynamic environments in which they are most common, and the archetype of convection (smaller convective cells, or single or multiple bands) will be displayed. Ancillary information from dual-polarization X-band mobile Doppler radar, ground-based vertically pointing X-band Doppler radar, rawinsondes, and microphysical, kinematic, and thermodynamic data from the UWKA is included to support these findings. This work is unique in that it presents the first statistical analysis of the distribution of vertical air motions within lake-effect systems.
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