Downdraft Convective Available Potential Energy and Downdraft Convective Inhibition with Warning Decision Making in central California

The warning forecaster in the central valley of California faces many challenges, because of the dearth of observed severe weather reports and severe thunderstorms. Strikingly, two of the limiting factors of strong and severe convective wind gusts in California, moisture and topography, are also the same two factors that contribute to the amount of Downdraft Convective Available Potential Energy (DCAPE) and Downdraft Convective Inhibition (DCIN) available in the troposphere. Thunderstorm downdrafts can occur when DCAPE is greater than DCIN, and a subjective relationship has been observed by warning forecasters at the National Weather Service in Hanford. Therefore, the focus of this study was to analyze severe wind gusts over a 10 year period, (2012-2022), to determine an objective value of DCAPE / DCIN, which can be used to aid warning forecasters. Values of DCAPE and DCIN were obtained from archived Storm Prediction Center mesoanalysis data and modified upper air soundings. A caveat of our results is that neither DCAPE or DCIN can account for the amount of dry air entrainment that occurs within thunderstorms. The results focus not only on favorable ratios of DCAPE and DCIN, but also how the time of year and topography can alter these favorable ratios for severe convective wind gusts.. Analysis over the period of study found that DCAPE and DCIN, when used with other severe weather indices, can be useful to increase lead time of severe thunderstorm warnings, during meteorological spring and fall, at elevations of 2,000 feet above sea level or greater. Our presentations will also focus on particular synoptic features that alter the ratio by which severe thunderstorm warnings are recommended.