Tuesday, 14 January 2020
Hall B1 (Boston Convention and Exhibition Center)
A strong mesovortex developed across north central Lake Superior on December 30th 2017 and eventually tracked southward reaching far southern Lake Michigan by the evening of December 31st. This mesovortex produced a variety of high impact weather conditions across the Great Lakes region over a 2 day period including strong wind gusts to 60 mph, waterspouts, and intense snow bands that disrupted holiday travel. This event fit the conceptual model of the Type VI snowband (Lashley and Hitchcock National Weather Association 2008) and was well captured by numerical modeling up to 2 days before the initial mesovortex formation. The success of numerical modeling allowed for an opportunity to conduct several sensitivity runs to determine the relative importance of Great Lakes surface fluxes to the evolution of the mesovortex. Three different model simulations were run utilizing the WRF-UEMS including a full physics run, a no latent heat release run, and a no sensible heat flux run. Results from this sensitivity study indicated that sensible heat fluxes played a first order role in the initial development of the mesovortex. As the mesovortex tracked across southern Lake Michigan the following day, the contribution of sensible and latent heat fluxes appeared to play comparable roles in the maintenance and longevity of the mesovortex. Results of this sensitivity study will then be compared to a historical case of strong mesovortex across Lake Huron in order to determine if any similarities exist between these two strong Great Lakes mesovortex events.
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