Comparisons Between GOES-12 Overshooting Top Detections, WSR-88D Radar Reflectivity, and Severe Storm Reports

ABSTRACT With an objective overshooting top (OT) detection method - IR-Texture Method, using GOES-12 (Geostationary Operational Environmental Satellite-East) infrared data, a parallax corrected OT multi-year (2004-2009) dataset for the contiguous U.S. has been completed. With this dataset the frequency of OT detections in the vicinity of confirmed severe weather reports and the frequency of severe weather reports coinciding with an OT can be determined from the Storm Prediction Center Geographic Information System (SPCGIS). Furthermore, parallax corrected OTs are compared to NEXRAD (Next Generation Radar) composite reflectivity to validate whether an OT coincides with a significant precipitation maximum. In addition, NEXRAD base reflectivity is used to investigate the intensity of a storm preceding and following the detection of a characteristic OT signature in GOES-12 visible imagery.

Results from this study will show a strong relationship between OT detection and significant precipitation maximum (50<=dbz), with the strongest storm radar reflectivity occurring near the time of OT detection. The OT-severe weather relationship is strong for large hail, severe wind and tornado events, with an OT occurring more than 50% of the cases. The relatively strong overall OT-severe weather relationship suggests that OT detections can be used to increase forecaster confidence that a given storm is severe, especially in the absence of Doppler weather radar observations.