Dr. Peterka elaborated on his methodology. Essentially, Dr. Peterka explained that he validated his WRF results with 2007 observed data from the Automated Surface Observing System (ASOS) located at the Ramona Airport. Dr. Peterka stated, “the largest 3-second gust measured at the Ramona Airport during [October 2007] was 55 mph. Based on the ESDU procedure used to estimate the 3-second gust from the WRF simulations, the gusts are predicted to be between 60 and 76 mph, or 9 to 38 percent higher than the actual measurements. The validation exercise is dependent on the overall match between ASOS and WRF wind speeds and directions….as well as the comparison of peak gusts. This validation supports my methodologies.” Dr. Peterka explained that he believed the RAWS and ASOS data were obtained from stations that were improperly sited. Dr. Peterka asserts that the improper siting resulted in recorded wind speeds that are too low. For this reason, Dr. Peterka discarded the 2007 RAWS and ASOS and came up with a result that is 9 to 38 percent higher. In addition to providing analyses of the wind and weather events surrounding the ignition of the 2007 Wildfires, SDG&E’s experts highlighted the utility’s involvement in developing the Santa Ana Wildfire Threat Index (SAWTI). SDG&E notes, “to develop the SAWTI, SDG&E and UCLA worked to configure the WRF model by calibrating it against actual observations of temperatures, winds, and dew points collected from SDG&E weather stations during Santa Ana wind events.” SDG&E highlights that the SAWTI allows an individual to understand the fire potential by comparing it to past and present conditions. As such, SDG&E’s experts utilized the SAWTI in testifying that the wind and weather conditions in San Diego County in 2007 had the largest fire potential since 1984. Because of this, SDG&E maintains that it had no way to
Dr. Peterka elaborated on his methodology. Essentially, Dr. Peterka explained that he validated his WRF results with 2007 observed data from the Automated Surface Observing System (ASOS) located at the Ramona Airport. Dr. Peterka stated, “the largest 3-second gust measured at the Ramona Airport during [October 2007] was 55 mph. Based on the ESDU procedure used to estimate the 3-second gust from the WRF simulations, the gusts are predicted to be between 60 and 76 mph, or 9 to 38 percent higher than the actual measurements. The validation exercise is dependent on the overall match between ASOS and WRF wind speeds and directions….as well as the comparison of peak gusts. This validation supports my methodologies.” Dr. Peterka explained that he believed the RAWS and ASOS data were obtained from stations that were improperly sited. Dr. Peterka asserts that the improper siting resulted in recorded wind speeds that are too low. For this reason, Dr. Peterka discarded the 2007 RAWS and ASOS and came up with a result that is 9 to 38 percent higher. In addition to providing analyses of the wind and weather events surrounding the ignition of the 2007 Wildfires, SDG&E’s experts highlighted the utility’s involvement in developing the Santa Ana Wildfire Threat Index (SAWTI). SDG&E notes, “to develop the SAWTI, SDG&E and UCLA worked to configure the WRF model by calibrating it against actual observations of temperatures, winds, and dew points collected from SDG&E weather stations during Santa Ana wind events.” SDG&E highlights that the SAWTI allows an individual to understand the fire potential by comparing it to past and present conditions. As such, SDG&E’s experts utilized the SAWTI in testifying that the wind and weather conditions in San Diego County in 2007 had the largest fire potential since 1984. Because of this, SDG&E maintains that it had no way to
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