Date of Award

2017

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Atmospheric Science

Committee Chair

Lawrence Carey

Committee Member

Kevin Knupp

Committee Member

Walter Petersen

Subject(s)

Nowcasting (Meteorology), Winds., Radar.

Abstract

The purpose of this study was to identify radar and environmental signatures that may improve lead times and statistical performances of convective wind nowcasts at Cape Canaveral, Florida. Weather tower sensors provided wind velocities associated with 32 threshold-level downbursts and 32 null downbursts. Environmental results indicate that early-morning temperature lapse rate and late-morning relative humidity profiles may be useful in convective wind nowcasting. Five dual-polarization radar signatures were identified in threshold-level downburst-producing thunderstorms: peak height of 1 dB differential reflectivity (Zdr) column, peak height of precipitation ice signature, peak reflectivity, height where Zdr increases to 3 dB during melting within a descending reflectivity core (DRC), and vertical Zdr gradient within a DRC. Mean lead times of 34.8 to 51.8 minutes resulted from analyzing precipitation ice within long-lived multicell thunderstorms, with greater lead times and higher probability of detection often yielding higher probability of false alarm and lower skill scores.

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