Snowband Characteristics Associated With Lake‐Effect Misovortices During the OWLeS Project. Issue 17 (2nd September 2022)

• Record Type: Journal Article
• Authors: Steiger, Scott M.; Lynne, Matthew; Mulholland, Jake P.; Kosiba, Karen A.; Wurman, Joshua
• Is Part Of: Journal of geophysical research. Volume 127:Issue 17(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-09-02
• Subjects: Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1029/2022JD036855
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: Vortices of diameters 100 m to 10 km have been observed during lake‐effect snowstorms. Lines of misovortices (diameters = 40–4, 000 m) have recently been documented forming over Lake Ontario during long lake‐axis‐parallel (LLAP)‐type lake‐effect storms. Using National Weather Service Weather Surveillance Radar—1988 Doppler (WSR‐88D) and Doppler on Wheels radar data from the Ontario Winter Lake‐effect Systems (OWLeS) project, lines of misovortices (also referred to as "misovortex lines" in this study) were investigated for intensive observation period (IOP)7 (7 January 2014) and IOP9 (9 January 2014). Results revealed that the misovortex lines formed on the southern or northern side of the west‐to‐east‐oriented LLAP band, whichever was closest to a low‐level boundary nearest the corresponding south or north shoreline (northern part in IOP7, southern part in IOP9). Examination of these two IOPs in the context of a total of 23 OWLeS IOPs, 11 of which had predominantly LLAP band morphology, showed that, in 4 of the 11 LLAP IOPs, horizontal shear zones/reflectivity bands formed in preferred regions over Lake Ontario and nearby land areas where low‐level boundaries (e.g., land breeze fronts) have been noted to develop near shoreline irregularities. Horizontal shear zones were predominant in approximately half of the OWLeS LLAP IOPs and were associated with storms having a well‐organized, solid banded reflectivity structure. Misovortices occurred when horizontal shear zones were prevalent, supporting the idea that horizontal shearing instability was important to their formation. Plain Language Summary: Previous work has shown lake‐effect snowstorm bands that form along the long axis of Lake Ontario develop on/near preexisting low‐level boundaries (e.g., land breeze fronts). Multiple local areas of rotation (vorticity) have been observed to form within these bands, especially when using high‐resolution Doppler weather radar, and these vorticity centers are associated with heavier precipitation and gustier winds. We test the hypothesis that these small‐scale vortices (also known as "misovortices") form due to the low‐level horizontal shear associated with the aforementioned boundaries. The hypothesis that horizontal shear zones set the stage for vortex development in these storms is well‐supported, but the hypothesis that it is previously identified boundaries that lead to shear zones upon which misovortices form is not well‐supported when using data collected from over 20 storm events during the Ontario Winter Lake‐effect Systems field project. Key Points: Misovortices had preferred locations with respect to lake‐effect band centers during the Ontario Winter Lake‐effect Systems (OWLeS) project Most long lake‐axis‐parallel lake‐effect storms during the OWLeS project had embedded horizontal shear zones leading to misocyclogenesis A hypothesis relating these shear zones and their associated misovortices to previously identified low‐level boundaries was not supported