Abstract
Identifying radar signatures indicative of damaging surface winds produced by convection remains a challenge for operational meteorologists, especially within environments characterized by strong low-level static stability and convection for which inflow is presumably entirely above the planetary boundary layer. Numerical model simulations suggest the most prevalent method through which elevated convection generates damaging surface winds is via “up–down” trajectories, where a near-surface stable layer is dynamically lifted and then dropped with little to no connection to momentum associated with the elevated convection itself. Recently, a number of unique convective episodes during which damaging surface winds were produced by apparently elevated convection coincident with mesoscale gravity waves were identified and cataloged for study. A novel radar signature indicative of damaging surface winds produced by elevated convection is introduced through six representative cases. One case is then explored further via a high-resolution model simulation and related to the conceptual model of up–down trajectories. Understanding the processes responsible for, and radar signature indicative of, damaging surface winds produced by gravity wave coincident convection will help operational forecasters identify and ultimately warn for a previously underappreciated phenomenon that poses a threat to lives and property.
Significance Statement
We identified unique radar and observational signatures of thunderstorms that produce damaging surface winds through a recently discovered mechanism. The radar and observational signatures can be used to issue warnings to protect lives and property in situations where damaging winds were previously unexpected. Key observational signatures include associated increases in surface pressure, sustained wind, and wind gust magnitudes, as well as little to no change or an increase in surface temperature. In addition, base radar data exhibit a divergence signature, including in regions of little or no detectable precipitation. Additional study is needed to answer why some atmospheric environments are supportive of the unique damaging-wind-producing mechanism while others are not.
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