Assessment of MRMS Severe Weather Algorithm Performance during 2018 Landfalling Tropical Cyclones

Supercells in the outer rainbands of tropical cyclones can produce tornadoes that are exceptionally difficult to identify, track, and warn. This is because circulations within these storms are typically fast-moving, shallow, and transient in nature. The Multi-Radar Multi-Sensor (MRMS) severe weather product suite includes several products that aid researchers and forecasters in detecting and warning all tornadic storms. These operational and research products need to be analysed in-depth, across a wide variety of storm types, to demonstrate their utility to NWS forecasters for warning and warning verification.

In this study, the U.S.-landfalling tropical cyclones of the 2018 Atlantic hurricane season are used to examine the value of MRMS severe weather products during cyclone landfall events. Products such as azimuthal shear, isothermal reflectivity, and echo tops will be evaluated in and around supercells and embedded rotating storms during landfall and extratropical transition. These products will also be applied to local vorticity enhancements observed in and near the eyewall and inner core of well-structured Hurricanes Florence and Michael. In addition to providing information about storm structure, much of the radar data shown here can be used to relate sub-storm-scale, radar-indicated features to observed damage at the ground, similar to non-tropical convective severe weather events.