Systemwide Events Calendar

Atmospheric Sciences Master's Defense

June 6, 2:00pm - 3:00pm
Mānoa Campus, IPRC Conference Room, POST 414

A Radar-Based Climatology of Thunderstorms in Hawaii

Mr. Robert A. Ballard
Atmospheric Sciences M.S. Candidate
Department of Atmospheric Sciences, S.O.E.S.T.
University of Hawaii at Manoa

Date: Wednesday, June 6, 2018
Time: 2:00pm
Location: IPRC Conference Room, POST 414

Abstract:
While relatively infrequent, hazards related to severe convection in Hawaiâ€˜i do occasionally occur. Our understanding of these events can be improved by using algorithm data from the Weather Surveillance Radar-1988 Doppler (WSR-88D) to help build a spatial, temporal, and intensity climatology which eliminates population density and diurnal sampling biases. Radar can also expand the climatological area by approximately 17 times over that offered by land-based reports only. Surface and upper air observations and storm reports are used to validate the radar algorithm output. Parameters and indices from sounding data at LÄ«huâ€˜e are compared to observed thunderstorms, as well as to output from the Maximum Estimated Hail Size (MEHS) and Tornado Vortex Signature (TVS) algorithms, to establish values significant for the occurrence of these events. The data show that greater instability is typically needed to support thunderstorms in Hawaiâ€˜i, approximately double that found for similar events over the continental United States. MEHS values greater than 32 mm appear to indicate a higher risk of severe hail in Hawaiâ€˜i, and these occur within radar range on average every 5.5 days per year. MEHS values likely to be associated with supercells and very large hail occur within radar range about 1.5 day per year. Most TVSs in Hawaiâ€˜i are associated with delta-V values of <30 m s-1, but values â‰¥ 45 m s-1 (known to be associated with strong tornadoes) have been observed. The results presented here should help forecasters to better evaluate the risk of these rare but important events.