Sunday, 10 January 2016
Hall E ( New Orleans Ernest N. Morial Convention Center)
The Ontario Winter Lake-effect Systems experiment was completed during December 2013-January 2014. This project utilized multiple in-situ and remotely-sensing instruments in order to acquire small-scale through large-scale kinematic and thermodynamic measurements of lake-effect snow bands. This poster presents an analysis using multiple sensors of a Long-Lake Axis Parallel (LLAP) Band on 15-16 December 2013. Multiple ground-based and in-situ measurements were acquired through Intensive Observing Periods (IOPs) from the various fixed and mobile sensors. These sensors included: multiple radiosondes from weather balloon launches, weather pods and mobile mesonets from the Center for Severe Weather Research (CSWR), the Doppler On Wheels (DOW) radars, including DOW6, DOW7, and DOW8, the University of Wyoming King Air (UWKA) airplane, and the University of Alabama in Huntsville (UAH) Mobile Integrated Profiling System (MIPS). The band first formed and remained rather stationary near the MIPS before moving northward. Later, the band narrowed and gained intensity, before moving southward. This southward movement was thought to be caused by a density current and/or a shallow cold front interacting with the band. This study focuses on 0550-0630 UTC, the time around when the band came ashore and traveled over the MIPS. In order to best characterize the features of the band as it passed, the vertically pointing instruments of the MIPS have been used to gain an understanding of the vertical characteristics of the band. Additionally, Dual-Doppler analyses, using DOW6 and DOW7, were performed in order to characterize the horizontal characteristics of the band. Five different features of interest were explored through a more careful study of the band. The feature that helped push the band south was related to a density current and/or a shallow cold front that was observed in RHI's taken by DOW7 from 0500-0630 UTC. This density current and/or shallow cold front seems to have produced something like a zone of horizontal wind shear on the north side of the band, as seen in the Dual-Doppler analyses done from 0550-0630 UTC. With this possible shear zone in place, undulations in the atmospheric flow were observed by the MIPS 915 MHz Doppler Wind Profiler (915). These undulations had upward and downward vertical motion pockets of +/- 3-5 m/s multiple times close to the band passing over the MIPS. It is observed by the MIPS X-Band Profiling Radar (XPR) and the 915 that at least one, though possibly a second, misovortex passed over the MIPS. Subsequent to the possible second misovortex passing over the MIPS, there was a maximum in the vertical velocity of about +10-12 m/s observed by the XPR, for which an explanation has yet to be deduced.
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