Studies from several other field campaigns ( Goodman et al. (1986) showed that the NIC method is a probable method of charge separation between −10° and −20☌. 1983) show that NIC is a more plausible charging mechanism than inductive charging theory, which is theorized to require an initial electric field stronger than the earth’s fair weather electric field ( MacGorman and Rust 1998 Rakov and Uman 2006). 1957 Takahashi 1978 Gaskell and Illingworth 1980 Jayaratne et al. Laboratory results (e.g., Reynolds et al. One of the most widely accepted thunderstorm charging theories is the noninductive graupel–ice collision mechanism, also called noninductive charging (NIC). Currently, no automated lightning forecasting algorithm is in operational use. The 2008 National Weather Service’s (NWS) 30-yr (1978–20) average of weather fatality, injury, and damage statistics indicates that lightning remains the second most frequent cause of weather-related fatalities in the United States with an average of 58 per year. Texas was ranked in the top 10 states for the numbers of lightning fatalities (third), casualties (seventh), injuries (eighth), and damage reports (ninth) yet there has been only one study ( Clements and Orville 2008) that examined lightning forecasting within the state. (2000) showed that lightning ranked second in weather-related deaths in the United States between 19 and ranked first in some years. The forecasting of cloud-to-ground (CG) lightning flashes is of great importance. In general, cells tracked for multiple scans provide higher CSIs and lead times than decreasing the range from the radar or changing the reflectivity threshold and height. Lead times greater than 10 min occurred with less stringent predictors (e.g., 30 dB Z at −10☌ or VII greater than 0.25 kg m −2 on cells within 125 km with a minimum track count of 2), but lower CSI values result. Lead times for these predictors were 10.0 and 13.4 min, respectively. The best VII predictor values were 0.42 or 0.58 kg m −2 on cells within 75 km of the radar that have been tracked for at least two consecutive scans, producing a CSI of 0.67. Results show that using 30 dB Z at the −15° or −20☌ isotherm on cells within 75 km of the radar that have been tracked for at least two consecutive scans produces the best lightning forecasts with a critical success index (CSI) of 0.68. This study objectively analyzed 67 384 unique cells and 1 028 510 lightning flashes to find the best lightning forecast criteria. Forecasts were also delineated by range and the number of times a cell was identified and tracked by the modified SCIT algorithm. Combinations of three radar reflectivity values (30, 35, and 40 dB Z) at four isothermal levels (−10°, −15°, −20°, and updraft −10☌) and a new radar-derived product, vertically integrated ice (VII), were used to optimize a radar-based lightning forecast algorithm. 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). Ten years (1997–2006) of summer (June–August) daytime (1400–0000 UTC) Weather Surveillance Radar-1988 Doppler data for Houston, Texas, were examined to determine the best radar-derived predictors of the first cloud-to-ground lightning flash from a convective cell.
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