The Structure, Dynamics, and Expected Future Changes in Diablo Winds Over Central/Northern California

University Of Washington, Seattle WA

Investigators

Abstract

Devastating wildfires in California are often aided by extreme wind conditions. In Southern California these include the well-known, and well-studied, Santa Ana winds. In Central and Northern California there is another kind of downslope windstorm which has been termed the "Diablo" winds. The Diablo winds have aided numerous wildfires including the recent 2017 Wine Country fires that resulted in 44 deaths and billions of dollars of damage. Despite the grave impact of Diablo winds, there has been a relative lack of detailed research on the causes and climatology of these events. This award will allow for a detailed characterization of Diablo wind events, an assessment of weather model skill in predicting the events, and an assessment of the projected trend of Diablo wind events in future years. The main societal impact of the work will be to give operational weather forecasters more confidence in their ability to forecast these events, which may allow more preventative fire measures to take place. The lead researcher is very experienced with outreach and will continue activities to better inform the public of the relevance of scientific research. In addition, the project will help to train the next generation of scientists. This study will investigate the structure, evolution, and underlying physical mechanisms of Diablo winds, which are strong, dry offshore-directed winds occurring over central and northern California. The project will involve both analysis and modeling approaches. The range of deliverables to be expected include: 1) a comprehensive description of the Diablo wind phenomenon, including its structure, evolution, dynamics and control by the synoptic scale flow, 2) a detailed climatology of Diablo winds, including their frequency, duration, annual modulation, and long-term trends over the past 70 years, 3) an evaluation of future trends in Diablo wind frequency, structure, and amplitude based on dynamically downscaled high-resolution models, driven by GCMs, and GCMs driving statistical models of Diablo wind occurrence, and 4) an evaluation of the forecast skill of operational weather forecast model guidance now currently available, and the appraisal of deficiencies in current modeling systems with respect to the Diablo wind phenomenon. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.