Mosier, Richard Matthew (2009-12). Radar-Derived Forecasts of Cloud-to-Ground Lightning Over Houston, Texas. Master's Thesis. Thesis uri icon

abstract

  • Ten years (1997 - 2006) of summer (June, July, August) daytime (14 - 00 Z) Weather Surveillance Radar - 1988 Doppler data for Houston, TX were examined to determine the best radar-derived lightning forecasting predictors. Convective cells were tracked using a modified version of the Storm Cell Identification and Tracking (SCIT) algorithm and then correlated to cloud-to-ground lightning data from the National Lightning Detection Network (NLDN). Combinations of three radar reflectivity values (30, 35, and 40 dBZ) at four isothermal levels (-10, -15, -20, and updraft -10 degrees C) and a new radar-derived product, vertically integrated ice (VII), were used to optimize a radar-based lightning forecast algorithm. Forecasts were also delineated by range and the number of times a cell was identified and tracked by the modified SCIT algorithm. This study objectively analyzed 65,399 unique cells, and 1,028,510 to find the best lightning forecast criteria. Results show that using 30 dBZ at the -20 degrees C isotherm on cells within 75 km of the radar that have been tracked for at least 2 consecutive scan produces the best forecasts with a critical success index (CSI) of 0.71. The best VII predictor was 0.734 kg m-2 on cells within 75 km of the radar that have been tracked for at least 2 consecutive scans producing a CSI of 0.68. Results of this study further suggest that combining the radar reflectivity and VII methods can result in a more accurate lightning forecast than either method alone.
  • Ten years (1997 - 2006) of summer (June, July, August) daytime (14 - 00 Z)

    Weather Surveillance Radar - 1988 Doppler data for Houston, TX were examined to

    determine the best radar-derived lightning forecasting predictors. Convective cells were

    tracked using a modified version of the Storm Cell Identification and Tracking (SCIT)

    algorithm and then correlated to cloud-to-ground lightning data from the National

    Lightning Detection Network (NLDN).

    Combinations of three radar reflectivity values (30, 35, and 40 dBZ) at four

    isothermal levels (-10, -15, -20, and updraft -10 degrees C) and a new radar-derived product,

    vertically integrated ice (VII), were used to optimize a radar-based lightning forecast

    algorithm. Forecasts were also delineated by range and the number of times a cell was

    identified and tracked by the modified SCIT algorithm. This study objectively analyzed

    65,399 unique cells, and 1,028,510 to find the best lightning forecast criteria.

    Results show that using 30 dBZ at the -20 degrees C isotherm on cells within 75 km of

    the radar that have been tracked for at least 2 consecutive scan produces the best forecasts

    with a critical success index (CSI) of 0.71. The best VII predictor was 0.734 kg m-2 on

    cells within 75 km of the radar that have been tracked for at least 2 consecutive scans producing a CSI of 0.68. Results of this study further suggest that combining the radar

    reflectivity and VII methods can result in a more accurate lightning forecast than either

    method alone.

publication date

  • December 2009