Brian Frei
Weather-Ready Nation
Mentors: Todd Hall & John Dumas
Collaborator: David Gomberg
National Weather Service Forecast Office Los Angeles/Oxnard
National Oceanic and Atmospheric Administration (NOAA)
Sundowner winds are foehn-style downslope winds that affect populated areas of coastal Santa Barbara County. As air accelerates down the lee side of the Santa Ynez range, an east-west oriented mountain range located north of Santa Barbara, it can become hot and dry due to dry-adiabatic compressional heating. Sundowner winds often produce potentially damaging wind gusts, critical fire weather conditions, and increase the growth rate and unpredictability of existing wildfires. These downslope winds have caused some of the most damaging wildfires in Santa Barbara history, creating a need for accurate forecasts. Current Sundowner wind forecasts are based primarily on pressure gradients from Santa Barbara to Santa Maria, and Santa Barbara to Bakersfield. To supplement this method and hopefully improve Sundowner forecast accuracy, this project focuses on correlating the Santa Barbara to Santa Maria and Santa Barbara to Bakersfield temperature gradients with wind speeds. A database containing meteorological variables during historical Sundowner events was updated to include data through May 2018. This was accomplished by filtering out data gathered from University of Utah’s MesoWest site to only include conditions indicative of Sundowner winds. Once this database was updated, temperature gradients were analyzed alongside pressure gradients and wind speeds and displayed through reanalysis maps to correlate cold air advection and strong Sundowner events. The goal of this project is to increase forecast accuracy of Sundowner winds, and in turn reduce the extent of their damaging effects.
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