Start
April 10, 2019 - 3:00 pm
End
April 10, 2019 - 4:30 pm
Categories
Weather and Climate SystemsQuantifying Precipitation Efficiency and the Drivers of Excessive Precipitation in Post-Landfall Hurricane Harvey
Weather and Climate Systems
Noah Brauer
April 10, 2019
3:00pm/ NWC 5600
Abstract: Hurricane Harvey produced widespread rainfall amounts over 100 cm to portions of Southeast Texas, including Houston from 26-31 August 2017. The highly efficient and prolonged warm rain processes associated with Harvey are hypothesized to play a key component in the catastrophic flooding that occurred throughout the region. Precipitation efficiency (PE) is widely referred to in previous literature when discussing excessive precipitation events that lead to catastrophic flash flooding, but has yet to be explored or quantified in tropical cyclones. With the introduction of dual-polarization radar to the NEXRAD WSR-88D network, observed polarimetric radar variables such as the horizontal reflectivity factor (ZH), differential reflectivity (ZDR), and specific differential phase (KDP) can be used to gain insight into the precipitation processes that contribute to enhanced PE. 6-hour means of enhanced ZH, ZDR, and KDP are found to be collocated with the regions of highest PE between 27-29 August. Additionally, 3-6 km Multi Radar Multi Sensor (MRMS) rotation tracks were plotted atop 2 kilometer 1-hour means of the polarimetric radar variables, which displays an evident collocation of swaths of enhanced positive ZH, ZDR, and KDP with the radar-derived rotation. This implies that the supercells embedded in the outer rainbands of Harvey have a high PE and played a significant contribution to the excessive precipitation event that occurred over the region.