Estimating the fraction of winter orographic precipitation produced under conditions meeting the seeding criteria for the Wyoming Weather Modification Pilot Project

Addressing the second question motivated the work here. The seeding criteria--700-hPa temperatures ≤-8°C, 700-hPa winds between 210° and 315°, and the presence of supercooled liquid water--were applied to eight winters to determine the percent of winter precipitation that may fall under the seeding criteria. Since no observational datasets provide precipitation and all of the atmospheric variables required for this study, a regional climate model dynamical downscaling of historical data over 8 years was used.

The accuracy of the model was tested against several measurements, and the small model biases were removed. On average, ~26% of the time between 15 November and 15 April atmospheric conditions were seedable over the barriers in southeastern Wyoming. These seedable conditions were accompanied by precipitation ~12%-14% of the time, indicating that ~27%-30% of the winter precipitation resulted from seedable clouds.